QUESTION:
I have a modem connecting my RS/6000 to a leased SNA/SDLC line. The
applicaiton that uses this line blocks when the line is not active.
When the modem is powered up and ready but the line is not active,
the application successfully allocates the snaopen() routine but
the ensuing snalloc() call blocks forever until the line becomes
active. The books says the snalloc() should time out. I have received
and installed the latest SNA and SDLC fixes, but the problem persists.
I would like to circumvent this problem by using the alarm() function
to provide a timeout on the snalloc(). The program will periodically
retry the connection. Will I cause a problem if I bail out of the
snalloc() with a SIGALARM multiple times?
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A: It is recommended that you code the return_control allo_str field to
ALLOC_IMMEDIATE as the snalloc call will fail if no such sessions
are immediately available preventing the block you are experiencing.
The use of SIGALARM is known to cause problems.
Application of PTF U423978 may be required if you are not able
to code ALLOC_IMMEDIATE for return_control and SNA Services/6000 is
installed. Verify the installation of the PTF with the following
command:
lslpp -ah sna.sna.obj
If the PTF is not displayed or is not installed with a state of
APPLIED or COMMIT, contact appropriate channel to order. PTF
U432978 was a result of APAR IX35153.
If you have SNA Server/6000, the ALLOC_IMMEDIATE value incorporated
and there is no need for a PTF.
For the return_control of the Allocate, the alloc_immediate means
the following:
Allocates a session if a session is immediately available. (A
session is immediately available if it is active, is not in use by
another conversation, and is a contention winner session.) The call
fails if no such sessions are available.
Documentation is located the "Transaction Program Reference" for
AIX SNA Server/6000, SC31-7003-01, P. 318.
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This item was created from library item Q672741 CWCVM
Additional search words:
ALARM AUTO AUTOMATIC BLOCKING CALL COMMUNICATIO CWCVM IX OCT94 OZIBM
OZNEW RISCSNA RISCSYSTEM SNA SNALLOC SOFTWARE TIMEOUT
WWQA: ITEM: RTA000049574 ITEM: RTA000049574
Dated: 11/1996 Category: RISCSNA
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