Rajesh and team are hard at work plugging in more JMX monitoring features in WebSpace Server and Liferay (see the detailed proposal). This will give administrators a nice overview of performance metrics, fault diagnostics, and in general keeping WebSpace running smoothly. Speaking of performance, Srikanth has also written up an integration of WebSpace Server with Apache Solr, which is recommended for use with GlassFish clusters. The WebSpace Wiki is a great source of material like this for developers and administrators.

John just posted a very nice screencast showing how to go From Zero to a v2 Cluster in 10 minutes, including download, asadmin configuration, GUI configuration, and tests. Pretty neat, check it out. Easy configuration of Clustering is one of the assets of GlassFish, and, as users move into production, the interest is growing. A couple of weeks ago I highlighted some Posts and Slides on Clustering and also uploaded slides to SLX and SlideShare and they have proven quite popular.

Given the interest, I have started collecting links for a Proposed Webinar Set on the topic; hopefully in January.

Clustering - supported in GlassFish since Sept 2007 - will be further improved in the GFv2.1 release (companion to SailFin). One of the improvements is Apache 2.2 support and Kshitiz has written an good writeup on the configuration steps and mentions the automated support also. Clustering is used for horizontal scalability and high availability; interest and use of the feature is increasing quickly with GlassFish deployments. Check the official documentation and our recent White Paper on HA. Also, Satyajit just put together a set of slides on the topic (writeup, PDF@SLX, SlideShare).

We will cover Clustering in a future TA Online event; the Seam Online Event on Thursday went very well and I think the new format with multiple, shorter, presentations around a single topic is well suited to this new medium.

Shreedhar is announcing a new build release for Shoal 1.1, the GlassFish dynamic clustering framework. Version 1.1 is work in progress and offers a JoinedAndReadyNotificationSignal, multiple clusters support for the same member (useful for Sailfin's Converged Load-Balancer), cross subnet clustering support, etc.

The most important driver for the Shoal project lately has been the Sailfin project (now in alpha stage). Compared to HTTP, SIP sessions are smaller in size but greater in number so this has been a very interesting set of constraints for this group management and data replication technology.

If you're new to the technology, Shoal is at the heart of the GlassFish v2 clustering architecture and uses JXTA as an underlying technology. This article is a nice introduction if you're new to the technology which is also used in other projects such as GreenFire.

Kedar has a blog on GlassFish cluster administration (domain, DAS, Node Agents, Instances, ...). This should come handy to people looking at understanding when synchronisation actually happen with the DAS (Domain Administration Server) which is where the centralized repository sits. We often claim to have BEA's features at JBoss' price. This centralized cluster management is certainly one such feature.

Most GlassFish subprojects (Grizzly, Metro, Woodstock, HK2, Jersey, mq, Mojarra, ...) can be used independently from the application server. Project Shoal is no exception. This Group Management Service used by GlassFish clustering can also be applied to other use-cases.

Community members Juan Pedro Danculovic and Diego Naya have a nice article over on java.net covering in a single place most of the Shoal features. It goes into the definition of all the basic terms such as Group, Member, Member Token, Spectator, Core, Group Management Service, Components, and Signals. The article also covers how to integrate your own code into the clustering infrastructure (not only for Java EE applications, but SE applications too). Given the artifact's size (JARs are less than 2MB), together with a stripped-down GlassFish v3, the possibilities become very interesting.

Previous Shoal resources include:
•  Previous Shoal posts
•  Other introductory Shoal article
•  GlassFish podcast interview about GlassFish Clustering and Shoal

Linda has two new posts; one builds on her popular JMS 101 introduction; in the Follow-up Entry she expands the hello world example to use JNDI and administered objects. The second entry is more advanced and covers High Availability in JMS. Linda talks about brokers, clusters, and stores in the OpenMQ implementation and points to the future directions for the project. The OpenMQ team is always interested in your comments at USERS@mq; the binaries are included in GlassFish and separately at their Download Page. Enjoy!

• How-Tos: Clustering, Launchd, Metro & JAXB and GF Profiles • Community - Interviews, RedHat and OpenJDK and Governance Board • Future Releases - IPS in UC2, GFv3 Schedule and Sailfin Tooling • Adoption Indicators - New GeoMap, Nuxeo Core and GF and Geronimo • Web.Next - JavaFX, jMaki Charting, Bayeux/Comet and JAX-RS • Events - IJTC • Try this: GlassFish.ORG

In this third episode of the GlassFish Podcast, HA engineering lead Shreedhar Ganapathy discusses project Shoal and how it's applied to GlassFish clustering as a GMS (Group Management System) technology but also how it does in-memory replication to provide High Availability (depending on the profile used). If you're interested in the max number of nodes in a cluster, buddy replication, recovery failure notification, sticky load-balancing, availability level, or distributed state cache, this interview gets into all of these. It also tries to go from first steps to setup the cluster to tips on running and managing it effectively. Finally it touches on what's next for clustering in GlassFish in the next 18 months.

This is a longer podcast that the earlier two (40 minutes). Feedback is welcome about what you think is the optimal duration (although I suspect this varies depending on one's commute).

When it comes to clustering in an application server, defining the vocabulary is the first thing that needs to be done. This new article does this and much more. It defines key concepts for GlassFish such as Domain Administration Server (DAS), Node Agents, server instances, discusses deployment topologies, and explains how the Shoal and JXTA technologies are used to set up the cluster and replicate data in-memory. It also provides instructions on how to get the GlassFish "Cluster" profile running.

The second article explains how the application server can take advantage of the Zones technology built in Solaris 10 and OpenSolaris. It has a quick intro on what are Solaris zones and how they provide isolated environments for application instances. Propagation among zones can complicate installations and updates, so the article going into the details of installing and using the GlassFish application server in a global or a sparse zone. It also covers upgrading from previous versions of the software that may have come bundled with Solaris.

One of the key features in GlassFish v2 is clustering support. With greater power comes greater responsibility, so Prashanth has a detailed post on setting up and using the clustering, load-balancing and data replication features from the newly released GlassFish v2. Prashanth goes into the various options in terms of replication and load-balancing using either software (web servers) or hardware solutions. It also covers more advanced topics such as establishing a secure connection between the DAS (Domain Admin Server) and the web server. Shreedhar comments with interesting GMS/Shoal prerequisites like syncing machine clocks.

Update: The clustering features briefly described here are meant to give readers a feel for how this all works and is not intended to replace the product documentation
•  Sun Java System Application Server 9.1 High Availability Administration Guide
•  Sun Java System Application Server 9.1 Deployment Planning Guide
•  Sun Java System Application Server 9.1 HADB Commands Reference Manual.

A tip from Shalini: 2 Machine Cluster Setup for GlassFish - CLI mode

A recent USERS thread asked about Load Balancers and GlassFish; from there and with a couple of additions: • Load Balancer Module Home Page • Daniel on Balancing with Mod_JK • Prashanth on BigIP - F5, a hardware appliance. • Sreeram and Jason on using Sun Secure Application Switch • Pankaj on using LB Plugin (which can be used with SJS Web Server) • More LB Plugin Info from Satish.

We are going to start an FAQ at the GlassFish Wiki for frequent questions like this; stay tuned.

On a different direction, one of Sailfin's improvements is integrated Load Balancer - see Milestone 1.

Shreedhar is beginning to document how Shoal works and has just written a Shoal 101. Shoal is the Group Management Service (GMS) used in GlassFish but it can also be used independently. The writeup includes a Sample Example that shows how to register for group events, join a pre-defined group, get notifications of group events, send/receive messages, and leave the group.

Artima has a feature entry on Project Shoal which just reached 1.0 Early Access. Project Shoal is a Group Management System heavily used in GlassFish v2 but it can also be used in other contexts. The JXTA implementation used by default and which brings close-to-zero clustering configuration in GlassFish can also be replaced (by JGroups for instance) using the appropriate SPIs.

One of the reasons for the GlassFish v2 delay was the time needed to make sure we could go through as many customer scenarios as possible, specifically in the clustering area. Shreedhar reports on the 8-node GlassFish clustering quality tests which led to improved quality of Shoal itself. This and future use of Shoal in SailFin (the SIP supported application server based on GlassFish with Ericsson as a major contributor) shows the greater GlassFish Community at work.