aboutsummaryrefslogtreecommitdiff
path: root/java/core/src/main/java/com/google/protobuf/RpcController.java
blob: a92dd7be6d502772e87b85198ce598ce8c1da925 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package com.google.protobuf;

/**
 * <p>An {@code RpcController} mediates a single method call.  The primary
 * purpose of the controller is to provide a way to manipulate settings
 * specific to the RPC implementation and to find out about RPC-level errors.
 *
 * <p>Starting with version 2.3.0, RPC implementations should not try to build
 * on this, but should instead provide code generator plugins which generate
 * code specific to the particular RPC implementation.  This way the generated
 * code can be more appropriate for the implementation in use and can avoid
 * unnecessary layers of indirection.
 *
 * <p>The methods provided by the {@code RpcController} interface are intended
 * to be a "least common denominator" set of features which we expect all
 * implementations to support.  Specific implementations may provide more
 * advanced features (e.g. deadline propagation).
 *
 * @author kenton@google.com Kenton Varda
 */
public interface RpcController {
  // -----------------------------------------------------------------
  // These calls may be made from the client side only.  Their results
  // are undefined on the server side (may throw RuntimeExceptions).

  /**
   * Resets the RpcController to its initial state so that it may be reused in
   * a new call.  This can be called from the client side only.  It must not
   * be called while an RPC is in progress.
   */
  void reset();

  /**
   * After a call has finished, returns true if the call failed.  The possible
   * reasons for failure depend on the RPC implementation.  {@code failed()}
   * most only be called on the client side, and must not be called before a
   * call has finished.
   */
  boolean failed();

  /**
   * If {@code failed()} is {@code true}, returns a human-readable description
   * of the error.
   */
  String errorText();

  /**
   * Advises the RPC system that the caller desires that the RPC call be
   * canceled.  The RPC system may cancel it immediately, may wait awhile and
   * then cancel it, or may not even cancel the call at all.  If the call is
   * canceled, the "done" callback will still be called and the RpcController
   * will indicate that the call failed at that time.
   */
  void startCancel();

  // -----------------------------------------------------------------
  // These calls may be made from the server side only.  Their results
  // are undefined on the client side (may throw RuntimeExceptions).

  /**
   * Causes {@code failed()} to return true on the client side.  {@code reason}
   * will be incorporated into the message returned by {@code errorText()}.
   * If you find you need to return machine-readable information about
   * failures, you should incorporate it into your response protocol buffer
   * and should NOT call {@code setFailed()}.
   */
  void setFailed(String reason);

  /**
   * If {@code true}, indicates that the client canceled the RPC, so the server
   * may as well give up on replying to it.  This method must be called on the
   * server side only.  The server should still call the final "done" callback.
   */
  boolean isCanceled();

  /**
   * Asks that the given callback be called when the RPC is canceled.  The
   * parameter passed to the callback will always be {@code null}.  The
   * callback will always be called exactly once.  If the RPC completes without
   * being canceled, the callback will be called after completion.  If the RPC
   * has already been canceled when NotifyOnCancel() is called, the callback
   * will be called immediately.
   *
   * <p>{@code notifyOnCancel()} must be called no more than once per request.
   * It must be called on the server side only.
   */
  void notifyOnCancel(RpcCallback<Object> callback);
}