The following describes the message communication process when using an MHP. The process differs according to the communication protocol.
The message processing described below applies only to an MHP.
Figure 3-29 shows message processes and the type of MHP application.
Figure 3-29 Message processing and MHP application type
In inquiry-response communication, a message is received from another system, and a response message is sent back. The dc_mcf_receive function is used to receive a message, and the dc_mcf_reply function is used to send the response.
An MHP that performs communication in inquiry-response mode is specified as a response-type (ans-type) application. If a response-type MHP ends without calling the dc_mcf_reply function, an error is assumed and the MHP ends abnormally.
In non-inquiry-response communication, a message is received from another system, but no response is returned. The dc_mcf_receive function is used to receive the message.
An MHP that performs non-inquiry-response processing (receive-only mode) is specified as a non-response (noans-type) application.
Continuous inquiry-response communication consists of a series of inquiry-response messages. The dc_mcf_receive function is used to receive a message from another system, and the dc_mcf_reply function is used to send the response. Subsequent messages are received after each response, either by the same MHP or by a different MHP. Continuous inquiry-response communication is ended by issuing the dc_mcf_contend function.
An MHP that performs continuous inquiry-response processing is specified as a continuous inquiry response type (cont-type) application.