Pierre De Rop | 3a00a21 | 2015-03-01 09:27:46 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Licensed to the Apache Software Foundation (ASF) under one |
| 3 | * or more contributor license agreements. See the NOTICE file |
| 4 | * distributed with this work for additional information |
| 5 | * regarding copyright ownership. The ASF licenses this file |
| 6 | * to you under the Apache License, Version 2.0 (the |
| 7 | * "License"); you may not use this file except in compliance |
| 8 | * with the License. You may obtain a copy of the License at |
| 9 | * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | * |
| 12 | * Unless required by applicable law or agreed to in writing, |
| 13 | * software distributed under the License is distributed on an |
| 14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| 15 | * KIND, either express or implied. See the License for the |
| 16 | * specific language governing permissions and limitations |
| 17 | * under the License. |
| 18 | */ |
| 19 | package org.apache.felix.dm; |
| 20 | |
| 21 | import java.util.Dictionary; |
| 22 | |
| 23 | import org.osgi.framework.ServiceRegistration; |
| 24 | |
| 25 | |
| 26 | /** |
| 27 | * Component interface. Components are the main building blocks for OSGi applications. |
| 28 | * They can publish themselves as a service, and they can have dependencies. These |
| 29 | * dependencies will influence their life cycle as component will only be activated |
| 30 | * when all required dependencies are available. |
| 31 | * |
| 32 | * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a> |
| 33 | */ |
| 34 | public interface Component { |
| 35 | /** |
| 36 | * Sets the implementation for this component. You can actually specify |
| 37 | * an instance you have instantiated manually, or a <code>Class</code> |
| 38 | * that will be instantiated using its default constructor when the |
| 39 | * required dependencies are resolved, effectively giving you a lazy |
| 40 | * instantiation mechanism. |
| 41 | * |
| 42 | * There are four special methods that are called when found through |
| 43 | * reflection to give you life cycle management options: |
| 44 | * <ol> |
| 45 | * <li><code>init()</code> is invoked after the instance has been |
| 46 | * created and dependencies have been resolved, and can be used to |
| 47 | * initialize the internal state of the instance or even to add more |
| 48 | * dependencies based on runtime state</li> |
| 49 | * <li><code>start()</code> is invoked right before the service is |
| 50 | * registered</li> |
| 51 | * <li><code>stop()</code> is invoked right after the service is |
| 52 | * unregistered</li> |
| 53 | * <li><code>destroy()</code> is invoked after all dependencies are |
| 54 | * removed</li> |
| 55 | * </ol> |
| 56 | * In short, this allows you to initialize your instance before it is |
| 57 | * registered, perform some post-initialization and pre-destruction code |
| 58 | * as well as final cleanup. If a method is not defined, it simply is not |
| 59 | * called, so you can decide which one(s) you need. If you need even more |
| 60 | * fine-grained control, you can register as a service state listener too. |
| 61 | * |
| 62 | * @param implementation the implementation |
| 63 | * @return this component |
| 64 | * @see ComponentStateListener |
| 65 | */ |
| 66 | public Component setImplementation(Object implementation); |
| 67 | |
| 68 | /** |
| 69 | * Adds dependency(ies) to this component, atomically. If the component is already active or if you add |
| 70 | * dependencies from the init method, then you should add all the dependencies in one single add method call |
| 71 | * (using the varargs argument), because this method may trigger component activation (like |
| 72 | * the ServiceTracker.open() method does). |
| 73 | * |
| 74 | * @param dependencies the dependencies to add. |
| 75 | * @return this component |
| 76 | */ |
| 77 | public Component add(Dependency ... dependencies); |
| 78 | |
| 79 | /** |
| 80 | * Removes a dependency from the component. |
| 81 | * @param d the dependency to remove |
| 82 | * @return this component |
| 83 | */ |
| 84 | public Component remove(Dependency d); |
| 85 | |
| 86 | /** |
| 87 | * Adds a component state listener to this component. |
| 88 | * |
| 89 | * @param listener the state listener |
| 90 | */ |
| 91 | public Component add(ComponentStateListener listener); |
| 92 | |
| 93 | /** |
| 94 | * Removes a component state listener from this component. |
| 95 | * |
| 96 | * @param listener the state listener |
| 97 | */ |
| 98 | public Component remove(ComponentStateListener listener); |
| 99 | |
| 100 | /** |
| 101 | * Sets the public interface under which this component should be registered |
| 102 | * in the OSGi service registry. |
| 103 | * |
| 104 | * @param serviceName the name of the service interface |
| 105 | * @param properties the properties for this service |
| 106 | * @return this component |
| 107 | */ |
| 108 | public Component setInterface(String serviceName, Dictionary<?,?> properties); |
| 109 | |
| 110 | /** |
| 111 | * Sets the public interfaces under which this component should be registered |
| 112 | * in the OSGi service registry. |
| 113 | * |
| 114 | * @param serviceNames the names of the service interface |
| 115 | * @param properties the properties for these services |
| 116 | * @return this component |
| 117 | */ |
| 118 | public Component setInterface(String[] serviceNames, Dictionary<?, ?> properties); |
| 119 | |
| 120 | /** |
| 121 | * Configures auto configuration of injected classes in the component instance. |
| 122 | * The following injections are currently performed, unless you explicitly |
| 123 | * turn them off: |
| 124 | * <dl> |
| 125 | * <dt>BundleContext</dt><dd>the bundle context of the bundle</dd> |
| 126 | * <dt>ServiceRegistration</dt><dd>the service registration used to register your service</dd> |
| 127 | * <dt>DependencyManager</dt><dd>the dependency manager instance</dd> |
| 128 | * <dt>Component</dt><dd>the component instance of the dependency manager</dd> |
| 129 | * </dl> |
| 130 | * |
| 131 | * @param clazz the class (from the list above) |
| 132 | * @param autoConfig <code>false</code> to turn off auto configuration |
| 133 | */ |
| 134 | public Component setAutoConfig(Class<?> clazz, boolean autoConfig); |
| 135 | |
| 136 | /** |
| 137 | * Configures auto configuration of injected classes in the component instance. |
| 138 | * |
| 139 | * @param clazz the class (from the list above) |
| 140 | * @param instanceName the name of the instance to inject the class into |
| 141 | * @see #setAutoConfig(Class, boolean) |
| 142 | */ |
| 143 | public Component setAutoConfig(Class<?> clazz, String instanceName); |
| 144 | |
| 145 | /** |
| 146 | * Returns the service registration for this component. The method |
| 147 | * will return <code>null</code> if no service registration is |
| 148 | * available, for example if this component is not registered as a |
| 149 | * service at all. |
| 150 | * |
| 151 | * @return the service registration |
| 152 | */ |
| 153 | public ServiceRegistration getServiceRegistration(); |
| 154 | |
| 155 | /** |
| 156 | * Returns the instance that make up this component. If the component has a composition of instances, |
| 157 | * then the first instance of the composition is returned. Null is returned if the component has not |
| 158 | * even been instantiated. |
| 159 | * |
| 160 | * @return the component instances |
| 161 | */ |
| 162 | public <T> T getInstance(); |
| 163 | |
| 164 | /** |
| 165 | * Returns the composition instances that make up this component, or just the |
| 166 | * component instance if it does not have a composition, or an empty array if |
| 167 | * the component has not even been instantiated. |
| 168 | * |
| 169 | * @return the component instances |
| 170 | */ |
| 171 | public Object[] getInstances(); |
| 172 | |
| 173 | /** |
| 174 | * Returns the service properties associated with the component. |
| 175 | * |
| 176 | * @return the properties or <code>null</code> if there are none |
| 177 | */ |
| 178 | public <K,V> Dictionary<K,V> getServiceProperties(); |
| 179 | |
| 180 | /** |
| 181 | * Sets the service properties associated with the component. If the service |
| 182 | * was already registered, it will be updated. |
| 183 | * |
| 184 | * @param serviceProperties the properties |
| 185 | */ |
| 186 | public Component setServiceProperties(Dictionary<?, ?> serviceProperties); |
| 187 | |
| 188 | /** |
| 189 | * Sets the names of the methods used as callbacks. These methods, when found, are |
| 190 | * invoked as part of the life cycle management of the component implementation. The |
| 191 | * dependency manager will look for a method of this name with the following signatures, |
| 192 | * in this order: |
| 193 | * <ol> |
| 194 | * <li>method(Component component)</li> |
| 195 | * <li>method()</li> |
| 196 | * </ol> |
| 197 | * |
| 198 | * @param init the name of the init method |
| 199 | * @param start the name of the start method |
| 200 | * @param stop the name of the stop method |
| 201 | * @param destroy the name of the destroy method |
| 202 | * @return the component |
| 203 | */ |
| 204 | public Component setCallbacks(String init, String start, String stop, String destroy); |
| 205 | |
| 206 | /** |
| 207 | * Sets the names of the methods used as callbacks. These methods, when found, are |
| 208 | * invoked on the specified instance as part of the life cycle management of the component |
| 209 | * implementation. |
| 210 | * <p> |
| 211 | * See setCallbacks(String init, String start, String stop, String destroy) for more |
| 212 | * information on the signatures. Specifying an instance means you can create a manager |
| 213 | * that will be invoked whenever the life cycle of a component changes and this manager |
| 214 | * can then decide how to expose this life cycle to the actual component, offering an |
| 215 | * important indirection when developing your own component models. |
| 216 | * |
| 217 | * @return this component |
| 218 | */ |
| 219 | public Component setCallbacks(Object instance, String init, String start, String stop, String destroy); |
| 220 | |
| 221 | /** |
| 222 | * Sets the factory to use to create the implementation. You can specify |
| 223 | * both the factory class and method to invoke. The method should return |
| 224 | * the implementation, and can use any method to create it. Actually, this |
| 225 | * can be used together with <code>setComposition</code> to create a |
| 226 | * composition of instances that work together to implement a component. The |
| 227 | * factory itself can also be instantiated lazily by not specifying an |
| 228 | * instance, but a <code>Class</code>. |
| 229 | * |
| 230 | * @param factory the factory instance or class |
| 231 | * @param createMethod the name of the create method |
| 232 | * @return this component |
| 233 | */ |
| 234 | public Component setFactory(Object factory, String createMethod); |
| 235 | |
| 236 | /** |
| 237 | * Sets the factory to use to create the implementation. You specify the |
| 238 | * method to invoke. The method should return the implementation, and can |
| 239 | * use any method to create it. Actually, this can be used together with |
| 240 | * <code>setComposition</code> to create a composition of instances that |
| 241 | * work together to implement a component. |
| 242 | * <p> |
| 243 | * Note that currently, there is no default for the factory, so please use |
| 244 | * <code>setFactory(factory, createMethod)</code> instead. |
| 245 | * |
| 246 | * @param createMethod the name of the create method |
| 247 | * @return this component |
| 248 | */ |
| 249 | public Component setFactory(String createMethod); |
| 250 | |
| 251 | /** |
| 252 | * Sets the instance and method to invoke to get back all instances that |
| 253 | * are part of a composition and need dependencies injected. All of them |
| 254 | * will be searched for any of the dependencies. The method that is |
| 255 | * invoked must return an <code>Object[]</code>. |
| 256 | * |
| 257 | * @param instance the instance that has the method |
| 258 | * @param getMethod the method to invoke |
| 259 | * @return this component |
| 260 | */ |
| 261 | public Component setComposition(Object instance, String getMethod); |
| 262 | |
| 263 | /** |
| 264 | * Sets the method to invoke on the service implementation to get back all |
| 265 | * instances that are part of a composition and need dependencies injected. |
| 266 | * All of them will be searched for any of the dependencies. The method that |
| 267 | * is invoked must return an <code>Object[]</code>. |
| 268 | * |
| 269 | * @param getMethod the method to invoke |
| 270 | * @return this component |
| 271 | */ |
| 272 | public Component setComposition(String getMethod); |
| 273 | |
| 274 | /** |
| 275 | * Returns the dependency manager associated with this component. |
| 276 | * @return the dependency manager associated with this component. |
| 277 | */ |
| 278 | public DependencyManager getDependencyManager(); |
| 279 | |
| 280 | /** |
| 281 | * Returns the component description (dependencies, service provided, etc ...). |
| 282 | * @return the component description (dependencies, service provided, etc ...). |
| 283 | */ |
| 284 | public ComponentDeclaration getComponentDeclaration(); |
| 285 | |
| 286 | /** |
| 287 | * Activate debug for this component. Informations related to dependency processing will be displayed |
| 288 | * using osgi log service, our to standard output if no log service is currently available. |
| 289 | * @param label |
| 290 | */ |
| 291 | public Component setDebug(String label); |
| 292 | } |