[mod_cluster-dev] Enabling mod_cluster by default in AS6

[Paul Ferraro]

On Tue, 2010-05-04 at 22:18 +0200, Bela Ban wrote:
<snip>
> >> So when this is done, what will the configuration steps be (on the 
> >> JBoss AS side) ?
> >>
> >> 1. Add a jvmRoute to server.xml [optional, as jvmRoute is generated 
> >> if absent]
> >
> > The default JvmRouteFactory allows system property override as well, 
> > via -Djboss.mod_cluster.jvmRoute
> 
> I assume you're referring to the *factory*, so would the property be 
> something like -Djboss.mod_cluster.jvmRoute.factory=CLASSNAME ?

No - the jvm route itself.
e.g. -Djboss.mod_cluster.jvmRoute=node1

Implementation-wise, the default JvmRouteFactory is:
new SystemPropertyJvmRouteFactory(new UUIDJvmRouteFactory(),
"jboss.mod_cluster.jvmRoute");

So, it returns the given system property, if defined; or if not, a UUID.

If you want to override the factory itself, you would modify the
jvmRouteFactory property of the ModClusterConfig bean within
mod_cluster-jboss-beans.xml.
e.g.
<bean name="ModClusterConfig" class="...">
  ...
  <property name="jvmRouteFactory">
    <!-- Generates jvm route as: bind-address:port:engine-name -->
    <bean class="org.jboss.mod_cluster.SimpleJvmRouteFactory"/>
  </property>
  ...
</bean>

> >> 2. mod-cluster.sar:
> >> 1. Set the proxy list (jboss.mod_cluster.proxyList) [optional
> >> if IP multicasting works, as advertise is enabled by default]
> >
> > Advertise is not enabled by default - in order to minimize jboss's
> > default port footprint. Advertise can be enabled via a system property.
> >
> > So, in summary, the servers just need to be started with either:
> > -Djboss.mod_cluster.advertise=true
> > or
> > -Djboss.mod_cluster.proxyList=....
> 
> OK. In order to create virtual images for GoGrid, EC2 and Rackspace, I 
> want to avoid using system properties as much as possible. So jvmRoutes 
> need to be either hard coded, or my startup script (/etc/init.d/jboss) 
> will have to provide unique values for them, e.g. via uuidgen.

You don't need to use a system property to get unique auto-generated jvm
routes by default.  See above.
In general, system properties are only used for convenience, i.e. to
allow the user to override commonly used configuration properties via
command line.