JGroups - A Toolkit for Reliable Messaging

In the context of the IST POPEYE project, we have modified JGroups to support MANET environments.
You can find more information on our website: http://ast-deim.urv.cat/mchannel.
And in a recent publication: Pedro Garcia Lopez, Marc Espelt, Raul Gracia, Marcel Arrufat, Gerard Paris and Roc Messeger. "Topology-Aware Group Communication Middleware for MANETs". ICST COMSWARE 2009. Dublin, Ireland. http://ast-deim.urv.cat/mchannel_documentation/comsware_2009.pdf
Thanks to the excellent JGroups toolkit (and elegant architecture) we could create our MANET middleware in a straight-forward fashion.

Description:
M-Channel is a Topology-Aware Group Communication Middleware for MANETs based on the JGroups Tookit.
We have modified the JGroups protocol stack to incorporate two protocols: jOLSR and OMOLSR. jOLSR is a Java implementation of the MANET OLSR unicast protocol using UDP. On top of it, we have developed an overlay Multicast protocol (OMOLSR) that directly benefits from the jOLSR protocol to improve communication efficiency.
In our middleware, group membership is obtained from the overlay multicast protocol (OMOLSR), failure detection is received from the jOLSR protocol, and our modified flow control protocol benefits from jOLSR topology information.
Pedro Garcia-Lopez, Universitat Rovira i Virgili

Sunnyvale is mainly focused on enterprise application integration and software development. We benefitted from JGroups capabilities in our latest project named ALA (Adapter-Logic Application).
As you might have understood our product is supposed to be some kind of adapter, able to connect to different platforms allowing them to talk together and exchange data in XML format. We decided to design ALA to have front-end components (named controllers) and backend components (connectors) so we can combine them and create services that can be consumed in a pure SOA style.
For a big Italian gas and energy company we deployed a controller module that connect to a SAP R/3 gateway and waits for outgoing (from SAP point of view) RFC calls or IDOCs to be exchanged with non-SAP world (Tibco Businessworks, Axis web services etc). Embedding JGroups into ALA Controller for SAP R/3 allowed us to start many ALA instances in a single cluster group with only one node active at a time. JGroups APIs are responsible for cluster changes replication to all components sharing the same channel so we ensure high avaibility of our software.
Denis Maggiorotto

HA-JDBC is a JDBC driver proxy that adds light-weight, transparent, fault tolerant clustering capability to any JDBC driver or datasource.
Using transaction-aware, statement-based replication, an application can survive a database node failure without interrupting current queries or transactions.
Additionally, HA-JDBC can help scale query-heavy applications by balancing database reads across individual database nodes.
HA-JDBC uses JGroups for database node state management and for coordinating identifier generation mechanisms (e.g. sequences, identity columns).
Paul Ferraro

We use JGroups as the underlying framework for implementing the clustering features of the JBoss J2EE Application server. JGroups gave us the opportunity to concentrate our efforts on the clustering features of JBoss instead of the very complex aspects of reliable group communication protocols. Through a very flexible and esthetic API we were able to built our clustering features without making strong assumption about the underlying protocols and network scheme (LAN, WAN, ...) that the end-users would face. As JGroups is an LGPL Open Source Project (which JBoss, as an open source project, requires), we were able to quickly find some minor bugs and implement new features that fitted our needs. Furthermore, thanks to Bela Ban recognized strong competencies in this arena and its growing user community, JGroups is a very dynamic project.
Sacha Labourey (co-developer of JBoss Clustering)

FactoryPMI is a popular commercial SCADA application from Inductive Automation. It is a distributed HMI package designed for industrial control applications, from process monitoring to full control. JGroups is used between "FactoryPMI Gateway" web servers to form a cluster that provides client load balancing and connection redundancy.
JGroups has allowed FactoryPMI clustering to be easy to configure and incredibly reliable.
Nathan Boeger

Jtrix is all about creating distributed applications which can move themselves around and find their best home. By using JGroups we are able to cluster Jtrix nodes. Several servers can cluster together to present a unified runtime environment, which is actually physically split up over several machines. JGroups handles communication between the nodes. By virtue of its maturity, modular design and comprehensive documentation we were able to add clustering at a fraction of the effort it would have taken to create our own system, which would have been significant.
Nik Silver (jtrix.org)

GroupPac is a open source implementation of the Fault-Tolerant CORBA specification. Because of the complexity of implementing reliable multicast group communication, GroupPac was limited to passive replication.
By using JGroups, we were enabled to redirect our efforts to others equally important aspect of the FT-CORBA specification, such as scalability and group communication tool support.
Because of the time and effort spared by JGroups, GroupPac now offers active replication through a simple, elegant way of plugging in any group communication tool. Of course, the only supported group communication tool is JGroups!
Ricardo S. Padilha (analyst and developer of GroupPac)

INSP (Internet Seismic Processing System) is a Java based client-server application that enables geophysicists to remotely create and submit for execution seismic processing flows, and also to visualize and QC seismic data. An important feature of INSP is the capability for real-time collaboration. INSP allows users from geographically distributed locations to interact by sharing cursors, do collaborative picking and coordinated image browsing.
The collaboration module is built on top of JGroups, which takes care of multicast and the group membership management. Using JGroups allowed us to delegate the transport related problems and concentrate on the application details.
Ovidiu Feodorov (3DGeo Development Inc.)

The Autodesk^® LocationLogic platform supports carrier network and location determination infrastructure, geographic content, and location-sensitive applications. ARC, a core component of the LocationLogic platform is a replicable cache based on reliable IP Multicasting feature of JGroups.
Using JGroups allows the Autodesk^® Location Services Software Development team to provide a reliable cache replication mechanism without making many assumptions about underlying network capabilities. JGroups also allows us to overcome the limitations of Distributed JMS features in Application Servers.
Kumar Mettu (Autodesk Location Services)

d4cms is a CMS which specializes in being highly scalable and available while generating dynamic content. The underlying message-oriented-middleware, which aims to be fault tolerant, needs to communicate between several VMs and physical Servers. Our former RPC-via-HTTP implementation had several drawbacks facing the restrictions of HTTP and the complexity of ensuring atomicity between all members of a cluster.

Now, using a 'Building Block' based on JGroups - namely the NotificationBus - greatly eases our lifes.

Its extremely simple API, was exactly what we needed. Furthermore its performance is dramatically better than the solution we now dropped.
Uwe Schaefer, Developer at imagetransfer GmbH

The Group Communication Toolkit (GCT) is a .NET toolkit that provides reliable and customisable group communication. The toolkit is written in C# and can be incorporated into any .NET application.

The GCT is based on JGroups. It takes the design of JGroups, adapts it to the .NET environment and expands it to provide .NET Remoting group communication.
Chris Koiak, Computer Science Department The University of Strathclyde

OSCache is a widely used, high performance J2EE caching solution.

I needed to add some clustering to OSCache due to a requirement at work, and I was pleasantly surprised at how easy it was to use JGroups for this. It saved me a *lot* of time and pain so thank you, your efforts are much appreciated. You'll hopefully be as pleased as I am to know the clustering support has generated quite a bit of new interest in OSCache, far more than I had been expecting.
Chris Miller, Lead Developer OSCache

JCS is a distributed caching system written in java for server-side java applications. It is intended to speed up dynamic web applications by providing a means to manage cached data of various dynamic natures. Like any caching system, the JCS is most useful for high read, low put applications. Dynamic content and reporting systems can benefit most. However, any site that repeatedly constructs pages, dropdowns, or common search results form a database that is updated at intervals (rather than across categories continuously) can improve performance and scalability by implementing caching. Latency times drop sharply and bottlenecks move away from the database in an effectively cached system.

JOnAS (Java Open Application Server) is an Open-Source / LGPL implementation of J2EE [TM]. It is developed within the ObjectWeb consortium, an open-source software community which aims at developing distributed middleware. JOnAS is a widely used application server which counts many operational applications.
JGroups has been integrated within JOnAS for the purpose of implementing clustering features. JOnAS provides clustering mechanisms at two levels, Web (http requests) and EJB (rmi requests). JGroups is used for HTTP session replication within a cluster, through the Tomcat-Replication module, and for EJB components clustering. In this last case, the "Clustered Method Invocation" protocol of JOnAS makes use of JGroups for synchronising registries of the cluster nodes. See the JOnAS documentation about clustering for more details.
Francois Exertier, JOnAS Chief Architect, Bull, JOnAS Team

Jetty is a popular open source web container. From a number of different backends to its distributable HttpSession manager, the JGroups based implementation is my current recommendation.
JGroups' flexibility enables our users to tailor it to their networking environment. It is self-contained, needing no additional complex infrastructure, making installation and use simple. It is lightweight, partnering well with Jetty, which is streamlined for use on small as well as large platforms.
The API is straightforward and powerful, allowing me to become productive very quickly. These features combine to form a very useful piece of infrastructure that no cluster should be without.
Jules Gosnell, author of Jetty distributable HttpSession manager

The first implementation of Tomcat session replication was made using JGroups. Thanks to JGroups I was able to within days implement session replication since I didn't have to write any of the underlying logic.
JGroups will be one of the pluggable communication/cluster adapters in Tomcat 5.x
Filip Hanik, Lead Developer Session Replication Tomcat 4.X/5.X

This framework is based on a generic RMI interceptor design ( net.sf.extrmi).
JGroups has been successfully used to provide transparent (client-side) RMI multicast and FT replication support. Both closed group (VSYNC) and open group (clients are not part of the multicast group) are supported. Strict consistency (as offered by VSYNC) is maintained for both configurations. It also supports most replication semantics seen in the FT-CORBA standard, as well as the concept of object group.
More efforts are yet to be made to extend this framework to support PBCAST (www.jgroups.org) type of optimistic multicast protocols and still meet strict consistency and high reliability requirements commonly defined for distributed FT computing.
Contribution/comments are welcome! Wenbo Zhu