| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.felix.dm.annotation.api; |
| |
| import java.lang.annotation.ElementType; |
| import java.lang.annotation.Retention; |
| import java.lang.annotation.RetentionPolicy; |
| import java.lang.annotation.Target; |
| import java.util.Collection; |
| import java.util.Dictionary; |
| import java.util.Map; |
| |
| /** |
| * Annotates a method for injecting a Configuration Dependency. |
| * |
| * <p> A configuration dependency |
| * is required by default, and allows you to depend on the availability of a valid configuration |
| * for your component. This dependency requires the OSGi Configuration Admin Service. |
| * |
| * Configuration Dependency callback is always invoked before any service dependency callbacks, and before init/start callbacks. |
| * |
| * The annotation can be applied on a callback method which accepts the following parameters: |
| * |
| * <ul> |
| * <li>callback(Dictionary) |
| * <li>callback(Component, Dictionary) |
| * <li>callback(Component, Configuration ... configTypes) // type safe configuration interface(s) |
| * <li>callback(Configuration ... configTypes) // type safe configuration interface(s) |
| * <li>callback(Dictionary, Configuration ... configTypes) // type safe configuration interfaces(s) |
| * <li>callback(Component, Dictionary, Configuration ... configTypes) // type safe configuration interfaces(s) |
| * </ul> |
| * |
| * <h3>Usage Examples</h3> |
| * |
| * <p> In the following example, the Printer components depends on a configuration |
| * whose PID name is "sample.Printer". This service will initialize |
| * its ip/port number from the provided configuration. |
| * |
| * <blockquote> |
| * <pre> |
| * |
| * package sample; |
| * |
| * @Component |
| * public class Printer { |
| * @ConfigurationDependency(propagate=true) // Will use the fqdn of the Printer interface as the pid. |
| * void updated(Dictionary cnf) { |
| * if (cnf != null) { |
| * String ip = cnf.get("address"); |
| * int port = Integer.parseInt(cnf.get("port")); |
| * } |
| * } |
| * } |
| * </pre> |
| * </blockquote> |
| * |
| * You can also define your own component properties using a custom type-safe interface: |
| * |
| * <blockquote> |
| * <pre> |
| * package sample; |
| * |
| * interface PrinterConfig { |
| * String getAddress(); |
| * int getPort(); |
| * } |
| * </pre> |
| * </blockquote> |
| * |
| * Next, we define our Printer service which depends on the PrinterConfig: |
| * |
| * <blockquote> |
| * <pre> |
| * package sample; |
| * |
| * @Component |
| * public class Printer { |
| * @ConfigurationDependency // Will use the fqdn of the PrinterConfig interface as the pid. |
| * void updated(PrinterConfig cnf) { |
| * if (cnf != null) { |
| * String ip = cnf.getAddress(); |
| * int port = cnf.getPort(); |
| * } |
| * } |
| * } |
| * </pre> |
| * </blockquote> |
| * |
| * In the above example, the updated callback accepts a type-safe configuration type (and its fqdn is used as the pid). |
| * <p> Configuration type is a new feature that allows you to specify an interface that is implemented |
| * by DM and such interface is then injected to your callback instead of the actual Dictionary. |
| * Using such configuration interface provides a way for creating type-safe configurations from a actual {@link Dictionary} that is |
| * normally injected by Dependency Manager. |
| * The callback accepts in argument an interface that you have to provide, and DM will inject a proxy that converts |
| * method calls from your configuration-type to lookups in the actual map or dictionary. The results of these lookups are then |
| * converted to the expected return type of the invoked configuration method.<br> |
| * As proxies are injected, no implementations of the desired configuration-type are necessary! |
| * </p> |
| * <p> |
| * The lookups performed are based on the name of the method called on the configuration type. The method names are |
| * "mangled" to the following form: <tt>[lower case letter] [any valid character]*</tt>. Method names starting with |
| * <tt>get</tt> or <tt>is</tt> (JavaBean convention) are stripped from these prefixes. For example: given a dictionary |
| * with the key <tt>"foo"</tt> can be accessed from a configuration-type using the following method names: |
| * <tt>foo()</tt>, <tt>getFoo()</tt> and <tt>isFoo()</tt>.<p> |
| * If the property contains a dot (which is invalid in java method names), then dots (".") can be converted using the following conventions: |
| * <ul> |
| * |
| * <li> if the method name follows the javabean convention and/or kamel casing convention, then each capital letter is assumed to map to a "dot", |
| * followed by the same letter in lower case. This means only lower case properties are |
| * supported in this case. Example: getFooBar() or fooBar() will map to "foo.bar" property. |
| * |
| * <li> else, if the method name follows the standard OSGi metatype specification, then dots |
| * are encoded as "_"; and "_" is encoded as "__". (see OSGi r6 compendium, chapter 105.9.2). |
| * Example: "foo_BAR()" is mapped to "foo.BAR" property; "foo__BAR_zoo()" is mapped to "foo_BAR.zoo" property. |
| * </ul> |
| * <p> |
| * The return values supported are: primitive types (or their object wrappers), strings, enums, arrays of |
| * primitives/strings, {@link Collection} types, {@link Map} types, {@link Class}es and interfaces. When an interface is |
| * returned, it is treated equally to a configuration type, that is, it is returned as a proxy. |
| * </p> |
| * <p> |
| * Arrays can be represented either as comma-separated values, optionally enclosed in square brackets. For example: |
| * <tt>[ a, b, c ]</tt> and <tt>a, b,c</tt> are both considered an array of length 3 with the values "a", "b" and "c". |
| * Alternatively, you can append the array index to the key in the dictionary to obtain the same: a dictionary with |
| * "arr.0" => "a", "arr.1" => "b", "arr.2" => "c" would result in the same array as the earlier examples. |
| * </p> |
| * <p> |
| * Maps can be represented as single string values similarly as arrays, each value consisting of both the key and value |
| * separated by a dot. Optionally, the value can be enclosed in curly brackets. Similar to array, you can use the same |
| * dot notation using the keys. For example, a dictionary with |
| * |
| * <pre>{@code "map" => "{key1.value1, key2.value2}"}</pre> |
| * |
| * and a dictionary with |
| * |
| * <pre>{@code "map.key1" => "value1", "map2.key2" => "value2"}</pre> |
| * |
| * result in the same map being returned. |
| * Instead of a map, you could also define an interface with the methods <tt>getKey1()</tt> and <tt>getKey2</tt> and use |
| * that interface as return type instead of a {@link Map}. |
| * |
| * <p> |
| * In case a lookup does not yield a value from the underlying map or dictionary, the following rules are applied: |
| * <ol> |
| * <li>primitive types yield their default value, as defined by the Java Specification; |
| * <li>string, {@link Class}es and enum values yield <code>null</code>; |
| * <li>for arrays, collections and maps, an empty array/collection/map is returned; |
| * <li>for other interface types that are treated as configuration type a null-object is returned. |
| * </ol> |
| * |
| * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a> |
| */ |
| @Retention(RetentionPolicy.CLASS) |
| @Target(ElementType.METHOD) |
| public @interface ConfigurationDependency |
| { |
| /** |
| * Returns the pid for a given service (by default, the pid is the service class name, of the FQDN of |
| * the configuration type found in the updated callback signature. |
| * @return the pid for a given service (default = Service class name) |
| */ |
| String pid() default ""; |
| |
| /** |
| * Returns the pid from a class name. The full class name will be used as the configuration PID. |
| * @return the pid class whose FQDN name is used as the configuration PID. |
| */ |
| Class<?> pidClass() default Object.class; |
| |
| /** |
| * Returns true if the configuration properties must be published along with the service. |
| * Any additional service properties specified directly are merged with these. The configuration |
| * dependency properties take precedence over the component service properties, meaning that a given configuration |
| * property will override the same property that is already present in the component service properties. |
| * |
| * @return true if configuration must be published along with the service, false if not. |
| */ |
| boolean propagate() default false; |
| |
| /** |
| * Sets the required flag which determines if this configuration dependency is required or not. |
| * A configuration dependency is required by default. |
| * |
| * @return this service dependency |
| */ |
| boolean required() default true; |
| |
| /** |
| * The name for this configuration dependency. When you give a name a dependency, it won't be evaluated |
| * immediately, but after the component's init method has been called, and from the init method, you can then return |
| * a map in order to dynamically configure the configuration dependency (the map has to contain a "pid" and/or "propagate" |
| * flag, prefixed with the dependency name). Then the dependency will be evaluated after the component init method, and will |
| * be injected before the start method. |
| * |
| * <p> Usage example of a Configuration dependency whose pid and propagate flag is configured dynamically from init method: |
| * |
| * <blockquote><pre> |
| * /** |
| * * A Service that dynamically defines an extra dynamic configuration dependency from its init method. |
| * */ |
| * @Component |
| * class X { |
| * private Dictionary m_config; |
| * |
| * // Inject initial Configuration (injected before any other required dependencies) |
| * @ConfigurationDependency |
| * void componentConfiguration(Dictionary config) { |
| * // you must throw an exception if the configuration is not valid |
| * m_config = config; |
| * } |
| * |
| * /** |
| * * All unnamed dependencies are injected: we can now configure our dynamic configuration whose dependency name is "global". |
| * */ |
| * @Init |
| * Map init() { |
| * return new HashMap() {{ |
| * put("global.pid", m_config.get("globalConfig.pid")); |
| * put("global.propagate", m_config.get("globalConfig.propagate")); |
| * }}; |
| * } |
| * |
| * // Injected after init, and dynamically configured by the init method. |
| * @ConfigurationDependency(name="global") |
| * void globalConfiguration(Dictionary globalConfig) { |
| * // you must throw an exception if the configuration is not valid |
| * } |
| * |
| * /** |
| * * All dependencies are injected and our service is now ready to be published. |
| * */ |
| * @Start |
| * void start() { |
| * } |
| * } |
| * </pre></blockquote> |
| * @return the dependency name used to configure the dependency dynamically from init callback |
| */ |
| String name() default ""; |
| } |
