Using IWMWMCON When Distributing Work in a Sysplex

The expected use of the IWMWMCON service is in a multiple system work environment, where work is received by a work router and distributed to other systems in the sysplex. In this case, the enclave or address space transaction of the originator cannot be used to manage the work request, because a transaction has a single system scope. When a request or a part of a request is distributed to a different system, it must run under a new transaction. The example below shows how IWMWMCON can be used in conjunction with the IWM4ECRE service to create an independent enclave on the system receiving the work request. For details on using enclaves, see Creating and Using Enclaves.

Example of Using IWMWMCON

Suppose a subsystem work manager called DISS splits complex work requests into pieces and distributes the split work to six data base manager address spaces, called DB1 through DB6, each running on a separate system in the sysplex. DISS might communicate with the data base address spaces through a shared queue on DASD or a coupling facility, or through sysplex services. The DISS subsystem does the following:

1. Receives a work request.
2. Determines the work requestor's classification attributes using the SYSEVENT REQASCL macro.
3. Splits the request and distributes pieces to DB1 through DB6, passing the information returned by REQASCL.

Each data base subsystem, DB1 through DB6, does the following:

1. Receives the split work request along with its classification attributes.
2. Obtains a latch or lock prior to issuing IWMWMCON to serialize the use of the work manager connect environment.
3. Modifies the connect environment by issuing IWMWMCON with the subsystem name and type passed by DISS.
4. Builds a classification parameter list with the attributes passed by DISS using the modify form of the IWM4CLSY macro.
5. Creates an independent enclave using the IWM4ECRE macro to manage the split work request.
6. Restores the previous connect environment using the IWMWMCON macro with the previous subsystem type and name.
7. Releases the latch or lock being used to serialize the connect environment.
8. Processes the work by joining tasks to the enclave and/or scheduling SRBs into it.
9. When the work is finished, deletes the enclave using the IWM4EDEL macro.