Some Open Source Project
JoinWork
http://www.joinwork.net/document/developer/sample_apply.htm
a work flow model
OSWorkFlow
http://www.opensymphony.com/osworkflow/
OSWorkflow is fairly different from most other workflow systems available, both commercially and in the open source world. What makes OSWorkflow different is that it is extremely flexible. This can be hard to grasp at first, however. For example, OSWorkflow does not mandate a graphical tool for developing workflows, and the recommended approach is to write the xml workflow descriptors 'by hand'. It is up to the application developer to provide this sort of integration, as well as any integration with existing code and databases. These may seem like problems to someone who is looking for a quick "plug-and-play" workflow solution, but we've found that such a solution never provides enough flexibility to properly fulfill all requirements in a full-blown application.
Typestry
http://jakarta.apache.org/tapestry/
Tapestry is a powerful, open-source, all-Java framework for creating leading edge web applications in Java.
Hibernate
Hibernate is a powerful, ultra-high performance object/relational persistence and query service for Java. Hibernate lets you develop persistent classes following common Java idiom - including association, inheritance, polymorphism, composition and the Java collections framework. The Hibernate Query Language, designed as a "minimal" object-oriented extension to SQL, provides an elegant bridge between the object and relational worlds. Hibernate also allows you to express queries using native SQL or Java-based Criteria and Example queries. Hibernate is now the most popular object/relational mapping solution for Java.
Maven
Maven is a Java project management and project comprehension tool. Maven is based on the concept of a project object model (POM) in that all the artifacts produced by Maven are a result of consulting a well defined model for your project. Builds, documentation, source metrics, source cross-references and a countless number of reports are all controlled by your POM. Look here to see the full list of Maven's features.
Spring
http://www.springframework.org/
Spring is a layered Java/J2EE application framework, based on code published in Expert One-on-One J2EE Design and Development by Rod Johnson
WebWork
http://www.opensymphony.com/webwork/
WebWork is a Java web-application development framework. It is built specifically with developer productivity and code simplicity in mind. WebWork is built on top of XWork, which provides a generic command pattern framework as well as an Inversion of Control container. In addition to these features, WebWork provides robust support for building reusable UI templates, such as form controls, UI themes, internationalization, dynamic form parameter mapping to JavaBeans, robust client and server side validation, and much more.
OpenLDAP
OpenLDAP is an open source implementation of the Lightweight Directory Access Protocol.
JetSpeed
http://portals.apache.org/jetspeed-1/
Jetspeed is an Open Source implementation of an Enterprise Information Portal, using Java and XML. A portal makes network resources (applications, databases and so forth) available to end-users. The user can access the portal via a web browser, WAP-phone, pager or any other device. Jetspeed acts as the central hub where information from multiple sources are made available in an easy to use manner.