Enterprise JavaBeans® (EJB™) workload management (WLM) and weighting in V5.0
 Technote (troubleshooting)
 
Problem(Abstract)
A brief description of how EJB workload management and weighting works in WebSphere® Application Server V5.0.
 
Resolving the problem
Definitions:

Cluster:
A set of application servers that are managed together and participate in workload management. The application servers that are members of a cluster can be on the same or on separate nodes.

Weight:
The number of requests that each cluster member will receive. This parameter is used to estimate the percent of requests that this cluster member will receive. For example, consider two cluster members, A and B. The weight for cluster member A is equal to three and the weight for cluster member B is equal to one. Cluster member A will receive about 75% of the requests.

Prefer Local:
Enabling the Prefer Local setting in the cluster routes the request to the local node, if possible, before going to the other cluster members. This routing setting does not mean that the request stays in that cluster member Java(TM) virtual machine (JVM), but rather on that cluster member node.

Horizontal Cluster Members:
Application servers that are part of a cluster that spans multiple nodes.

Vertical Cluster Members:
Application servers that are part of a cluster that does not span multiple nodes.

Scenarios:

Stand-alone Application

Design: A client application with the complete V5.0 client installation or a WebSphere Application Server V5.0 installation on the same machine that is the only supported V5.0 Java client. You can use the launchclient script that is located in the $WAS_HOME/bin directory or when you run the java command, make sure that you include all the WebSphere libraries, for example: "-Djava.ext.dirs=%WAS_HOME%\java\lib;%WAS_HOME%\java\jre\lib\ext;%WAS_HOME%\classes;%WAS_HOME%\lib".

The client connects to the EJB container of the cluster and workload manages the request to all the cluster member enterprise beans, based on the weights and settings. The lookup and method calls will be the only request that are enterprise bean workload-managed.

Tracing: To trace what is happening with the Java client:

  1. Add the following argument to the java command: "-DtraceSettingsFile=ClientTraceSettings.properties".
  2. Make a properties file called "ClientTraceSettings.properties" using the "TraceSettings.properties" file located in the $WAS_HOME/properties directory as a template.
  3. Enable tracing on each cluster member to see what is happening on the other side.

Combined Web and EJB container cluster members

Design: If the EJB container and Web container are on the same cluster member, then you will not see EJB workload management. IBM Developer Kit process optimization overrides the EJB workload management in V5.0. There is no way to remove this V5.0 design.

Separate Web container and EJB container servers

Design: Creating application servers with servlets that call enterprise beans in a cluster. In this scenario, the Web container that the client is on and the EJB container are on separate servers, showing you the EJB workload management capabilities of V5.0. The Web container connects to the EJB container of the cluster and manages the request to all the cluster member enterprise beans, based on the weights and settings. The lookup and method calls are the only requests that are enterprise bean workload-managed.

Tracing: Enable tracing on both the cluster members individually and the application server that contains the servlets that are calling the enterprise beans.

Help

If you are having a problem, refer to the WebSphere Application Server V5.0 Information Center:

http://publib7b.boulder.ibm.com/webapp/wasinfo1/index.jsp?deployment=NetworkDeployment

This site has many helpful links. Look at the "Workload Management component troubleshooting tips" located under the "Monitoring and troubleshooting" -> "Problems" -> "Troubleshooting by components: What is not working?" section.

If you still cannot find the information you are looking for, call 800-IBM-SERV.

 
 
Cross Reference information
Segment Product Component Platform Version Edition
Application Servers Runtimes for Java Technology Java SDK
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Workload Management (WLM)
Operating system(s): Windows
Software version: 5.0
Software edition:
Reference #: 1112198
IBM Group: Software Group
Modified date: Mar 3, 2004