Shared Management Object Layer

The shared management object layer is a temporary holding area, storing data about SNA Server services and resources. When a change occurs in a service, the information is written into shared management.

Access to shared memory is by means of a set of objects. Objects contain data about the various components of SNA Server. Each process has its own copy of the object interfacing to shared memory. The object provides a wrapper for changes to shared memory, and will propagate change notifications to all the processes that have requested notification for that object. Each process may have only a subset of the complete object set. The actual object data is common for all the processes. The objects also enforce access control on the data to prevent conflicts (mutual exclusion).

Each shared management object keeps track of which processes have a reference to the shared data, and what type of notifications each process has requested per object.

The Agent Notify Queue is used to queue update notifications from the underlying management objects, and to dispatch the queued notifications to the proper place for handling. Each process creates a "notify queue" for receiving events. The events are dispatched to the Notify Sink (defined below) that is registered to accept messages for the manage object that generated the event. If a new manage object is created, notification is sent to the sink of the parent object.

The Agent Notify Queue resides in shared memory, allowing the service process to place notifications in the queue and the MngAgent to remove and process the notifications.

The Service Notify Queue is used to queue requests, commands, and notification of changes to the underlying management objects, and to dispatch the queued notifications to the service process for handling. It is identical to the Agent Notify Queue, except that the source and destination are switched.

The Service Notify Queue resides in shared memory, allowing the Agent process to place notifications in the queue and the service process to remove and process the notification.

Each process that requires notification of events to manage objects will create a Notify Sink. The Notify Sink is the destination object of an event notification. The sinks do not exist in the shared management objects layer; however, they are used when needed. The Notify Sink receives notification after information is taken out of the queue by a process.