1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2008 Google Inc. All rights reserved. 3 // https://developers.google.com/protocol-buffers/ 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 31 package com.google.protobuf; 32 33 /** 34 * Abstract base interface for protocol-buffer-based RPC services. Services themselves are abstract 35 * classes (implemented either by servers or as stubs), but they subclass this base interface. The 36 * methods of this interface can be used to call the methods of the service without knowing its 37 * exact type at compile time (analogous to the Message interface). 38 * 39 * <p>Starting with version 2.3.0, RPC implementations should not try to build on this, but should 40 * instead provide code generator plugins which generate code specific to the particular RPC 41 * implementation. This way the generated code can be more appropriate for the implementation in use 42 * and can avoid unnecessary layers of indirection. 43 * 44 * @author kenton@google.com Kenton Varda 45 */ 46 public interface Service { 47 /** Get the {@code ServiceDescriptor} describing this service and its methods. */ getDescriptorForType()48 Descriptors.ServiceDescriptor getDescriptorForType(); 49 50 /** 51 * Call a method of the service specified by MethodDescriptor. This is normally implemented as a 52 * simple {@code switch()} that calls the standard definitions of the service's methods. 53 * 54 * <p>Preconditions: 55 * 56 * <ul> 57 * <li>{@code method.getService() == getDescriptorForType()} 58 * <li>{@code request} is of the exact same class as the object returned by {@code 59 * getRequestPrototype(method)}. 60 * <li>{@code controller} is of the correct type for the RPC implementation being used by this 61 * Service. For stubs, the "correct type" depends on the RpcChannel which the stub is using. 62 * Server-side Service implementations are expected to accept whatever type of {@code 63 * RpcController} the server-side RPC implementation uses. 64 * </ul> 65 * 66 * <p>Postconditions: 67 * 68 * <ul> 69 * <li>{@code done} will be called when the method is complete. This may be before {@code 70 * callMethod()} returns or it may be at some point in the future. 71 * <li>The parameter to {@code done} is the response. It must be of the exact same type as would 72 * be returned by {@code getResponsePrototype(method)}. 73 * <li>If the RPC failed, the parameter to {@code done} will be {@code null}. Further details 74 * about the failure can be found by querying {@code controller}. 75 * </ul> 76 */ callMethod( Descriptors.MethodDescriptor method, RpcController controller, Message request, RpcCallback<Message> done)77 void callMethod( 78 Descriptors.MethodDescriptor method, 79 RpcController controller, 80 Message request, 81 RpcCallback<Message> done); 82 83 /** 84 * {@code callMethod()} requires that the request passed in is of a particular subclass of {@code 85 * Message}. {@code getRequestPrototype()} gets the default instances of this type for a given 86 * method. You can then call {@code Message.newBuilderForType()} on this instance to construct a 87 * builder to build an object which you can then pass to {@code callMethod()}. 88 * 89 * <p>Example: 90 * 91 * <pre> 92 * MethodDescriptor method = 93 * service.getDescriptorForType().findMethodByName("Foo"); 94 * Message request = 95 * stub.getRequestPrototype(method).newBuilderForType() 96 * .mergeFrom(input).build(); 97 * service.callMethod(method, request, callback); 98 * </pre> 99 */ getRequestPrototype(Descriptors.MethodDescriptor method)100 Message getRequestPrototype(Descriptors.MethodDescriptor method); 101 102 /** 103 * Like {@code getRequestPrototype()}, but gets a prototype of the response message. {@code 104 * getResponsePrototype()} is generally not needed because the {@code Service} implementation 105 * constructs the response message itself, but it may be useful in some cases to know ahead of 106 * time what type of object will be returned. 107 */ getResponsePrototype(Descriptors.MethodDescriptor method)108 Message getResponsePrototype(Descriptors.MethodDescriptor method); 109 } 110