If UTM messages are intended for a transport system application of the type PTYPE=APPLI or SOCKET (message destination = PARTNER), you must ensure that the application recognizes the messages and responds accordingly. If it does not, it can happen, for example, when two UTM applications are linked as TS applications, that the applications keep sending each other messages such as
K009 Transaction code K009 is invalid.
In this case the UTM application could, for example, define a TAC K009, and assign a program to this which is to respond to this message.
USP header in the case of UTM messages to a socket USP application
For UTM messages to a socket application (PTYPE=SOCKET, message destination = PARTNER), you can specify at UTM generation whether openUTM is to precede the message with a USP header (openUTM Socket Protocol header). One of the purposes of the USP header is to output the length of the received messages to the socket partner.
To do this, specify the following at KDCDEF generation in the USP-HDR= operand of the PTERM or TPOOL statement:
USP-HDR = MSG or USP-HDR = ALL
If you generate USP-HDR = NO (default setting), a USP header is not created.
You will find a description of the USP header in the openUTM manual „Programming Applications with KDCS”.
UTM messages to HTTP clients
UTM does not send K-messages to HTTP clients, not even then, if the K-message is configured with message destination PARTNER.
Exception:
The messages K017 and K034 are always sent to HTTP clients, even then, if the message destination PARTNER is not set for these messages.