Queue Manager Manual

Queue Manager Application Example
Queue Management
46517 Tandem Computers Incorporated 1-9
This configuration will encounter severe difficulties without Queue Manager support.
The sales order process—possibly terminal-based and operated by a clerk who must
serve other customers—has to wait to enter another transaction until the inventory
control process confirms receipt of the sale. The inventory control process must wait
until purchasing accepts the PO, and so on.
Figure 1-4. Retail Application Without Queue Manager
Sales
Order
PO Invoice
Check to
Vendor
Sales
Accounts
Payable
Inventory
Purchasing
004
When the application is redesigned with Queue Manager as shown in Figure 1-5, the
sales order process can enqueue transactions on the Queue file without waiting for a
confirmation from the inventory control process. This means the sales order process
can continue to take sales orders without interruption. The Wait Manager notifies the
inventory control process that sales order entries are waiting to be processed. This
notification by the Wait Manager is actually a response to a WAITQ UOW sent
previously by the inventory control process, asking to be told when a sales order ENQ
arrives on the queue. Once it has processed the sales order by checking its inventories,
inventory control can enqueue a purchase order request on the Queue file. This causes
the Wait Manager to trigger the purchase order process to dequeue the PO entry, and
so on until a check is processed for the vendor.