Confluence Docs 3.0 : Component Plugins This page last changed on Sep 07, 2009 by ggaskell. On this page: Recommended Plugin Module Type Purpose of this Module Type Configuration Attributes Elements Example Notes Accessing Your Components ## Recommended Plugin Module Type The Component plugin module described below is available to OSGi-based plugins using version 2.x of the Atlassian Plugin Framework, supported in Confluence 2.10 and later. We recommend that you use the new plugin module type described below, rather than the old-style Component and Spring Component module types. Confluence still supports the earlier module types, but the new OSGi-based plugin framework fixes a number of bugs and limitations experienced by the old-style plugin modules. ## Purpose of this Module Type Component plugin modules enable you to share Java components between other modules in your plugin and optionally with other plugins in the application. ## Configuration The root element for the Component plugin module is `component`. It allows the following attributes and child elements for configuration: #### Attributes
Name | Required | Description | Default
--- | --- | --- | ---
alias |  | The alias to use for the component when registering it in the internal bean factory. | The plugin key
class |  | The class which implements this plugin module. The class you need to provide depends on the module type. For example, Confluence theme, layout and colour-scheme modules can use classes already provided in Confluence. So you can write a theme-plugin without any Java code. But for macro and listener modules you need to write your own implementing class and include it in your plugin. The Java class of the component. This does not need to extend or implement any class or interface. |
key |  | The identifier of the plugin module. This key must be unique within the plugin where it is defined. Sometimes you will need to uniquely identify a module. Do this with the module complete key. A module with key `fred` in a plugin with key `com.example.modules` will have a complete key of `com.example.modules:fred`. I.e. the identifier of the component. | N/A
i18n-name-key |  | The localisation key for the human-readable name of the plugin module. |
name |  | The human-readable name of the plugin module. I.e. the human-readable name of the component. | The plugin key.
public |  | Indicates whether this component should be made available to other plugins via the Component Import Plugin Module or not. | false
system |  | Indicates whether this plugin module is a system plugin module (value='true') or not (value='false'). Only available for non-OSGi plugins. | false
#### Elements
Name | Required | Description | Default
--- | --- | --- | ---
interface |  | The Java interface under which this component should be registered. This element can appear zero or more times. | N/A
description |  | The description of the plugin module. The 'key' attribute can be specified to declare a localisation key for the value instead of text in the element body. |
## Example Here is an example `atlassian-plugin.xml` file containing a single public component:
    <atlassian-plugin name="Hello World" key="example.plugin.helloworld" plugins-version="2">
        <plugin-info>
            <description>A basic component module test</description>
            <vendor name="Atlassian Software Systems" url="http://www.atlassian.com"/>
            <version>1.0</version>
        </plugin-info>

        <component key="helloWorldService" class="com.myapp.DefaultHelloWorldService">
            <description>Provides hello world services.</description>
            <interface>com.myapp.HelloWorldService</interface>
        </component>
    </atlassian-plugin>
## Notes Some information to be aware of when developing or configuring a Component plugin module: Components, at installation time, are used to generate the `atlassian-plugins-spring.xml` Spring Framework configuration file, transforming Component plugin modules into Spring bean definitions. The generated file is stored in a temporary plugin jar and installed into the framework. The plugin author should very rarely need to override this file. The injection model for components first looks at the constructor with the largest number of arguments and tries to call it, looking up parameters by type in the plugin's bean factory. If only a no-arg constructor is found, it is called then Spring tries to autowire the bean by looking at the types used by setter methods. If you wish to have more control over how your components are created and configured, you can create your own Spring configuration file, stored in `META-INF/spring` in your plugin jar. If the `public` attribute is set to 'true', the component will be turned into an OSGi service under the covers, using Spring Dynamic Modules to manage its lifecycle. This module type in non-OSGi (version 1) plugins supported the StateAware interface in some products to allow a component to react to when it is enabled or disabled. To achieve the same effect, you can use the two Spring lifecycle interfaces: InitializingBean and DisposableBean. The init() and destroy() methods on these interfaces will be called when the module is enabled or disabled, exactly like StateAware. Making this change to a component in an existing plugin will be backwards compatible in all but JIRA. That is, a component module in a legacy plugin which implements InitializingBean will have its init() method called when it is enabled, exactly the same as such a component in an OSGi plugin. Components for non-OSGi (version 1) plugins behave very differently to components for OSGi plugins. For version 1 plugins, components are loaded into the application's object container, be it PicoContainer for JIRA or Spring for all other products that support components. For OSGi plugins, components are turned into beans for the Spring bean factory for that specific plugin. This provides more separation for plugins, but means you cannot do things like override JIRA components in OSGi plugins, as you can for static plugins. ## Accessing Your Components Accessing your components from within other plugin modules is extremely simple. All plugin modules in OSGi plugins are autowired. So to access a component, you need to add a Java setter method to your plugin module class. For example, if you wanted to use the above `helloWorldService` component in an event listener module, you would add a field for the component and a setter method to the listener class as follows:
    public class MyEventListener implements EventListener {
        private HelloWorldService helloWorldService;

        // ...

        public void setHelloWorldService(HelloWorldService helloWorldService) {
            this.helloWorldService = helloWorldService;
        }
    }
Note that to access components in other plugins, the module needs to be marked as 'public' (as covered above) and imported into your plugin using a component-import. ##### RELATED TOPICS Writing Confluence Plugins Installing and Configuring Plugins Manually Information sourced from Plugin Framework documentation

Document generated by Confluence on Nov 05, 2009 23:34