TI-RPC is a powerful technique for constructing distributed, client-server based applications. It is based on extending the notion of conventional, or local, procedure calling so that the called procedure need not exist in the same address space as the calling procedure. The two processes might be on the same system, or they might be on different systems with a network connecting them.
By using RPC, programmers of distributed applications avoid the details of the interface with the network. The transport independence of RPC isolates the application from the physical and logical elements of the data communications mechanism and enables the application to use a variety of transports.
Figure 2 How RPC Works
An RPC is analogous to a function call. Like a function call, when an RPC is made, the calling arguments are passed to the remote procedure and the caller waits for a response to be returned from the remote procedure.
Figure 2-1 shows the flow of activity that takes place during an RPC call between two networked systems. The client makes a procedure call that sends a request to the server and waits. The thread is blocked from processing until either a reply is received, or the request times out. When the request arrives, the server calls a dispatch routine that performs the requested service, and sends the reply to the client. After the RPC call is completed, the client program continues.
RPC specifically supports network applications. TI-RPC runs on available networking mechanisms such as TCP/IP. Other RPC standards are OSF DCE (based on Apollo's NCS system), Xerox Courier, and Netwise.