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| |
| <document> |
| |
| <properties> |
| <title>Fulcrum YAAFI Avalon Container Service Lifecycle</title> |
| <author email="siegfried.goeschl@it20one.at">Siegfried Goeschl</author> |
| </properties> |
| |
| <body> |
| |
| <section name="Incarnation"> |
| |
| <p> |
| The incarnation of a service covers the creation and configuration of a |
| service |
| </p> |
| |
| <p> |
| The following methods are invoked: |
| <ul> |
| <li>Constructor()</li> |
| <li>LogEnabled.enableLogging(Logger)</li> |
| <li>Contextualizable.contextualize(Context)</li> |
| <li>Serviceable.service(ServiceManager)</li> |
| <li>Configurable.configure(Configuration)</li> |
| <li>Parameterizable.parameterize(Parameters)</li> |
| <li>Initializable.initialize()</li> |
| <li>Executable.execute()</li> |
| <li>Startable.start()</li> |
| </ul> |
| </p> |
| |
| <p> |
| The good news are that you don't have to implement all these interfaces |
| if you have a simple service. The bad news are that you might need all of |
| this interfaces in a complex application ... :-) |
| </p> |
| |
| <subsection name="Constructor()"> |
| <p> |
| This doesn't come as a surprise |
| </p> |
| </subsection> |
| |
| <subsection name="LogEnabled.enableLogging(Logger)"> |
| <p> |
| Here you get the logger for your service implementation. This |
| is again an interface to an implementation of a logger provided |
| by the caller of the service framework. You can skip this interface |
| if you use org.apache.avalon.framework.logger.AbstractLogEnabled |
| as base class for your service. |
| </p> |
| </subsection> |
| |
| <subsection name="Contextualizable.contextualize(Context)"> |
| <p> |
| The context contains information about your application |
| environment including the current working directory and |
| the temporary directory. YAAFI provides you with different |
| context entries depending on the component type, e.g. |
| "phoenix" or "fortress". |
| </p> |
| </subsection> |
| |
| <subsection name="Serviceable.service(ServiceManager)"> |
| <p> |
| At this point you get a reference to the ServiceManager. This |
| is the right moment to lookup all dependent services just to make |
| sure that everything is fine. |
| </p> |
| </subsection> |
| |
| <subsection name="Configurable.configure(Configuration)"> |
| <p> |
| A common task is to access configuration information whereas |
| the Configuration instance is a light-weight XML DOM tree. This |
| means you can use nested XML files for the configuration of your |
| service. |
| </p> |
| </subsection> |
| |
| <subsection name="Parameterizable.parameterize(Parameters)"> |
| <p> |
| Quite frankly I'm not sure why this method is needed. The only |
| reason I can think of is a command-line application ... |
| </p> |
| </subsection> |
| |
| <subsection name="Initializable.initialize()"> |
| <p> |
| This method is used for initializing your service implementation |
| since you have all your configuration information by now, |
| </p> |
| </subsection> |
| |
| <subsection name="Executable.execute()"> |
| <p> |
| If the component implements Executable the execute method will be |
| invoked before the component instance is exposed to any other component. |
| </p> |
| </subsection> |
| |
| <subsection name="Startable.start()"> |
| <p> |
| The Startable interface is used by any component that is constantly |
| running for the duration of its life. This is the method to go if |
| you want to start a worker thread in the background. |
| </p> |
| </subsection> |
| |
| </section> |
| |
| </body> |
| |
| </document> |
