Declaring variables for a BPD or a service

For each business process definition (BPD) or service that you create, you must declare variables to capture the business data that activities in that BPD or steps in that service use.

About this task

You can add the following variables to your BPDs:

Table 1. Variables available for addition to business process definitions

Variable	Description
Private	Local variables that are used only within the process.
Input	Variable that represents input data passed to the current BPD or service.
Output	Variable that represents output data that the current BPD or service returns to its caller.
Exposed process variable (EPV)	Special type of variables that you can create to set or alter values while instances of a process are running.

Only BPD variables that are marked as process instance identifiers can be used for instance-based correlation of intermediate message events that use the SCA triggering mechanism. A process instance identifier variable can be a private, input, or output variable, and can be a simple or complex variable type.

If you want to add an exposed process variable, click Link EPV, and then select the EPV from the list. If you want to add a private, input, or output variable, complete the following steps:

1. Open your BPD or service diagram in Process Designer.
2. In the Variables tab, click Add Private, Add Input, or Add Output to create the corresponding variable.
3. In the Details section:
   1. Type a variable name in the Name field.
      Note: Variable names start with a lowercase letter, with subsequent words capitalized, for example: myVar. Do not use underscores or spaces in variable names. Variable names are case-sensitive.
   2. Click Select next to the Variable Type field to select the type of the variable. Custom business objects that you created are also listed.
   3. Optional: Type a description of the variable in the Documentation field.
   4. Optional: If you want your variable to be an array, select Is List.
4. Optional: To set a default value for the variable, in the Default Value section, select Has Default, and enter the value in the corresponding field.
5. Optional: To include the BPD variable in the business data that users can view in Process Portal, in the Business Data section, select Visible in Process Portal, and type an alias in the Alias field.
   Tip: The search alias must be unique to the variable type throughout the process server on which the BPD runs. If a variable is used in parent and nested processes, use the same search alias if you want search results to include all related processes.
6. Optional: To include the BPD variable values in the data that is collected and used to create reports, in the Performance Tracking section, select Track this Field.
7. To declare a BPD variable as a secondary process identifier, you must mark it as a process instance identifier. In the Process Identification section, select Variable is used as Process Instance Identifier. While it is possible to mark any variable as process instance identifier, it is advisable to use a variable for this purpose that is not too complex.
   Important: The value that is written to the variable must be unique for each instance of the BPD. Because variables that are selected as process instance identifiers can be written to only once, be careful during initialization, data mapping, pre-assignments, and post-assignments to avoid it ever being written to twice for an instance. Writing any value to such a variable more than once causes an error.
   Tip: If you clear the selection for a variable that is already used for correlation, the variable is marked with an error icon on the Data Mapping tab.
   Variables that are marked as process instance identifiers can be selected to be used for correlation, and are indicated in variable selection dialogs by the text [Identifier].
8. To save the configuration, click Save in the main toolbar.