Designing the Procedure Dialog › Define Exit States › Rules for Assigning Exit State Definitions

Rules for Assigning Exit State Definitions

When an exit state is set during a procedure step execution, the results must be unambiguous.

The following rules govern the assignment of exit state definitions to dialog flows:

• An exit state value may appear on the Flows On exit state list of only one dialog flow from a given procedure step.
• No exit state value that appears on the Returns On Exit State list of a link to a given procedure step may appear on a Flows On exit state list of dialog flows from the same procedure step.

The following illustration, Exit State Rule Violation, shows violations of both rules using an annotated Dialog Flow Diagram.

The illustration shows three procedures, P1, P2 and P3, and six dialog flows, each of which has been assigned a number. The Flows On and Returns On Exit States associated with each flow are also listed.

Despite the confused use of exit states in this diagram, there are actually only two violations:

• For procedure P1, flows 1 and 3 violate the first rule because they both use ES1 as a Flows On exit state.
• For procedure P3, flows 5 and 6 violate the second rule because flow 5 uses ES3 as a Flows On exit state and flow 6 uses ES3 as a Returns On exit state.

This discussion reveals an interesting property of Returns On exit states; they depend entirely on the context of a particular link.

The following illustration, Context Sensitivity of Returns on Exit States, shows that both Take Order and Change Order can link to Maintain Customer. (Assume that the Returns On Exit State for both links is Request Successful.)

According to this illustration, there are three possible results if MAINTAIN CUSTOMER sets Request Successful during its execution:

• If MAINTAIN CUSTOMER was linked to from TAKE ORDER, control is returned to TAKE ORDER.
• If MAINTAIN CUSTOMER was linked to from CHANGE ORDER, control is returned to Change Order.
• If MAINTAIN CUSTOMER was not the destination of a link, the Maintain Customer display is redisplayed along with the exit state message associated with the exit state value Request Successful.

The result depends on how MAINTAIN CUSTOMER was initiated.