The goal of the Apache Tomcat Project is to provide commercial-quality server solutions based on the Java Platform that are developed in an open and cooperative fashion. Tomcat 3.x is an implementation of the Java Servlet 2.2 and JavaServer Pages 1.1 Specifications. Tomcat 4.x is an implementation of the Java Servlet 2.3 and JavaServer Pages 1.2 Specifications, and is a re-implementation of the Tomcat servlet engine from the ground up. The current branch, Tomcat 5.x, is an implementation of the Java Servlet 2.4 and JavaServer Pages 2.0 specifications, with increased attention to scalability, reliability, and management functionality.
YaCy is a search engine that anyone can use to index the Internet (WWW and FTP) or to create a search portal for others (Internet or intranet). The scale of YaCy is limited only by the number of users. and can index billions of web pages. In P2P mode it is fully decentralized. All users of the search engine network are equal and it is not possible for anyone to censor the content of the distributed index.
RabbIt is a mutating, caching Web proxy used to speed up surfing over slow links like modems. It does this by removing advertising and background images and scaling down images to low quality JPEGs. RabbIT is written in Java and should be able to run on any platform. It does depend upon an image converter if image scaling is on. The recommended image converter is "convert" from the ImageMagick package.
Restlet is a REST framework for Java. It supports all REST concepts (Resource, Representation, Connector, Component, etc.) and is suitable for both client and server Web applications. It supports major Web standards like HTTP, SMTP, XML, JSON, WADL, and Atom. Many extensions are also available to integrate with Servlet, Spring, Jetty, Grizzly, Simple, JAXB, JAX-RS, JiBX, Velocity, or FreeMarker. A GWT version is also available.
BIE (Business Integration Engine) is an open source integration system that makes it easy for organizations to exchange data with external trading partners regardless of their native applications. It competes in the same space as applications like Microsoft BizTalk except that it is truly cross-platform since it written in Java.
BEJY is a modular server application. It is packaged, by default, as a Web application container and mail server with SSL. It has functionality similar to inetd, and has some helper classes/functions to ease the implementation of new protocols. It provides a generic multithreaded TPC/IP server implementation with optional SSL support, covering the complete connection and thread management. Each supported service provides its protocol implementation. The current version comes with HTTP, SMTP, POP3, and IMAP protocol implementations. The HTTP protocol implementation also contains a servlet engine, a JSP 1.2 engine, a handler to invoke CGI, and other useful things. The mail protocols require a database using JDBC, as MySQL, MSSQL, and others.