cause ---------------------------------------------------------------------
Exception: java.lang.NoClassDefFoundError Message: org/apache/log/LogTarget
</snip>
It seems like the logging isn't getting set up properly because it needs LogTarget? Which doesn't seem to exist?
Loks to me like you probably have an implementation jar file in your project.xml that also references logkit.
Basically, I am trying to find the shortest path to getting a working kernel
up and running.
Under 3.2.5 the shortest path is:
InitialContext context = new DefaultInitialContext();
Artifact artifact =
Artifact.createArtifact( "merlin:merlin-impl;3.2.5" );
Builder builder = new DefaultBuiilder( artifact );
Factory factory = builder.getFactory();
Object merlin = factory.crteate();But I'm taking lots of shortcuts and skipping all of the hard work of parametrization.
I'll attach my current .java class for you to see. (note, it is rather rough!).
Attachement never made it - can you send it to me privately?
Cheers, Steve.
Eric Pugh
However, it is being masked by this error:
-----Original Message----- From: Stephen McConnell [mailto:[EMAIL PROTECTED] Sent: Sunday, January 25, 2004 11:36 PM To: Avalon framework users Subject: Re: [merlin] introduction to embedding
Sonu Vijay wrote:
Hi,
What does the "merlin.deployment" property exactly specify.I read abt it yesterday somewhere on avalon site but can't find it now.
The DefaultFactory class in the merlin/kernel/impl package is responsible for (a) establishing an initial factory criteria, and (b) creating a kernel instance using a default or modified criteria argument. When the DefaultFactory prepares the initial criteria, it builds up the default values using a combination of:
- hard coded defaults - defaults derived from merlin.properties files in * MERLIN_HOME/merlin.properties * ${merlin.dir}/merlin.properties * ${user.home}/merlin.properties - system properties
Property names and the corresponding allowable values are declared in the following page:
http://avalon.apache.org/merlin/merlin/kernel/properties.html
The merlin.deployment property defines a comma separated sequence of blocks to be included in the root merlin application block on startup.
Stephen.
thanks
--- Stephen McConnell <[EMAIL PROTECTED]> wrote:
Mathews Julien wrote:"artifact:avalon-logging/avalon-logkit?version=1.0-SNAPSHOT"
Yeah Stephen, This helps in making things more
clear.
Stephen wrote: The
avalon-repository system uses artifact references as the key to
locating meta data
about embedded classloaders. The classloader
meta data is
maintained as a properties file with the .meta
extension. For
example the above artifact meta address
translates to:
The content of the meta file is automatically
generated using the
avalon-plugin avalon:artifact goal.
How does the avalon:artifact goal generate the
meta information in the
.meta info. I mean where does is get the info abt
the "implementation
dependencies" etc.
From some project.xml or some meta tags or where
?
The avalon:artifact goal scans the project PMC (Maven's project definition) and looks at all of the dependencies that are listed. For each dependency, the plugin looks for a declared dependency properties and does some special processing for properties named "avalon.classloader". For example the following is a dependency declaration within the merlin/kernel/impl project.xml:
<dependency> <groupId>merlin</groupId> <artifactId>merlin-api</artifactId> <version>3.3-SNAPSHOT</version> <properties>
<avalon.classloader>spi</avalon.classloader> </properties> </dependency>
The plugin will look for the property name "avalon.classloader" and if the property value is "api" then the dependency will be loaded into an api classloader. If the property is "spi" the dependency will be loaded into a spi classloader which is created as a child of the spi loader. If no "avalon.classloader" property is declared that dependency will be loaded into a impl classloader which is created as a child of the spi loader.
The avalon-repository bootstrapping system will attempt to construct a classloader chain that looks like the following:
|----------------------| | api classloader | |----------------------| ^ | |----------------------| | spi classloader | |----------------------| ^ | |----------------------| | imp classloader | |----------------------|
Could you pls explain a little bit.
The avalon:artifact source file is a jelly script in
avalon/util/plugin/plugin.jelly.
Cheers, Stephen.
Thanks Mathews
From: Stephen McConnell <[EMAIL PROTECTED]> Reply-To: "Avalon framework users"
<[EMAIL PROTECTED]>
To: Avalon Users <[EMAIL PROTECTED]> Subject: [merlin] introduction to embedding Date: Sun, 25 Jan 2004 16:17:19 +0100
This is a little introduction to embedding
Merlin. The descriptions
starts off with an overview of the Avalon
Repository bootstrapping
system - which at the end of the day is the core
embedding technology
used within the merlin platform.
Simple Embedding Example: -------------------------
1. creating an initial context
File cache = new File( "my-cache" ); InitialContext context = new
DefaultInitialContext( cache );
The above code defines a cache directory for
the repository
system to use when loading resources needed in
your embedded
application - and provides the directory as an
argument when
creating a new InitialContext object. The
InitialContext is
you hook into the repository system and the
embedding machinery.
2. declare what you want to embed
String spec =
[host]/avalon-logging/jars/avalon-logkit-impl-1.0-SNAPSHOT.jar.metaArtifact artifact = Artifact.createArtifact( spec );
An artifact is a logical reference to a jar
file (or other type
of resource) that the repository can access.
The avalon-repository
system uses artifact references as the key to
locating meta data
about embedded classloaders. The classloader
meta data is
maintained as a properties file with the .meta
extension. For
example the above artifact meta address
translates to:
The content of the meta file is automatically
generated using the
avalon-plugin avalon:artifact goal. Two real
examples are attached
(the logkit factory and the merlin factory
meta).
The contents of the meta file includes:
* a ordered list of jar files that are
required to
construct a classloader for the embedded
application
* the name of a factory class to be used as
the embedded
instance creator
3. create the factory
Using the initial context and the artifact you
now have everything
you need to create you embedded instance.
Builder builder = m_context.newBuilder(
artifact );
Factory factory = builder.getFactory();
Behind the scenes the avalon-repository system
has gone off, pulled
down the meta data, downloaded and cached all
of the classloader
entries, constructed a new classloader, and
instantiated the
factory.
4. parameterizing the factory
The factory object is the central entry point
of
=== message truncated ===
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