Transferring input and output data

Follow this task to see how to transfer data between a parent and a child activity. The task uses the Delivery activity Sale application as an example.

About this task

The DFH0SAL2 root activity creates the Delivery child activity by issuing a DEFINE ACTIVITY command.

Figure 1. Creating the Delivery activity

Delivery-Activity.
    .
    EXEC CICS DEFINE ACTIVITY('Delivery')
                 TRANSID('SDEL')
                 EVENT('Delivry-Complete')
             RESP(data-area) RESP2(data-area) END-EXEC
    .
    EXEC CICS GET CONTAINER(Order-Container)
                  ACTIVITY('Order') INTO(Order-Buffer)
             RESP(data-area) RESP2(data-area) END-EXEC
 
    EXEC CICS PUT CONTAINER(Order-Container)
                  ACTIVITY('Delivery') FROM(Order-Buffer)
             RESP(data-area) RESP2(data-area) END-EXEC

The GET CONTAINER command retrieves the data returned by the Order activity, and places it in a storage buffer. The data is retrieved from the output data-container of the Order activity, which is named Order.

Note: A child activity's data-containers are accessible to its parent even after the child has completed. An activity's containers are only destroyed when the activity itself is destroyed. An activity is destroyed:

Automatically by CICS®, when its parent completes.
Before this, if its parent issues a DELETE ACTIVITY command against it.

The PUT CONTAINER command associates a data-container (also named Order) with the Delivery activity, and places the retrieved data in it.

The implementation of the Delivery activity is shown in Figure 2.

Figure 2. Pseudocode for the Delivery activity

Identification Division.
Program-id. DFH0DEL1.
Environment Division.
Data Division.
Working-Storage Section.
01  Event-Name              pic x(16).
    88  DFH-Initial         value 'DFHINITIAL'.
01  Order-Ptr               usage is pointer.
01  Order-Container         pic x(16) value 'Order'.
01  Delivery-Container      pic x(16) value 'Delivery'.
01  Deliver-Data.
    .
Linkage Section.
01  DFHEIBLK.
    .
01  Order-Details.
    05  Order-Number        pic 9(8).
    .

Procedure Division..
Begin-Process.
    .
    EXEC CICS RETRIEVE REATTACH EVENT(Event-Name)
             RESP(RC) END-EXEC
    .
    If RC NOT = DFHRESP(NORMAL)
      .
    End-If.
    .
    Evaluate True
      When DFH-Initial
        Perform Delivery-Work
        Perform End-Activity
      When Other
        .
    End Evaluate.
    .
    EXEC CICS RETURN END-EXEC
    .
Delivery-Work.
    .
    EXEC CICS GET CONTAINER(Order-Container) SET(Order-Ptr)
             RESP(data-area) RESP2(data-area) END-EXEC
    .
    set address of Order-Details to Order-Ptr.
    .
    EXEC CICS READ FILE .....
              RESP(data-area) RESP2(data-area) END-EXEC
    .
    .  logic to print delivery details
    .
    .
    EXEC CICS PUT CONTAINER(Delivery-Container) FROM(Delivery-Data)
             RESP(data-area) RESP2(data-area) END-EXEC
    .
End-Activity.
    .
    EXEC CICS RETURN ENDACTIVITY
             RESP(data-area) RESP2(data-area) END-EXEC

The Delivery activity issues a GET CONTAINER command to retrieve data from a data-container named Order. Because the command does not specify the ACTIVITY option, it references a data-container associated with the current activity; in other words, it references the same Order data-container as that referenced by the PUT CONTAINER command in Figure 1.

The Delivery activity uses the input data to execute its logic. Then it issues a PUT CONTAINER command to store its output in a data-container named Delivery. Again, the ACTIVITY option is not specified, so the data-container is associated with the current (Delivery) activity.