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Using Variables

A BPEL process receives, manipulates, and sends data using XML variables. Variables contain data. Variables are used to represent inputs and outputs to the BPEL process and to Web service operations that may be invoked by the process. Just as in an object-oriented programming language, all variables that are derived from complex schema types (those having structure and hierarchy) must be initialized before you can assign to or read from the XML contained inside them.

Variables are XML-based and must be based on a

  • WSDL message type
  • XML schema type definition


  • XML schema element declaration

By default, all variables are automatically initialized in the Process Design Studio when they are created or when an Assign activity is first used. You can choose to initialize your variables manually by clearing this option in Windows > Preferences > BPEL Properties.

See Initializing Variables for information on how to initialize variables in the Design Studio.

Tips for using variables:

  • Variables are automatically initialized when variables are assigned to the project. You can see the initializer on the Initialization tab in the Properties view. Click variable icon on the Properties view toolbar to edit the initializer.

  • XPath expressions can be used to initialize variables or assign values into variables.

  • The variables defined within a Scope are visible only within that Scope.
  • Element names cannot contain spaces. For example: use this— *call_back*, not this— *call back*.

More information