IMS Connectivity in an On Demand Environment: A Practical Guide to IMS Connectivity

Chapter 14. Building roll your own clients 279

14.4 Complete pseudocode samples

In this section, we provide you complete pseudocode for several useful execution flows. In

14.5, “Detailed code examples” on page 282, we provide two implementations of these

programming models in the C and Java programming languages.

14.4.1 Commit mode 1 send-receive programming

In this sample, we assume that you are interested in writing a program to send one

transaction to an IMS system using IMS Connect, under the commit mode 1

(send-then-commit) protocol, acknowledging the response (synchronization level confirm),

and using a transaction socket.

This program model corresponds to the simplified example presented at the beginning of the

chapter. Example 14-1 shows the pseudocode to implement this model.

Example 14-1 Pseudocode for a commit mode 1, sync level confirm, transactional socket

PROGRAM send_receive_cm1(host, port, datastore, transaction_data)

socket := open_socket(host, port) 1.

IRM := build_irm(commit_mode=1, synch_level=CONFIRM, data_store=datastore, 2.

type=SEND_RECEIVE, transaction=transaction_data);

send(socket,IRM);

response := receive(socket); 3.

if (response is a RSM) 4.

print_error_details(response.RSM_data);

else

if (response contains a CSM)

process_response(response.segment_data);

if (response.ack_needed) 5.

IRM := build_irm(commit_mode=1, synch_level=CONFIRM, data_store=datastore,

type=ACK, transaction=NULL);

send(socket,IRM);

response := receive(socket); 6.

if (response.RSM IS NOT “deallocate commit”)

print_error_details(response.RSM_data);

<prepare abnormal termination>

else

<everything OK, prepare normal termination>

endif

endif

else

print_error_details(response.RSM_data);

<prepare abnormal termination>

endif

endif

close(socket); 7.

END send_receive_cm1;

The following numbers correspond to the numbers in Example 14-1:

1. To communicate to IMS Connect, we need to create and open a TCP socket bound to the

host and port where IMS Connect is listening.

2. Next, we prepare and send the input message structure, according to 14.2.1, “The IMS

Connect input message” on page 268.

3. Now, we read the response from the socket. IMS Connect waits for OTMA up to the

maximum time we specified in the IRM_TIMER field of the IRM prefix. We can also use

the TCP/IP timeout features to avoid blocking too much time.