RFC1895 - The Application/CALS-1840 Content-type

王朝other·作者佚名  2008-05-31
窄屏简体版  字體: |||超大  

Network Working Group E. Levinson

Request for Comments: 1895 Accurate Info. Sys., Inc.

Category: Informational February 1996

The Application/CALS-1840 Content-type

Status of this Memo

This memo provides information for the Internet community. This memo

does not specify an Internet standard of any kind. Distribution of

this memo is unlimited.

Abstract

This memorandum provides guidelines for using the United States

Department of Defense Military Standard MIL-STD-1840, "Automated

Interchange of Technical Information," with the Internet electronic

mail standards, RFC822 and RFC1521. Electronic mail provides a

more convenient mechanism that delivery via physical media for

certain types and quantities of data. Software already exists to

support data exchanges based on MIL-STD-1840 and it can continue to

be used in conjunction with electronic mail exchanges defined in this

document. This document defines a new media type and a MIME message

strUCture for exchanging data in conformance with MIL-STD-1840.

1. Introduction

The United States Department of Defense (DOD) has defined a standard,

MIL-STD-1840 [1840], for the exchange of digital data. Most

applications of that standard use 9-track tape as the transport

medium. The Application/CALS-1840 media-type is proposed to

facilitate such exchanges using the Multipurpose Internet Mail

Extensions [MIME] and network based transport media, i.e. electronic

mail [822].

This memo has been reviewed and authorized by the Continuous

Acquistion and Life-cycle Support (CALS) Industry Steering Group

(ISG). CALS is a US DOD initiative for the use and exchange of

digital data. The Industry Steering Group, which consists of members

drawn from government and industry, guides the development of CALS

standards such as [1840].

2. Definition

An [1840] exchange consists of a set of files with well defined file

names (see below). Each set consists of a declaration file and one

or more data files. The data files, in turn, consist of header

records immediately followed by the data. The data itself may be

formatted in accordance with a published specification or a

contractual agreement.

MIL-STD-1840 encodes the file's data type in the file name.

It might seem appropriate to transform the 1840 headers into MIME

headers and use the appropriate media type, essentially transforming

the 1840 files into MIME body parts. There are three reasons for not

doing that. First, not all of the "types" used in [1840] are

registered MIME types. Second, there exists an installed base of

software capable of reading the 1840 formatted files and processing

the data appropriately. Finally the three existing revisions to the

standard have maintained the same file structure. Consequently, a

processor for the data may be able to handle any one of the

standard's revisions. Thus, a single Application/CALS-1840 is being

proposed and its body part body contains headers and data in the

[1840] format.

A set of related files constitutes a "transfer unit" in 1840 and each

transfer unit shall correspond to a Multipart/Mixed MIME entity.

Included in each transfer unit is a declaration file which shall be

the first body part in the Multipart/Mixed entity. Several transfer

units may be included in a single MIME message.

2.1 Registration Information

The following form is copied from RFC1590, Appendix A for the

purpose of registering this media-type.

To: IANA@isi.edu

Subject: Registration of new Media Type content-type/suBType

Media Type name: Application

Media subtype name: CALS-1840

Required parameters: filename, version

Optional parameters: None

Encoding considerations: Any valid MIME encodings my be used

Security considerations: Depends solely on the referenced type

Published specification: This document

Person & email address

to contact for further

information: Alan Peltzman <peltzmaa@ncr.disa.mil>

+1 (703) 735-3568

Defense Information Systems Agency

Center for Standards

Code JIEO/JEBEB

10701 Parkridge Blvd

Reston, VA 22091-4398

2.2. The Filename Parameter

The filename parameter gives the transfer unit filename as defined by

[1840]. The parameter's value, called <1840-name>, has the syntax

given by the grammer below.

1840-name := "D" 1840-tuseq [ 1840-type 1840-dfseq ]

1840-type := letter ; limited to the set defined in

; the appropriate version of

; [1840, Table III]

1840-tuseq := 1840-seq

1840-dfseq := 1840-seq

1840-seq := alphnum alphnum alphnum

alphanum := letter / digit

letter := "A" / "B" / "C" / "D" / "E" / "F" / "G" /

"H" / "I" / "J" / "K" / "L" / "M" / "N" /

"O" / "P" / "Q" / "R" / "S" / "T" / "U" /

"V" / "W" / "X" / "Y" / "Z"

digit := "0" / "1" / "2" / "3" / "4" / "5" /

"6" / "7" / "8" / "9" /

All Application/CALS-1840 body parts in a single Multipart/Mixed MIME

entity shall have the same <1840-tuseq>. Within a single message all

filename values shall be unique.

Notes: 1) Tuseq and dfseq correspond to transfer unit sequence number

and data file sequence number respectively. 2) The filename for a

declaration file has the form "D" 1840-tuseq and for data files, the

form "D" 1840-tuseq <letter> 1840-dfseq.

2.3. The Version Parameter

The specversion parameter's value shall indicate the particular

version of MIL-STD-1840 to which the data conforms. Valid values

are:

MIL-STD-1840C, 0, 199XXXXX

MIL-STD-1840B, 0, 19921103

MIL-STD-1840A, 0, 19871222

Notes: (1) The value "199XXXXX" is to be replaced with the actual

issue date for MIL-STD-1840C. (2) The embedded blanks in the above

strings are required, hence the value must be enclosed in quote marks

(").

3. Example

In the example below a single transfer unit is provided. It consists

of three data files, the declaration, a contract defined file and an

IGES file. The headers and data are in accordance with MIL-STD-

1840B. The content-transfer-encoding perserves the data file's fixed

record length.

To: you@some.org

From: me@here.com

Date: Fri, 03 Nov 1995 18:23:10 -0500

MIME-Version: 1.0

Content-Type: Multipart/Mixed;

Boundary="DISA CFS - SFC ASID"

--DISA CFS - SFC ASID

Content-Type: Application/CALS-1840; filename=D001;

version="MIL-STD-1840B, 0, 19921103"

Content-Transfer-Encoding: Base64

[Declaration File]

--DISA CFS - SFC ASID

Content-Type: Application/CALS-1840; filename=D001A001;

version="MIL-STD-1840B, 0, 19921103"

Content-Transfer-Encoding: Base64

[Data File -- Contract Defined including headers]

--DISA CFS - SFC ASID

Content-Type: Application/CALS-1840; filename=D001Q001;

version="MIL-STD-1840B, 0, 19921103"

Content-Transfer-Encoding: Base64

[Data File -- Raster including 1840 headers]

--DISA CFS - SFC ASID--

4. Security Considerations

None of the body parts, as constitued, represent executable data.

When the 1840 file format is processed the resultant data may be

executable. Processing will be under the control of the process

associated with Application/CALS-1840.

Classified information or other information that cannot be disclosed

except to authorized personnel should not be sent via the Internet

without using appropriate privacy enhancements, [PEM], [MOSS], or

other privacy mechanism.

5. Acknowledgments

The author acknowledges the encouragement of Alan Peltzman, US DOD,

DISA, and the suggestions of Richard Klobuchar, SAIC.

This work was supported under U.S. Dept. of the Army, Contract

DAAB07-93-D-T001 and prepared under the direction of the MIL-STD-1840

Revision C Review Team.

6. References

[1840] MIL-STD-1840B, "Automated Interchange of Technical

Information", US Department of Defense, 3 November 1992.

[822] Crocker, D., "Standard for the Format of ARPA Internet

Text Messages", STD 11, RFC822, UDEL, August 1982.

[MIME] Borenstein, N. and N. Freed, "MIME (Multipurpose Internet

Mail Extensions): Mechanisms for Specifying and

Describing the Format of Internet Message Bodies", RFC

1521, Bellcore and Innosoft, September 1993.

[MOSS] Crocker, S., Freed, N., Galvin, J., and S. Murphy, "MIME

Object Security Services", RFC1848, Cybercash, Innosoft,

TIS, October 1995.

[PEM] Linn, J., "Privacy Enhancement for Internet Electronic Mail:

Part I: Message Encryption and Authentication Procedures",

RFC1421, IAB IRTF PSRG, IETF PEM WG, February 1993.

9. Author's Address

Edward Levinson

Accurate Information Systems, Inc.

2 Industrial Way

Eatontown, NJ 07724-2265

USA

Phone: +1 908 389 5550

 
 
 
免责声明:本文为网络用户发布,其观点仅代表作者个人观点,与本站无关,本站仅提供信息存储服务。文中陈述内容未经本站证实,其真实性、完整性、及时性本站不作任何保证或承诺,请读者仅作参考,并请自行核实相关内容。
 
 
© 2005- 王朝網路 版權所有 導航