10:04 a.m.
This attribute does not support use of expressions, so any data you
provide is evaluated simply as a string.
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.
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,
*Dennis Brouwer*
Extraordinary Goalkeeper
ZEEF - Kizitos B.V.
Amstelboulevard 184
1096 HM Amsterdam
www.ZEEF.com <http://www.zeef.com/>
US: +1 (415) 992-9409
NL: +31 (085) 888-3186
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--
Brian Stansberry
Senior Principal Software Engineer
JBoss by Red Hat