In this section, examples are used to show how a CPI-C program can communicate with a UTM application in single-step and multi-step services. In a multi-step service, more than one transaction may be executed in the UTM application. This can also include distributed transaction processing (see diagram Communicating in a multi-step UTM service with distributed transaction processing.
The calls used in the following examples are explained below:
sign on to the UPIC carrier system (Enable_UTM_UPIC)
initialize the conversation characteristics (Initialize_Conversation)
establish the conversation (Allocate)
send data (Send_Data; you can also use Send_Mapped_Data)
receive the response (Receive; you can also use Receive_Mapped_Data)
sign off from the UPIC carrier system (Disable_UTM_UPIC)
To simplify the diagrams in this section, the buffering of the data in the local UPIC memory during sending and receiving is not shown.