IDMS DDS TCP/IP example

Products

• IDMS

Issue/Introduction

This article contains sample SYSGEN source showing how to establish a DDS connection between two IDMS CVs on different LPARs using TCP/IP as the communications method.

Environment

Environment: All supported releases.

Resolution

Download and unzip the attached .zip file and review the contents while reading the following comments.

The example shown assumes that you have CV01 on LPAR01 and CV02 on LPAR02, and you want to access a DBNAME defined on CV02 from CV01.

The TCP/IP statement and the TCPIP line must be defined on both CVs. They most likely already exist if the CV in question already contains any TCP/IP processing, but are included here for completeness.

The TCPJSRV listener pterm/lterm pair is the means by which your CV initially receives DDS traffic from other CVs in a TCP/IP environment. They must be there whether the CV is a front-end (CV01) or back-end (CV02) in the connection. The port number must be unique across the LPAR on which that CV resides. Any CV only needs one such pair. They are defined in the same way that a listener pterm/lterm pair for IDMS/Server connections is defined. The same listener definition can be used for DDS and IDMS/Server connections. There is no technical or performance reason to define more than one pair, although it may be useful to do so for security or limit enforcement reasons.

The TCPDDSnn pterm/lterm pair points a front-end CV to a back-end CV by telling it where to find it (LPAR host name and port number). If this pair is not defined on CV02, then CV02 must be started first. To avoid this requirement, define the TCPDDSnn pterm/lterm pairs to both CVs, even if the desired connection is not bi-directional.

The TCPP0001/TCPL0001 bulk pterm/lterm pairs are required for each user connection. The CVs most likely already have some defined if any pre-existing TCP/IP processing is there, but may require more with the addition of DDS. Assign the REPEAT COUNT in TCPP0001 according to the expected load - the value of 39 provides for 40 concurrent connections.

The NODE definition is only required in the direction that the communication is to take place. In this example, with CV01 as the front-end and CV02 as the back-end, it is necessary only to define SYST0002 on CV01. SYST0002 is the SYSTEM ID in the SYSGEN SYSTEM statement of CV02.

 

Additional Information

DDS Design and Operations
- TCP/IP Considerations
SOCKET (in the Teleprocessing Network Statements chapter of the System Generation manual)