Servers and server objects

In DSOM, the process that manages a target object is called the object's server. Servers are implemented as programs that use SOM classes. The example above placed no constraints on the DSOM Object Manager as to which server should create the remote "Car" object. However, if the client desires more control over distribution of objects, the DSOM Object Manager provides methods for finding specific servers.

Server implementations are registered with DSOM in an Implementation Repository. Server implementations are described by a unique ID, a unique (user-friendly) name, the program name that implements the server, the classes that are implemented by the server, the machine on which the server is located, whether the server is multi-threaded, and so forth. (See section 6.6 for more information on registering server implementations.) A client can ask the DSOM Object Manager to find a particular server:

• By name

• By ID

• By a class it supports

When a client asks for a "server", it is given (a proxy to) a server object that provides interfaces for managing the objects in the server. There is one server object per server process. All server objects are instances of the SOMDServer class, or its subclasses. The default method provided by SOMDServer for creating objects is:

  // (from file somdserv.idl)
  SOMObject somdCreateObj(in Identifier objclass, in string hints);

  // Creates an object of the specified class.  This method
  // may optionally define creation "hints" which the client
  // may specify in this call.  (Hints are ignored by default.)

Section 6.4 explains how to create application-specific server objects, derived from SOMDServer, which override SOMDServer methods and introduce their own methods for object management.