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RFC2244 - ACAP -- Application Configuration Access Protocol

王朝other·作者佚名  2008-05-31
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Network Working Group C. Newman

Request for Comments: 2244 Innosoft

Category: Standards Track J. G. Myers

Netscape

November 1997

ACAP -- Application Configuration Access Protocol

Status of this Memo

This document specifies an Internet standards track protocol for the

Internet community, and requests discussion and suggestions for

improvements. Please refer to the current edition of the "Internet

Official Protocol Standards" (STD 1) for the standardization state

and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society 1997. All Rights Reserved.

Abstract

The Application Configuration Access Protocol (ACAP) is designed to

support remote storage and access of program option, configuration

and preference information. The data store model is designed to

allow a client relatively simple access to interesting data, to allow

new information to be easily added without server re-configuration,

and to promote the use of both standardized data and custom or

proprietary data. Key features include "inheritance" which can be

used to manage default values for configuration settings and access

control lists which allow interesting personal information to be

shared and group information to be restricted.

Table of Contents

Status of this Memo ............................................... i

Copyright Notice .................................................. i

Abstract .......................................................... i

ACAP Protocol Specification ....................................... 1

1. IntrodUCtion ............................................. 1

1.1. Conventions Used in this Document ........................ 1

1.2. ACAP Data Model .......................................... 1

1.3. ACAP Design Goals ........................................ 1

1.4. Validation ............................................... 2

1.5. Definitions .............................................. 2

1.6. ACAP Command Overview .................................... 4

2. Protocol Framework ....................................... 4

2.1. Link Level ............................................... 4

2.2. Commands and Responses ................................... 4

2.2.1. Client Protocol Sender and Server Protocol Receiver ...... 4

2.2.2. Server Protocol Sender and Client Protocol Receiver ...... 5

2.3. Server States ............................................ 6

2.3.1. Non-Authenticated State .................................. 6

2.3.2. Authenticated State ...................................... 6

2.3.3. Logout State ............................................. 6

2.4. Operational Considerations ............................... 7

2.4.1. Untagged Status Updates .................................. 7

2.4.2. Response when No Command in Progress ..................... 7

2.4.3. Auto-logout Timer ........................................ 7

2.4.4. Multiple Commands in Progress ............................ 8

2.5. Server Command Continuation Request ...................... 8

2.6. Data Formats ............................................. 8

2.6.1. Atom ..................................................... 9

2.6.2. Number ................................................... 9

2.6.3. String ................................................... 9

2.6.3.1. 8-bit and Binary Strings ................................. 10

2.6.4. Parenthesized List ....................................... 10

2.6.5. NIL ...................................................... 10

3. Protocol Elements ........................................ 10

3.1. Entries and Attributes ................................... 10

3.1.1. Predefined Attributes .................................... 11

3.1.2. Attribute Metadata ....................................... 12

3.2. ACAP URL scheme .......................................... 13

3.2.1. ACAP URL User Name and Authentication Mechanism .......... 13

3.2.2. Relative ACAP URLs ....................................... 14

3.3. Contexts ................................................. 14

3.4. Comparators .............................................. 15

3.5. Access Control Lists (ACLs) .............................. 17

3.6. Server Response Codes .................................... 18

4. Namespace Conventions .................................... 21

4.1. Dataset Namespace ........................................ 21

4.2. Attribute Namespace ...................................... 21

4.3. Formal Syntax for Dataset and Attribute Namespace ........ 22

5. Dataset Management ....................................... 23

5.1. Dataset Inheritance ...................................... 23

5.2. Dataset Attributes ....................................... 24

5.3. Dataset Creation ......................................... 25

5.4. Dataset Class Capabilities ............................... 25

5.5. Dataset Quotas ........................................... 26

6. Command and Response Specifications ...................... 26

6.1. Initial Connection ....................................... 26

6.1.1. ACAP Untagged Response ................................... 26

6.2. Any State ................................................ 27

6.2.1. NOOP Command ............................................. 27

6.2.2. LANG Command ............................................. 28

6.2.3. LANG Intermediate Response ............................... 28

6.2.4. LOGOUT Command ........................................... 29

6.2.5. OK Response .............................................. 29

6.2.6. NO Response .............................................. 29

6.2.7. BAD Response ............................................. 30

6.2.8. BYE Untagged Response .................................... 30

6.2.9. ALERT Untagged Response .................................. 31

6.3. Non-Authenticated State .................................. 31

6.3.1. AUTHENTICATE Command ..................................... 31

6.4. Searching ................................................ 33

6.4.1. SEARCH Command ........................................... 33

6.4.2. ENTRY Intermediate Response .............................. 37

6.4.3. MODTIME Intermediate Response ............................ 38

6.4.4. REFER Intermediate Response .............................. 38

6.4.5. Search Examples .......................................... 38

6.5. Contexts ................................................. 39

6.5.1. FREECONTEXT Command ...................................... 39

6.5.2. UPDATECONTEXT Command .................................... 40

6.5.3. ADDTO Untagged Response .................................. 40

6.5.4. REMOVEFROM Untagged Response ............................. 41

6.5.5. CHANGE Untagged Response ................................. 41

6.5.6. MODTIME Untagged Response ................................ 42

6.6. Dataset modification ..................................... 42

6.6.1. STORE Command ............................................ 42

6.6.2. DELETEDSINCE Command ..................................... 45

6.6.3. DELETED Intermediate Response ............................ 45

6.7. Access Control List Commands ............................. 45

6.7.1. SETACL Command ........................................... 46

6.7.2. DELETEACL Command ........................................ 46

6.7.3. MYRIGHTS Command ......................................... 47

6.7.4. MYRIGHTS Intermediate Response ........................... 47

6.7.5. LISTRIGHTS Command ....................................... 47

6.7.6. LISTRIGHTS Intermediate Response ......................... 48

6.8. Quotas ................................................... 48

6.8.1. GETQUOTA Command ......................................... 48

6.8.3. QUOTA Untagged Response .................................. 49

6.9. Extensions ............................................... 49

7. Registration Procedures .................................. 49

7.1. ACAP Capabilities ........................................ 50

7.2. ACAP Response Codes ...................................... 50

7.3. Dataset Classes .......................................... 51

7.4. Vendor SuBTree ........................................... 51

8. Formal Syntax ............................................ 52

9. Multi-lingual Considerations ............................. 61

10. Security Considerations .................................. 62

11. Acknowledgments .......................................... 63

12. Authors' Addresses ....................................... 63

Appendices ........................................................ 64

A. References ............................................... 64

B. ACAP KeyWord Index ....................................... 66

C. Full Copyright Statement

ACAP Protocol Specification

1. Introduction

1.1. Conventions Used in this Document

In examples, "C:" and "S:" indicate lines sent by the client and

server respectively. If such lines are wrapped without a new "C:" or

"S:" label, then the wrapping is for editorial clarity and is not

part of the command.

The key words "REQUIRED", "MUST", "MUST NOT", "SHOULD", "SHOULD NOT",

and "MAY" in this document are to be interpreted as described in "Key

words for use in RFCs to Indicate Requirement Levels" [KEYWORDS].

1.2. ACAP Data Model

An ACAP server eXPorts a hierarchical tree of entries. Each level of

the tree is called a dataset, and each dataset is made up of a list

of entries. Each entry has a unique name and may contain any number

of named attributes. Each attribute within an entry may be single

valued or multi-valued and may have associated metadata to assist

access and interpretation of the value.

The rules with which a client interprets the data within a portion of

ACAP's tree of entries are called a dataset class.

1.3. ACAP Design Goals

ACAP's primary purpose is to allow users access to their

configuration data from multiple network-connected computers. Users

can then sit down in front of any network-connected computer, run any

ACAP-enabled application and have access to their own configuration

data. Because it is hoped that many applications will become ACAP-

enabled, client simplicity was preferred to server or protocol

simplicity whenever reasonable.

ACAP is designed to be easily manageable. For this reason, it

includes "inheritance" which allows one dataset to inherit default

attributes from another dataset. In addition, access control lists

are included to permit delegation of management and quotas are

included to control storage. Finally, an ACAP server which is

conformant to this base specification should be able to support most

dataset classes defined in the future without requiring a server

reconfiguration or upgrade.

ACAP is designed to operate well with a client that only has

intermittent access to an ACAP server. For this reason, each entry

has a server maintained modification time so that the client may

detect changes. In addition, the client may ask the server for a

list of entries which have been removed since it last accessed the

server.

ACAP presumes that a dataset may be potentially large and/or the

client's network connection may be slow, and thus offers server

sorting, selective fetching and change notification for entries

within a dataset.

As required for most Internet protocols, security, scalability and

internationalization were important design goals.

Given these design goals, an attempt was made to keep ACAP as simple

as possible. It is a traditional Internet text based protocol which

massively simplifies protocol debugging. It was designed based on

the successful IMAP [IMAP4] protocol framework, with a few

refinements.

1.4. Validation

By default, any value may be stored in any attribute for which the

user has appropriate permission and quota. This rule is necessary to

allow the addition of new simple dataset classes without

reconfiguring or upgrading the server.

In some cases, such as when the value has special meaning to the

server, it is useful to have the server enforce validation by

returning the INVALID response code to a STORE command. These cases

MUST be explicitly identified in the dataset class specification

which SHOULD include specific fixed rules for validation. Since a

given ACAP server may be unaware of any particular dataset class

specification, clients MUST NOT depend on the presence of enforced

validation on the server.

1.5. Definitions

access control list (ACL)

A set of identifier, rights pairs associated with an object. An

ACL is used to determine which operations a user is permitted to

perform on that object. See section 3.5.

attribute

A named value within an entry. See section 3.1.

comparator

A named function which can be used to perform one or more of

three comparison operations: ordering, equality and substring

matching. See section 3.4.

context

An ordered subset of entries in a dataset, created by a SEARCH

command with a MAKECONTEXT modifier. See section 3.3.

dataset

One level of hierarchy in ACAP's tree of entries.

dataset class specification

The rules which allow a client to interpret the data within a

portion of ACAP's tree of entries.

entry

A set of attributes with a unique entry name. See section 3.1.

metadata

Information describing an attribute, its value and any access

controls associated with that attribute. See section 3.1.2.

NIL This represents the non-existence of a particular data item.

NUL A control character encoded as 0 in US-ASCII [US-ASCII].

octet

An 8-bit value. On most modern computer systems, an octet is

one byte.

SASL Simple Authentication and Security Layer [SASL].

UTC Universal Coordinated Time as maintained by the Bureau

International des Poids et Mesures (BIPM).

UTF-8

An 8-bit transformation format of the Universal Character Set

[UTF8]. Note that an incompatible change was made to the coded

character set referenced by [UTF8], so for the purpose of this

document, UTF-8 refers to the UTF-8 encoding as defined by

version 2.0 of Unicode [UNICODE-2], or ISO 10646 [ISO-10646]

including amendments one through seven.

1.6. ACAP Command Overview

The AUTHENTICATE, NOOP, LANG and LOGOUT commands provide basic

protocol services. The SEARCH command is used to select, sort, fetch

and monitor changes to attribute values and metadata. The

UPDATECONTEXT and FREECONTEXT commands are also used to assist in

monitoring changes in attribute values and metadata. The STORE

command is used to add, modify and delete entries and attributes.

The DELETEDSINCE command is used to assist a client in

re-synchronizing a cache with the server. The GETQUOTA, SETACL,

DELETEACL, LISTRIGHTS and MYRIGHTS commands are used to examine

storage quotas and examine or modify access permissions.

2. Protocol Framework

2.1. Link Level

The ACAP protocol assumes a reliable data stream such as provided by

TCP. When TCP is used, an ACAP server listens on port 674.

2.2. Commands and Responses

An ACAP session consists of the establishment of a client/server

connection, an initial greeting from the server, and client/server

interactions. These client/server interactions consist of a client

command, server data, and a server completion result.

ACAP is a text-based line-oriented protocol. In general,

interactions transmitted by clients and servers are in the form of

lines; that is, sequences of characters that end with a CRLF. The

protocol receiver of an ACAP client or server is either reading a

line, or is reading a sequence of octets with a known count (a

literal) followed by a line. Both clients and servers must be

capable of handling lines of arbitrary length.

2.2.1. Client Protocol Sender and Server Protocol Receiver

The client command begins an operation. Each client command is

prefixed with a identifier (an alphanumeric string of no more than 32

characters, e.g., A0001, A0002, etc.) called a "tag". A different

tag SHOULD be generated by the client for each command.

There are two cases in which a line from the client does not

represent a complete command. In one case, a command argument is

quoted with an octet count (see the description of literal in section

2.6.3); in the other case, the command arguments require server

feedback (see the AUTHENTICATE command). In some of these cases, the

server sends a command continuation request if it is ready for the

next part of the command. This response is prefixed with the token

"+".

Note: If, instead, the server detected an error in a

command, it sends a BAD completion response with tag

matching the command (as described below) to reject the

command and prevent the client from sending any more of the

command.

It is also possible for the server to send a completion or

intermediate response for some other command (if multiple

commands are in progress), or untagged data. In either

case, the command continuation request is still pending;

the client takes the appropriate action for the response,

and reads another response from the server.

The ACAP server reads a command line from the client, parses the

command and its arguments, and transmits server data and a server

command completion result.

2.2.2. Server Protocol Sender and Client Protocol Receiver

Data transmitted by the server to the client come in four forms:

command continuation requests, command completion results,

intermediate responses, and untagged responses.

A command continuation request is prefixed with the token "+".

A command completion result indicates the success or failure of the

operation. It is tagged with the same tag as the client command

which began the operation. Thus, if more than one command is in

progress, the tag in a server completion response identifies the

command to which the response applies. There are three possible

server completion responses: OK (indicating success), NO (indicating

failure), or BAD (indicating protocol error such as unrecognized

command or command syntax error).

An intermediate response returns data which can only be interpreted

within the context of a command in progress. It is tagged with the

same tag as the client command which began the operation. Thus, if

more than one command is in progress, the tag in an intermediate

response identifies the command to which the response applies. A

tagged response other than "OK", "NO", or "BAD" is an intermediate

response.

An untagged response returns data or status messages which may be

interpreted outside the context of a command in progress. It is

prefixed with the token "*". Untagged data may be sent as a result

of a client command, or may be sent unilaterally by the server.

There is no syntactic difference between untagged data that resulted

from a specific command and untagged data that were sent

unilaterally.

The protocol receiver of an ACAP client reads a response line from

the server. It then takes action on the response based upon the

first token of the response, which may be a tag, a "*", or a "+" as

described above.

A client MUST be prepared to accept any server response at all times.

This includes untagged data that it may not have requested.

This topic is discussed in greater detail in the Server Responses

section.

2.3. Server States

An ACAP server is in one of three states. Most commands are valid in

only certain states. It is a protocol error for the client to

attempt a command while the server is in an inappropriate state for

that command. In this case, a server will respond with a BAD command

completion result.

2.3.1. Non-Authenticated State

In non-authenticated state, the user must supply authentication

credentials before most commands will be permitted. This state is

entered when a connection starts.

2.3.2. Authenticated State

In authenticated state, the user is authenticated and most commands

will be permitted. This state is entered when acceptable

authentication credentials have been provided.

2.3.3. Logout State

In logout state, the session is being terminated, and the server will

close the connection. This state can be entered as a result of a

client request or by unilateral server decision.

+--------------------------------------+

initial connection and server greeting

+--------------------------------------+

(1) (2)

VV

+-----------------+

non-authenticated

+-----------------+

(4) (3)

VV

+----------------+

authenticated

+----------------+

(4)

VV VV VV

+--------------------------------------+

logout and close connection

+--------------------------------------+

(1) connection (ACAP greeting)

(2) rejected connection (BYE greeting)

(3) successful AUTHENTICATE command

(4) LOGOUT command, server shutdown, or connection closed

2.4. Operational Considerations

2.4.1. Untagged Status Updates

At any time, a server can send data that the client did not request.

2.4.2. Response when No Command in Progress

Server implementations are permitted to send an untagged response

while there is no command in progress. Server implementations that

send such responses MUST deal with flow control considerations.

Specifically, they must either (1) verify that the size of the data

does not exceed the underlying transport's available window size, or

(2) use non-blocking writes.

2.4.3. Auto-logout Timer

If a server has an inactivity auto-logout timer, that timer MUST be

of at least 30 minutes duration. The receipt of ANY command from the

client during that interval MUST suffice to reset the auto-logout

timer.

2.4.4. Multiple Commands in Progress

The client is not required to wait for the completion result of a

command before sending another command, subject to flow control

constraints on the underlying data stream. Similarly, a server is

not required to process a command to completion before beginning

processing of the next command, unless an ambiguity would result

because of a command that would affect the results of other commands.

If there is such an ambiguity, the server executes commands to

completion in the order given by the client.

2.5. Server Command Continuation Request

The command continuation request is indicated by a "+" token instead

of a tag. This indicates that the server is ready to accept the

continuation of a command from the client.

This response is used in the AUTHENTICATE command to transmit server

data to the client, and request additional client data. This

response is also used if an argument to any command is a

synchronizing literal (see section 2.6.3).

The client is not permitted to send the octets of a synchronizing

literal unless the server indicates that it expects it. This permits

the server to process commands and reject errors on a line-by-line

basis, assuming it checks for non-synchronizing literals at the end

of each line. The remainder of the command, including the CRLF that

terminates a command, follows the octets of the literal. If there

are any additional command arguments the literal octets are followed

by a space and those arguments.

Example: C: A099 FREECONTEXT {10}

S: + "Ready for additional command text"

C: FRED

C: FOOB

S: A099 OK "FREECONTEXT completed"

C: A044 BLURDYBLOOP {102856}

S: A044 BAD "No such command as 'BLURDYBLOOP'"

2.6. Data Formats

ACAP uses textual commands and responses. Data in ACAP can be in one

of five forms: atom, number, string, parenthesized list or NIL.

2.6.1. Atom

An atom consists of one to 1024 non-special characters. It must

begin with a letter. Atoms are used for protocol keywords.

2.6.2. Number

A number consists of one or more digit characters, and represents a

numeric value. Numbers are restricted to the range of an unsigned

32-bit integer: 0 < number < 4,294,967,296.

2.6.3. String

A string is in one of two forms: literal and quoted string. The

literal form is the general form of string. The quoted string form

is an alternative that avoids the overhead of processing a literal at

the cost of restrictions of what may be in a quoted string.

A literal is a sequence of zero or more octets (including CR and LF),

prefix-quoted with an octet count in the form of an open brace ("{"),

the number of octets, close brace ("}"), and CRLF. In the case of

literals transmitted from server to client, the CRLF is immediately

followed by the octet data.

There are two forms of literals transmitted from client to server.

The form where the open brace ("{") and number of octets is

immediately followed by a close brace ("}") and CRLF is called a

synchronizing literal. When sending a synchronizing literal, the

client must wait to receive a command continuation request before

sending the octet data (and the remainder of the command). The other

form of literal, the non-synchronizing literal, is used to transmit a

string from client to server without waiting for a command

continuation request. The non-synchronizing literal differs from the

synchronizing literal by having a plus ("+") between the number of

octets and the close brace ("}") and by having the octet data

immediately following the CRLF.

A quoted string is a sequence of zero to 1024 octets excluding NUL,

CR and LF, with double quote (<">) characters at each end.

The empty string is represented as "" (a quoted string with zero

characters between double quotes), as {0} followed by CRLF (a

synchronizing literal with an octet count of 0), or as {0+} followed

by a CRLF (a non-synchronizing literal with an octet count of 0).

Note: Even if the octet count is 0, a client transmitting a

synchronizing literal must wait to receive a command

continuation request.

2.6.3.1. 8-bit and Binary Strings

Most strings in ACAP are restricted to UTF-8 characters and may not

contain NUL octets. Attribute values MAY contain any octets

including NUL.

2.6.4. Parenthesized List

Data structures are represented as a "parenthesized list"; a sequence

of data items, delimited by space, and bounded at each end by

parentheses. A parenthesized list can contain other parenthesized

lists, using multiple levels of parentheses to indicate nesting.

The empty list is represented as () -- a parenthesized list with no

members.

2.6.5. NIL

The special atom "NIL" represents the non-existence of a particular

data item that is represented as a string or parenthesized list, as

distinct from the empty string "" or the empty parenthesized list ().

3. Protocol Elements

This section defines data formats and other protocol elements used

throughout the ACAP protocol.

3.1. Entries and Attributes

Within a dataset, each entry name is made up of zero or more UTF-8

characters other than slash ("/"). A slash separated list of

entries, one at each level of the hierarchy, forms the full path to

an entry.

Each entry is made up of a set of attributes. Each attribute has a

hierarchical name in UTF-8, with each component of the name separated

by a period (".").

The value of an attribute is either single or multi-valued. A single

value is NIL (has no value), or a string of zero or more octets. A

multi-value is a list of zero or more strings, each of zero or more

octets.

Attribute names are not permitted to contain asterisk ("*") or

percent ("%") and MUST be valid UTF-8 strings which do not contain

NUL. Invalid attribute names result in a BAD response. Entry names

are not permitted to begin with "." or contain slash ("/") and MUST

be valid UTF-8 strings which do not contain NUL. Invalid entry names

in the entry field of a command result in a BAD response.

Use of non-visible UTF-8 characters in attribute and entry names is

discouraged.

3.1.1. Predefined Attributes

Attribute names which do not contain a dot (".") are reserved for

standardized attributes which have meaning in any dataset. The

following attributes are defined by the ACAP protocol.

entry

Contains the name of the entry. MUST be single valued.

Attempts to use illegal or multi-valued values for the entry

attribute are protocol errors and MUST result in a BAD

completion response. This is a special case.

modtime

Contains the date and time any read-write metadata in the entry

was last modified. This value MUST be in UTC, MUST be

automatically updated by the server.

The value consists of 14 or more US-ASCII digits. The first

four indicate the year, the next two indicate the month, the

next two indicate the day of month, the next two indicate the

hour (0 - 23), the next two indicate the minute, and the next

two indicate the second. Any further digits indicate fractions

of a second.

The time, particularly fractions of a second, need not be

accurate. It is REQUIRED, however, that any two entries in a

dataset changed by successive modifications have strictly

ascending modtime values. In addition, each STORE command

within a dataset (including simultaneous stores from different

connections) MUST use different modtime values.

This attribute has enforced validation, so any attempt to STORE

a value in this attribute MAY result in a NO response with an

INVALID response code.

subdataset

If this attribute is set, it indicates the existence of a sub-

dataset of this entry.

The value consists of a list of relative ACAP URLs (see section

3.2) which may be used to locate the sub-dataset. The base URL

is the full path to the entry followed by a slash ("/"). The

value "." indicates a subdataset is located directly under this

one. Multiple values indicate replicated copies of the

subdataset.

For example, if the dataset "/folder/site/" has an entry

"public-folder" with a subdataset attribute of ".", then there

exists a dataset "/folder/site/public-folder/". If the value of

the subdataset attribute was instead

"//other.acap.domain//folder/site/public-folder/", that would

indicate the dataset is actually located on a different ACAP

server.

A dataset can be created by storing a "subdataset" attribute

including ".", and a sub-hierarchy of datasets is deleted by

storing a NIL value to the "subdataset" attribute on the entry

in the parent dataset.

This attribute has enforced syntax validation. Specifically, if

an attempt is made to STORE a non-list value (other than NIL),

an empty list, or one of the values does not follow the URL

syntax rules [BASIC-URL, REL-URL], then this will result in a NO

response with an INVALID response code.

3.1.2. Attribute Metadata

Each attribute is made up of metadata items which describe that

attribute, its value and any associated access controls. Metadata

items may be either read-only, in which case the client is never

permitted to modify the item, or read-write, in which case the client

may modify the item if the access control list (ACL) permits.

The following metadata items are defined in this specification:

acl The access control list for the attribute, if one exists. If

the attribute does not have an ACL, NIL is returned.

Read-write. See section 3.5 for the contents of an ACL.

attribute

The attribute name. Read-only.

myrights

The set of rights that the client has to the attribute.

Read-only. See section 3.5 for the possible rights.

size This is the length of the value. In the case of a

multi-value, this is a list of lengths for each of the values.

Read-only.

value The value. For a multi-value, this is a list of single

values. Read-write.

Additional items of metadata may be defined in extensions to this

protocol. Servers MUST respond to unrecognized metadata by returning

a BAD command completion result.

3.2. ACAP URL scheme

ACAP URLs are used within the ACAP protocol for the "subdataset"

attribute, referrals and inheritance. They provide a convenient

syntax for referring to other ACAP datasets. The ACAP URL follows

the common Internet scheme syntax as defined in [BASIC-URL] except

that plaintext passwords are not permitted. If :<port> is omitted,

the port defaults to 674.

An ACAP URL has the following general form:

url-acap = "acap://" url-server "/" url-enc-entry [url-filter]

[url-extension]

The <url-server> element includes the hostname, and optional user

name, authentication mechanism and port number. The <url-enc-entry>

element contains the name of an entry path encoded according to the

rules in [BASIC-URL].

The <url-filter> element is an optional list of interesting attribute

names. If omitted, the URL refers to all attributes of the named

entry. The <url-extension> element is reserved for extensions to

this URL scheme.

Note that unsafe or reserved characters such as " " or "?" MUST be

hex encoded as described in the URL specification [BASIC-URL]. Hex

encoded octets are interpreted according to UTF-8 [UTF8].

3.2.1. ACAP URL User Name and Authentication Mechanism

A user name and/or authentication mechanism may be supplied. They

are used in the "AUTHENTICATE" command after making the connection to

the ACAP server. If no user name or authentication mechanism is

supplied, then the SASL ANONYMOUS [SASL-ANON] mechanism is used by

default. If an authentication mechanism is supplied without a user

name, then one SHOULD be obtained from the specified mechanism or

requested from the user as appropriate. If a user name is supplied

without an authentication mechanism then ";AUTH=*" is assumed.

The ";AUTH=" authentication parameter is interpreted as described in

the IMAP URL Scheme [IMAP-URL].

Note that if unsafe or reserved characters such as " " or ";" are

present in the user name or authentication mechanism, they MUST be

encoded as described in the URL specification [BASIC-URL].

3.2.2. Relative ACAP URLs

Because ACAP uses "/" as the hierarchy separator for dataset paths,

it works well with the relative URL rules defined in the relative URL

specification [REL-URL].

The <aauth> grammar element is considered part of the user name for

purposes of resolving relative ACAP URLs.

The base URL for a relative URL stored in an attribute's value is

formed by taking the path to the dataset containing that attribute,

appending a "/" followed by the entry name of the entry containing

that attribute followed by "/".

3.3. Contexts

A context is subset of entries in a dataset or datasets, created by a

SEARCH command with a MAKECONTEXT modifier. Context names are

client-generated strings and must not start with the slash ('/')

character.

When a client creates a context, it may request automatic

notification of changes. A client may also request enumeration of

entries within a context. Enumeration simplifies the implementation

of a "virtual scrollbar" by the client.

A context exists only within the ACAP session in which it was

created. When the connection is closed, all contexts associated with

that connection are automatically discarded. A server is required to

support at least 100 active contexts within a session. If the server

supports a larger limit it must advertise it in a CONTEXTLIMIT

capability.

3.4. Comparators

A comparator is a named function which takes two input values and can

be used to perform one or more of four comparison operations:

ordering, equality, prefix and substring matching.

The ordering operation is used both for the SORT search modifier and

the COMPARE and COMPARESTRICT search keys. Ordering comparators can

determine the ordinal precedence of any two values. When used for

ordering, a comparator's name can be prefixed with "+" or "-" to

indicate that the ordering should be normal order or reversed order

respectively. If no prefix is included, "+" is assumed.

For the purpose of ordering, a comparator may designate certain

values as having an undefined ordinal precedence. Such values always

collate with equal value after all other values regardless of whether

normal or reversed ordering is used. Unless the comparator

definition specifies otherwise, multi-values and NIL values have an

undefined ordinal precedence.

The equality operation is used for the EQUAL search modifier, and

simply determines if the two values are considered equal under the

comparator function. When comparing a single value to a multi-value,

the two are considered equal if any one of the multiple values is

equal to the single value.

The prefix match operation is used for the PREFIX search modifier,

and simply determines if the search value is a prefix of the item

being searched. In the case of prefix search on a multi-value, the

match is successful if the value is a prefix of any one of the

multiple values.

The substring match operation is used for the SUBSTRING search

modifier, and simply determines if search value is a substring of the

item being searched. In the case of substring search on a multi-

value, the match is successful if the value is a substring of any one

of the multiple values.

Rules for naming and registering comparators will be defined in a

future specification. Servers MUST respond to unknown or improperly

used comparators with a BAD command completion result.

The following comparators are defined by this standard and MUST be

implemented:

i;octet

Operations: Ordering, Equality, Prefix match, Substring match

For collation, the i;octet comparator interprets the value of

an attribute as a series of unsigned octets with ordinal

values from 0 to 255. When ordering two strings, each octet

pair is compared in sequence until the octets are unequal or

the end of the string is reached. When collating two strings

where the shorter is a prefix of the longer, the shorter

string is interpreted as having a smaller ordinal value. The

"i;octet" or "+i;octet" forms collate smaller ordinal values

earlier, and the "-i;octet" form collates larger ordinal

values earlier.

For the equality function, two strings are equal if they are

the same length and contain the same octets in the same

order. NIL is equal only to itself.

For non-binary, non-nil single values, i;octet ordering is

equivalent to the ANSI C [ISO-C] strcmp() function applied to

C string representations of the values. For non-binary,

non-nil single values, i;octet substring match is equivalent

to the ANSI C strstr() function applied to the C string

representations of the values.

i;ascii-casemap

Operations: Ordering, Equality, Prefix match, Substring match

The i;ascii-casemap comparator first applies a mapping to the

attribute values which translates all US-ASCII letters to

uppercase (octet values 0x61 to 0x7A are translated to octet

values 0x41 to 0x5A respectively), then applies the i;octet

comparator as described above. With this function the values

"hello" and "HELLO" have the same ordinal value and are

considered equal.

i;ascii-numeric

Operations: Ordering, Equality

The i;ascii-numeric comparator interprets strings as decimal

positive integers represented as US-ASCII digits. All values

which do not begin with a US-ASCII digit are considered equal

with an ordinal value higher than all non-NIL single-valued

attributes. Otherwise, all US-ASCII digits (octet values

0x30 to 0x39) are interpreted starting from the beginning of

the string to the first non-digit or the end of the string.

3.5. Access Control Lists (ACLs)

An access control list is a set of identifier, rights pairs used to

restrict access to a given dataset, attribute or attribute within an

entry. An ACL is represented by a multi-value with each value

containing an identifier followed by a tab character followed by the

rights. The syntax is defined by the "acl" rule in the formal syntax

in section 8.

Identifier is a UTF-8 string. The identifier "anyone" is reserved to

refer to the universal identity (all authentications, including

anonymous). All user name strings accepted by the AUTHENTICATE

command to authenticate to the ACAP server are reserved as

identifiers for the corresponding user. Identifiers starting with a

slash ("/") character are reserved for authorization groups which

will be defined in a future specification. Identifiers MAY be

prefixed with a dash ("-") to indicate a revocation of rights. All

other identifiers have implementation-defined meanings.

Rights is a string listing a (possibly empty) set of alphanumeric

characters, each character listing a set of operations which is being

controlled. Letters are reserved for "standard" rights, listed

below. The set of standard rights may only be extended by a

standards-track or IESG approved experimental RFC. Digits are

reserved for implementation or site defined rights. The currently

defined standard rights are:

x - search (use EQUAL search key with i;octet comparator)

r - read (access with SEARCH command)

w - write (modify with STORE command)

i - insert (perform STORE on a previously NIL value)

a - administer (perform SETACL or STORE on ACL attribute/metadata)

An implementation may force rights to always or never be granted. In

particular, implementations are expected to grant implicit read and

administer rights to a user's personal dataset storage in order to

avoid denial of service problems. Rights are never tied, unlike the

IMAP ACL extension [IMAP-ACL].

It is possible for multiple identifiers in an access control list to

apply to a given user (or other authentication identity). For

example, an ACL may include rights to be granted to the identifier

matching the user, one or more implementation-defined identifiers

matching groups which include the user, and/or the identifier

"anyone". These rights are combined by taking the union of all

positive rights which apply to a given user and subtracting the union

of all negative rights which apply to that user. A client MAY avoid

this calculation by using the MYRIGHTS command and metadata items.

Each attribute of each entry of a dataset may potentially have an

ACL. If an attribute in an entry does not have an ACL, then access

is controlled by a default ACL for that attribute in the dataset, if

it exists. If there is no default ACL for that attribute in the

dataset, access is controlled by a default ACL for that dataset. The

default ACL for a dataset must exist.

In order to perform any access or manipulation on an entry in a

dataset, the client must have 'r' rights on the "entry" attribute of

the entry. Implementations should take care not to reveal via error

messages the existence of an entry for which the client does not have

'r' rights. A client does not need access to the "subdataset"

attribute of the parent dataset in order to access the contents of a

dataset.

Many of the ACL commands and responses include an "acl object"

parameter, for specifying what the ACL applies to. This is a

parenthesized list. The list contains just the dataset name when

referring to the default ACL for a dataset. The list contains a

dataset name and an attribute name when referring to the default ACL

for an attribute in a dataset. The list contains a dataset name, an

attribute name, and an entry name when referring to the ACL for an

attribute of an entry of a dataset.

3.6. Server Response Codes

An OK, NO, BAD, ALERT or BYE response from the server MAY contain a

response code to describe the event in a more detailed machine

parsable fashion. A response code consists of data inside

parentheses in the form of an atom, possibly followed by a space and

arguments. Response codes are defined when there is a specific

action that a client can take based upon the additional information.

In order to support future extension, the response code is

represented as a slash-separated hierarchy with each level of

hierarchy representing increasing detail about the error. Clients

MUST tolerate additional hierarchical response code detail which they

don't understand.

The currently defined response codes are:

AUTH-TOO-WEAK

This response code is returned on a tagged NO result from an

AUTHENTICATE command. It indicates that site security policy

forbids the use of the requested mechanism for the specified

authentication identity.

ENCRYPT-NEEDED

This response code is returned on a tagged NO result from an

AUTHENTICATE command. It indicates that site security policy

requires the use of a strong encryption mechanism for the

specified authentication identity and mechanism.

INVALID

This response code indicates that a STORE command included

data which the server implementation does not permit. It

MUST NOT be used unless the dataset class specification for

the attribute in question explicitly permits enforced server

validation. The argument is the attribute which was invalid.

MODIFIED

This response code indicates that a conditional store failed

because the modtime on the entry is later than the modtime

specified with the STORE command UNCHANGEDSINCE modifier.

The argument is the entry which had been modified.

NOEXIST

This response code indicates that a search or NOCREATE store

failed because a specified dataset did not exist. The

argument is the dataset which does not exist.

PERMISSION

A command failed due to insufficient permission based on the

access control list or implicit rights. The argument is the

acl-object which caused the permission failure.

QUOTA

A STORE or SETACL command which would have increased the size

of the dataset failed due to insufficient quota.

REFER

This response code may be returned in a tagged NO response to

any command that takes a dataset name as a parameter. It has

one or more arguments with the syntax of relative URLs. It

is a referral, indicating that the command should be retried

using one of the relative URLs.

SASL This response code can occur in the tagged OK response to a

successful AUTHENTICATE command and includes the optional

final server response data from the server as specified by

SASL [SASL].

TOOMANY

This response code may be returned in a tagged OK response to

a SEARCH command which includes the LIMIT modifier. The

argument returns the total number of matching entries.

TOOOLD

The modtime specified in the DELETEDSINCE command is too old,

so deletedsince information is no longer available.

TRANSITION-NEEDED

This response code occurs on a NO response to an AUTHENTICATE

command. It indicates that the user name is valid, but the

entry in the authentication database needs to be updated in

order to permit authentication with the specified mechanism.

This can happen if a user has an entry in a system

authentication database such as Unix /etc/passwd, but does

not have credentials suitable for use by the specified

mechanism.

TRYLATER

A command failed due to a temporary server failure. The

client MAY continue using local information and try the

command later.

TRYFREECONTEXT

This response code may be returned in a tagged NO response to

a SEARCH command which includes the MAKECONTEXT modifier. It

indicates that a new context may not be created due to the

server's limit on the number of existing contexts.

WAYTOOMANY

This response code may be returned in a tagged NO response to

a SEARCH command which includes a HARDLIMIT search modifier.

It indicates that the SEARCH would have returned more entries

than the HARDLIMIT permitted.

Additional response codes MUST be registered with IANA according

to the proceedures in section 7.2. Client implementations MUST

tolerate response codes that they do not recognize.

4. Namespace Conventions

4.1. Dataset Namespace

The dataset namespace is a slash-separated hierarchy. The first

component of the dataset namespace is a dataset class. Dataset

classes MUST have a vendor prefix (vendor.<vendor/product>) or be

specified in a standards track or IESG approved experimental RFC.

See section 7.3 for the registration template.

The second component of the dataset name is "site", "group", "host",

or "user" referring to server-wide data, administrative group data,

per-host data and per-user data respectively.

For "group", "host", and "user" areas, the third component of the

path is the group name, the fully qualified host domain name, or the

user name. A path of the form "/<dataset-class>/~/" is a convenient

abbreviation for "/<dataset-class>/user/<current-user>/".

Dataset names which begin with "/byowner/" are reserved as an

alternate view of the namespace. This provides a way to see all the

dataset classes which a particular owner uses. For example,

"/byowner/~/<dataset-class>/" is an alternate name for

"/<dataset-class>/~/". Byowner provides a way to view a list of

dataset classes owned by a given user; this is done using the dataset

"/byowner/user/<current-user>/" with the NOINHERIT SEARCH modifier.

The dataset "/" may be used to find all dataset classes visible to

the current user. A dataset of the form "/<dataset-class>/user/" may

be used to find all users which have made a dataset or entry of that

class visible to the current user.

The formal syntax for a dataset name is defined by the "dataset-name"

rule in section 4.3.

4.2. Attribute Namespace

Attribute names which do not contain a dot (".") are reserved for

standardized attributes which have meaning in any dataset. In order

to simplify client implementations, the attribute namespace is

intended to be unique across all datasets. To achieve this,

attribute names are prefixed with the dataset class name followed by

a dot ("."). Attributes which affect management of the dataset are

prefixed with "dataset.". In addition, a subtree of the "vendor."

attribute namespace may be registered with IANA according to the

rules in section 7.4. ACAP implementors are encouraged to help

define interoperable dataset classes specifications rather than using

the private attribute namespace.

Some users or sites may wish to add their own private attributes to

certain dataset classes. In order to enable this, the "user.<user-

name>." and "site." subtrees of the attribute namespace are reserved

for user-specific and site-specific attributes respectively and will

not be standardized. Such attributes are not interoperable so are

discouraged in favor of defining standard attributes. A future

extension is expected to permit discovery of syntax for user or

site-specific attributes. Clients wishing to support display of user

or site-specific attributes should display the value of any non-NIL

single-valued "user.<user-name>." or "site." attribute which has

valid UTF-8 syntax.

The formal syntax for an attribute name is defined by the

"attribute-name" rule in the next section.

4.3. Formal Syntax for Dataset and Attribute Namespace

The naming conventions for datasets and attributes are defined by the

following ABNF. Note that this grammar is not part of the ACAP

protocol syntax in section 8, as dataset names and attribute names

are encoded as strings within the ACAP protocol.

attribute-dacl = "dataset.acl" *("." name-component)

attribute-dset = dataset-std 1*("." name-component)

;; MUST be defined in a dataset class specification

attribute-name = attribute-std / attr-site / attr-user / vendor-name

attribute-std = "entry" / "subdataset" / "modtime" /

"dataset.inherit" / attribute-dacl / attribute-dset

attr-site = "site" 1*("." name-component)

attr-user = "user." name-component 1*("." name-component)

byowner = "/byowner/" owner "/"

[dataset-class "/" dataset-sub]

dataset-class = dataset-std / vendor-name

dataset-normal = "/" [dataset-class "/"

(owner-prefix / dataset-tail)]

dataset-name = byowner / dataset-normal

dataset-std = name-component

;; MUST be registered with IANA and the spec MUST

;; be published as a standards track or

;; IESG-approved experimental RFC

dataset-sub = *(dname-component "/")

;; The rules for this portion of the namespace may

;; be further restricted by the dataset class

;; specification.

dataset-tail = owner "/" dataset-sub

dname-component = 1*UTF8-CHAR

;; MUST NOT begin with "." or contain "/"

name-component = 1*UTF8-CHAR

;; MUST NOT contain ".", "/", "%", or "*"

owner = "site" / owner-host / owner-group /

owner-user / "~"

owner-group = "group/" dname-component

owner-host = "host/" dname-component

owner-prefix = "group/" / "host/" / "user/"

owner-user = "user/" dname-component

vendor-name = vendor-token *("." name-component)

vendor-token = "vendor." name-component

;; MUST be registered with IANA

5. Dataset Management

The entry with an empty name ("") in the dataset is used to hold

management information for the dataset as a whole.

5.1. Dataset Inheritance

It is possible for one dataset to inherit data from another. The

dataset from which the data is inherited is called the base dataset.

Data in the base dataset appears in the inheriting dataset, except

when overridden by a STORE to the inheriting dataset.

The base dataset is usually a system-wide or group-wide set of

defaults. A system-wide dataset usually has one inheriting dataset

per user, allowing each user to add to or modify the defaults as

appropriate.

An entry which exists in both the inheriting and base dataset

inherits a modtime equal to the greater of the two modtimes. An

attribute in such an entry is inherited from the base dataset if it

was never modified by a STORE command in the inheriting dataset or if

DEFAULT was stored to that attribute. This permits default entries

to be amended rather than replaced in the inheriting dataset.

The "subdataset" attribute is not directly inherited. If the base

dataset includes a "subdataset" attribute and the inheriting dataset

does not, then the "subdataset" attribute will inherit a virtual

value of a list containing a ".". The subdataset at that node is

said to be a "virtual" dataset as it is simply a virtual copy of the

appropriate base dataset with all "subdataset" attributes changed to

a list containing a ".". A virtual dataset is not visible if

NOINHERIT is specified on the SEARCH command.

Servers MUST support at least two levels of inheritance. This

permits a user's dataset such as "/options/user/fred/common" to

inherit from a group dataset such as "/options/group/dinosaur

operators/common" which in turn inherits from a server-wide dataset

such as "/options/site/common".

5.2. Dataset Attributes

The following attributes apply to management of the dataset when

stored in the "" entry of a dataset. These attributes are not

inherited.

dataset.acl

This holds the default access control list for the dataset.

This attribute is validated, so an invalid access control list

in a STORE command will result in a NO response with an INVALID

response code.

dataset.acl.<attribute>

This holds the default access control list for an attribute

within the dataset. This attribute is validated, so an invalid

access control list in a STORE command will result in a NO

response with an INVALID response code.

dataset.inherit

This holds the name of a dataset from which to inherit according

to the rules in the previous section. This attribute MAY refer

to a non-existent dataset, in which case nothing is inherited.

This attribute is validated, so illegal dataset syntax or an

attempt to store a multi-value will result in a NO response with

an INVALID response code.

5.3. Dataset Creation

When a dataset is first created (by storing a "." in the subdataset

attribute or storing an entry in a previously non-existent dataset),

the dataset attributes are initialized with the values from the

parent dataset in the "/byowner/" hierarchy. In the case of the

"dataset.inherit" attribute, the appropriate hierarchy component is

added. For example, given the following entry (note that \t refers

to the US-ASCII horizontal tab character):

entry path "/byowner/user/joe/"

dataset.acl ("joe\txrwia" "fred\txr")

dataset.inherit "/byowner/site"

If a new dataset class "/byowner/user/joe/new" is created, it will

have the following dataset attributes:

entry path "/byowner/user/joe/new/"

dataset.acl ("joe\txrwia" "fred\txr")

dataset.inherit "/byowner/site/new"

Note that the dataset "/byowner/user/joe/new/" is equivalent to

"/new/user/joe/".

5.4. Dataset Class Capabilities

Certain dataset classes or dataset class features may only be useful

if there is an active updating client or integrated server support

for the feature. The dataset class "capability" is reserved to allow

clients or servers to advertise such features. The "entry" attribute

within this dataset class is the name of the dataset class whose

features are being described. The attributes are prefixed with

"capability.<dataset-class>." and are defined by the appropriate

dataset class specification.

Since it is possible for an unprivileged user to run an active client

for himself, a per-user capability dataset is useful. The dataset

"/capability/~/" holds information about all features available to

the user (via inheritance), and the dataset "/capability/site/" holds

information about all features supported by the site.

5.5. Dataset Quotas

Management and scope of quotas is implementation dependent. Clients

can check the applicable quota limit and usage (in bytes) with the

GETQUOTA command. Servers can notify the client of a low quota

situation with the QUOTA untagged response.

6. Command and Response Specifications

ACAP commands and responses are described in this section. Commands

are organized first by the state in which the command is permitted,

then by a general category of command type.

Command arguments, identified by "Arguments:" in the command

descriptions below, are described by function, not by syntax. The

precise syntax of command arguments is described in the Formal Syntax

section.

Some commands cause specific server data to be returned; these are

identified by "Data:" in the command descriptions below. See the

response descriptions in the Responses section for information on

these responses, and the Formal Syntax section for the precise syntax

of these responses. It is possible for server data to be transmitted

as a result of any command; thus, commands that do not specifically

require server data specify "no specific data for this command"

instead of "none".

The "Result:" in the command description refers to the possible

tagged status responses to a command, and any special interpretation

of these status responses.

6.1. Initial Connection

Upon session startup, the server sends one of two untagged responses:

ACAP or BYE. The untagged BYE response is described in section

6.2.8.

6.1.1. ACAP Untagged Response

Data: capability list

The untagged ACAP response indicates the session is ready to

accept commands and contains a space-separated listing of

capabilities that the server supports. Each capability is

represented by a list containing the capability name optionally

followed by capability specific string arguments.

ACAP capability names MUST be registered with IANA according to

the rules in section 7.1.

Client implementations SHOULD NOT require any capability name

beyond those defined in this specification, and MUST tolerate any

unknown capability names. A client implementation MAY be

configurable to require SASL mechanisms other than CRAM-MD5

[CRAM-MD5] for site security policy reasons.

The following initial capabilities are defined:

CONTEXTLIMIT

The CONTEXTLIMIT capability has one argument which is a

number describing the maximum number of contexts the server

supports per connection. The number 0 indicates the server

has no limit, otherwise this number MUST be greater than

100.

IMPLEMENTATION

The IMPLEMENTATION capability has one argument which is a

string describing the server implementation. ACAP clients

MUST NOT alter their behavior based on this value. It is

intended primarily for debugging purposes.

SASL The SASL capability includes a list of the authentication

mechanisms supported by the server. See section 6.3.1.

Example: S: * ACAP (IMPLEMENTATION "ACME v3.5")

(SASL "CRAM-MD5") (CONTEXTLIMIT "200")

6.2. Any State

The following commands and responses are valid in any state.

6.2.1. NOOP Command

Arguments: none

Data: no specific data for this command (but see below)

Result: OK - noop completed

BAD - command unknown or arguments invalid

The NOOP command always succeeds. It does nothing. It can be

used to reset any inactivity auto-logout timer on the server.

Example: C: a002 NOOP

S: a002 OK "NOOP completed"

6.2.2. LANG Command

Arguments: list of language preferences

Data: intermediate response: LANG

Result: OK - lang completed

NO - no matching language available

BAD - command unknown or arguments invalid

One or more arguments are supplied to indicate the client's

preferred languages [LANG-TAGS] for error messages. The server

will match each client preference in order against its internal

table of available error string languages. For a client

preference to match a server language, the client's language tag

MUST be a prefix of the server's tag and match up to a "-" or the

end of string. If a match is found, the server returns an

intermediate LANG response and an OK response. The LANG response

indicates the actual language selected and appropriate comparators

for use with the languages listed in the LANG command.

If no LANG command is issued, all error text strings MUST be in

the registered language "i-default" [CHARSET-LANG-POLICY],

intended for an international audience.

Example: C: A003 LANG "fr-ca" "fr" "en-ca" "en-uk"

S: A003 LANG "fr-ca" "i;octet" "i;ascii-numeric"

"i;ascii-casemap" "en;primary" "fr;primary"

S: A003 OK "Bonjour"

6.2.3. LANG Intermediate Response

Data: language for error responses

appropriate comparators

The LANG response indicates the language which will be used for

error responses and the comparators which are appropriate for the

languages listed in the LANG command. The comparators SHOULD be

in approximate order from most efficient (usually "i;octet") to

most appropriate for human text in the preferred language.

6.2.4. LOGOUT Command

Arguments: none

Data: mandatory untagged response: BYE

Result: OK - logout completed

BAD - command unknown or arguments invalid

The LOGOUT command informs the server that the client is done with

the session. The server must send a BYE untagged response before

the (tagged) OK response, and then close the network connection.

Example: C: A023 LOGOUT

S: * BYE "ACAP Server logging out"

S: A023 OK "LOGOUT completed"

(Server and client then close the connection)

6.2.5. OK Response

Data: optional response code

human-readable text

The OK response indicates an information message from the server.

When tagged, it indicates successful completion of the associated

command. The human-readable text may be presented to the user as

an information message. The untagged form indicates an

information-only message; the nature of the information MAY be

indicated by a response code.

Example: S: * OK "Master ACAP server is back up"

6.2.6. NO Response

Data: optional response code

human-readable text

The NO response indicates an operational error message from the

server. When tagged, it indicates unsuccessful completion of the

associated command. The untagged form indicates a warning; the

command may still complete successfully. The human-readable text

describes the condition.

Example: C: A010 SEARCH "/addressbook/" DEPTH 3 RETURN ("*")

EQUAL "entry" "+i;octet" "bozo"

S: * NO "Master ACAP server is down, your data may

be out of date."

S: A010 OK "search done"

...

C: A222 STORE ("/folder/site/comp.mail.misc"

"folder.creation-time" "19951206103412")

S: A222 NO (PERMISSION ("/folder/site/")) "Permission

denied"

6.2.7. BAD Response

Data: optional response code

human-readable text

The BAD response indicates an error message from the server. When

tagged, it reports a protocol-level error in the client's command;

the tag indicates the command that caused the error. The untagged

form indicates a protocol-level error for which the associated

command can not be determined; it may also indicate an internal

server failure. The human-readable text describes the condition.

Example: C: ...empty line...

S: * BAD "Empty command line"

C: A443 BLURDYBLOOP

S: A443 BAD "Unknown command"

C: A444 NOOP Hello

S: A444 BAD "invalid arguments"

6.2.8. BYE Untagged Response

Data: optional response code

human-readable text

The untagged BYE response indicates that the server is about to

close the connection. The human-readable text may be displayed to

the user in a status report by the client. The BYE response may

be sent as part of a normal logout sequence, or as a panic

shutdown announcement by the server. It is also used by some

server implementations as an announcement of an inactivity auto-

logout.

This response is also used as one of two possible greetings at

session startup. It indicates that the server is not willing to

accept a session from this client.

Example: S: * BYE "Auto-logout; idle for too long"

6.2.9. ALERT Untagged Response

Data: optional response code

human-readable text

The human-readable text contains a special human generated alert

message that MUST be presented to the user in a fashion that calls

the user's attention to the message. This is intended to be used

for vital messages from the server administrator to the user, such

as a warning that the server will soon be shut down for

maintenance.

Example: S: * ALERT "This ACAP server will be shut down in

10 minutes for system maintenance."

6.3. Non-Authenticated State

In non-authenticated state, the AUTHENTICATE command establishes

authentication and enters authenticated state. The AUTHENTICATE

command provides a general mechanism for a variety of authentication

techniques.

Server implementations may allow non-authenticated access to certain

information by supporting the SASL ANONYMOUS [SASL-ANON] mechanism.

Once authenticated (including as anonymous), it is not possible to

re-enter non-authenticated state.

Only the any-state commands (NOOP, LANG and LOGOUT) and the

AUTHENTICATE command are valid in non-authenticated state.

6.3.1. AUTHENTICATE Command

Arguments: SASL mechanism name

optional initial response

Data: continuation data may be requested

Result: OK - authenticate completed, now in authenticated state

NO - authenticate failure: unsupported authentication

mechanism, credentials rejected

BAD - command unknown or arguments invalid,

authentication exchange cancelled

The AUTHENTICATE command indicates a SASL [SASL] authentication

mechanism to the server. If the server supports the requested

authentication mechanism, it performs an authentication protocol

exchange to authenticate and identify the user. Optionally, it

also negotiates a security layer for subsequent protocol

interactions. If the requested authentication mechanism is not

supported, the server rejects the AUTHENTICATE command by sending

a tagged NO response.

The authentication protocol exchange consists of a series of

server challenges and client answers that are specific to the

authentication mechanism. A server challenge consists of a

command continuation request with the "+" token followed by a

string. The client answer consists of a line consisting of a

string. If the client wishes to cancel an authentication

exchange, it should issue a line with a single unquoted "*". If

the server receives such an answer, it must reject the

AUTHENTICATE command by sending a tagged BAD response.

The optional initial-response argument to the AUTHENTICATE command

is used to save a round trip when using authentication mechanisms

that are defined to send no data in the initial challenge. When

the initial-response argument is used with such a mechanism, the

initial empty challenge is not sent to the client and the server

uses the data in the initial-response argument as if it were sent

in response to the empty challenge. If the initial-response

argument to the AUTHENTICATE command is used with a mechanism that

sends data in the initial challenge, the server rejects the

AUTHENTICATE command by sending a tagged NO response.

The service name specified by this protocol's profile of SASL is

"acap".

If a security layer is negotiated through the SASL authentication

exchange, it takes effect immediately following the CRLF that

concludes the authentication exchange for the client, and the CRLF

of the tagged OK response for the server.

All ACAP implementations MUST implement the CRAM-MD5 SASL

mechanism [CRAM-MD5], although they MAY offer a configuration

option to disable it if site security policy dictates. The

example below is the same example described in the CRAM-MD5

specification.

If an AUTHENTICATE command fails with a NO response, the client

may try another authentication mechanism by issuing another

AUTHENTICATE command. In other words, the client may request

authentication types in decreasing order of preference.

Example: S: * ACAP (IMPLEMENTATION "Blorfysoft v3.5")

(SASL "CRAM-MD5" "KERBEROS_V4")

C: A001 AUTHENTICATE "CRAM-MD5"

S: + "<1896.697170952@postOffice.reston.mci.net>"

C: "tim b913a602c7eda7a495b4e6e7334d3890"

S: A001 OK "CRAM-MD5 authentication successful"

6.4. Searching

This section describes the SEARCH command, for retrieving data from

datasets.

6.4.1. SEARCH Command

Arguments: dataset or context name

optional list of modifiers

search criteria

Data: intermediate responses: ENTRY, MODTIME, REFER

untagged responses: ADDTO, REMOVEFROM, CHANGE, MODTIME

Result: OK - search completed

NO - search failure: can't perform search

BAD - command unknown or arguments invalid

The SEARCH command identifies a subset of entries in a dataset and

returns information on that subset to the client. Inherited

entries and attributes are included in the search unless the

NOINHERIT search modifier is included or the user does not have

permission to read the attributes in the base dataset.

The first argument to SEARCH identifies what is to be searched.

If the string begins with a slash ("/"), it is the name of a

dataset to be searched, otherwise it is a name of a context that

was created by a SEARCH command given previously in the session.

A successful SEARCH command MAY result in intermediate ENTRY

responses and MUST result in a MODTIME intermediate response.

Following that are zero or more modifiers to the search. Each

modifier may be specified at most once. The defined modifiers

are:

DEPTH number

The SEARCH command will traverse the dataset tree up to the

specified depth. ENTRY responses will include the full path

to the entry. A value of "0" indicates that the search

should traverse the entire tree. A value of "1" is the

default and indicates only the specified dataset should be

searched. If a dataset is traversed which is not located on

the current server, then a REFER intermediate response is

returned for that subtree and the search continues.

HARDLIMIT number

If the SEARCH command would result in more than number

entries, the SEARCH fails with a NO completion result with a

WAYTOOMANY response code.

LIMIT number number

Limits the number of intermediate ENTRY responses that the

search may generate. The first numeric argument specifies

the limit, the second number specifies the number of entries

to return if the number of matches exceeds the limit. If the

limit is exceeded, the SEARCH command still succeeds,

returning the total number of matches in a TOOMANY response

code in the tagged OK response.

MAKECONTEXT [ENUMERATE] [NOTIFY] context

Causes the SEARCH command to create a context with the name

given in the argument to refer to the matching entries. If

the SEARCH is successful, the context name may then be given

as an argument to subsequent SEARCH commands to search the

set of matching entries. If a context with the specified

name already exists, it is first freed. If a new context may

not be created due to the server's limit on the number of

existing contexts, the command fails, returning a

TRYFREECONTEXT response code in the NO completion response.

The optional "ENUMERATE" and "NOTIFY" arguments may be

included to request enumeration of the context (for virtual

scroll bars) or change notifications for the context. If

"NOTIFY" is not requested, the context represents a snapshot

of the entries at the time the SEARCH was issued.

ENUMERATE requests that the contents of the context be

ordered according to the SORT modifier and that sequential

numbers, starting with one, be assigned to the entries in the

context. This permits the RANGE modifier to be used to fetch

portions of the ordered context.

NOTIFY requests that the server send untagged ADDTO,

REMOVEFROM, CHANGE, and MODTIME responses while the context

created by this SEARCH command exists. The server MAY issue

untagged ADDTO, REMOVEFROM, CHANGE and MODTIME notifications

for a context at any time between the issuing of the SEARCH

command with MAKECONTEXT NOTIFY and the completion of a

FREECONTEXT command for the context. Notifications are only

issued for changes which occur after the server receives the

SEARCH command which created the context. After issuing a

sequence of ADDTO, REMOVEFROM or CHANGE notifications, the

server MUST issue an untagged MODTIME notification indicating

that the client has all updates to the entries in the context

up to and including the given modtime value. Servers are

permitted a reasonable delay to batch change notifications

before sending them to the client.

The position arguments of the ADDTO, REMOVEFROM and CHANGE

notifications are 0 if ENUMERATE is not requested.

NOINHERIT

This causes the SEARCH command to operate without

inheritance. It can be used to tell which values are

explicit overrides. If MAKECONTEXT is also specified, the

created context is also not affected by inheritance.

RETURN (metadata...)

Specifies what is to be returned in intermediate ENTRY

responses. If this modifier is not specified, no

intermediate ENTRY responses are returned.

Inside the parentheses is an optional list of attributes,

each optionally followed by a parenthesized list of metadata.

If the parenthesized list of metadata is not specified, it

defaults to "(value)".

An attribute name with a trailing "*" requests all attributes

with that prefix. A "*" by itself requests all attributes.

If the parenthesized list of metadata is not specified for an

attribute with a trailing "*", it defaults to "(attribute

value)". Results matching such an attribute pattern are

grouped in parentheses.

Following the last intermediate ENTRY response, the server

returns a single intermediate MODTIME response.

SORT (attribute comparator ...)

Specifies the order in which any resulting ENTRY replies are

to be returned to the client. The SORT modifier takes as an

argument a parenthesized list of one or more

attribute/comparator pairs. Attribute lists the attribute to

sort on, comparator specifies the name of the collation rule

to apply to the values of the attribute. Successive

attribute/comparator pairs are used to order two entries only

when all preceding pairs indicate the two entries collate the

same.

If the SORT modifier is used in conjunction with the

MAKECONTEXT modifier, the SORT modifier specifies the

ordering of entries in the created context.

If no SORT modifier is specified, or none of the

attribute/comparator pairs indicates an order for the two

entries, the server uses the order of the entries that exists

in the context or dataset being searched.

Following the modifiers is the search criteria. Searching

criteria consist of one or more search keys. Search keys may be

combined using the AND, and OR search keys. For example, the

criteria (the newline is for readability and not part of the

criteria):

AND COMPARE "modtime" "+i;octet" "19951206103400"

COMPARE "modtime" "-i;octet" "19960112000000"

refers to all entries modified between 10:34 December 6 1995 and

midnight January 12, 1996 UTC.

The currently defined search keys are as follows.

ALL This matches all entries.

AND search-key1 search-key2

Entries that match both search keys.

COMPARE attribute comparator value

Entries for which the value of the specified attribute

collates using the specified comparator the same or later

than the specified value.

COMPARESTRICT attribute comparator value

Entries for which the specified attribute collates using the

specified comparator later than the specified value.

EQUAL attribute comparator value

Entries for which the value of the attribute is equal to the

specified value using the specified comparator.

NOT search-key

Entries that do not match the specified search key.

OR search-key1 search-key2

Entries that match either search key.

PREFIX attribute comparator value

Entries which begin with the specified value using the

specified comparator. If the specified comparator doesn't

support substring matching, a BAD response is returned.

RANGE start end time

Entries which are within the specified range of the

enumerated context's ordering. The lowest-ordered entry in

the context is assigned number one, the next lowest entry is

assigned number two, and so on. The numeric arguments

specify the lowest and highest numbers to match. The time

specifies that the client has processed notifications for the

context up to the specified time. If the context has been

modified since then, the server MUST either return a NO with

a MODIFIED response code, or return the results that the

SEARCH would have returned if none of the changes since that

time had been made.

RANGE is only permitted on enumerated contexts. If RANGE is

used with a dataset or non-enumerated context, the server

MUST return a BAD response.

SUBSTRING attribute comparator value

Entries which contain the specified value, using the

specified comparator. If the specified comparator doesn't

support substring matching, a BAD response is returned.

6.4.2. ENTRY Intermediate Response

Data: entry name

entry data

The ENTRY intermediate response occurs as a result of a SEARCH or

STORE command. This is the means by which dataset entries are

returned to the client.

The ENTRY response begins with the entry name, if a SEARCH command

without the DEPTH modifier was issued, or the entry path in other

cases. This is followed by a set of zero or more items, one for

each metadata item in the RETURN search modifier. Results

matching an attribute pattern or returning multiple metadata items

are grouped in parentheses.

6.4.3. MODTIME Intermediate Response

Data: modtime value

The MODTIME intermediate response occurs as a result of a SEARCH

command. It indicates that the just created context or the

previously returned ENTRY responses include all updates to the

returned entries up to and including the modtime value in the

argument.

6.4.4. REFER Intermediate Response

Data: dataset path

relative ACAP URLs

The REFER intermediate response occurs as a result of a

multi-level SEARCH where one of the levels is located on a

different server. The response indicates the dataset which is not

located on the current server and one or more relative ACAP URLs

for where that dataset may be found.

6.4.5. Search Examples

Here are some SEARCH command exchanges between the client and server:

C: A046 SEARCH "/addressbook/" DEPTH 3 RETURN ("addressbook.Alias"

"addressbook.Email" "addressbook.List") OR NOT EQUAL

"addressbook.Email" "i;octet" NIL NOT EQUAL

"addressbook.List" "i;octet" NIL

S: A046 ENTRY "/addressbook/user/joe/A0345" "fred"

"fred@stone.org" NIL

S: A046 ENTRY "/addressbook/user/fred/A0537" "joe" "joe@stone.org"

NIL

S: A046 ENTRY "/addressbook/group/Dinosaur Operators/A423"

"saurians" NIL "1"

S: A046 MODTIME "19970728105252"

S: A046 OK "SEARCH completed"

C: A047 SEARCH "/addressbook/user/fred/" RETURN ("*") EQUAL "entry"

"i;octet" "A0345"

S: A047 ENTRY "A0345" (("modtime" "19970728102226")

("addressbook.Alias" "fred") ("addressbook.Email"

"fred@stone.org") ("addressbook.CommonName"

"Fred Flintstone") ("addressbook.Surname" "Flintstone")

("addressbook.GivenName" "Fred"))

S: A047 MODTIME "19970728105258"

S: A047 OK "SEARCH completed"

C: A048 SEARCH "/options/~/vendor.example/" RETURN

("option.value"("size" "value" "myrights"))

SORT ("entry" "i;octet") COMPARE "modtime" "i;octet"

"19970727123225"

S: A048 ENTRY "blurdybloop" (5 "ghoti" "rwia")

S: A048 ENTRY "buckybits" (2 "10" "rwia")

S: A048 ENTRY "windowSize" (7 "100x100" "rwia")

S: A048 MODTIME "19970728105304"

S: A048 OK "SEARCH completed"

C: A049 SEARCH "/addressbook/~/public" RETURN ("addressbook.Alias"

"addressbook.Email") MAKECONTEXT ENUMERATE "blob" LIMIT 100 1

SORT ("addressbook.Alias" "i;octet") NOT EQUAL

"addressbook.Email" NIL

S: A049 ENTRY "A437" "aaguy" "aaguy@stone.org"

S: A049 MODTIME "19970728105308"

S: A049 OK (TOOMANY 347) "Context 'blob' created"

C: A050 SEARCH "blob" RANGE 2 2 "19970728105308" ALL

S: A050 ENTRY "A238" "abguy" "abguy@stone.org"

S: A050 MODTIME "19970728105310"

S: A050 OK "SEARCH Completed"

6.5. Contexts

The following commands use contexts created by a SEARCH command with

a MAKECONTEXT modifier.

6.5.1. FREECONTEXT Command

Arguments: context name

Data: no specific data for this command

Result: OK - freecontext completed

NO - freecontext failure: no such context

BAD - command unknown or arguments invalid

The FREECONTEXT command causes the server to free all state

associated with the named context. The context may no longer be

searched and the server will no longer issue any untagged

responses for the context. The context is no longer counted

against the server's limit on the number of contexts.

Example: C: A683 FREECONTEXT "blurdybloop"

S: A683 OK "Freecontext completed"

6.5.2. UPDATECONTEXT Command

Arguments: list of context names

Data: untagged responses: ADDTO REMOVEFROM CHANGE MODTIME

Result: OK - Updatecontext completed: all updates completed

NO - Updatecontext failed: no such context

not a notify context

BAD - command unknown or arguments invalid

The UPDATECONTEXT command causes the server to ensure that the

client is notified of all changes known to the server for the

contexts listed as arguments up to the current time. The contexts

listed in the arguments must have been previously given to a

successful SEARCH command with a MAKECONTEXT NOTIFY modifier. A

MODTIME untagged response MUST be returned if any read-write

metadata in the context changed since the last MODTIME for that

context. This includes metadata which is not listed in the RETURN

modifier for the context.

While a server may issue untagged ADDTO, REMOVEFROM, CHANGE, and

MODTIME at any time, the UPDATECONTEXT command is used to "prod"

the server to send any notifications it has not sent yet.

The UPDATECONTEXT command SHOULD NOT be used to poll for updates.

Example: C: Z4S9 UPDATECONTEXT "blurdybloop" "blarfl"

S: Z4S9 OK "client has been notified of all changes"

6.5.3. ADDTO Untagged Response

Data: context name

entry name

position

metadata list

The untagged ADDTO response informs the client that an entry has

been added to a context. The response includes the position

number of the added entry (the first entry in the context is

numbered 1) and those metadata contained in the entry which match

the RETURN statement when the context was created.

For enumerated contexts, the ADDTO response implicitly adds one to

the position of all members of the context which had position

numbers that were greater than or equal to the ADDTO position

number. For non-enumerated contexts, the position field is always

0.

Example: S: * ADDTO "blurdybloop" "fred" 15

("addressbook.Email" "fred@stone.org")

6.5.4. REMOVEFROM Untagged Response

Data: context name

entry name

old position

The untagged REMOVEFROM response informs the client that an entry

has been removed from a context. The response includes the

position number that the removed entry used to have (the first

entry in the context is numbered 1).

For enumerated contexts, the REMOVEFROM response implicitly

subtracts one from the position numbers of all members of the

context which had position numbers greater than the REMOVEFROM

position number. For non-enumerated contexts, the position field

is always 0.

Example: S: * REMOVEFROM "blurdybloop" "fred" 15

6.5.5. CHANGE Untagged Response

Data: context name

entry name

old position

new position

metadata list

The untagged CHANGE response informs the client that an entry in a

context has either changed position in the context or has changed

the values of one or more of the attributes specified in the

RETURN modifier when the context was created.

The response includes the previous and current position numbers of

the entry (which are 0 if ENUMERATE was not specified on the

context) and the attribute metadata requested in the RETURN

modifier when the context was created.

For enumerated contexts, the CHANGE response implicitly changes

the position numbers of all entries which had position numbers

between the old and new position. If old position is less than

new position, than one is subtracted from all entries which had

position numbers in that range. Otherwise one is added to all

entries which had position numbers in that range. If the old

position and new position are the same, then no implicit position

renumbering occurs.

CHANGE responses are not issued for entries which have changed

position implicitly due to another ADDTO, REMOVEFROM or CHANGE

response.

Example: S: * CHANGE "blurdybloop" "fred" 15 10

("addressbook.Email" "fred@stone.org")

6.5.6. MODTIME Untagged Response

Data: context name

modtime value

The untagged MODTIME response informs the client that it has

received all updates to entries in the context which have modtime

values less than or equal to the modtime value in the argument.

Example: S: * MODTIME mycontext "19970320162338"

6.6. Dataset modification

The following commands and responses handle modification of datasets.

6.6.1. STORE Command

Arguments: entry store list

Data: intermediate responses: ENTRY

Result: OK - store completed

NO - store failure: can't store that name

UNCHANGEDSINCE specified and entry changed

BAD - command unknown or arguments invalid

invalid UTF-8 syntax in attribute name

Creates, modifies, or deletes the named entries in the named

datasets. The values of metadata not specified in the command are

not changed. Setting the "value" metadata of an attribute to NIL

removes that attribute from the entry. Setting the "value" of the

"entry" attribute to NIL removes that entry from the dataset and

cancels inheritance for the entire entry. Setting the "value" of

the "entry" attribute to DEFAULT removes that entry from the

inheriting dataset and reverts the entry and its attributes to

inherited values, if any. Changing the value of the "entry"

attribute renames the entry.

Storing DEFAULT to the "value" metadata of an attribute is

equivalent to storing NIL, except that inheritance is enabled for

that attribute. If a non-NIL value is inherited then an ENTRY

intermediate response is generated to notify the client of the

this change. The ENTRY response includes the entry-path and the

attribute name and value metadata for each attribute which

reverted to a non-NIL inherited setting.

Storing NIL to the "value" metadata of an attribute MAY be treated

equivalent to storing DEFAULT to that "value" if there is a NIL

value in the base dataset.

The STORE command is followed by one or more entry store lists.

Each entry store list begins with an entry path followed by STORE

modifiers, followed by zero or more attribute store items. Each

attribute store item is made up of the attribute name followed by

NIL (to remove the attribute's value), DEFAULT (to revert the item

to any inherited value), a single value (to set the attribute's

single value), or a list of metadata items to modify. The

following STORE modifiers may be specified:

NOCREATE

By default, the server MUST create any datasets necessary to

store the entry, including multiple hierarchy levels. If

NOCREATE is specified, the STORE command will fail with a

NOEXIST error unless the parent dataset already exists.

UNCHANGEDSINCE

If the "modtime" of the entry is later than the

unchangedsince time, then the store fails with a MODIFIED

response code. Use of UNCHANGEDSINCE with a time of

"00000101000000" will always fail if the entry exists.

Clients writing to a shared dataset are encouraged to use

UNCHANGEDSINCE when modifying an existing entry.

The server MUST either make all the changes specified in a single

STORE command or make none of them. If successful, the server

MUST update the "modtime" attribute for every entry which was

changed.

It is illegal to list any metadata item within an attribute twice,

any attribute within an entry twice or any entry path twice. The

server MUST return a BAD response if this happens.

The server MAY re-order the strings in a multi-value on STORE and

MAY remove duplicate strings. However, SEARCH MUST return multi-

values and the associated size list metadata in a consistant

order.

Example: C: A342 STORE ("/addressbook/user/fred/ABC547"

"addressbook.TelephoneNumber" "555-1234"

"addressbook.CommonName" "Barney Rubble"

"addressbook.AlternateNames" ("value"

("Barnacus Rubble" "Coco Puffs Thief"))

"addressbook.Email" NIL)

S: A342 OK "Store completed"

C: A343 STORE ("/addressbook/user/joe/ABD42"

UNCHANGEDSINCE "19970320162338"

"user.joe.hair-length" "10 inches")

S: A343 NO (MODIFIED) "'ABD42' has been changed

by somebody else."

C: A344 STORE ("/addressbook/group/Developers/ACD54"

"entry" NIL)

S: A344 OK "Store completed"

C: A345 STORE ("/option/~/common/SMTPserver"

"option.value" DEFAULT)

S: A345 ENTRY "/option/~/common/SMTPserver"

"option.value" "smtp.server.do.main"

S: A345 OK "Store completed"

C: A347 STORE ("/addressbook/~/" "dataset.inherit"

"/addressbook/group/Developers")

S: A347 OK "Store completed"

6.6.2. DELETEDSINCE Command

Arguments: dataset name

time

Data: intermediate response: DELETED

Result: OK - DELETEDSINCE completed

NO - DELETEDSINCE failure: can't read dataset

date too far in the past

BAD - command unknown or arguments invalid

The DELETEDSINCE command returns in intermediate DELETED replies

the names of entries that have been deleted from the named dataset

since the given time.

Servers may impose a limit on the number or age of deleted entry

names they keep track of. If the server does not have information

going back to the specified time, the command fails, returning a

TOOOLD response code in the tagged NO response.

Example: C: Z4S9 DELETEDSINCE "/folder/site/" 19951205103412

S: Z4S9 DELETED "blurdybloop"

S: Z4S9 DELETED "anteaters"

S: Z4S9 OK "DELETEDSINCE completed"

C: Z4U3 DELETEDSINCE "/folder/site/" 19951009040854

S: Z4U3 NO (TOOOLD) "Don't have that information"

6.6.3. DELETED Intermediate Response

Data: entry name

The intermediate DELETED response occurs as a result of a

DELETEDSINCE command. It returns an entry that has been deleted

from the dataset specified in the DELETEDSINCE command.

6.7. Access Control List Commands

The commands in this section are used to manage access control lists.

6.7.1. SETACL Command

Arguments: acl object

authentication identifier

access rights

Data: no specific data for this command

Result: OK - setacl completed

NO - setacl failure: can't set acl

BAD - command unknown or arguments invalid

The SETACL command changes the access control list on the

specified object so that the specified identifier is granted the

permissions enumerated in rights. If the object did not

previously have an access control list, one is created.

Example: C: A123 SETACL ("/addressbook/~/public/") "anyone" "r"

S: A123 OK "Setacl complete"

C: A124 SETACL ("/folder/site/") "B1FF" "rwa"

S: A124 NO (PERMISSION ("/folder/site/")) "'B1FF' not

permitted to modify access rights

for '/folder/site/'"

6.7.2. DELETEACL Command

Arguments: acl object

optional authentication identifier

Data: no specific data for this command

Result: OK - deleteacl completed

NO - deleteacl failure: can't delete acl

BAD - command unknown or arguments invalid

If given the optional identifier argument, the DELETEACL command

removes any portion of the access control list on the specified

object for the specified identifier.

If not given the optional identifier argument, the DELETEACL

command removes the ACL from the object entirely, causing access

to be controlled by a higher-level default ACL. This form of the

DELETEACL command is not permitted on the default ACL for a

dataset and servers MUST return a BAD.

Example: C: A223 DELETEACL ("/addressbook/~/public") "anyone"

S: A223 OK "Deleteacl complete"

C: A224 DELETEACL ("/folder/site")

S: A224 BAD "Can't delete ACL from dataset"

C: A225 DELETEACL ("/addressbook/user/fred"

"addressbook.Email" "barney")

S: A225 OK "Deleteacl complete"

6.7.3. MYRIGHTS Command

Arguments: acl object

Data: intermediate responses: MYRIGHTS

Result: OK - myrights completed

NO - myrights failure: can't get rights

BAD - command unknown or arguments invalid

The MYRIGHTS command returns the set of rights that the client has

to the given dataset or dataset attribute.

Example: C: A003 MYRIGHTS ("/folder/site")

S: A003 MYRIGHTS "r"

S: A003 OK "Myrights complete"

6.7.4. MYRIGHTS Intermediate Response

Data: rights

The MYRIGHTS response occurs as a result of a MYRIGHTS command.

The argument is the set of rights that the client has for the

object referred to in the MYRIGHTS command.

6.7.5. LISTRIGHTS Command

Arguments: acl object

authentication identifier

Data: untagged responses: LISTRIGHTS

Result: OK - listrights completed

NO - listrights failure: can't get rights list

BAD - command unknown or arguments invalid

The LISTRIGHTS command takes an object and an identifier and

returns information about what rights the current user may revoke

or grant to that identifier in the ACL for that object.

Example: C: a001 LISTRIGHTS ("/folder/~/") "smith"

S: a001 LISTRIGHTS "xra" "w" "i"

S: a001 OK Listrights completed

C: a005 LISTRIGHTS ("/folder/site/archive/imap") "anyone"

S: a005 LISTRIGHTS "" "x" "r" "w" "i"

S: a005 OK Listrights completed

6.7.6. LISTRIGHTS Intermediate Response

Data: required rights

list of optional rights

The LISTRIGHTS response occurs as a result of a LISTRIGHTS

command. The first argument is a string containing the (possibly

empty) set of rights the identifier will always be granted on the

dataset or attribute.

Following this are zero or more strings each containing a single

right which the current user may revoke or grant to the identifier

in the dataset or attribute.

The same right MUST NOT be listed more than once in the LISTRIGHTS

response.

6.8. Quotas

The section defines the commands and responses relating to quotas.

6.8.1. GETQUOTA Command

Arguments: dataset

Data: untagged responses: QUOTA

Result: OK - Quota information returned

NO - Quota failure: can't access resource limit

no resource limit

BAD - command unknown or arguments invalid

The GETQUOTA command takes the name of a dataset, and returns in

an untagged QUOTA response the name of the dataset, quota limit in

bytes that applies to that dataset and the quota usage within that

limit. The scope of a quota limit is implementation dependent.

Example: C: A043 GETQUOTA "/option/user/fred/common"

S: * QUOTA "/option/user/fred/common" 1048576 2475

S: A043 OK "Getquota completed"

6.8.3. QUOTA Untagged Response

Data: dataset

quota limit in bytes

amount of quota limit used

extension data

The QUOTA untagged response is generated as a result of a GETQUOTA

command or MAY be generated by the server in response to a SEARCH

or STORE command to warn about high usage of a quota. It includes

the name of the applicable dataset, the quota limit in bytes, the

quota usage and some optional extension data. Clients MUST

tolerate the extension data as its use is reserved for a future

extension.

6.9. Extensions

In order to simplify the process of extending the protocol, clients

MUST tolerate unknown server responses which meet the syntax of

response-extend. In addition, clients MUST tolerate unknown server

response codes which meet the syntax of resp-code-ext. Availability

of new commands MUST be announced via a capability on the initial

greeting line and such commands SHOULD meet the syntax of

command-extend.

Servers MUST respond to unknown commands with a BAD command

completion result. Servers MUST skip over non-synchronizing literals

contained in an unknown command. This may be done by assuming the

unknown command matches the command-extend syntax, or by reading a

line at a time and checking for the non-synchronizing literal syntax

at the end of the line.

7. Registration Procedures

ACAP's usefulness comes from providing a structured storage model for

all sorts of configuration data. However, for its potential to be

achieved, it is important that the Internet community strives for the

following goals:

(1) Standardization. It is very important to standardize dataset

classes. The authors hope that ACAP achieves the success that SNMP

has seen with the definition of numerous standards track MIBs.

(2) Community Review. In the absence of standardization, it is

important to get community review on a proposal to improve its

engineering quality. Community review is strongly recommended prior

to registration. The ACAP implementors mailing list

<ietf-acap@andrew.cmu.edu> should be used for this purpose.

(3) Registration. Registration serves a two-fold purpose. First it

prevents use of the same name for different purposes, and second it

provides a one-stop list which can be used to locate existing

extensions or dataset classes to prevent duplicate work.

The following registration templates may be used to register ACAP

protocol elements with the Internet Assigned Numbers Authority

(IANA).

7.1. ACAP Capabilities

New ACAP capabilities MUST be registered prior to use. Careful

consideration should be made before extending the protocol, as it can

lead to complexity or interoperability problems. Review of proposals

on the acap implementors mailing list is strongly encouraged prior to

registration.

To: iana@iana.org

Subject: Registration of ACAP capability

Capability name:

Capability keyword:

Capability arguments:

Published Specification(s):

(Optional, but strongly encouraged)

Person and email address to contact for further information:

7.2. ACAP Response Codes

ACAP response codes are registered on a first come, first served

basis. Review of proposals on the acap implementors mailing list is

strongly encouraged prior to registration.

To: iana@iana.org

Subject: Registration of ACAP response code

Response Code:

Arguments (use ABNF to specify syntax):

Purpose:

Published Specification(s):

(Optional, but strongly encouraged)

Person and email address to contact for further information:

7.3. Dataset Classes

A dataset class provides a core set of attributes for use in a

specified hierarchy. It may also define rules for the dataset

hierarchy underneath that class. Dataset class specifications must

be standards track or IESG approved experimental RFCs.

To: iana@iana.org

Subject: Registration of ACAP dataset class

Dataset class name/attribute prefix:

Purpose:

Published Specification(s):

(Standards track or IESG approved experimental RFC)

Person and email address to contact for further information:

7.4. Vendor Subtree

Vendors may reserve a portion of the ACAP namespace for private use.

Dataset class names beginning with "vendor.<company/product name>."

are reserved for use by that company or product. In addition, all

attribute names beginning with "vendor.<company/product name>." are

reserved for use by that company or product once registered.

Registration is on a first come, first served basis. Whenever

possible, private attributes and dataset classes should be avoided in

favor of improving interoperable dataset class definitions.

To: iana@iana.org

Subject: Registration of ACAP vendor subtree

Private Prefix: vendor.<company/product name>.

Person and email address to contact for further information:

(company names and addresses should be included when appropriate)

8. Formal Syntax

The following syntax specification uses the augmented Backus-Naur

Form (BNF) notation as specified in [ABNF]. This uses the ABNF core

rules as specified in Appendix A of the ABNF specification [ABNF].

Except as noted otherwise, all alphabetic characters are

case-insensitive. The use of upper or lower case characters to

define token strings is for editorial clarity only. Implementations

MUST accept these strings in a case-insensitive fashion.

The "initial-greeting" rule below defines the initial ACAP greeting

from the server. The "command" rule below defines the syntax for

commands sent by the client. The "response" rule below defines the

syntax for responses sent by the server.

ATOM-CHAR = "!" / %x23-27 / %x2A-5B / %x5D-7A / %x7C-7E

;; Any CHAR except ATOM-SPECIALS

ATOM-SPECIALS = "(" / ")" / "{" / SP / CTL / QUOTED-SPECIALS

CHAR = %x01-7F

DIGIT-NZ = %x31-39

; non-zero digits ("1" - "9")

QUOTED-CHAR = SAFE-UTF8-CHAR / "\" QUOTED-SPECIALS

QUOTED-SPECIALS = <"> / "\"

SAFE-CHAR = %x01-09 / %x0B-0C / %x0E-21 /

%x23-5B / %x5D-7F

;; any TEXT-CHAR except QUOTED-SPECIALS

SAFE-UTF8-CHAR = SAFE-CHAR / UTF8-2 / UTF8-3 / UTF8-4 /

UTF8-5 / UTF8-6

TAG-CHAR = %x21 / %x23-27 / %x2C-5B / %x5D-7A / %x7C-7E

;; Any ATOM-CHAR except "*" or "+"

TEXT-CHAR = %x01-09 / %x0B-0C / %x0E-7F

;; any CHAR except CR and LF

TEXT-UTF8-CHAR = SAFE-UTF8-CHAR / QUOTED-SPECIALS

UTF8-1 = %x80-BF

UTF8-2 = %xC0-DF UTF8-1

UTF8-3 = %xE0-EF 2UTF8-1

UTF8-4 = %xF0-F7 3UTF8-1

UTF8-5 = %xF8-FB 4UTF8-1

UTF8-6 = %xFC-FD 5UTF8-1

UTF8-CHAR = TEXT-UTF8-CHAR / CR / LF

acl = "(" [acl-identrights *(SP acl-identrights)] ")"

*(SPACE acl-identrights)] ")"

acl-identifier = string-utf8

;; MUST NOT contain HTAB

acl-identrights = string-utf8

;; The identifier followed by a HTAB,

;; followed by the rights.

acl-delobject = "(" dataset SP attribute [SP entry-name] ")"

acl-object = "(" dataset [SP attribute [SP entry-name]] ")"

acl-rights = quoted

atom = ALPHA *1023ATOM-CHAR

attribute = string-utf8

;; dot-separated attribute name

;; MUST NOT contain "*" or "%"

attribute-store = attribute SP (value-nildef /

"(" 1*(metadata-write-q SP value-store) ")")

;; MUST NOT include the same metadata twice

auth-type = <"> auth-type-name <">

auth-type-name = iana-token

;; as defined in SASL [SASL]

command = tag SP (command-any / command-auth /

command-nonauth) CRLF

;; Modal based on state

command-authent = "AUTHENTICATE" SP auth-type

[SP string] *(CRLF string)

command-any = "NOOP" / command-lang / "LOGOUT" /

command-extend

command-auth = command-delacl / command-dsince /

command-freectx / command-getquota /

command-lrights / command-myrights /

command-search / command-setacl /

command-store

;; only valid in authenticated state

command-delacl = "DELETEACL" SP acl-delobject [SP acl-identifier]

command-dsince = "DELETEDSINCE" SP dataset SP time

command-extend = extend-token [SP extension-data]

command-freectx = "FREECONTEXT" SP context

command-getquota = "GETQUOTA" SP dataset

command-lang = "LANG" *(SP lang-tag)

command-lrights = "LISTRIGHTS" SP acl-object

command-myrights = "MYRIGHTS" SP acl-object

command-nonauth = command-authent

;; only valid in non-authenticated state

command-search = "SEARCH" SP (dataset / context)

*(SP search-modifier) SP search-criteria

;; MUST NOT include same search-modifier twice

command-setacl = "SETACL" SP acl-object SP acl-identifier

SP acl-rights

command-store = "STORE" SP store-entry-list

comparator = <"> comparator-name <">

comparator-name = ["+" / "-"] iana-token

context = string-utf8

;; MUST NOT begin with slash ("/")

dataset = string-utf8

;; slash-separated dataset name

;; begins with slash

entry = entry-name / entry-path

entry-name = string-utf8

;; entry name MUST NOT contain slash

;; MUST NOT begin with "."

entry-path = string-utf8

;; slash-separated path to entry

;; begins with slash

entry-relative = string-utf8

;; potentially relative path to entry

extend-token = atom

;; MUST be defined by a standards track or

;; IESG approved experimental protocol extension

extension-data = extension-item *(SP extension-item)

extension-item = extend-token / string / number /

"(" [extension-data] ")"

iana-token = atom

;; MUST be registered with IANA

initial-greeting = "*" SP "ACAP" *(SP "(" init-capability ")") CRLF

init-capability = init-cap-context / init-cap-extend /

init-cap-implem / init-cap-sasl

init-cap-context = "CONTEXTLIMIT" SP string

init-cap-extend = iana-token [SP string-list]

init-cap-implem = "IMPLEMENTATION" SP string

init-cap-sasl = "SASL" SP string-list

lang-tag = <"> Language-Tag <">

;; Language-Tag rule is defined in [LANG-TAGS]

literal = "{" number [ "+" ] "}" CRLF *OCTET

;; The number represents the number of octets

;; MUST be literal-utf8 except for values

literal-utf8 = "{" number [ "+" ] "}" CRLF *UTF8-CHAR

;; The number represents the number of octets

;; not the number of characters

metadata = attribute [ "(" metadata-type-list ")" ]

;; attribute MAY end in "*" as wildcard.

metadata-list = metadata *(SP metadata)

metadata-type = "attribute" / "myrights" / "size" /

"count" / metadata-write

metadata-type-q = <"> metadata-type <">

metadata-type-list = metadata-type-q *(SP metadata-type-q)

metadata-write = "value" / "acl"

metadata-write-q = <"> metadata-write <">

nil = "NIL"

number = *DIGIT

;; A 32-bit unsigned number.

;; (0 <= n < 4,294,967,296)

nz-number = DIGIT-NZ *DIGIT

;; A 32-bit unsigned non-zero number.

;; (0 < n < 4,294,967,296)

position = number

;; "0" if context is not enumerated

;; otherwise this is non-zero

quota-limit = number

quota-usage = number

quoted = <"> *QUOTED-CHAR <">

;; limited to 1024 octets between the <">s

response = response-addto / response-alert / response-bye /

response-change / response-cont /

response-deleted / response-done /

response-entry / response-extend /

response-listr / response-lang /

response-mtimei / response-mtimeu /

response-myright / response-quota /

response-refer / response-remove / response-stat

response-addto = "*" SP "ADDTO" SP context SP entry-name

SP position SP return-data-list

response-alert = "*" SP "ALERT" SP resp-body CRLF

;; Client MUST display alert text to user

response-bye = "*" SP "BYE" SP resp-body CRLF

;; Server will disconnect condition

response-change = "*" SP "CHANGE" SP context SP entry-name

SP position SP position SP return-data-list

response-cont = "+" SP string

response-deleted = tag SP "DELETED" SP entry-name

response-done = tag SP resp-cond-state CRLF

response-entry = tag SP "ENTRY" SP entry SP return-data-list

response-extend = (tag / "*") SP extend-token [SP extension-data]

response-lang = "*" SP "LANG" SP lang-tag 1*(SP comparator)

response-listr = tag SP "LISTRIGHTS" SP acl-rights

*(SP acl-rights)

response-mtimei = tag SP "MODTIME" SP time

response-mtimeu = "*" SP "MODTIME" SP context SP time

response-myright = tag SP "MYRIGHTS" SP acl-rights

response-quota = "*" SP "QUOTA" SP dataset SP quota-limit

SP quota-usage [SP extension-data]

response-refer = tag SP "REFER" SP dataset

1*(SP <"> url-relative <">)

response-remove = "*" SP "REMOVEFROM" SP context SP

entry-name SP position

response-stat = "*" SP resp-cond-state CRLF

resp-body = ["(" resp-code ")" SP] quoted

resp-code = "AUTH-TOO-WEAK" / "ENCRYPT-NEEDED" /

resp-code-inval / resp-code-mod /

resp-code-noexist / resp-code-perm / "QUOTA" /

resp-code-refer / resp-code-sasl /

resp-code-toomany / "TOOOLD" /

"TRANSITION-NEEDED" / "TRYFREECONTEXT" /

"TRYLATER" / "WAYTOOMANY" / resp-code-ext

resp-code-ext = iana-token [SP extension-data]

;; unknown codes MUST be tolerated by the client

resp-code-inval = "INVALID" 1*(SP entry-path SP attribute)

resp-code-mod = "MODIFIED" SP entry-path

resp-code-noexist = "NOEXIST" SP dataset

resp-code-perm = "PERMISSION" SP acl-object

resp-code-refer = "REFER" 1*(SP <"> url-relative <">)

resp-code-sasl = "SASL" SP string

resp-code-toomany = "TOOMANY" SP nz-number

resp-cond-state = ("OK" / "NO" / "BAD") SP resp-body

;; Status condition

return-attr-list = "(" return-metalist *(SP return-metalist) ")"

;; occurs when "*" in RETURN pattern on SEARCH

return-data = return-metadata / return-metalist /

return-attr-list

return-data-list = return-data *(SP return-data)

return-metalist = "(" return-metadata *(SP return-metadata) ")"

;; occurs when multiple metadata items requested

return-metadata = nil / string / value-list / acl

searchkey-equal = "EQUAL" SP attribute SP comparator SP value-nil

searchkey-comp = "COMPARE" SP attribute SP comparator SP value

searchkey-prefix = "PREFIX" SP attribute SP comparator SP value

searchkey-range = "RANGE" SP nz-number SP nz-number SP time

searchkey-strict = "COMPARESTRICT" SP attribute SP comparator

SP value

searchkey-substr = "SUBSTRING" SP attribute SP comparator SP value

searchmod-depth = "DEPTH" SP number

searchmod-hard = "HARDLIMIT" SP nz-number

searchmod-limit = "LIMIT" SP number SP number

searchmod-make = "MAKECONTEXT" [SP "ENUMERATE"]

[SP "NOTIFY"] SP context

searchmod-ninh = "NOINHERIT"

searchmod-return = "RETURN" SP "(" [metadata-list] ")"

searchmod-sort = "SORT" SP "(" sort-list ")"

search-criteria = "ALL" / searchkey-equal / searchkey-comp /

searchkey-strict / searchkey-range /

searchkey-prefix / searchkey-substr /

"NOT" SP search-criteria /

"OR" SP search-criteria SP search-criteria /

"AND" SP search-criteria SP search-criteria

search-modifier = searchmod-depth / searchmod-hard /

searchmod-limit / searchmod-make /

searchmod-ninh / searchmod-return /

searchmod-sort

sort-list = sort-item *(SP sort-item)

sort-item = attribute SP comparator

store-entry = "(" entry-path *(SP store-modifier)

*(SP attribute-store) ")"

;; MUST NOT include same store-modifier twice

;; MUST NOT include same attribute twice

store-entry-list = store-entry *(SP store-entry)

;; MUST NOT include same entry twice

store-modifier = store-mod-unchang / store-mod-nocreate

store-mod-nocreate = "NOCREATE"

store-mod-unchang = "UNCHANGEDSINCE" SP time

string = quoted / literal

string-list = string *(SP string)

string-utf8 = quoted / literal-utf8

tag = 1*32TAG-CHAR

time = <"> time-year time-month time-day time-hour

time-minute time-second time-subsecond <">

;; Timestamp in UTC

time-day = 2DIGIT ;; 01-31

time-hour = 2DIGIT ;; 00-23

time-minute = 2DIGIT ;; 00-59

time-month = 2DIGIT ;; 01-12

time-second = 2DIGIT ;; 00-60

time-subsecond = *DIGIT

time-year = 4DIGIT

value = string

value-list = "(" [value *(SP value)] ")"

value-nil = value / nil

value-nildef = value-nil / "DEFAULT"

value-store = value-nildef / value-list / acl

url-acap = "acap://" url-server "/" url-enc-entry

[url-filter] [url-extension]

;; url-enc-entry interpreted relative to "/"

url-attr-list = url-enc-attr *("&" url-enc-attr)

url-auth = ";AUTH=" ("*" / url-enc-auth)

url-achar = uchar / "&" / "=" / "~"

;; See RFC1738 for definition of "uchar"

url-char = uchar / "=" / "~" / ":" / "@" / "/"

;; See RFC1738 for definition of "uchar"

url-enc-attr = 1*url-char

;; encoded version of attribute name

url-enc-auth = 1*url-achar

;; encoded version of auth-type-name above

url-enc-entry = 1*url-char

;; encoded version of entry-relative above

url-enc-user = *url-achar

;; encoded version of login userid

url-extension = *("?" 1*url-char)

url-filter = "?" url-attr-list

url-relative = url-acap / [url-enc-entry] [url-filter]

;; url-enc-entry is relative to base URL

url-server = [url-enc-user [url-auth] "@"] hostport

;; See RFC1738 for definition of "hostport"

9. Multi-lingual Considerations

The IAB charset workshop [IAB-CHARSET] came to a number of

conclusions which influenced the design of ACAP. The decision to use

UTF-8 as the character encoding scheme was based on that work. The

LANG command to negotiate a language for error messages is also

included.

Section 3.4.5 of the IAB charset workshop report states that there

should be a way to identify the natural language for human readable

strings. Several promising proposals have been made for use within

ACAP, but no clear consensus on a single method is apparent at this

stage. The following rules are likely to permit the addition of

multi-lingual support in the future:

(1) A work in progress called Multi-Lingual String Format (MLSF)

proposes a layer on top of UTF-8 which uses otherwise illegal UTF-8

sequences to store language tags. In order to permit its addition to

a future version of this standard, client-side UTF-8 interpreters

MUST be able to silently ignore illegal multi-byte UTF-8 characters,

and treat illegal single-byte UTF-8 characters as end of string

markers. Servers, for the time being, MUST be able to silently

accept illegal UTF-8 characters, except in attribute names and entry

names. Clients MUST NOT send illegal UTF-8 characters to the server

unless a future standard changes this rule.

(2) There is a proposal to add language tags to Unicode. To support

this, servers MUST be able to store UTF-8 characters of up to 20 bits

of data.

(3) The metadata item "language" is reserved for future use.

10. Security Considerations

The AUTHENTICATE command uses SASL [SASL] to provide basic

authentication, authorization, integrity and privacy services. This

is described in section 6.3.1.

When the CRAM-MD5 mechanism is used, the security considerations for

the CRAM-MD5 SASL mechanism [CRAM-MD5] apply. The CRAM-MD5 mechanism

is also susceptible to passive dictionary attacks. This means that

if an authentication session is recorded by a passive observer, that

observer can try common passwords through the CRAM-MD5 mechanism and

see if the results match. This attack is reduced by using hard to

guess passwords. Sites are encouraged to educate users and have the

password change service test candidate passwords against a

dictionary. ACAP implementations of CRAM-MD5 SHOULD permit passwords

of at least 64 characters in length.

ACAP protocol transactions are susceptible to passive observers or

man in the middle attacks which alter the data, unless the optional

encryption and integrity services of the AUTHENTICATE command are

enabled, or an external security mechanism is used for protection.

It may be useful to allow configuration of both clients and servers

to refuse to transfer sensitive information in the absence of strong

encryption.

ACAP access control lists provide fine grained authorization for

access to attributes. A number of related security issues are

described in section 3.5.

ACAP URLs have the same security considerations as IMAP URLs

[IMAP-URL].

ACAP clients are encouraged to consider the security problems

involved with a lab computer situation. Specifically, a client cache

of ACAP configuration information MUST NOT allow access by an

unauthorized user. One way to assure this is for an ACAP client to

be able to completely flush any non-public cached configuration data

when a user leaves.

As laptop computers can be easily stolen and a cache of configuration

data may contain sensitive information, a disconnected mode ACAP

client may wish to encrypt and password protect cached configuration

information.

11. Acknowledgments

Many thanks to the follow people who have contributed to ACAP over

the past four years: Wallace Colyer, Mark Crispin, Jack DeWinter, Rob

Earhart, Ned Freed, Randy Gellens, Terry Gray, J. S. Greenfield,

Steve Dorner, Steve Hole, Steve Hubert, Dave Roberts, Bart Schaefer,

Matt Wall and other participants of the IETF ACAP working group.

12. Authors' Addresses

Chris Newman

Innosoft International, Inc.

1050 Lakes Drive

West Covina, CA 91790 USA

Email: chris.newman@innosoft.com

John Gardiner Myers

Netscape Communications

501 East Middlefield Road

Mail Stop MV-029

Mountain View, CA 94043

Email: jgmyers@netscape.com

Appendices

A. References

[ABNF] Crocker, Overell, "Augmented BNF for Syntax Specifications:

ABNF", RFC2234, Internet Mail Consortium, Demon Internet Ltd,

November 1997.

<FTP://ds.internic.net/rfc/rfc2234.txt>

[BASIC-URL] Berners-Lee, Masinter, McCahill, "Uniform Resource

Locators (URL)", RFC1738, CERN, Xerox Coproration, University of

Minnesota, December 1994.

<ftp://ds.internic.net/rfc/rfc1738.txt>

[CHARSET-LANG-POLICY] Alvestrand, "IETF Policy on Character Sets and

Languages", work in progress.

[CRAM-MD5] Klensin, Catoe, Krumviede, "IMAP/POP AUTHorize Extension

for Simple Challenge/Response", RFC2195, MCI, September 1997.

<ftp://ds.internic.net/rfc/rfc2195.txt>

[IAB-CHARSET] Weider, Preston, Simonsen, Alvestrand, Atkinson,

Crispin, Svanberg, "The Report of the IAB Character Set Workshop held

29 February - 1 March, 1996", RFC2130, April 1997.

<ftp://ds.internic.net/rfc/rfc2130.txt>

[IMAP4] Crispin, M., "Internet Message Access Protocol - Version

4rev1", RFC2060, University of Washington, December 1996.

<ftp://ds.internic.net/rfc/rfc2060.txt>

[IMAP-ACL] Myers, J., "IMAP4 ACL extension", RFC2086, Carnegie

Mellon, January 1997.

<ftp://ds.internic.net/rfc/rfc2086.txt>

[IMAP-URL] Newman, "IMAP URL Scheme", RFC2192, Innosoft, July 1997.

<ftp://ds.internic.net/rfc/rfc2192.txt>

[ISO-10646] ISO/IEC 10646-1:1993(E) "Information Technology--

Universal Multiple-octet Coded Character Set (UCS)." See also

amendments 1 through 7, plus editorial corrections.

[ISO-C] "Programming languages -- C", ISO/IEC 9899:1990,

International Organization for Standardization. This is effectively

the same as ANSI C standard X3.159-1989.

[KEYWORDS] Bradner, "Key words for use in RFCs to Indicate

Requirement Levels", RFC2119, Harvard University, March 1997.

<ftp://ds.internic.net/rfc/rfc2119.txt>

[LANG-TAGS] Alvestrand, H., "Tags for the Identification of

Languages", RFC1766.

<ftp://ds.internic.net/rfc/rfc1766.txt>

[REL-URL] Fielding, "Relative Uniform Resource Locators", RFC1808,

UC Irvine, June 1995.

<ftp://ds.internic.net/rfc/rfc1808.txt>

[SASL] Myers, J., "Simple Authentication and Security Layer (SASL)",

RFC2222, Netscape Communications, October 1997.

<ftp://ds.internic.net/rfc/rfc2222.txt>

[SASL-ANON] Newman, C., "Anonymous SASL Mechanism", RFC2245,

November 1997.

[UNICODE-2] The Unicode Consortium, "The Unicode Standard, Version

2.0", Addison-Wesley, 1996. ISBN 0-201-48345-9.

[US-ASCII] "USA Standard Code for Information Interchange," X3.4.

American National Standards Institute: New York (1968).

[UTF8] Yergeau, F. "UTF-8, a transformation format of Unicode and ISO

10646", RFC2044, Alis Technologies, October 1996.

<ftp://ds.internic.net/rfc/rfc2044.txt>

B. ACAP Keyword Index

ACAP (untagged response) ................................... 26

ADDTO (untagged response) .................................. 40

ALERT (untagged response) .................................. 31

ALL (search keyword) ....................................... 36

AND (search keyword) ....................................... 36

AUTH-TOO-WEAK (response code) .............................. 19

AUTHENTICATE (command) ..................................... 31

BAD (response) ............................................. 30

BYE (untagged response) .................................... 30

CHANGE (untagged response) ................................. 41

COMPARE (search keyword) ................................... 36

COMPARESTRICT (search keyword) ............................. 36

CONTEXTLIMIT (ACAP capability) ............................. 27

DELETEACL (command) ........................................ 46

DELETED (intermediate response) ............................ 45

DELETEDSINCE (command) ..................................... 45

DEPTH (search modifier) .................................... 34

ENCRYPT-NEEDED (response code) ............................. 19

ENTRY (intermediate response) .............................. 37

EQUAL (search keyword) ..................................... 37

FREECONTEXT (command) ...................................... 39

GETQUOTA (command) ......................................... 48

HARDLIMIT (search modifier) ................................ 34

IMPLEMENTATION (ACAP capability) ........................... 27

INVALID (response code) .................................... 19

LANG (command) ............................................. 28

LANG (intermediate response) ............................... 28

LIMIT (search modifier) .................................... 34

LISTRIGHTS (command) ....................................... 47

LISTRIGHTS (intermediate response) ......................... 48

LOGOUT (command) ........................................... 29

MAKECONTEXT (search modifier) .............................. 34

MODIFIED (response code) ................................... 19

MODTIME (intermediate response) ............................ 38

MODTIME (untagged response) ................................ 42

MYRIGHTS (command) ......................................... 47

MYRIGHTS (intermediate response) ........................... 47

NO (response) .............................................. 29

NOCREATE (store modifier) .................................. 44

NOEXIST (response code) .................................... 19

NOINHERIT (search modifier) ................................ 35

NOOP (command) ............................................. 27

NOT (search keyword) ....................................... 37

OK (response) .............................................. 29

OR (search keyword) ........................................ 37

PERMISSION (response code) ................................. 19

PREFIX (search keyword) .................................... 37

QUOTA (response code) ...................................... 19

QUOTA (untagged response) .................................. 49

RANGE (search keyword) ..................................... 37

REFER (intermediate response) .............................. 38

REFER (response code) ...................................... 19

REMOVEFROM (untagged response) ............................. 41

RETURN (search modifier) ................................... 35

SASL (ACAP capability) ..................................... 27

SASL (response code) ....................................... 20

SEARCH (command) ........................................... 33

SETACL (command) ........................................... 46

SORT (search modifier) ..................................... 36

STORE (command) ............................................ 42

SUBSTRING (search keyword) ................................. 37

TOOMANY (response code) .................................... 20

TOOOLD (response code) ..................................... 20

TRANSITION-NEEDED (response code) .......................... 20

TRYFREECONTEXT (response code) ............................. 20

TRYLATER (response code) ................................... 20

UNCHANGEDSINCE (store modifier) ............................ 44

UPDATECONTEXT (command) .................................... 40

WAYTOOMANY (response code) ................................. 20

acl (attribute metadata) ................................... 12

anyone (ACL identifier) .................................... 17

attribute (attribute metadata) ............................. 12

dataset.acl (dataset attribute) ............................ 24

dataset.acl.<attribute> (dataset attribute) ................ 24

dataset.inherit (dataset attribute) ........................ 24

entry (predefined attribute) ............................... 11

i;ascii-casemap (comparator) ............................... 16

i;ascii-numeric (comparator) ............................... 16

i;octet (comparator) ....................................... 16

modtime (predefined attribute) ............................. 11

myrights (attribute metadata) .............................. 12

size (attribute metadata) .................................. 13

subdataset (predefined attribute) .......................... 11

value (attribute metadata) ................................. 13

C. Full Copyright Statement

Copyright (C) The Internet Society 1997. All Rights Reserved.

This document and translations of it may be copied and furnished to

others, and derivative works that comment on or otherwise explain it

or assist in its implmentation may be prepared, copied, published and

distributed, in whole or in part, without restriction of any kind,

provided that the above copyright notice and this paragraph are

included on all such copies and derivative works. However, this

document itself may not be modified in any way, such as by removing

the copyright notice or references to the Internet Society or other

Internet organizations, except as needed for the purpose of developing

Internet standards in which case the procedures for copyrights defined

in the Internet Standards process must be followed, or as required to

translate it into languages other than English.

The limited permissions granted above are perpetual and will not be

revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an

"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING

TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT

NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN

WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF

MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

 
 
 
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