Windchill System Administrator's Guide

The Windchill server manager is responsible for guaranteeing that background
processing takes place. The implementation of processing queues and triggering
mechanisms actually resides in the Windchill method servers. The server manager
is simply responsible for keeping an instance of the method server running so that
background processing can take place.
As described in the chapter entitled Administering Runtime Services, your
environment can be configured such that there are multiple method servers, one of
which is dedicated to running background processing queues.
For more information about queue configuration and maintenance, see
Configuring and Administering Background Queues.
Session Credentials and Properties
Windchill leverages the user authentication capability of the HTTP server.
However, the vast majority of client requests do not come through the HTTP
server, but instead come directly from the client through Java RMI. This requires
a place to cache the HTTP authenticated user names so they can be securely
associated with subsequent RMI calls. Because the server manager represents a
daemon process that outlives individual method server processes, that place is
within the server manager VM.
As discussed previously, when clients need valid credentials, Windchill is
uninvolved until after the HTTP server allows access to a protected Windchill
HTTP gateway. The gateway then passes the authenticated HTTP request to a
method server for processing. The method server processes the request for
credentials by storing the authenticated user name and associated session
properties (passed on the request) with a session manager that runs in the server
manager VM.
Live connections are not used to maintain the session database within the server
manager. To reduce resource consumption, credentials are validated by the
method server, even though the client is disconnected from the server manager.
Rather than live connections, a limited size, most-recently-used caching algorithm
is used. In the event a client is still alive after its session credentials have been
aged out, automatic exception handling transparently reestablishes the credentials.
Client Time-Out and Connection Limits
Scalability demands that individual clients do not consume significant server
resources indefinitely. A large number of infrequent users should not require that
the system is hosted on super-server hardware. Server host sizing should be a
function of transaction throughput, not of user count.
The Java I/O model, in particular the Java RMI implementation, dedicates at least
one thread to each network connection. To make this scalable to large number of
users, Windchill implements two mechanisms to free network connections and
threads. The first is to time out connections that remain idle for a specified period
of time. The second is to limit the total number of client sockets the RMI runtime
is allowed to consume. This limit is enforced by closing the least-recently-used
Windchill Runtime Environment A-13