xdocs/lifecycle/incarnation.xml (97 lines of code) (raw):
<?xml version="1.0"?>
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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>