TS/MP 2.5 Release Supplement

1. The application requestor calls the Pathsend API, either to a specific PATHMON process or
to a configured Pathway domain. The system library checks the supplied parameters, formats
a message, and sends it to the local ROUT process.
NOTE: For SCOBOL APIs, the application requestor calls the SCOBOL API, either to a
specific PATHMON process or to a configured Pathway domain. The PATHTCP4 checks the
supplied parameters, formats a message, acts as a Pathsend requestor, and calls the
appropriate Pathsend API to be processed by the local ROUT process.
2. The ROUT process receives the request and queues it to an available link. If no link is available
for the server class, the ROUT process sends a link request to the PB. The PB either assigns an
available server process from its pool or requests an additional copy of the server process.
3. If the PB does not have a server process available to handle the request, it requests to
communicate to the PATHMON process for a new link.
4. If the original Pathsend request is directed for a Pathway domain, the PB applies the static
load balancing algorithm to select the best PATHMON process from which to get the server
link. Once the best PATHMON process is selected, the PB requests a new link.
NOTE: The best PATHMON is defined as a PATHMON that resolves into a link distribution
pattern, which is as near as the defined weights of the PATHMONs in the ACSCTL file. For
more information on the ACSCTL file configuration, see “ACSCTL File Configuration” (page 18).
For information on link distribution, see “Load Balancing PATHMON Link Requests in a Pathway
Domain” (page 25).
5. If the PATHMON process does not have a server process available and the maximum server
processes is not reached, the PATHMON process starts a server process.
6. The PATHMON process may reject the link request either because the server class is not in
the proper state or the PB has already taken the number of links for the concerned server class
available for it. If the send request is for a Pathway domain, the PB might retry the link request
to other PATHMON processes within that domain to process the link request.
NOTE: When the best PATHMON rejects a link, the next PATHMON is selected based on
the defined weights in the ACSCTL file. The PATHMONs are selected in the ascending order
of their weights till the link request is accepted or rejected by all the PATHMONs.
7. When the PB acquires the server process from the PATHMON process, it creates the objects
needed to control the link through the ROUT process.
8. The local ROUT process checks for security rights and configuration information. If the requestor
has the access rights to perform the send operation, the ROUT forwards the request to the
server process.
9. Other PBs in the system might also be requesting server processes from the PATHMON process
at the same time. Server processes can be shared between PBs if the MAXLINKS attribute is
set to a value greater than 1.
10. Parallel requests to a server process are queued on the server's $RECEIVE file until they are
handled by the server process.
Pathway Domain Support
Pathsend APIs SERVERCLASS_SEND_, SERVERCLASS_DIALOG_BEGIN_,
SERVERCLASS_SENDL_, SERVERCLASS_DIALOG_BEGINL_,
SERVERCLASS_DIALOG_SENDL_, SERVERCLASS_DIALOG_BEGINL64_,
SERVERCLASS_DIALOG_SENDL64_, and SERVERCLASS_SENDL64_ include the new Pathway
domain syntax in place of the PATHMON name. Also, the existing optional flags parameter is
updated to override the default behavior of sending requests to a Pathway domain.
Pathsend API 23