Using a Multisystem Enclave

In this case, a work manager will process a work request using one or more supporting address spaces on different systems in a parallel sysplex.

Figure 10 shows how this works.

Figure 10. Using a Multisystem Enclave

• Connect as work manager

  The work manager issues IWM4CON, with WORK_MANAGER=YES specified or defaulted so that it can create independent enclaves, and EXPTIMPT=YES specified to allow for exporting the enclaves.

  Note:

  It is assumed here that the CFRM policy already contains the coupling facility structure SYSZWLM_WORKUNIT, which is required for the use of multisystem enclaves. If the coupling facility structure is not available, IWM4CON will succeed, but export and import requests will return errors. See z/OS MVS Planning: Workload Management for more information.
• Create original enclave E

  The work manager creates an independent enclave in address space A on system 1 by issuing IWM4ECRE. Address space A is the owner of the original enclave. Classification information is passed in with IWM4ECRE so workload management can assign the enclave to a service class or performance group. IWM4ECRE passes back the enclave token tokenE to the work manager.

• Address Space A on System 1: Export enclave E

  The work manager exports enclave E to all other systems in the parallel sysplex by issuing IWMEXPT with the enclave token tokenE. IWMEXPT passes back the export token tokenX. The work manager can now pass this sysplex-wide unique export token to supporting address spaces on other systems, using its own communication mechanism.

• Address Space B on System 2: Import enclave E'

  Once an enclave has been exported, a work manager in the supporting address space B can import the enclave by issuing IWMIMPT with the export token tokenX. A foreign enclave E' is created. It receives back an enclave token tokenE' that is valid on system 2 only.

  Although this example shows only one supporting address space on one separate system, the enclave can be imported by several address spaces on several different systems in the parallel sysplex. These foreign enclaves can all be running work simultaneously, with each unit of work being managed to the goals of the original enclave.

• Task J: join foreign enclave E'

  Task J in address space B on system 2 joins the foreign enclave by issuing IWMEJOIN with the enclave token tokenE'.

• Task J: leave foreign enclave E'

  Task J in address space B on system 2 leaves the foreign enclave by issuing IWMELEAV with the enclave token tokenE'. Any further processing in Task J after it leaves the enclave is now managed to the goal of the address space B, not of the enclave.

• Task K: join original enclave E

  If work is to be done in the original enclave at the same time that work is being done in the foreign enclaves, task J in address space A on system 1 can join the original enclave by issuing IWMEJOIN with the enclave token tokenE. The work in Task K is now managed to the goals of the original enclave. At any point in time, a multisystem enclave can have multiple tasks and/or SRBs running in it across multiple address spaces on multiple systems, and they are all managed to the original enclave's goal.

• Task K: leave original enclave E

  Task K in address space A on system 1 leaves the original enclave by issuing IWMELEAV with the enclave token tokenE. Any further processing in Task K after it leaves the enclave is now managed to the goal of the address space A, not of the enclave.

• Address Space B on System 2: Unimport enclave E'

  Once the task has left the foreign enclave, the work manager in the supporting address space B unimports the enclave by issuing IWMUIMPT with the export token tokenX. This deletes the foreign enclave E'. The supporting work manager now reports its completion and any results to the original work manager using its own communication mechanism.

• Address Space A on System 1: Unexport enclave E'

  After every supporting work manager has reported its completion, the original work manager unexports the enclave by issuing IWMUEXPT with the export token tokenX.

• Delete enclave X

  The transaction is now complete, so the work manager deletes the enclave using IWM4EDEL with enclave token tokenE.