SNAX/HLS Application Programming Manual

Life Cycle of a Session
Sessions
104707 Tandem Computers Incorporated 3–3
Pipelined LU Resources
An LU resource can be declared as pipelined by setting the PIPELINE–LU–IND to Y.
Such resources can be allocated by more than one requester. When an LU is declared
as PIPELINED in the RDT entry, all allocation requests must also declare that they
expect pipelined LUs.
Enhanced Session Opening
and Closing
The operation of the HLS–OPEN verb depends upon the session rules given in the
PROFILE, which designate your half–session as either primary or secondary and
designate your half–session to be in accept or acquire mode:
The primary partner (PLU) issues the SNA BIND request; the secondary partner
(SLU) receives the BIND request.
The process of establishing a session begins by having the ACQUIRE partner issue
the first message and having the ACCEPT partner receive the first message.
Viewed from a half–session, session acquisition proceeds as follows:
If your session is the primary operating in the ACQUIRE mode, the first activity of
the session is initiated on your behalf by SNAX/HLS sending the BIND message
to the partner.
If your session is the primary operating in the ACCEPT mode, the first activity of
the session is initiated by your partner sending an INIT–SELF (or character–coded
LOGON message). This is converted by SNA protocol rules into a CINIT message
that SNAX/HLS receives on your behalf. In response, SNAX/HLS sends the
BIND message.
If your session is the secondary operating in the ACQUIRE mode, the first activity
of the session is initiated on your behalf by SNAX/HLS sending an INIT–SELF
message to the SSCP (a character–coded logon message would be acceptable at
this point, but SNAX/HLS does not support it). It is converted to a CINIT and
delivered to your partner, the PLU. The PLU should send a BIND that the
SNAX/HLS server receives and responds to.
If your session is secondary operating in ACCEPT mode, the first activity of the
session is the receipt of the BIND message.
Session communication can be stopped with the HLS–CLOSE verb. If you wish to
make sure that your partner has flushed (or cleared) its queues, you should use the
PREPARE–TO–CLOSE verb for an orderly shutdown of the session.
The HLS–CLOSE verb causes SNAX/HLS to perform a CLOSE of the SNAX/XF LU or
SNAX/CDF APPL object associated with the session. If the session is being shared
among more than one opener (pipelined), only the last close event causes this closure.
Simple Session Opening
and Closing
The CLOSE–SESSION verb causes SNAX/HLS to perform a CLOSE of the SNAX/XF
LU or the SNAX/CDF APPL associated with the indicated session. If no preceding
PREPARE–TO–CLOSE verb has been executed, this verb produces a forced
termination of the session. If a successful PREPARE–TO–CLOSE verb has been
executed, this verb merely causes a resource cleanup for the indicated session.