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8 posts from August 2010


Troubleshooting JGroups & Multicast IP

Although the jgroups manual implies that you should start looking for a new job if you can not figure out what is wrong with jgroups and multicast ip, I find that in the real world, we systems administrators support many different types of "clusters".  We've got Oracle RAC clusters, GFS Clusters, VCS Clusters, Microsoft clusters, hardware clusters, load-balancing clusters with mod_jk or mod_proxy, etc.  A JGroups cluster is simply one of the many different types of clusters we support and its default configuration uses multicast IP, which is not something we run into every day.

I've written a couple of short posts already on jgroups problems (see JBoss: Clustered Node Startup Failures & JBoss:  Overlooked Solution for JGroups-Related Startup Errors) but I thought a short troubleshooting guide might be helpful.  This post will serve to consolidate the two previously mentioned posts plus add some additional recently discovered information.  The howto leans more towards running jgroups services on a unix-like platform running jboss but, for the most part, the information in it applies to Windows as well.  I've not had much of an opportunity with jgroups over a WAN or across multiple VLANs so if you are doing that and having problems, this post may not be all that helpful but if you are having problems with a jgroups cluster over a Cisco LAN and all your servers are on the same network segment (a fairly common deployment configuration), this howto is for you!

Let me know if you've come across other causes of multicast IP failures with jboss/jgroups and I'll add them to the HOWTO.

Here is the link to the new doc =>  HOWTO: Troubleshoot JGroups and Multicast IP Issues


WebSphere Application Server v8.0 is in Beta

I don't typically write about WebSphere but it is a pretty big player in the java application server space and a couple of days ago, IBM released WebSphere Application Server v8.0 as beta.  Not intended at all for production deployments, this version does give us something to play with.  WebSphere App Server v8 looks like it is IBM's first JEE6 implementation, supporting the following JEE6 features:

  • Enterprise JavaBeans 3.1
  • Java Persistence API (JPA) 2.0
  • JavaServer Faces (JSF) 2.0
  • JavaServer Pages (JSP) 2.2
  • Servlet 3.0
  • Java EE Connector Architecture 1.6

A full list of capabilities is on the WebSphere App Server v8.0 Overview page.  The WebSphere App Server v8.0 Download page lists downloadable binaries for Windows, Linux, AIX, HP-UX, zOS, and Solaris.


Tomcat 7.0.2 Beta Released

The Tomcat project team announced the release of the second beta of Tomcat 7.  This release incorporates fixes from the initial tomcat 7.0.0 beta release from a few weeks ago.  This version also incorporates a bunch of fixes and updates from unreleased version 7.0.1.

The Tomcat 7.0.2 Changelog contains more information on what's changed and downloads are available at a mirror near you!  A Tomcat 7 Migration Guide is also available for folks planning to upgrade from tomcat 5.5 or 6.0.