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I am charged with prototyping a port of a suite of Web Applications from Web Logic to JBoss EAP (version 6.2). I am by no means an expert at either Web Logic or JBoss.

The high-level requirements of this system are as follows:

a. Load balancing will be handled by hardware sitting in front of the JBoss Servers.

b. We DON'T want or need to deploy a separate Apache Web Server. The requirement is to use the internal out-of-the-box web server that comes with JBoss EAP.

c. However we do want clustering for high-availability purposes and session replication.

d. The domain-model features of JBoss EAP (for deployment, etc.) are a nice-to-have, but might be expendable if it creates too many complications, and in that event we could go with clustered standalone servers.

In an effort to achieve the above, I am starting JBoss with the full-ha domain profile. I can't get session replication to work and thus clustering fails in a simple cluster with two servers. There are errors in the logs indicating that something isn't set up correctly but I don't know what that might be. The jgroups tests and the multicasting udp network setup tests all work correctly, however.

Here are a few of the error messages on the second server.

[Server:beta] 08:26:09,863 WARN  [org.jgroups.protocols.TP$ProtocolAdapter] (Incoming-6,shared=udp) dropping unicast message to wrong destination master:alpha/web; my local_addr is slave02:beta/web

[Server:beta] 08:27:58,647 DEBUG [org.jgroups.protocols.pbcast.STABLE] (OOB-19,shared=udp) slave02:beta/web: received digest from master:alpha/web (digest=master:alpha/web: [0 (0)]) which does not match my own digest (slave02:beta/web: [0 (0)]): ignoring digest and re-initializing own digest

[Server:beta] 08:28:38,067 DEBUG [org.jgroups.protocols.pbcast.STABLE] (OOB-19,shared=udp) slave02:beta/web: received digest from master:alpha/web (digest=master:alpha/web: [0 (0)]) which does not match my own digest (slave02:beta/web: [0 (0)]): ignoring digest and re-initializing own digest

On the first server it's much the same:

[Server:alpha] 08:27:43,430 DEBUG [org.jgroups.protocols.pbcast.STABLE] (OOB-20,shared=udp) master:alpha/web: received digest from slave02:beta/web (digest=slave02:beta/web: [0 (0)]) which does not match my own digest (master:alpha/web: [0 (0)]): ignoring digest and re-initializing own digest

I show these just to show a sample of what I'm trying to deal with. But rather than looking for answers to these, I'm looking for answers to two more basic questions.

  1. Does the mod-cluster package, which is installed by default in the JBoss full-ha domain profile come into play or work at all if you DON'T deploy JBoss behind an external web server? We're having some internal debate about that.

  2. Would we be better advised trying to cluster standalone servers than trying to put clustering on top of the JBoss domain model?

Thanks.

Steve Cohen
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1 Answers1

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Mod_cluster is a httpd-based load balancer. So you need a httpd/ webserver with a installed mod_cluster component that works together with the mod_cluster component installed in de HA profiles of JBoss. http://mod-cluster.jboss.org

A Domain setup of JBoss gives the ability to manage multiple AS instances from a single control point which standalone setup won't do. Clustering works the same way in both setup modes. https://developer.jboss.org/wiki/JBossAS7UserGuide

Regards,

Laurens

Laurens
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