Using Unicast for cluster communications_Oracle WebLogic Server 12c Advanced Administration Cookbook-QQ阅读男生科幻网

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Using Unicast for cluster communications

The Oracle WebLogic Server 12c can use either Multicast or Unicast for cluster communications. Since WebLogic version 10, the default cluster communication is the Unicast.

To improve Unicast reliability it's recommended to enable two extra configurations.

Getting ready

The first thing is to add a JVM argument to every WebLogic Managed Server instance of the cluster. The Administration Server must be running to make the changes.

After adding the JVM argument, the config.xml configuration file must be manually edited to make the second change. Therefore you will need to make sure every WebLogic Server instance is down, including the Administration Server.

How to do it...

Add the JVM argument:

Access the Administration Console with your web browser at http://prod01.domain.local:7001/console.
Click on the Lock & Edit button to start a new edit session.
Navigate to Configuration | Server Start by clicking on the WebLogic Server name, then on the Server Start tab.
Add the argument-Dweblogic.unicast.HttpPing=true to the Arguments field. The argument must be added to all Managed Server instances of PROD_Cluster: PROD_Server01, PROD_Server02, PROD_Server03, and PROD_Server04. Click on the Save button for every change.
Click on the Activate Changes button.
Navigate to Domain | Control by clicking on the PROD_DOMAIN link to the left and then on the Control tab.
Select and shut down all servers from the list.

Edit the config.xml file:

Log in as a wls user to the first machine prod01 and navigate to the folder:
```
[wls@prod01]$ cd $DOMAIN_HOME/config
```

Make a backup of the config.xml file:

[wls@prod01]$ cp config.xml config.xml_backup

Open config.xml to be edited:
```
[wls@prod01]$ vi config.xml
```

Find the <cluster> definition tag of PROD_Cluster:

    <cluster>
        <name>PROD_Cluster</name>
        <cluster-messaging-mode>unicast</cluster-messaging-mode>
    </cluster>

Add the <message-ordering-enabled tag:

    <cluster>
        <name>PROD_Cluster</name>
        <cluster-messaging-mode>unicast</cluster-messaging-mode>
        <message-ordering-enabled>true</message-ordering-enabled>
    </cluster>

Type :wq! to save the file and exit.

Copy the file to all machines in the domain:

[wls@prod01]$ scp config.xml wls@prod02:$DOMAIN_HOME/config

Start the Administration Server.

How it works...

The-Dweblogic.unicast.HttpPing=true argument enables an internal health check on Unicast communications that improves its reliability.

The <message-ordering-enabled> tag forces Unicast communications to be processed in order, avoiding some issues with JNDI updates and JMS Topics.