1
Introduction

Oracle connects to CICS through Oracle Application Server InterConnect Adapter for CICS (CICS adapter). This book introduces the CICS environment and CICS specific information. This chapter provides an overview of the CICS adapter.

What is CICS?

The IBM Customer Information Control System (CICS) allows data exchanges by sending and receiving buffers to and from an application using the CICS adapter. The CICS adapter uses the CPI-C LU6.2 SNA (LU6.2) protocol API and/or the ECI protocol API. The LU 6.2 protocol communicates with a CICS transaction, while the ECI protocol communicates with a CICS program. A CICS transaction contains presentation logic and business logic, while the CICS program contains only the business logic.

System Requirements and Platforms

To use CICS adapter with Oracle Application Server InterConnect (OracleAS InterConnect), the following requirements must be met.

For the ECI protocol:

• IBM CICS Universal client

For using CPI-C LU6.2 SNA (LU6.2):

• IBM SNA client or the MS SNA client

The CICS adapter runs on:

• Windows 2000 with service pack 1 or above

• Windows NT 4.0 with service pack 6 or above

Definitions

The following terms are specific to the CICS adapter:

• Logical Unit (LU)

• CPI-C

Logical Unit (LU)

A logical unit represents the logical destination of a communication data flow. The formal definition of a logical unit is the means by which an end user gains entry into a network. An end user is defined as the ultimate source, or destination, of data flow in a network. SNA supports several different types of logical units. These are grouped together in numbered logical unit types, such as logical unit type 2 for 3270 display terminals, and logical unit type 4 for printers. The logical unit type for CICS-to-CICS communication is logical unit type 6.2, and is frequently referred to as advanced program-to-program communication (APPC). Each logical unit is given a unique name that identifies it in the network. There are two types of logical units 6.2 pertinent to CICS adapter:

• Dependent logical unit 6.2 can have only a single session and therefore only one conversation at a time.

• Independent logical unit 6.2 can have more one session with other logical units--any conversations can be held simultaneously between two logical units.

CPI-C

CPI (CPI Communications) provides a cross-system-consistent and easy-to-use programming interface for applications that require program-to-program communication. From an application's perspective, CPI-C provides the function necessary to enable this communication. The conversational model is implemented in two major communications protocols: Advanced Program-to-Program Communication (APPC) and Open Systems Interconnection Distributed Transaction Processing (OSI TP). The APPC protocol is also referred to as Logical Unit type 6.2 (logical unit 6.2). CPI-C provides access to both APPC and OSI-TP.