mcconnell 2004/03/29 11:51:57
Modified: merlin/platform/xdocs/reference/component/artifacts
index.xml
Log:
Logger lifecycle artifact spec.
Revision Changes Path
1.3 +54 -0
avalon/merlin/platform/xdocs/reference/component/artifacts/index.xml
Index: index.xml
===================================================================
RCS file:
/home/cvs/avalon/merlin/platform/xdocs/reference/component/artifacts/index.xml,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- index.xml 29 Mar 2004 18:10:29 -0000 1.2
+++ index.xml 29 Mar 2004 19:51:57 -0000 1.3
@@ -28,7 +28,61 @@
<section name="Lifecycle Artifacts">
+ <p>
+Component-based solutions leverage the principals of Inversersion of Control (IoC).
This principal leads to the notion that a component should be supplied with the
resources it needs in order to function. Another way of looking at this is that the
component code should not be cluttered with content that is attempting to resolve
resources relative to its environment. Through the application of a meta-info model a
container has available to it a complete description of the component type and from
this information can build the necessary resources that a component needs. These
resources are supplied to a component through a set of standard Avalon lifecycle
artificats. These include
+<a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/logger/Logger.html";>Logger</a>,
+<a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/context/Context.html";>Context</a>,
+<a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/configuration/Configuration.html";>Configuration</a>,
+<a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/parameters/Parameters.html";>Parameters</a>,
and
+<a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/service/ServiceManager.html";>ServiceManager</a>.
+ </p>
+
+ <p>
+Two styles of artifact delivery are supported:
+ </p>
+
+ <subsection name="Delivery Strategies">
+
+ <table>
+ <tr>
+ <td>injection</td>
+ <td>
+The artifact injection strategy enables the passing of artifacts via the component
constructor. This approach minimises lines of code dealing with establishment,
enables the allocation of final variables, and eliminates the requirement for explict
initialization of startup phases.
+ </td>
+ </tr>
+ <tr>
+ <td>phased</td>
+ <td>
+The phased artifact delivery strategy is based on a set of delivery interfaces (<a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/logger/LogEnabled.html";>LogEnabled</a>,
<a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/context/Contextualizable.html";>Contextualizable</a>,
<a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/configuration/Configurable.html";>Configurable</a>,
<a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/parameters/Parameterizable.html";>Parameterizable</a>
and <a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/service/Serviceable.html";>Serviceable</a>).
The advantage of phased delivery over the injection strategy relates to artifact
re-assignment by a component management subsystem. Phased artifact delivery is the
traditional approach used be earlier Avalon solutions.
+ </td>
+ </tr>
+ </table>
+ </subsection>
+
<subsection name="Logger">
+ <p>
+The <a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/logger/Logger.html";>Logger</a>
defines a implementation independent logging channel. The logging channel supplied
to a component represents the root loggging channel for the component. A component
may aquire additional subsidiary channels using the <a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/logger/Logger.html#getChildLogger(java.lang.String)">getChildLogger()</a>
operation. The Logger interface exposes a set of operations to check if a particular
logging priority is enabled, thus enabling optimization of typically expensive string
manipulation operations related to log message construction.
+ </p>
+ <p>
+A logging channel may be supplied via constructor or under an implementation of the
<a
href="http://avalon.apache.org/framework/api/org/apache/avalon/framework/logger/LogEnabled.html";>LogEnabled</a>
lifecycle stage interface.
+ </p>
+<p><i>Example:</i></p>
+<source>
+ /**
+ * Creation of a new widget. The implementation assigns
+ * the supplied logging channel as the default channel and
+ * constructs a subsidiary channel for connection related log
+ * messages. Tgh
+ *
+ * @param logger a logging channel
+ */
+ public DefaultWidget( Logger logger )
+ {
+ m_logger = logger;
+ m_connectionLogger = logger.getChildLogger( "connection" );
+ }
+</source>
+
</subsection>
<subsection name="Context">
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