gtpd2m1z | Data Communications Services Reference |
This chapter describes the function and procedures that comprise the TPF message routing facility. The chapter is intended for system programmers, application programmers, and system operation personnel who are familiar with the TPF system as described in TPF Concepts and Structures. It is recommended that you review the information in TPF Concepts and Structures about the message router before using the information in this book.
SNA cross domain management and TPF message routing are related and occasionally entangled. Generally, TPF message routing implies that software in a CPU must be invoked to select a path for reaching a TPF application. The term application is always used in this chapter to indicate a class of related programs needed to accomplish a specific function, Coupon Remittance, Hotel Reservation, Credit Verification, Car Rental, and so on. In this context, a TPF application is defined as a software package that is reached through an entry in the Routing Control Application Table (RCAT). Complexity arises when the path to an application or terminal includes more than one CPU. This could involve multiple communications controllers or a single controller shared among several CPUs. The following information identifies some of the complexities of this topic. It is recommended that you review the information in TPF Concepts and Structures.
Applications resident in the loosely coupled complex are defined to be resident in each of the LC processors. Therefore, if the loosely coupled complex consists of CPUs A and B, an application defined as locally resident in CPU A is also defined as locally resident in CPU B. The only exception to this is the System Message Processor (SMP) application. Viewed from CPU A, SMPA is locally resident and SMPB is resident in CPU B.
The Multiple Data Base Facility (MDBF) has minimal functional impact on the message router support. An application definition requires an identifier to associate the application with a Subsystem User name.