Building the Action Diagram › Define Action Blocks › Define External Action Blocks

Define External Action Blocks

External action blocks that you create with the Action Diagram tool define the interface between Procedure Steps (or action blocks) and subroutines created outside CA Gen. The external action block provides a structure to match the views of the Procedure Step with the views (input and output arguments) of the handwritten subroutine.

An external action block contains only import views, export views, and an EXTERNAL designation, as shown in the following example:

READHIST
IMPORTS: Entity View new customer
EXPORTS: Entity View existing customer
EXTERNAL

CA Gen Procedure Step or action block that uses the external action block supplies the import views. The Procedure Step or action block calls the external action block through the USE control action. The import views define the data passed from the CA Gen-generated application to the interface routine. The export views define the data returned to the generated application from the interface routine.

When an EXTERNAL action block is generated, only the views structure and a program shell are built. You must supply any program logic required by your application.

Note: For more information about external action blocks, see the Workstation Construction User Guide.