WebSphere variables

WebSphere variables are name and value pairs used to provide settings for any of the string data type attributes used to configure the product. After a variable is defined, the symbolic name specified for that variable can be specified in the Value field of any other configuration field for the product that accepts a string value.

WebSphere variables can be used to configure:

• WebSphere Application Server path names, such as JAVA_HOME, and APP_INSTALL_ROOT
• A path value for the extendedDocumentRoot JSP or file serving attribute. This capability allows us to add an application to each node in a clustered environment without modifying the ibm-web-ext.xmi file for that application on each node.

  For IBM extension and binding files, the .xmi or .xml file name extension is different depending on whether we are using a pre-Java EE 5 application or module or a Java EE 5 or later application or module. An IBM extension or binding file is named ibm-*-ext.xmi or ibm-*-bnd.xmi where * is the type of extension or binding file such as app, application, ejb-jar, or web. The following conditions apply:

  • For an application or module that uses a Java EE version prior to version 5, the file extension must be .xmi.

  • For an application or module that uses Java EE 5 or later, the file extension must be .xml. If .xmi files are included with the application or module, the product ignores the .xmi files.

  However, a Java EE 5 or later module can exist within an application that includes pre-Java EE 5 files and uses the .xmi file name extension.

  The ibm-webservices-ext.xmi, ibm-webservices-bnd.xmi, ibm-webservicesclient-bnd.xmi, ibm-webservicesclient-ext.xmi, and ibm-portlet-ext.xmi files continue to use the .xmi file extensions.

• Certain cell-wide customization values

• The location service for the z/OS platform.

When a variable is defined, it is given a scope. The scope is the range of locations within the product network where the variable is applicable.

• A variable with a cell-wide scope is available across the entire deployment manager cell.
• A variable with a cluster-wide scope is available across the entire cluster in the cell.
• A variable with a node-level scope is available only on the node and the servers on that node. If a node-level variable has the same name as a cell-wide variable, the node-level variable value takes precedence.
• A server variable is available only on the one server process. A server variable takes precedence over a variable with the same name that is defined at a higher level.

The value of a configuration attribute can contain references to one or more variables. The syntax for such an attribute is the name of the variable, enclosed in either a pair of curly braces { } or a pair of parenthesis ( ). In either case, the variable is proceeded by the dollar sign.

A string configuration attribute value can consist of:

• String literals, including the null value and an empty string
• Variable references that each includes one or more levels of indirection
• Nested variable references.

• Any combination of non-null and non-empty string literals, variable references, and nested variable references.

(Windows) For Microsoft Windows operating systems, the specified file paths are prefixed wth /Program Files.

WebSphere variables and attributes

Configuration attribute consists of:	Configuration attribute value	Variable name	Second variable value	Third variable value	Fourth variable value	Expanded configuration attribute value
String literal	/IBM/WebSphere/AppServer	N/A	N/A	N/A	N/A	/IBM/WebSphere/AppServer
Variable reference	$(WAS_ INSTALL_ ROOT)	WAS_ INSTALL_ ROOT	/IBM/WebSphere/AppServer	N/A	N/A	/IBM/WebSphere/AppServer
Variable reference with a string literal	$(USER_ INSTALL_ ROOT)/temp	USER_ INSTALL_ ROOT	N/A	N/A	/IBM/WebSphere/AppServer/profiles/AppSrv01	/IBM/WebSphere/AppServer/profiles/AppSrv01/temp
Indirect variable reference with a string literal	$(WAS_ INSTALL_ ROOT)/lib	WAS_ INSTALL_ ROOT	$(MY_INSTALL_ ROOT)	MY_INSTALL_ ROOT	N/A	N/A
Nested variable references with string literal (Example 1)	$(${INSTALL_ TYPE}_ INSTALL_ ROOT)/lib	INSTALL_ TYPE	USER	USER_INSTALL_ ROOT	/IBM/WebSphere/AppServer/profiles/AppSrv01	/IBM/WebSphere/AppServer/profiles/AppSrv01/lib
Nested variable references with string literal (Example 2)	$(${INSTALL_ TYPE}_ INSTALL_ ROOT)/lib	INSTALL_ TYPE	WAS	WAS_INSTALL_ ROOT	/IBM/WebSphere/AppServer/AppServer	/IBM/WebSphere/AppServer/AppServer/lib

During the configuration process, whenever a variable is encountered as the value for a configuration attribute, a variable expansion is performed on that variable. A variable expansion is the process of recursively replacing variable references with variable values until only a string literal remains as the value for the configuration attribute. If the expansion process encounters a variable that is not properly defined, the expansion of that variable stops and a VariableExpansionException exception is issued. The product configuration process continues. However, processing errors might occur because the value for this configuration attribute is not properly established.

The variable expansion syntax that consists of a dollar sign, and a single letter variable name without any surrounding braces or parenthesis, is not supported. All WebSphere variable references must be surrounded by matching parenthesis or braces, even if it is a single letter. That syntax required escaping of dollar signs to avoid ambiguity.

Literal dollar sign

Input value	Value after expansion
$	$
$$	$
$$$	$$
$$$$	$$
$$$$$	$$$

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