Building Your Event-Driven Architecture : Service Development Help : Mapping Data in Flow Services : About Linking Variables : Creating a Link Between Variables
Creating a Link Between Variables
When you link variables in the pipeline, keep the following points in mind:
*The variable that you are linking from is the source. For example, when you link a variable in Pipeline In to one in Service In, the Pipeline In variable is the source. When you link a variable in Service Out to one in Pipeline Out, the Service Out variable is the source.
*The variable you are linking to is the target. For example, when you link a variable in Pipeline In to one in Service In, the Service In variable is the target. When you link a variable in Service Out to one in Pipeline Out, the Pipeline Out variable is the target.
*A Service In variable can be the target of more than one link only if you use array indexing or if you place conditions on the links to the variable.
*By linking variables to each other, you are copying data from the source variable to the target variable. (Documents, however, are copied by reference. For more information, see What Happens When Integration Server Executes a Link?.)
*Target variables can be connected to only one source variable. After you draw a link to a target variable, you cannot draw another link to the target variable. (Two exceptions to this rule involve array variables and conditional links. For more information about linking array variables, see Linking to and from Array Variables in the Pipeline. For more information about placing conditions on links between variables, see Linking Variables Conditionally.
*You cannot create a link to a variable if you already assigned a value to a variable.
*After a link executes, both the source and target variables exist in the pipeline. The target variable does not replace the source variable.
*You cannot create a link to a variable if the variable has a fixed null or default value assigned to it. Designer uses the symbol next to the variable icon to indicate that the variable has a fixed value that you cannot override by linking it to another variable.
To create a link between variables
1. In the flow service editor, select the INVOKE or MAP step containing the variables you want to link.
2. Open the Pipeline view.
3. If you want to create a link between a variable in Pipeline In and one in Service In, do the following:
a. In Pipeline In, click the pipeline variable you want to use as the source variable.
b. In Service In, click the input variable you want to use as the target variable.
c. Click on the Pipeline view toolbar.
4. If you want to create a link between a variable in Service Out and one in Pipeline Out, do the following:
a. In Service Out, click the output variable you want to use as the source variable.
b. In Pipeline Out, click the pipeline variable you want to use as the target variable.
c. Click on the toolbar.
5. Click File > Save.
Notes:
*If the variable types are incompatible and cannot be linked to one another, Designer prevents you from creating a link between the variables and displays a message stating that the operation is not allowed.
*If you created a link to or from an array variable, you must specify which element in the array you are linking to or from. For more information about array linking, see Linking to and from Array Variables in the Pipeline.
*If you want to place a condition on the execution of the link, see Linking Variables Conditionally.
*Do not link variables with different Object constraints. If you link variables with different Object constraints and input/output validation is selected, the run-time result is undefined.
Tip:  
You can also use your mouse to link variables to one another. To do this, select the source variable and drag your mouse to the appropriate target variable.
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