SNAX/APC Application Programming Manual

Using the Application Program Interface

SNAX/APC Application Programming Manual—138786

1-14

Local Source TP Example

1. Issue a (MC)GET-ATTRIBUTES verb sometime before the end of the conversation.

This will return, among other things, a session ID.

2. At the end of the conversation, issue a DEACTIVATE-SESSION verb using the

appropriate session ID.

Reusing Conversation Resources

A TP that repeatedly allocates and deallocates conversations using the same local LU

can reuse its conversation resources by issuing a single TP-READY request. When the

TP deallocates a conversation, it can reuse the conversation resources by using the same

resource ID in the IPC header for the next ALLOCATE verb request. Note that the TP

does not issue another TP-READY request.

Local Source TP Example

In Figure 1-2, a local TP needs to access a database used by the CICS application;

therefore, the local TP initiates the conversation. Note that LU 6.2 protocol gives the TP

that initiates a conversation the right to send data first.

1. The local TP sends a TP-READY request to the SNAX/APC process (the

SNAX/APC process has been previously opened). The TP-READY request

specifies the requested SNAX/APC LU and indicates that the local TP is initiating

the conversation by specifying LOCAL ATTACH=YES, DISPATCHED=NO.

2. The SNAX/APC process returns a TP-READY reply message, indicating the

creation of a TP instance. The reply contains the resource ID. The TP should check

the return code of the reply.

3. The TP sends an ALLOCATE request to the SNAX/APC process, specifying the

remote TP. If the LU-LU session does not exist, SNAX/APC initiates it. When a

session becomes available, SNAX/APC sends the ALLOCATE reply to the local TP.

4. When the SNAX/APC process is ready to transmit data to the remote TP, it sends an

SNA ATTACH request to the remote LU 6.2. (An ATTACH request is an SNA

Figure 1-2. Requesting a Conversation

002CDT .CDD

SNAX/APC

SNA

IBM Tandem

Remote TP Local TP

TP-READY request

TP-READY reply

ALLOCATE

ATTACH

ALLOCATE reply

CICS