Designing the Procedure Dialog › Flows › Types of Flows › Link Flows

Link Flows

A link flow is more complex than a transfer flow. As with a transfer flow, a link flow indicates that the source procedure step passes control and, optionally, data to the destination procedure step. However, the link flow also allows the destination procedure step to return control and data to the source procedure step. In addition, all export data known to the source procedure step when it completes its original execution is saved and made available after the destination procedure step returns.

For example, the illustration Dialog Flow Diagram shows a link between the procedure steps Add Order Header and Maintain Customer. Assume that this link only takes place when the user takes an order from a customer not yet known to the system. By linking to Maintain Customer, the system lets the user add the customer without losing any of the information already entered into the Add Order Header display. After the user adds the customer, the Add Order Header procedure step begins again with all the information from its original export view available in its import view, augmented by data returned by Maintain Customer.

A link lets a user acquire additional information from another procedure step when the initial procedure step needs it. After the information is acquired, the initial procedure step executes again from the beginning with all the information from its initial execution intact, plus any new data or commands returned from the destination procedure.

If multiple links execute consecutively, all information from each linked procedure step is saved in anticipation of its restart.

For example, suppose that MAINTAIN CUSTOMER flows to another procedure step called CHECK CREDIT STATUS under certain circumstances.

• If TAKE ORDER links to MAINTAIN CUSTOMER, all information required for TAKE ORDER is saved.
• If MAINTAIN CUSTOMER then links to CHECK CREDIT STATUS, all information required by MAINTAIN CUSTOMER is saved.
• When CHECK CREDIT STATUS ends, the data saved for MAINTAIN CUSTOMER is restored, and MAINTAIN CUSTOMER executes again from its beginning.
• When MAINTAIN CUSTOMER ends, the data saved for TAKE ORDER is restored, and TAKE ORDER executes again from its beginning.

If a transfer flow took place at any time during this process, all the information saved during the links would be discarded.

The following list details the properties of link flows:

• Flows On exit states.
• Flow Actions (Execute First, Display First) for the destination procedure step.
• A command triggers execution of the destination procedure step.
• Data sent from the source to the destination procedure step.
• Returns On exit states.
• Flow Actions (Execute First, Display First) for the source procedure step on return.
• A command triggers execution of the source procedure step on return.
• Data is returned from the destination to the source procedure step.