Object Adapters

A communicator contains one or more object adapters. An object adapter sits at the boundary between the Ice run time and the server application code and has a number of responsibilities:

  • Maps Ice objects to servants for incoming requests and dispatches the requests to the application code in each servant (that is, an object adapter implements an up-call interface that connects the Ice run time and the application code in the server).
  • Assists in life cycle operations so Ice objects and servants can be created and existing destroyed without race conditions.
  • Provides one or more transport endpoints. Clients access the Ice objects provided by the adapter via those endpoints. (It is also possible to create an object adapter without endpoints. In this case the adapter is used for bidirectional callbacks.

Each object adapter has one or more servants that incarnate Ice objects, as well as one or more transport endpoints. If an object adapter has more than one endpoint, all servants registered with that adapter respond to incoming requests on any of the endpoints. In other words, if an object adapter has multiple transport endpoints, those endpoints represent alternative communication paths to the same set of objects (for example, via different transports).

Each object adapter belongs to exactly one communicator (but a single communicator can have many object adapters). Each object adapter has a name that distinguishes it from all other object adapters in the same communicator.

Each object adapter can optionally have its own thread pool, enabled via the <adapter-name>.ThreadPool.Size property. If so, client invocations for that adapter are dispatched in a thread taken from the adapter's thread pool instead of using a thread from the communicator's server thread pool.

Servants are the physical manifestation of an Ice object, that is, they are entities that are implemented in a concrete programming language and instantiated in the server's address space. Servants provide the server-side behavior for operation invocations sent by clients. The same servant can be registered with one or more object adapters.


See Also