WAS v8.5 > Set up the application serving environment > Administer application servers

Configure WebSphere variables

We can use WebSphere variables to provide settings for any of the string data type attributes that are contained in the product configuration files.

Because applications cannot directly access WebSphere variables, if you define a WebSphere variable inside of an application, an error message, such as "Unknown variable," is returned. If you must reference a WebSphere variable from within an application, include the following method in the application to expand the string that uses the WebSphere variable.

Expanding WebSphere variables requires you to have administrative privileges. 

private String expandVariable(String s) throws
javax.management.JMException {  
com.ibm.websphere.management.AdminService as = 
com.ibm.websphere.management.AdminServiceFactory.getAdminService 
();  

String server = as.getProcessName();  

java.util.Set result = as.queryNames(new javax.management.ObjectName("*:*,type=AdminOperations,process=" 
+ server), null);  

return (String)as.invoke((javax.management.ObjectName) 
result.iterator().next(),"expandVariable",new Object[] 
{"${"+s+"}"}, new String[] {"java.lang.String"});

Similarly, we can include the following lines of code in a script file to use a script command to expand WebSphere variables.

WebSphere variables are usually used to specify file paths. The "Variable settings" topic supplies further details about specifying variables and highlights further details about product components that use them.

WebSphere variables are also used to configure:

The variable scoping mechanism for WebSphere variables enables you to define a variable at the node level, as well as at the server level. This mechanism enables you to specify a setting for all of the servers in a node, cluster, or cell, instead of individually specifying the setting for each server.

To define a new variable, change the value of an existing variable, or delete an existing variable complete the following steps, as appropriate.

  1. Click Environment > WebSphere variables in the dmgr console

  2. Create a new variable.

    1. Click New.

    2. Specify a name, a value, and, optionally, a description for the variable.

      We can create WebSphere variables that support substitution. For example, if you enter ${<variable name>} in the Name field, the value of <variable name> becomes the name of your new WebSphere variable. For example if you enter ${JAVA_HOME} as the name of your variable, the name of the WebSphere variable that is created is the Java home directory.

    3. Click OK.

    4. Click Environment > WebSphere variables in the dmgr console navigation, and verify the variable is displayed in the list of variables for the selected scope.

      The dmgr console does not pick up typing errors. The variable is ignored if it is referred to incorrectly.

  3. Modify the setting for an existing variable.

    1. Click on the name of the variable to change.

    2. Modify the content of the Values field.

      The Values field for some of the variables that are already defined when we install the product are read-only because changing the values specified for those variables might cause product processing errors.

    3. Click OK.

  4. Delete an existing variable.

    1. Select the variable to delete.

    2. Click Delete.

    3. Click OK.
    4. Verify that this variable was removed from the list of variables for the selected scope.

  5. Save your configuration.
  6. Stop the affected servers and start those servers again to put the variable configuration change into effect.

    If the change you made affects a node, stop and restart all of the servers on that node. Similarly if the change you made affects a cell, stop and restart all of the servers in that cell.


Subtopics


Related concepts:

Test connection service


Reference:

WebSphere variables settings
Session management custom properties


Related information:

HTTP transport custom properties


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