12 Geac System21 commerce.connect: Implementation on the iSeries Server
For vendor.connect, Figure 2-2 shows the relationship between the controlling servlet and the
vendor.connect subsystems.
Figure 2-2 vendor.connect dependencies
call.connect components are designed to be extensible, reusable, and replaceable. This
means that the business functionality can be extended without needing to cut and paste
entire programs. This helps to reduce maintenance overhead and allows existing code to be
reused.
2.2 Messaging: Java Message Service and IBM WebSphere MQ
The term messaging refers to the sending of structured information between two or more
subsystems. Typically the message is sent asynchronously. That is that the sender can
continue to run without waiting for a reply from the receiver. Also, the sender and receiver
typically run as separate processes and possibly on physically separate machines.
2.2.1 call.connect
Both call.connect and vendor.connect use asynchronous messaging to meet specific
requirements:
call.connect uses messaging to meet two requirements:
To send information back to the client user interface (UI) such as “the order has been put
on hold due to credit problems”, or “a given item is out of stock”
To allow for time-consuming steps to be completed asynchronously, for example, order
completion when the order is actually committed into System21
contract
shipment
purchaseorder
Generic
Servlet
supplier
fulfillment
