The DCE Remote Procedure Call (RPC) facility provides communications between client and server machines in a network. For the Cache Manager on a client machine to send a request for data or other resources to a server machine, it must know how to locate the File Server machine in the network and how to communicate with it. An RPC requires the use of a binding handle for the File Server machine on which a fileset resides.
The binding handle includes the server machine's network address, an identifier for the protocol used to communicate with the machine, and an "endpoint" (often a port number) for communications with the machine. It also contains user authentication information about a user who requests data. The Cache Manager uses this binding handle to communicate with the server machine.
The same process is used to effect communications between different server machines. For example, DFS employs Ubik to synchronize copies of the Fileset Location Database and Backup Database. Instances of Ubik that coordinate the databases on different server machines rely on RPCs to communicate with each other. Communication failures resulting from RPC problems can cause unnecessary disruption of database access.
When a server process first starts, it registers its process endpoint with the endpoint mapper service of the dced process. The dced process running on a server machine provides the remote location information required by clients to communicate with server processes running on the server machine. The dcecp program allows system administrators to manage the dced process on a machine. Many RPC administrative tasks, however, are performed automatically when a server first starts.
The UUID Facilities are another component of the DCE RPC employed by DFS and other DCE components. The commands and routines in the facility are used to generate Universal Unique Identifiers (UUIDs). These UUIDs are used to uniquely identify resources such as machines and processes. For example, the Backup System uses UUIDs to identity the Tape Coordinator processes on machines that are used to back up data to tape.