XCF provides the services that allow multisystem application functions (programs) on one z/OS system to communicate with functions on the same or other z/OS systems. The communication services are provided through authorized assembler macros and are as follows:
- Group services
- Signalling services
- Status monitoring services
XCF Group Services provide ways for defining members to XCF, establishing them as part of a group, and allowing them to find out about the other members in the group. A member introduces itself to XCF through the IXCJOIN macro. If a member identifies a group exit routine, XCF uses this routine to notify this member about status changes that occur to other members of the group, or systems in the sysplex; thus, members can have the most current information about the other members in their group without having to query each other.
The Signalling Services control the exchange of messages between members of an XCF group. The sender of a message requests services from XCF signalling services. XCF uses buffer pools to communicate between members in the same system, and it uses buffer pools plus signalling paths (CTCs or a CF list structure) to send messages between systems in the sysplex.
Status monitoring services
Status monitoring services provide a way for members to determine their own operational status and to notify the other members of the group when that operational status changes. An installation-written status exit routine identified to XCF determines whether a member is operating normally. An installation-written group exit routine identified to XCF allows a member to maintain current information about other members in the group, and systems in the sysplex.