mpoeschl 02/03/15 03:55:59
Modified: xdocs project.xml
Added: xdocs components-howto.xml
Removed: notes ComponentLoader.txt
Log:
add a little Componets howto (incl. the ComponentLoader notes)
as this stuff is used by turbine 2.2b1 it should be documented
Revision Changes Path
1.7 +4 -0 jakarta-turbine-stratum/xdocs/project.xml
Index: project.xml
===================================================================
RCS file: /home/cvs/jakarta-turbine-stratum/xdocs/project.xml,v
retrieving revision 1.6
retrieving revision 1.7
diff -u -r1.6 -r1.7
--- project.xml 22 Feb 2002 12:25:37 -0000 1.6
+++ project.xml 15 Mar 2002 11:55:59 -0000 1.7
@@ -10,6 +10,10 @@
<item name="Building" href="/building.html"/>
</menu>
+ <menu name="Documentation">
+ <item name="Components" href="/components-howto.html"/>
+ </menu>
+
<menu name="JCS Documentation">
<item name="Overview" href="/JavaCachingSystem.html"/>
<item name="JCS and JCACHE" href="/JCSandJCACHE.html"/>
1.1 jakarta-turbine-stratum/xdocs/components-howto.xml
Index: components-howto.xml
===================================================================
<?xml version="1.0"?>
<document>
<properties>
<title>Components Howto</title>
<author email="[EMAIL PROTECTED]">Martin Poeschl</author>
</properties>
<body>
<section name="Components Howto">
<p>
<b>
NOTE: This stuff is in its infancy and will more than likely change. Read the
<a href="#Notes">Notes</a> for more information about future plans!
</b>
</p>
<p>
This document describes how components (like Torque and Fulcrum) are used with
Turbine. It also descibes how to write new Components and how to use existing
Components in your project.
</p>
</section>
<section name="Components">
<p>
Components are Classes implementing the lifecycle interfaces
(org.apache.stratum.lifecycle). In the current version Components must implement
the Configurable and Initializable interfaces. (<b>NOTE: this may change in
future versions!</b>)
</p>
<p>
Here's the code used to make Fulcrum's BaseServiceBroker a Component:
</p>
<source><![CDATA[
package org.apache.fulcrum;
import org.apache.stratum.lifecycle.Configurable;
import org.apache.stratum.lifecycle.Initializable;
import org.apache.stratum.configuration.Configuration;
/**
* A implementation of a <code>ServiceBroker</code> which implements the
* lifecycle interfaces.
*
* @author <a href="mailto:[EMAIL PROTECTED]";>Martin Poeschl</a>
* @version $Id: components-howto.xml,v 1.1 2002/03/15 11:55:59 mpoeschl Exp $
*/
public class Fulcrum extends BaseServiceBroker
implements Configurable, Initializable
{
/**
* initialize fulcrum
*/
public void initialize() throws Exception
{
super.init();
}
/**
* configure fulcrum
*/
public void configure(Configuration configuration)
{
super.setConfiguration(configuration);
}
}
]]></source>
</section>
<section name="ComponentLoader">
<p>
The ComponentLoader loads components and initializes them by calling their
lifecycle methods.
</p>
<p>
Here's how Turbine 2.2 uses the ComponentLoader during the initialization:
</p>
<source><![CDATA[
// Initialize components like torque and fulcrum
ComponentLoader loader = new ComponentLoader(
TurbineResources.getConfiguration());
loader.load();
]]></source>
<p>
Configuration:
</p>
<source><![CDATA[
# -------------------------------------------------------------------
#
# C O M P O N E N T S
#
# -------------------------------------------------------------------
# Components implementing the lifecycle interfaces can be loaded,
# configured and initialized by Turbine
# -------------------------------------------------------------------
component.name = torque
component.torque.classname = org.apache.torque.Torque
component.torque.config = ${webappRoot}/WEB-INF/conf/Torque.properties
component.name = fulcrum
component.fulcrum.classname = org.apache.fulcrum.Fulcrum
component.fulcrum.config = ${webappRoot}/WEB-INF/conf/Fulcrum.properties
]]></source>
</section>
<section name="Notes">
<p>
<pre>
The ComponentLoader is used by Turbine and Fulcrum and Torque. It's
job is to load components (some of which might also be services) and
call their lifecycle methods.
One goal for the ComponentLoader is to enable someone to extend any
arbitrary class, implement the lifecycle interfaces, and use it as a
component in the Turbine family.
This trick will be useful for migrating some of Fulcrum's services
into components. It may also enable turbine users to migrate their
Turbine 2.1 services to components.
At the moment, the component loader is only used by Turbine to load
Torque and Fulcrum. The components are assumed to be self-sustaining,
and assumed to provide some static methods for interfacing with the
components. The ComponentLoader does not currently store any
references to components once they have been loaded.
FIXME: Still need a better definition to distinguish a service from a
component, including examples to illustrate the differences.
Components vs. Services Services are a kind of component. Many of
them seem to revolve around interactive network interfaces. Some
examples include xmlrpc and ftp. Some items are too fundamental to
any application to be either components or services. Examples include
pooling, caching, database access, security. These examples are
currently services but should be changed to components: upload
service, ??.
Other 2.1->Fulcrum migration plans:
jason can swap all the imports with the transformer in maven and then
people will probably have to poke around for a couple minutes.
Longer-term plans:
let the ComponentLoader reload components without stopping the server.
It will have its own classloader eventually (probably borrowing the
webapp classloader code from catalina). We can look for a
configuration.xml in a standard place in the component's jar or look
at the manifest and use that to configure the component.
We'll probably provide some kind of key->value map to store references
to the components, or treat them similarly to the way pull tools are
handled -- where request scope tools are loaded for each request.
Something similar might work for components as well. Another option
is to provide a reference to a pool of a particular kind of component.
</pre>
</p>
</section>
</body>
</document>
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