TS/MP Pathsend and Server Programming Manual (H06.05+, J06.03+)

messages if it uses FILE_GETRECEIVEINFO_, or CLOSE system messages if it uses
CRE_Receive_Read_ or the COBOL85 or FORTRAN language. The server should treat such messages
as dialog aborts.
Servers can monitor CPU down, remote CPU down, and loss of communication with network node
system messages by calling the Guardian procedures MONITORCPUS and MONITORNET, which
are described in the Guardian Programmer’s Guide.
It is also possible to get Pathsend dialog abort messages that do not represent actual aborted
dialogs. A server can receive such a message if the requester calls SERVERCLASS_DIALOG_BEGIN_
and then cancels the message. In that case, the LINKMON process or the ACS subsystem processes
send the Pathsend dialog abort message even though the server might not have received the first
message in the dialog. Similarly, if the requester calls SERVERCLASS_SEND_ with the nowait option
and then cancels the operation before being notified of completion of the operation through the
AWAITIOX procedure, the server receives the Pathsend dialog abort message even if it has already
replied to the last send operation.
A cancel operation can also occur if the requester abends while a server-class send operation is
in progress, whether or not the send operation was invoked with the nowait option.
Handling ACS Subsystem Failures
If the ACS core processes fail or are stopped on a processor, the links that the ROUT process
established with the server processes are relinquished. If any Pathsend dialogs are outstanding at
the time of failure, the dialogs can be considered invalid and must be cleaned up.
Writing Pathway Servers That Interoperate With NonStop Tuxedo
Requesters
A Pathway server can service requests from NonStop Tuxedo requesters (NonStop Tuxedo clients
or NonStop Tuxedo servers acting as clients). Such requesters can make their requests to a Pathway
server in either of two ways:
• Directly, by making calls to the Pathsend procedures described in this manual
• Indirectly, by using the Nonstop Tuxedo to Pathway translation server
Only those NonStop Tuxedo requesters that are NonStop Tuxedo native System/T clients can make
direct requests by using Pathsend procedure calls. For more information, refer to the NonStop
TUXEDO System Application Development Guide.
Native System /T clients, remote NonStop Tuxedo requesters using System /Domain, and non-native
NonStop Tuxedo workstation clients can indirectly invoke the services of a Pathway server by using
the NonStop Tuxedo to Pathway translation server. If you use this translation server, special
guidelines apply, and you might need to modify the code of existing Pathway servers. For further
information, refer to the NonStop TUXEDO System Pathway Translation Servers Manual.
74 Writing Pathway Servers