On Tue, Aug 25, 2015 at 5:04 PM, Brian Stansberry <brian.stansberry@redhat.com> wrote:
This attribute does not support use of expressions, so any data you
provide is evaluated simply as a string.
"This attribute" most likely refers to the name attribute in <channel name="ee"> if I interpret your sentence correctly. If so, why not create an extra attribute CLUSTER_NAME next to the existing STACK and MODULE attributes and use the CLUSTER_NAME to create the JChannel. Using the current configuration model all containers start up with default cluster name "ee" unless the standalone*.xml file is edited beforehand. This is practically undoable because the cluster name defaults to the name of the channel used and I didn't find a way to overrule this (I might have overlooked something of course).
The only way to make distinct clusters is to add a bunch of pre-defined channel definitions and change the channels default. example:
<subsystem xmlns="urn:jboss:domain:jgroups:3.0">
<channels default="${custom_clustername:ee}">
<channel name="ee"/>
<channel name="whee"/>
<channel name="foo"/>
</channels>
...
</subsytem>And then select one of the names using the -Dcustom_clustername=[|whee|foo] startup property. However the desired behavior is to be flexible and provide a random name at startup time. It doesn't support expressions because it is what we call a "model
reference" attribute. It's value refers to another element in the
configuration model. We do not allow expressions in those attributes
because it is not possible to have all the necessary data to resolve the
expression at the points in time when the correctness of the model must
be validated.
> *Dennis Brouwer*
On 8/25/15 9:31 AM, Dennis Brouwer wrote:
> Dear reader,
>
> We recently moved to Wildfly 9.0.1.Final (from 8.2.0) for testing and
> stumbled upon a bug regarding expression evaluation in the standalone*.xml.
>
> Let me give an example for the following subsystem:
>
> <subsystem xmlns="urn:jboss:domain:jgroups:3.0">
> <channels default="ee">
> <channel name="ee"/>
> </channels>
> ...
> </subsytem>
>
> Since we have several deployment stages on one physical server we need
> to separate the clusters by using a distinct name for each one of the
> stages deployed. Hence we introduced a startup property to be
> substituted in the standalone*.xml configuration like following snippet
> clarifies:
>
> <subsystem xmlns="urn:jboss:domain:jgroups:3.0">
> <channels default="${custom_clustername:ee}">
> <channel name="${custom_clustername:ee}"/>
> </channels>
> ...
> </subsytem>
>
> Using this approach however fails to start the container because the
> channels default attribute is properly evaluated to "ee" (accoding to
> specs). However the channel name attribute is not evaluated at all and
> is registered as "${custom_clustername:ee}" (without the quotes).
>
> I took the liberty to dig in the class:
> org.jboss.as.clustering.jgroups.subsystem.JGroupsSubsystemXMLReader and
> manually do the expression evaluation for the channel name. At first
> glance this seems to work however the container rewrites the
> standalone*.xml file at a certain moment resulting in this snippet:
>
> <subsystem xmlns="urn:jboss:domain:jgroups:3.0">
> <channels default="${custom_clustername:ee}">
> <channel name="ee"/>
> </channels>
> ...
> </subsytem>
>
> Which on subsequent container starts and when using the
> -Dcustom_clustername=whee startup property causes a problem because the
> channels default is evaluated to "whee" and the channel name remains "ee".
>
>
> So my questions are:
>
> 1] How to solve this issue in a correct way?
> 2] Can somebody provide another mechanism to configure a non default
> channel name on startup?
>
>
> --
> Best regards,
>
> Extraordinary Goalkeeper
>
>
>
>
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--
Brian Stansberry
Senior Principal Software Engineer
JBoss by Red Hat
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Best regards,
Dennis Brouwer
Extraordinary Goalkeeper
Dennis Brouwer
Extraordinary Goalkeeper
ZEEF - Kizitos B.V.
US: +1 (415) 992-9409Amstelboulevard 184
1096 HM Amsterdam