TS/MP Release Supplement

ACS Subsystem
HP NonStop TS/MP Release Supplement—546055-006
1-17
Pathsend API
1. The application requester 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.
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
process broker. The process broker either assigns an available server process
from its pool or requests an additional copy of the server process.
3. If the process broker does not have a server process available to handle the
request, it prepares to communicate to the
PATHMON process for a new link.
4. If the original Pathsend request is directed for a Pathway domain, the process
broker applies the static load balancing algorithm to select the best
PATHMON
process to which it should communicate for a link request. Once the best
PATHMON
process is selected, the process broker requests a new link.
5. If the
PATHMON process does not have a server process available and the
maximum server processes has not yet been reached, the
PATHMON process starts
a server process.
6. The
PATHMON process might reject the link request either because the server class
is not in the proper state or when 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 satisfy the link request.
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 requester has the access rights to perform the send operation, the ROUT
forwards the request to the server process.
Note. For SCOBOL APIs, the application requester 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 requester and calls the
appropriate Pathsend API to be processed by the local ROUT process.
Note. The best PATHMON is defined as a PATHMON that results 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.
For information on link distribution, see Load Balancing PATHMON Link Requests in a
Pathway Domain.
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 satisfied or rejected by all the PATHMONs.