WebLogic: Cluster Adress option

WebLogic: Cluster Adress option

Published on: Category: Oracle

Although I haven’t had time lately to do some blogposting, I’d like to pick it up from here with short articles from which I hope you will learn some about the features of Oracle Fusion Middleware areas with special focus on WebLogic.

One of the things I often encounter is that there is a misconception about something called the ‘Cluster Address Option’ within a WebLogic Domain Configuration. So, what is it? Every time you configure a WebLogic Cluster, you can set several configurations for your cluster to facilitate the high availability of an application. One of those is the Cluster Address Option, which you find on the General Tab of you Cluster:

Format is : <mshost1:port>,<mshost2:port>, etc… Each entry corresponds to  a Managed Server and port that received the request.

This is a static list for applications (EJB’s) to choose from. When not filled in, WebLogic  generates in each request dynamically an adress.

My best practise is to fill in it in when you have an Oracle Service Bus cluster. The OSB configuration, but also the reportingprovider rely to the underlying entity and stateless beans to generate a hostname as part of  a request URL for processing messages.

Another option is to fill in one Virtual hostname, that points to all available managed servers in the cluster, but be aware that in this case all managed servers should be set to the same listenport. If the request was received by a Managed Server, the listen address and port combinations in the cluster address reflect the ListenAddress and ListenPort values from the associated ServerMBean and/or SSLMBean instances.

The default number of the NumberOfServersInClusterAddress attribute on the ClusterMBean is 3. You can modify this value on the Environments—>Clusters—>ClusterName->Configuration->General

If there are fewer Managed Servers available in the cluster than the value of NumberOfServersInClusterAddress, the dynamically generated cluster address contains all available for each of the running Managed Servers.

If there are more Managed Servers available in the cluster than the value set in, WebLogic Server does a random select of the available managed servers in this value.

Michel Schildmeijer
About the author Michel Schildmeijer

Having made his start in the pharmacy sector, Michel transitioned to IT in 1996, working on a UNIX TTY terminal-based system and the MUMPS language. He currently works as a solutions architect at Qualogy, with a focus on middleware, application integration and service-oriented architecture. His passion for middleware started in 2000 when working as a support analyst for a financial institute with BEA WebLogic and Tuxedo. Michel is an expert on the WebLogic platform. He serves customers in his role as architect and advises them in all aspects of their IT landscape. He became an Oracle ACE in 2012 and wrote two books about WebLogic: Oracle WebLogic Server 11gR1 PS2: Administration Essentials and Oracle WebLogic Server 12c: First Look. He is a well-known speaker at national and international conferences and is recognised as an official Oracle Speaker. Read his blog: https://community.oracle.com/blogs/mnemonic

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