OSF DCE Application Development Guide--Introduction and Style Guide

Introduction to DCE Application Programming

recommended way for clients and servers to ﬁnd each other because it is a convenient

and easy to use service built into DCE.

1.5.6 Specifying Multithreadedness

The application may also spawn an additional thread for a signal handler. An example

follows:

if (pthread_create(&sigcatcher,

pthread_attr_default,

(pthread_startroutine_t)signal_handler,

(void*)0))

{

dce_svc_printf(NO_SIGNAL_CATCHER_MSG);

exit(1);

}

The max_calls_exec parameter to the rpc_server_listen() routine speciﬁes the number

of operations that the server can perform concurrently in response to client requests. The

max_calls_exec parameter is also used to derive the size of a buffer (the call request

buffer) for incoming client requests that cannot be immediately executed.

max_calls_exec speciﬁes the upper limit for the number of RPC threads that will be

spawned by the RPC runtime to handle incoming remote procedure calls. Thus, an

important side effect of rpc_server_listen( ), when the speciﬁed concurrency is greater

than 1, is to create multiple threads of execution in the server.

The threads are automatically spawned to handle whatever operation is requested by the

client. If the maximum number of manager threads is already active and more incoming

calls arrive, the RPC runtime buffers them in a call request buffer. The size of the call

request buffer depends on the max_calls_exec parameter; the larger the parameter, the

bigger the buffer. Incoming calls beyond the call request buffer capacity are rejected

(with an error code) by the RPC runtime.

Although the execution threads are automatically managed by the RPC runtime, the

developer is responsible for coding the manager routines according to thread-safe

guidelines so that the threads will execute properly. For further information on thread-

safe programming practices, see Chapter 2.

1.5.7 Listening for Incoming Service Requests

In order to begin listening for incoming remote procedure calls, the server calls the

following RPC library routine:

rpc_server_listen(max_calls_exec, &status);

124246 Tandem Computers Incorporated 1− 23