1// Protocol Buffers - Google's data interchange format 2// Copyright 2008 Google Inc. All rights reserved. 3// http://code.google.com/p/protobuf/ 4// 5// Redistribution and use in source and binary forms, with or without 6// modification, are permitted provided that the following conditions are 7// met: 8// 9// * Redistributions of source code must retain the above copyright 10// notice, this list of conditions and the following disclaimer. 11// * Redistributions in binary form must reproduce the above 12// copyright notice, this list of conditions and the following disclaimer 13// in the documentation and/or other materials provided with the 14// distribution. 15// * Neither the name of Google Inc. nor the names of its 16// contributors may be used to endorse or promote products derived from 17// this software without specific prior written permission. 18// 19// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31package com.google.protobuf; 32 33/** 34 * <p>An {@code RpcController} mediates a single method call. The primary 35 * purpose of the controller is to provide a way to manipulate settings 36 * specific to the RPC implementation and to find out about RPC-level errors. 37 * 38 * <p>Starting with version 2.3.0, RPC implementations should not try to build 39 * on this, but should instead provide code generator plugins which generate 40 * code specific to the particular RPC implementation. This way the generated 41 * code can be more appropriate for the implementation in use and can avoid 42 * unnecessary layers of indirection. 43 * 44 * <p>The methods provided by the {@code RpcController} interface are intended 45 * to be a "least common denominator" set of features which we expect all 46 * implementations to support. Specific implementations may provide more 47 * advanced features (e.g. deadline propagation). 48 * 49 * @author kenton@google.com Kenton Varda 50 */ 51public interface RpcController { 52 // ----------------------------------------------------------------- 53 // These calls may be made from the client side only. Their results 54 // are undefined on the server side (may throw RuntimeExceptions). 55 56 /** 57 * Resets the RpcController to its initial state so that it may be reused in 58 * a new call. This can be called from the client side only. It must not 59 * be called while an RPC is in progress. 60 */ 61 void reset(); 62 63 /** 64 * After a call has finished, returns true if the call failed. The possible 65 * reasons for failure depend on the RPC implementation. {@code failed()} 66 * most only be called on the client side, and must not be called before a 67 * call has finished. 68 */ 69 boolean failed(); 70 71 /** 72 * If {@code failed()} is {@code true}, returns a human-readable description 73 * of the error. 74 */ 75 String errorText(); 76 77 /** 78 * Advises the RPC system that the caller desires that the RPC call be 79 * canceled. The RPC system may cancel it immediately, may wait awhile and 80 * then cancel it, or may not even cancel the call at all. If the call is 81 * canceled, the "done" callback will still be called and the RpcController 82 * will indicate that the call failed at that time. 83 */ 84 void startCancel(); 85 86 // ----------------------------------------------------------------- 87 // These calls may be made from the server side only. Their results 88 // are undefined on the client side (may throw RuntimeExceptions). 89 90 /** 91 * Causes {@code failed()} to return true on the client side. {@code reason} 92 * will be incorporated into the message returned by {@code errorText()}. 93 * If you find you need to return machine-readable information about 94 * failures, you should incorporate it into your response protocol buffer 95 * and should NOT call {@code setFailed()}. 96 */ 97 void setFailed(String reason); 98 99 /** 100 * If {@code true}, indicates that the client canceled the RPC, so the server 101 * may as well give up on replying to it. This method must be called on the 102 * server side only. The server should still call the final "done" callback. 103 */ 104 boolean isCanceled(); 105 106 /** 107 * Asks that the given callback be called when the RPC is canceled. The 108 * parameter passed to the callback will always be {@code null}. The 109 * callback will always be called exactly once. If the RPC completes without 110 * being canceled, the callback will be called after completion. If the RPC 111 * has already been canceled when NotifyOnCancel() is called, the callback 112 * will be called immediately. 113 * 114 * <p>{@code notifyOnCancel()} must be called no more than once per request. 115 * It must be called on the server side only. 116 */ 117 void notifyOnCancel(RpcCallback<Object> callback); 118} 119