2 * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.controller.sal.binding.api;
10 import org.opendaylight.controller.md.sal.common.api.routing.RouteChangePublisher;
11 import org.opendaylight.controller.sal.binding.api.BindingAwareBroker.RoutedRpcRegistration;
12 import org.opendaylight.controller.sal.binding.api.BindingAwareBroker.RpcRegistration;
13 import org.opendaylight.controller.sal.binding.api.rpc.RpcContextIdentifier;
14 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
15 import org.opendaylight.yangtools.yang.binding.RpcService;
18 * Provides a registry for Remote Procedure Call (RPC) service implementations. The RPCs are
19 * defined in YANG models.
22 * There are 2 types of RPCs:
31 * An RPC is global if there is intended to be only 1 registered implementation. A global RPC is not
32 * explicitly declared as such, essentially any RPC that is not defined to be routed is considered global.
35 * Global RPCs are registered using the
36 * {@link #addRpcImplementation(Class, RpcService)} method.
41 * MD-SAL supports routing of RPC between multiple implementations where the appropriate
42 * implementation is selected at run time based on the content of the RPC message as described in
46 * RPC routing is based on:
48 * <li><b>Route identifier</b> -
49 * An {@link org.opendaylight.yangtools.yang.binding.InstanceIdentifier InstanceIdentifier} value
50 * which is part of the RPC input. This value is used to select the correct
51 * implementation at run time.</li>
52 * <li><b>Context Type</b> - A YANG-defined construct which constrains the subset of
53 * valid route identifiers for a particular RPC.</li>
56 * <h3>Context type</h3>
59 * A context type is modeled in YANG using a combination of a YANG <code>identity</code>
60 * and Opendaylight specific extensions from <code>yang-ext</code> module. These extensions are:
62 * <li><b>context-instance</b> - This is used in the data tree part of a YANG model to
63 * define a context type that associates nodes with a specified context <code>identity</code>.
64 * Instance identifiers that reference these nodes are valid route identifiers for RPCs that
65 * reference this context type.</li>
66 * <li><b>context-reference</b> - This is used in RPC input to mark a leaf of type
67 * <code>instance-identifier</code> as a reference to the particular context type defined by the
68 * specified context <code>identity</code>. The value of this
69 * leaf is used by the RPC broker at run time to route the RPC request to the correct implementation.
70 * Note that <code>context-reference</code> may only be used on leaf elements of type
71 * <code>instance-identifier</code> or a type derived from <code>instance-identifier</code>.</li>
75 * <h4>1. Defining a Context Type</h4>
78 * The following snippet declares a simple YANG <code>identity</code> named <code>example-context</code>:
83 * identity example-context {
84 * description "Identity used to define an example-context type";
91 * We then use the declared identity to define a context type by using it in combination
92 * with the <code>context-instance</code> YANG extension. We'll associate the context type
93 * with a list element in the data tree. This defines the set of nodes whose instance
94 * identifiers are valid for the <code>example-context</code> context type.
97 * The following YANG snippet imports the <code>yang-ext</code> module and defines the list
98 * element named <code>item</code> inside a container named <code>foo</code>:
103 * import yang-ext {prefix ext;}
108 * leaf id {type string;}
109 * ext:context-instance "example-context";
117 * The statement <code>ext:context-instance "example-context";</code> inside the list element
118 * declares that any instance identifier referencing <code>item</code> in the data
119 * tree is valid for <code>example-context</code>. For example, the following instance
122 * InstanceIdentifier.create(Foo.class).child(Item.class,new ItemKey("Foo"))
124 * is valid for <code>example-context</code>. However the following:
126 * InstanceIdentifier.create(Example.class)
131 * So using an <code>identity</code> in combination with <code>context-instance</code> we
132 * have effectively defined a context type that can be referenced in a YANG RPC input.
135 * <h5>2. Defining an RPC to use the Context Type</h5>
138 * To define an RPC to be routed based on the context type we need to add an input leaf element
139 * that references the context type which will hold an instance identifier value to be
140 * used to route the RPC.
143 * The following snippet defines an RPC named <code>show-item</code> with 2 leaf elements
144 * as input: <code>item</code> of type <code>instance-identifier</code> and <code>description</code>:
149 * import yang-ext {prefix ext;}
154 * type instance-identifier;
155 * ext:context-reference example-context;
166 * We mark the <code>item</code> leaf with a <code>context-reference</code> statement that
167 * references the <code>example-context</code> context type. RPC calls will then be routed
168 * based on the instance identifier value contained in <code>item</code>. Only instance
169 * identifiers that point to a <code>foo/item</code> node are valid as input.
172 * The generated RPC Service interface for the module is:
175 * interface FooService implements RpcService {
176 * Future<RpcResult<Void>> showItem(ShowItemInput input);
181 * For constructing the RPC input, there are generated classes ShowItemInput and ShowItemInputBuilder.
183 * <h5>3. Registering a routed RPC implementation</h5>
186 * To register a routed implementation for the <code>show-item</code> RPC, we must use the
187 * {@link #addRoutedRpcImplementation(Class, RpcService)} method. This
188 * will return a {@link RoutedRpcRegistration} instance which can then be used to register /
189 * unregister routed paths associated with the registered implementation.
192 * The following snippet registers <code>myImpl</code> as the RPC implementation for an
193 * <code>item</code> with key <code>"foo"</code>:
195 * // Create the instance identifier path for item "foo"
196 * InstanceIdentifier path = InstanceIdentifier.create(Foo.class).child(Item.class, new ItemKey("foo"));
198 * // Register myImpl as the implementation for the FooService RPC interface
199 * RoutedRpcRegistration reg = rpcRegistry.addRoutedRpcImplementation(FooService.class, myImpl);
201 * // Now register for the context type and specific path ID. The context type is specified by the
202 * // YANG-generated class for the example-context identity.
203 * reg.registerPath(ExampleContext.class, path);
207 * It is also possible to register the same implementation for multiple paths:
210 * InstanceIdentifier one = InstanceIdentifier.create(Foo.class).child(Item.class, new ItemKey("One"));
211 * InstanceIdentifier two = InstanceIdentifier.create(Foo.class).child(Item.class, new ItemKey("Two"));
213 * RoutedRpcRegistration reg = rpcRegistry.addRoutedRpcImplementation(FooService.class, myImpl);
214 * reg.registerPath(ExampleContext.class, one);
215 * reg.registerPath(ExampleContext.class, two);
219 * When another client invokes the <code>showItem(ShowItemInput)</code> method on the proxy instance
220 * retrieved via {@link RpcConsumerRegistry#getRpcService(Class)}, the proxy will inspect the
221 * arguments in ShowItemInput, extract the InstanceIdentifier value of the <code>item</code> leaf and select
222 * the implementation whose registered path matches the InstanceIdentifier value of the <code>item</code> leaf.
225 * <h2>Notes for RPC Implementations</h2>
231 * The generated interfaces require implementors to return
232 * {@link java.util.concurrent.Future Future}<{@link org.opendaylight.yangtools.yang.common.RpcResult RpcResult}
233 * <{RpcName}Output>> instances.
236 * Implementations should do processing of RPC calls asynchronously and update the
237 * returned {@link java.util.concurrent.Future Future} instance when processing is complete.
238 * However using {@link com.google.common.util.concurrent.Futures#immediateFuture(Object) Futures.immediateFuture}
239 * is valid only if the result is immediately available and asynchronous processing is unnecessary and
240 * would only introduce additional complexity.
243 * The {@link org.opendaylight.yangtools.yang.common.RpcResult RpcResult} is a generic
244 * wrapper for the RPC output payload, if any, and also allows for attaching error or
245 * warning information (possibly along with the payload) should the RPC processing partially
246 * or completely fail. This is intended to provide additional human readable information
247 * for users of the API and to transfer warning / error information across the system
248 * so it may be visible via other external APIs such as Restconf.
251 * It is recommended to use the {@link org.opendaylight.yangtools.yang.common.RpcResult RpcResult}
252 * for conveying appropriate error information
253 * on failure rather than purposely throwing unchecked exceptions if at all possible.
254 * While unchecked exceptions will fail the returned {@link java.util.concurrent.Future Future},
255 * using the intended RpcResult to convey the error information is more user-friendly.
257 * @deprecated Use {@link org.opendaylight.mdsal.binding.api.RpcProviderService} instead
260 public interface RpcProviderRegistry extends //
261 RpcConsumerRegistry, //
262 RouteChangePublisher<RpcContextIdentifier, InstanceIdentifier<?>> {
264 * Registers a global implementation of the provided RPC service interface.
265 * All methods of the interface are required to be implemented.
267 * @param serviceInterface the YANG-generated interface of the RPC Service for which to register.
268 * @param implementation "the implementation of the RPC service interface.
269 * @return an RpcRegistration instance that should be used to unregister the RPC implementation
270 * when no longer needed by calling {@link RpcRegistration#close()}.
272 * @throws IllegalStateException
273 * if the supplied RPC interface is a routed RPC type.
275 <T extends RpcService> RpcRegistration<T> addRpcImplementation(Class<T> serviceInterface, T implementation)
276 throws IllegalStateException;
279 * Registers an implementation of the given routed RPC service interface.
281 * See the {@link RpcProviderRegistry class} documentation for information and example on
282 * how to use routed RPCs.
284 * @param serviceInterface the YANG-generated interface of the RPC Service for which to register.
285 * @param implementation the implementation instance to register.
286 * @return a RoutedRpcRegistration instance which can be used to register paths for the RPC
287 * implementation via invoking RoutedRpcRegistration#registerPath(Class, InstanceIdentifer).
288 * {@link RoutedRpcRegistration#close()} should be called to unregister the implementation
289 * and all previously registered paths when no longer needed.
291 * @throws IllegalStateException
292 * if the supplied RPC interface is not a routed RPC type.
294 <T extends RpcService> RoutedRpcRegistration<T> addRoutedRpcImplementation(Class<T> serviceInterface,
296 throws IllegalStateException;