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Developing AppServer Applications
Design and Implementation Considerations : Distributed application design and implementation : Understanding procedure handles in distributed ABL sessions : PERSISTENT, SINGLE-RUN, and SINGLETON attributes
When you execute an external procedure from a local procedure call, as with any procedure, the external procedure can reference its own context, using the THIS-PROCEDURE system handle. This system handle returns a procedure handle to the external procedure's own context.
Also, the procedure that executes the RUN statement that creates the external procedure can obtain a reference to the same external procedure context, using the SET option of the RUN statement. This option returns the same procedure handle as the THIS-PROCEDURE system handle accessed from within the external procedure.
Thus, for a local persistent, single-run, or singleton procedure, there is only one handle for a specific external procedure context, but there might be many references to it. For any such reference to an external procedure handle, the PERSISTENT, SINGLE-RUN, or SINGLETON attribute (whichever matches the option used with the RUN statement that instantiated or initialized the external procedure) returns the value TRUE.