The WebLogic JMS
Topic are typically running in a WLS cluster. So as
your SOA composites that receive these
Topic messages. In some
situation, the two clusters are the same while in others they are
sepearate. The composites in SOA cluster are subscribers to the JMS
Topic in WebLogic cluster. As nature of JMS
Topic is meant to distribute
the same copy of messages to all its subscribers, two questions arise
immediately when it comes to load balancing the JMS
Topic messages
against the SOA composites:
How to assure all of the SOA cluster members receive different
messages instead of the same (duplicate) messages, even though the SOA
cluster members are all subscribers to the Topic?
How to make sure the messages are evenly distributed (load balanced) to SOA cluster members?
Here we will walk through how to configure the JMS
Topic, the
JmsAdapter connection factory, as well as the composite so that the JMS
Topic messages will be evenly distributed to same composite running off
different SOA cluster nodes without causing duplication.
2. The typical configuration
In this typical configuration, we achieve the load balancing of JMS
Topic messages to JmsAdapters by configuring a partitioned distributed
topic along with sharable subscriptions. You can reference the documentation for explanation of PDT. And this blog posting
does a very good job to visually explain how this combination of
configurations would message load balancing among clients of JMS Topics.
Our job is to apply this configuration in the context of SOA JMS Adapters. To do so would involve the following steps:
Step A. Configure JMS
Topic to be UDD and PDT, at the WebLogic cluster that house the JMS
Topic
Step B. Configure JCA Connection Factory with proper ServerProperties at the SOA cluster
Step C. Reference the JCA Connection Factory and define a durable subscriber name, at composite's JmsAdapter (or the *.jca file)
Here are more details of each step: Step A. Configure JMS
Topic to be UDD and PDT, You do this at the WebLogic cluster that house the JMS
Topic.
You can follow the instructions at Administration Console Online Help
to create a Uniform Distributed
Topic. If you use WebLogic Console,
then at the same administration screen you can specify "Distribution
Type" to be "Uniform", and the Forwarding policy to "Partitioned", which
would make the JMS
Topic Uniform Distributed Destination and a
Partitioned Distributed
Topic, respectively Step B: Configure ServerProperties of JCA Connection Factory
You do this step at the SOA cluster.
This step is to make the JmsAdapter that connect to the JMS
Topic
through this JCA Connection Factory as a certain type of "client".
When you configure the JCA Connection Factory for the JmsAdapter, you
define the list of properties in FactoryProperties field, in a semi
colon separated list:
ClientID=myClient;ClientIDPolicy=UNRESTRICTED;SubscriptionSharingPolicy=SHARABLE;TopicMessageDistributionAll=false
You can refer to Chapter 8.4.10 Accessing Distributed Destinations (Queues and Topics) on the WebLogic Server JMS of the Adapter User Guide for the meaning of these properties.
Please note:
Except for ClientID, other properties such as the ClientIDPolicy=UNRESTRICTED,
SubscriptionSharingPolicy=SHARABLE and
TopicMessageDistributionAll=false are all default settings for
the JmsAdapter's connection factory. Therefore you do NOT have to
explicitly specify them explicitly. All you need to do is the specify the ClientID.
The ClientID is different from the subscriber ID that we are to
discuss in the later steps. To make it simple, you just need to remember
you need to specify the client ID and make it unique per connection
factory.
Here is the example setting: Step C. Reference the JCA Connection Factory and define a durable subscriber name, at composite's JmsAdapter (or the *.jca file)
In the following example, the value 'MySubscriberID-1' was given as the value of property 'DurableSubscriber':
<adapter-config name="subscribe" adapter="JMS Adapter" wsdlLocation="subscribe.wsdl" xmlns="http://platform.integration.oracle/blocks/adapter/fw/metadata">
<connection-factory location="eis/wls/MyTestUDDTopic" UIJmsProvider="WLSJMS" UIConnectionName="ateam-hq24b"/>
<endpoint-activation portType="Consume_Message_ptt" operation="Consume_Message">
<activation-spec className="oracle.tip.adapter.jms.inbound.JmsConsumeActivationSpec">
<property name="DurableSubscriber" value="MySubscriberID-1"/>
<property name="PayloadType" value="TextMessage"/>
<property name="UseMessageListener" value="false"/>
<property name="DestinationName" value="jms/MyTestUDDTopic"/>
</activation-spec>
</endpoint-activation>
</adapter-config>
You can set the durable subscriber name either at composite's JmsAdapter
wizard,or by directly editing the JmsAdapter's *.jca file within the
Composite project.
2.The "atypical"
configurations:
For some systems, there may be restrictions that do not allow the afore
mentioned "typical" configurations be applied. For examples, some
deployments may be required to configure the JMS
Topic to be Replicated
Distributed
Topic rather than Partition Distributed
Topic. We would like
to discuss those scenarios here: Configuration A: The JMS
Topic is NOT PDT
In this case, you need to define the
message selector 'NOT
JMS_WL_DDForwarded' in the adapter's *.jca
file, to filter out those "replicated" messages. Configuration B. The ClientIDPolicy=RESTRICTED
In this case, you need separate
factories for different composites. More accurately, you need
separate factories for different *.jca file of JmsAdapter.
References:
Managing Durable Subscription
WebLogic JMS Partitioned Distributed Topics and Shared Subscriptions
JMS Troubleshooting:
Configuring JMS Message Logging:
Advanced Programming with Distributed Destinations Using the JMS Destination Availability Helper API
