Cooperative Processing Commands › Using SEND/RECEIVE Commands › How Cooperative Processing Works

How Cooperative Processing Works

The SEND/RECEIVE commands in CA ADS follow the standards set for Advanced Program to Program Communication (APPC).

APPC is an IBM standard that provides enhanced Systems Network Architecture (SNA) support for distributed processing. APPC enables 2 processors to work together: it describes the protocols the 2 processors' programs use to communicate as they execute a single distributed transaction.

APPC is composed of logical and physical definitions of the system network. The logical component is the LU 6.2 protocol, which defines the rules that govern the exchange of information between the 2 programs.

The LU 6.2 protocol structures a program-to-program conversation like a polite conversation: one side talks and the other side listens.

• One program (the primary program) starts the conversation by calling the other program (the secondary program).
• The 2 programs agree on the rules governing the conversation before the conversation can continue.
• The conversation goes back and forth, with the current speaker (in send state) always in control:
  1. When the listener (in receive state) wants to speak, the listener requests permission.
  2. If the speaker approves the request, the listener switches to send state and the speaker to receive state.