The following traces describe the most common scenario of the Change of Address application, that is, the actual change of address. In this scenario, the postal service operator makes a change to a registered person’s address using option 3 of the Change of Address application. This makes the change to the mainframe DB2 table and puts the hash code of the old address onto the publication queue. The CICS program finally sends a response screen to the operator indicating success and the new hashcode.
The HashPublication message flow running on the System z broker now publishes the hashcode to all the registered subscribers of the topic:
CICSWSAP/AddressChange, of which there are 3 in this trace example. This is the end of the HashPublication message flow.
The third component is a trace of a broker message flow, which represents the client side of the application. The client code receives the notification of the address change via the hashcode publication and checks to see if they have a client with that particular hashvalue. If so, it calls the CICS RetrieveAddress Web service to retrieve the new address for that person. If successful, the message flow updates the local customer database with the new address. This is the end of the sequence.
The flowcharts in the following pages may help to understand the time sequence and interactions of the various components. Note these flowcharts only represent this particular scenario and not the full logic of the application.
Flow of the Address Update CICS programs ITSOUA04/03
1. The trace through CICS
This section shows a trace through one scenario of the Change of Address application.
The trace begins with the postal service operator invoking the Address Change option by selecting Option 3 from the IT00 main menu. The sequence of events from a CICS perspective involves three maps and is seen in Figures below.
Option 3 to Add/Update Address
The operator then enters the new address details:
Entering new address details
Next the operator presses ENTER to perform the update.
New address successfully entered
The flowchart in Figure describes the action of this update process and names the CICS business logic programs that are invoked for this scenario:
a. Start the transaction
The CICS trace in Example shows the start of program ITSOUA01, which SENDs the entered name and new address details from Figure and then returns with transaction IT14.
Example: Starting the transaction
b. Call DB2 and generate an AddressHash
Transaction IT14 starts program ITSOUA02, which receives the entered data into a commarea and then LINKS to the business logic module ITSOUA04. This program performs the following and is highlighted in Example:
Example : Check that name exists, and generate a Hash value
c. Update database with new address
Program ITSOUA03 now adds the new address and new hash value to the local database. Example shows that the following is performed:
Example: Update new address
Call MQ to write the old AddressHash to a queue
The processing has now returned to ITSOUA04, which performs the following actions and is highlighted in Example:
Example: Call to MQ to write the Old AddressHash
d. Display results in CICS and terminate task
This is the conclusion of the CICS processing with a return to the presentation logic in program ITSOUA02 and task cleanup. Example shows the following actions:
Example: Results are displayed to the terminal, and the CICS task is terminated
2. Tracing the Broker on System z
The flowchart in Figure shows the Hash Publication message flow.
The Hash Publication Flow
Example: The HashPublication message flow trace
3. Tracing the Broker on Windows
Now the RetrieveAddressWithDB message flow is triggered on the Windows platform by the
receipt of the hash publication.
Example RetrieveAddressWithDB MsgFlow Pt1
4. Tracing the CICS Web service
We now pick up the trace on the CICS side where the CICS Web service pipeline processes the Web service request for the RetrieveAddress logic and hands back the result. The flowchart in Figure shows the interaction between the message flow running in the Broker on the client Windows platform and the Web service in CICS where we are exposing our business logic as a service provider.
The CICS program being called is ITSORA03.
Client calling CICS RetrieveAddress Web service
a. The Web service request enters CICS
When the client broker submits the Web service request to the CICS region, the receiving TCPIPSERVICE detects the incoming request and the actions are performed and displayed in the trace in Example.
Example: Request for Web services enters CICS
Of interest in the trace entries for Example 9-10 on page 234, is further detail on the trace point for WB 0905 that shows the URI mapping in the CICS FULL trace output in Example. In this entry you can see the following in the eyecatcher area:
Example: The FULL trace output showing URI mapping
b. A service provider pipeline is started
Transaction CPIH invokes the CICS program DFHPIDSH—the pipeline HTTP inbound router module—starting a service provider pipeline. This is shown in Example.
Example : Service provider pipeline is started
The FULL trace entry for trace point ID PI 0A2F shows the details of the PIPELINE, including the configuration file name, the HFS shelf, and pickup directories. This is seen in Example and shows the following:
Example : Full trace entry showing pipeline details
The incoming request
The trace point PI 0A41 contains the incoming request. The FULL entry showing the entire request is shown in Example.
Example: Full trace record of the incoming request data
c. Handling the Request
The trace in Example shows the CICS processing that continues:
Example: Parsing the incoming SOAP request
IBM-CICS Related Interview Questions
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Service-oriented Architecture And Cics
Cics As A Service Provider And Requester
Modern Web Services Development Tools
Development Of The Change Of Address Cics Application
Exposing Our Application As A Web Service
Developing Web Service Clients
Tracing The Change Of Address Scenario
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