1// Protocol Buffers - Google's data interchange format
2// Copyright 2008 Google Inc.  All rights reserved.
3// http://code.google.com/p/protobuf/
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30
31package com.google.protobuf;
32
33/**
34 * <p>Abstract interface for an RPC channel.  An {@code RpcChannel} represents a
35 * communication line to a {@link Service} which can be used to call that
36 * {@link Service}'s methods.  The {@link Service} may be running on another
37 * machine.  Normally, you should not call an {@code RpcChannel} directly, but
38 * instead construct a stub {@link Service} wrapping it.  Example:
39 *
40 * <pre>
41 *   RpcChannel channel = rpcImpl.newChannel("remotehost.example.com:1234");
42 *   RpcController controller = rpcImpl.newController();
43 *   MyService service = MyService.newStub(channel);
44 *   service.myMethod(controller, request, callback);
45 * </pre>
46 *
47 * <p>Starting with version 2.3.0, RPC implementations should not try to build
48 * on this, but should instead provide code generator plugins which generate
49 * code specific to the particular RPC implementation.  This way the generated
50 * code can be more appropriate for the implementation in use and can avoid
51 * unnecessary layers of indirection.
52 *
53 * @author kenton@google.com Kenton Varda
54 */
55public interface RpcChannel {
56  /**
57   * Call the given method of the remote service.  This method is similar to
58   * {@code Service.callMethod()} with one important difference:  the caller
59   * decides the types of the {@code Message} objects, not the callee.  The
60   * request may be of any type as long as
61   * {@code request.getDescriptor() == method.getInputType()}.
62   * The response passed to the callback will be of the same type as
63   * {@code responsePrototype} (which must have
64   * {@code getDescriptor() == method.getOutputType()}).
65   */
66  void callMethod(Descriptors.MethodDescriptor method,
67                  RpcController controller,
68                  Message request,
69                  Message responsePrototype,
70                  RpcCallback<Message> done);
71}
72