XCF Communication Services

The communication services that XCF provides fall into three broad categories:
  • Group services (group and member relationships)
  • Signaling services (sending and receiving messages)
  • Status monitoring services.
In designing the multisystem application to exploit XCF services, you need to decide the following:
  • The structure of the group (group services):
    • Will the group span more than one system or reside on only one system?
    • If the group will span more than one system, will there be one member per system or multiple members per system?
    • What function will each member perform?
    • Will some members duplicate the functions of other members?
    • For which members, if any, will you require a record of the member's existence after the member fails?
    • What name will the group have?
    • What names will the members have?
    • Will the members be associated with a task, a job step task, or only an address space?
    • How will the members be started?
  • Which members will be sending messages and which will be receiving messages (signaling services). If messages will be sent, you must plan the size of the messages, how frequently the messages will be sent, and the message content.
  • Which members will be notified of changes to other members and changes to systems in the sysplex, which members will take actions based on the notifications, and what those actions will be (group services and status monitoring services).
  • Which members will have their activity monitored by XCF (status monitoring services).
  • How will your multisystem application handle compatibility in a sysplex made up of varying system release levels?
  • How will your multisystem application handle compatibility with varying release levels of itself?
Other topics provide an overview on each of the three categories of XCF services (group, signaling, and status monitoring). XCF provides its services through authorized assembler macros. (See Table 1 for a summary of all the XCF macros.) Certain XCF services also require you to identify one or more user routines that you must code. Further details on how to use each of the XCF services, how to code the XCF macros, and how to code the user routines, appear in the topic "Using the Cross-System Coupling Facility (XCF)".