Queue Manager Manual

Queue Manager Components and Functions
Queue Management
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In the second scenario, Queue Manager allows A and B to operate in a loosely coupled
mode. Process A can continue with other activities after it has submitted its request.
Queue Manager frees A from having to wait while B obtains the resources required for
a response. B, on the other hand, need not wait for requests to come from A. It can
perform other tasks such as transactions with other requesters.
Note that Queue Manager, essentially a passive entity, performs its notification
functions based on prior instructions from the processes involved. In the second
scenario above, each process had previously instructed Queue Manager to notify it
when an event for its attention was submitted.
Queue Manager
Components and
Functions
Queue Manager provides a facility for queue entries to be submitted and retrieved by
different processes. Queue Manager handles queue entries strictly at the request of
other processes. These requests are initiated by external instructions.
Queue Manager comprises two servers, the Entry Manager and Wait Manager, and a
file, the Queue. Server and file functions are as follows:
The Entry Manager handles enqueuing, reading, and dequeuing of queue entries.
The Wait Manager stands by, waiting to be notified when new queue entries are
submitted, and alerts the appropriate process when an entry of interest has been
enqueued. By notifying a given application that a relevant communication has
been enqueued, Wait Manager makes it possible for applications to avoid wasting
time on file READs that do not yield new entries.
The Queue file contains many different logical queues. Each logical queue holds
queued entries from processes whose interactions are supported by Queue
Manager. The Entry Manager and Wait Manager servers operate on this file.
Queue Manager in
PATHWAY
When you configure the server classes for a PATHWAY system, you must follow these
guidelines:
A Queue file can be associated with multiple Entry Managers.
A Queue file can be associated with just one Wait Manager.
The Queue file is an audited, key-sequenced file. It has been previously created and
can store multiple, logical queues. Each queue entry in the file has a 32-byte queue
name field, a priority field, a timestamp field, a field for the CPU number and process
ID number of the server that places the entry on the queue, and a field for user-
specified data.
The maximum length for entries, or records, in the Queue file dictates the amount of
user data that can be present in each queue entry. Queue Manager reserves 128 bytes
at the beginning of the entry (physical record). User data can occupy the remaining
space in the entry.
The system manager can partition the Queue file by the first two bytes of the physical
key. To facilitate this partitioning, the first two bytes of the queue name field are used
as the first two bytes of the Queue file physical key.