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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 | |
31 """DEPRECATED: Declares the RPC service interfaces. | |
32 | |
33 This module declares the abstract interfaces underlying proto2 RPC | |
34 services. These are intended to be independent of any particular RPC | |
35 implementation, so that proto2 services can be used on top of a variety | |
36 of implementations. Starting with version 2.3.0, RPC implementations should | |
37 not try to build on these, but should instead provide code generator plugins | |
38 which generate code specific to the particular RPC implementation. This way | |
39 the generated code can be more appropriate for the implementation in use | |
40 and can avoid unnecessary layers of indirection. | |
41 """ | |
42 | |
43 __author__ = 'petar@google.com (Petar Petrov)' | |
44 | |
45 | |
46 class RpcException(Exception): | |
47 """Exception raised on failed blocking RPC method call.""" | |
48 pass | |
49 | |
50 | |
51 class Service(object): | |
52 | |
53 """Abstract base interface for protocol-buffer-based RPC services. | |
54 | |
55 Services themselves are abstract classes (implemented either by servers or as | |
56 stubs), but they subclass this base interface. The methods of this | |
57 interface can be used to call the methods of the service without knowing | |
58 its exact type at compile time (analogous to the Message interface). | |
59 """ | |
60 | |
61 def GetDescriptor(): | |
62 """Retrieves this service's descriptor.""" | |
63 raise NotImplementedError | |
64 | |
65 def CallMethod(self, method_descriptor, rpc_controller, | |
66 request, done): | |
67 """Calls a method of the service specified by method_descriptor. | |
68 | |
69 If "done" is None then the call is blocking and the response | |
70 message will be returned directly. Otherwise the call is asynchronous | |
71 and "done" will later be called with the response value. | |
72 | |
73 In the blocking case, RpcException will be raised on error. | |
74 | |
75 Preconditions: | |
76 * method_descriptor.service == GetDescriptor | |
77 * request is of the exact same classes as returned by | |
78 GetRequestClass(method). | |
79 * After the call has started, the request must not be modified. | |
80 * "rpc_controller" is of the correct type for the RPC implementation being | |
81 used by this Service. For stubs, the "correct type" depends on the | |
82 RpcChannel which the stub is using. | |
83 | |
84 Postconditions: | |
85 * "done" will be called when the method is complete. This may be | |
86 before CallMethod() returns or it may be at some point in the future. | |
87 * If the RPC failed, the response value passed to "done" will be None. | |
88 Further details about the failure can be found by querying the | |
89 RpcController. | |
90 """ | |
91 raise NotImplementedError | |
92 | |
93 def GetRequestClass(self, method_descriptor): | |
94 """Returns the class of the request message for the specified method. | |
95 | |
96 CallMethod() requires that the request is of a particular subclass of | |
97 Message. GetRequestClass() gets the default instance of this required | |
98 type. | |
99 | |
100 Example: | |
101 method = service.GetDescriptor().FindMethodByName("Foo") | |
102 request = stub.GetRequestClass(method)() | |
103 request.ParseFromString(input) | |
104 service.CallMethod(method, request, callback) | |
105 """ | |
106 raise NotImplementedError | |
107 | |
108 def GetResponseClass(self, method_descriptor): | |
109 """Returns the class of the response message for the specified method. | |
110 | |
111 This method isn't really needed, as the RpcChannel's CallMethod constructs | |
112 the response protocol message. It's provided anyway in case it is useful | |
113 for the caller to know the response type in advance. | |
114 """ | |
115 raise NotImplementedError | |
116 | |
117 | |
118 class RpcController(object): | |
119 | |
120 """An RpcController mediates a single method call. | |
121 | |
122 The primary purpose of the controller is to provide a way to manipulate | |
123 settings specific to the RPC implementation and to find out about RPC-level | |
124 errors. The methods provided by the RpcController interface are intended | |
125 to be a "least common denominator" set of features which we expect all | |
126 implementations to support. Specific implementations may provide more | |
127 advanced features (e.g. deadline propagation). | |
128 """ | |
129 | |
130 # Client-side methods below | |
131 | |
132 def Reset(self): | |
133 """Resets the RpcController to its initial state. | |
134 | |
135 After the RpcController has been reset, it may be reused in | |
136 a new call. Must not be called while an RPC is in progress. | |
137 """ | |
138 raise NotImplementedError | |
139 | |
140 def Failed(self): | |
141 """Returns true if the call failed. | |
142 | |
143 After a call has finished, returns true if the call failed. The possible | |
144 reasons for failure depend on the RPC implementation. Failed() must not | |
145 be called before a call has finished. If Failed() returns true, the | |
146 contents of the response message are undefined. | |
147 """ | |
148 raise NotImplementedError | |
149 | |
150 def ErrorText(self): | |
151 """If Failed is true, returns a human-readable description of the error.""" | |
152 raise NotImplementedError | |
153 | |
154 def StartCancel(self): | |
155 """Initiate cancellation. | |
156 | |
157 Advises the RPC system that the caller desires that the RPC call be | |
158 canceled. The RPC system may cancel it immediately, may wait awhile and | |
159 then cancel it, or may not even cancel the call at all. If the call is | |
160 canceled, the "done" callback will still be called and the RpcController | |
161 will indicate that the call failed at that time. | |
162 """ | |
163 raise NotImplementedError | |
164 | |
165 # Server-side methods below | |
166 | |
167 def SetFailed(self, reason): | |
168 """Sets a failure reason. | |
169 | |
170 Causes Failed() to return true on the client side. "reason" will be | |
171 incorporated into the message returned by ErrorText(). If you find | |
172 you need to return machine-readable information about failures, you | |
173 should incorporate it into your response protocol buffer and should | |
174 NOT call SetFailed(). | |
175 """ | |
176 raise NotImplementedError | |
177 | |
178 def IsCanceled(self): | |
179 """Checks if the client cancelled the RPC. | |
180 | |
181 If true, indicates that the client canceled the RPC, so the server may | |
182 as well give up on replying to it. The server should still call the | |
183 final "done" callback. | |
184 """ | |
185 raise NotImplementedError | |
186 | |
187 def NotifyOnCancel(self, callback): | |
188 """Sets a callback to invoke on cancel. | |
189 | |
190 Asks that the given callback be called when the RPC is canceled. The | |
191 callback will always be called exactly once. If the RPC completes without | |
192 being canceled, the callback will be called after completion. If the RPC | |
193 has already been canceled when NotifyOnCancel() is called, the callback | |
194 will be called immediately. | |
195 | |
196 NotifyOnCancel() must be called no more than once per request. | |
197 """ | |
198 raise NotImplementedError | |
199 | |
200 | |
201 class RpcChannel(object): | |
202 | |
203 """Abstract interface for an RPC channel. | |
204 | |
205 An RpcChannel represents a communication line to a service which can be used | |
206 to call that service's methods. The service may be running on another | |
207 machine. Normally, you should not use an RpcChannel directly, but instead | |
208 construct a stub {@link Service} wrapping it. Example: | |
209 | |
210 Example: | |
211 RpcChannel channel = rpcImpl.Channel("remotehost.example.com:1234") | |
212 RpcController controller = rpcImpl.Controller() | |
213 MyService service = MyService_Stub(channel) | |
214 service.MyMethod(controller, request, callback) | |
215 """ | |
216 | |
217 def CallMethod(self, method_descriptor, rpc_controller, | |
218 request, response_class, done): | |
219 """Calls the method identified by the descriptor. | |
220 | |
221 Call the given method of the remote service. The signature of this | |
222 procedure looks the same as Service.CallMethod(), but the requirements | |
223 are less strict in one important way: the request object doesn't have to | |
224 be of any specific class as long as its descriptor is method.input_type. | |
225 """ | |
226 raise NotImplementedError | |
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