JavaGroups is a Java package for reliable group communication. It consists of 3 parts: The first part is a socket-like API for application development, providing methods for joining and leaving a group, sending multicast messages to members, and receiving notifications when members join/leave/crash. The second part is a protocol stack which implements reliable communication, and can be configured according to the QoS desired. New protocols can easily be added, and existing ones removed/replaced/modified. The third part is a set of building blocks which give the application/protocol programmer high-level abstractions (e.g. DistributedHashtable, derived from java.util.Hashtable, which is similar to Linda/JavaSpaces).
JBoss is an Open Source, standards-compliant, Enterprise JavaBeans application server implemented in pure Java. JBoss provides JBossServer, the basic EJB container and JMX infrastructure, JBossMQ for JMS messaging, JBossMail for mail, JBossTX for JTA/JTS transactions, JBossSX for JAAS based security, JBossCX for JCA connectivity, and JBossCMP for CMP persistence. It integrates with Tomcat Servlet/JSP container and Jetty Web server/servlet container, and enables you to mix and match these components through JMX by replacing any component you wish with a JMX-compliant implementation for the same APIs. The goal is to provide a full J2EE stack in the Free/Open Source software world.
Momoko is a generic, object-oriented, modular, extensible environment for creating multi-user environments. It is suitable for writing MUDs, servers, and community-based Web sites. It is written in pure Java and supports Java and Python as internal scripting languages. Momoko provides facilities for organizing objects into tree-based hierarchies, orthogonal persistence, a transparent distributed objects system, remote access to source code and user files via WebDAV, a telnet-enabled shell for manipulating the object database, and an integrated build process which can be triggered remotely.
The Spread Toolkit provides tools for developing reliable and robust distributed applications ranging from collaboration tools to fault-tolerant database servers to replicated Web servers. It consists of a daemon which provides multicast messaging, reliability, ordering, and membership services, and a library which applications link with. Spread provides a simple API for writing group applications and is designed to provide high performance for local and wide area networking applications.
Aorta is a load-balancing clustered P2P application. It executes Tasklets (which have the ability to split themselves into sub tasks that can be executed in pararell). A typical cluster contains of a LAN with 1-256 computers, each one running aorta. A Tasklet can be of any type ranging from encoding MP3s, Genomic DNA Alignment, or simply to rendering Web pages for high speed/heavily loaded Web sites. You can make functions calls to C/C++, applications like Matlab, etc.