Establishing a DRDA or DDM connection over TCP/IP

 

To initiate a DDM server job that uses TCP/IP communications support, the DRDA^® Application Requester or DDM source system will connect to the well-known port number, 446 or 447. The DDM server also listens on port 448, but only for use with connections, which are not supported by DB2 Universal Database™ for iSeries™ application requesters or DDM clients. Figure 1. DRDA and DDM TCP/IP server

1. The DDM listener program must have been started (by using the Start TCP/IP Server (STRTCPSVR SERVER(*DDM)) to listen for and accept the client's connection request.

The DDM listener, on accepting this connection request, will issue an internal request to attach the client's connection to a DDM server job 2. This server job might be a prestarted job or, if the user has removed the QRWTSRVR prestart job entry from the QUSRSYS or user-defined subsystem (in which case prestart jobs are not used), a batch job that is submitted when the client connection request is processed. The server job will handle any further communications with the client.

The initial data exchange that occurs includes a request that identifies the user profile under which the server job is to run 3.

After the user profile and password (if it is sent with the user profile ID) have been validated, the server job will swap to this user profile as well as change the job to use the attributes, such as CCSID, defined for the user profile 4.

The functions of connecting to the listener program, attaching the client connection to a server job and exchanging data and validating the user profile and password are comparable to those performed when an APPC program start request is processed.

 

Parent topic:

TCP/IP communication support concepts for DDM

 

Related reference

Start TCP/IP Server (STRTCPSVR) command