In order that a UTM application is able to communicate with the TS application via the socket interface, a UTM socket protocol (USP) may be used on top of TCP/IP. openUTM uses this protocol to convert a bytestream received via the socket interface into a message. The partner application must issue the protocol and prefix it with the input message as the protocol header. openUTM does not usually create a protocol for output messages.
It is possible to set each generation option so that openUTM also prefixes a protocol header for output messages. This is specified in the PTERM or TPOOL statement using the operand USP-HDR=:
USP-HDR=ALL ensures that openUTM prefixes all output messages of this connection (dialog, or asynchronous message, K message) with a protocol header.
With USP-HDR=MSG the protocol header is prefixed for K messages only.
USP-HDR=NO means that no protocol header is prefixed for output messages.
The structure of the protocol header is described in the openUTM manual „Programming Applications with KDCS”.