The Workstation Listener (WSL) is a
Tuxedo process in the application server domain. It is configured to listen on
a specified IP address and port for incoming connections from Tuxedo client
process, which are any of the PeopleTools Windows client processes that operate
in three-tier mode.
The WSL spawns at least one
Workstation Handler (WSH) process, and it can be configured to start further
handlers on demand. The WSHs listen for incoming service requests on the same
IP address as the WSL and, unless they are configured to use a specific range
of ports, will use the next available port after the WSL port.
Initially the client contacts the WSL on the port specified
in the configuration. The WSL then assigns the client to one of the WSH
processes. The client then closes the connection to the WSL and thereafter only
communicates with the WSH.
The following
simplified steps describe the activity in the application server during a
transaction with a Windows client.
·
The service request is sent by the client to the
WSH process to which it is connected.
·
The WSH looks up the service on the BB to
determine which server or servers are advertising the service and which queues
lead to those servers.
·
The WSH then enqueues the message requesting that
service on an appropriate queue. In this case the service is placed on the
queue called APPQ. Note that not all the queues are explicitly named in Tuxedo.
·
The PSAPPSRV polls for service requests on APPQ,
dequeues that request, and executes the PeopleSoft code associated with that
service.
·
Processing the service request may involve several
interactions with the data. The PSAPPSRV server may need to read or update the
physical files that cache PeopleTools objects, as shown in this example.
·
Each WSH process has a return message queue. When
the service is complete, the PSAPPSRV server enqueues the return message on the
queue (WSHQ in this example) that leads back to the WSH process that sent the
request.
·
The WSH process polls and dequeues the return
message from the WSHQ.
·
WSH sends the return message back to the client
that has been waiting for a response.
