Hi Steve,
[...]
> >The URL analysing service is something we already have and I
> will havo integrate this into the webapp. So I assume I had
> to modify some of the DefaultXXX classes to convert my
> servlet into something that is part of the component logic.
> >
>
> In principal you should not need to extend anything (at least
> tha't the
> objective). The URL side really only comes in play when the
> servlet is
> handling dynamic content presentation. An HTTP request can include a
> service identifier and parameters. The servlet directs the
> request to a
> service running in Merlin which can then handle the request
> resolution.
> This works really nicely and makes for really compact code in the
> web-app - but more about this later in the week.
Well, we have really some very special URL encoding and - since the code analysing the
URL already runs - I would just like to avalonize it. My problem is that I am running
out of time for the start-up phase. If you can give me a hint how to install my
contoller servlet as Merlin block (or whatever) or a way to handle the request over to
a component I will be happy. If I can replace code later on with a better and much
more geenralized solution - fine. Currently I am feeling like a moron - with your demo
I have a wonderful running component logic running inside my webapp - but I cannot
access it anyway <g>!
> [...] But with Merlin
> I seem to have a lot of running threads communicating with
> each other for every single request.
> >
>
> Not following this. Merlin creates one thread per container
> so I don;t
> see where the "lots-of-threads" is comming from.
Gotcha. Somehow I had the impression that every component is running in its own thread
- possibly just a result of the one-component-per-block samples :)
Now anything comes right in the place.
> If you running one
> thread per request you may want to look at the per-thread lifecycle
> policy. This policy ensures that a new component instance is created
> once per-thread. There is an example of the per-thread
> componet in the
> playground. Default lifestyle behaviour is singleton (i.e.
> thread safe
> componet).
Hmmm. What means "singleton" in the context of a servlet. The servlet container is
free to create any number of instances of my servlet calling the same servlet instance
concurrently. The servlet instances itself will normally not be destroyed until the
servlet container terminates, but even this is part of the vender's implementation
strategy. So, normally I would define a singleton as a class with exaclty one instance
independent of any thread - which might not be true in this context here. I assume
this means one instance per servlet instance, which suits perfectly.
> To declare a per thread policy all you need to do
> is add an
> attribute to the .xinfo file for the component you want to be
> per-thread. Here is an example:
>
> <type>
> <info>
> <name>my-component</name>
> <attributes>
> <attribute key="urn:avalon:lifestyle" value="thread"/>
> </attributes>
> </info>
> </type>
Learned something new again :)
(Although I have the impresion that someone will really have to collect all these
urn-keys in one big overview table <g>)
>[...]
>
> Just for reference - case (b) was non-discovery of the
> component because
> of non-discovery of the jar file - but that will not be a problem
> because the engine automaticaly scans all of the jar files in the
> classloader heirachy when first initialized.
Hmm. Is there any way to read directly from the file system? The block.xml gives me
the class names of the services. The files are already in the classpath and all I
would need is to load the .xinfo using getClass().getClassLoader().getResource().
Because building every time a jar and deploying it to the servlet engine would be much
more effort than using code replacement features during debug. If I wanted to do so I
think I have to provide an overloaded DefaultRepositoryManager. This is only possible
by overloading EngineClassLoader overloading createResourceManager and therefore an
own DefaultKernel instanciating the overloaded engine ... or I need another
DefaultBlockLoader that inistailizes this overloaded <sigh>
> From the command line
>
> $ merlin -debug
>
> From an embedded scenario - when you contextualize the
> kernel you can
> control the default logging priority by passing in a conext entry
> "urn:merlin:debug" - with a value of a String with the
> logging priority
> level (e.g. "info", "warn", "error" or "debug"). The command line
> -debug option just passes in the "debug" string to the DefaultKernel
> context.
Did not work. Stepping through the code, the kernel initializes a
bootstrapLoggingManager from an entry "urn:assembly:logging.descriptor" and I am not
quite sure, what it expects in the xml file for a descriptor (and it does not work
either, for the context below). Here is the simplified code (omitting try/catch
blocks) from the kernel initialization:
================ snip =============
final DefaultLocator lContext = new DefaultLocator( );
lContext.put( "urn:merlin:debug", "DEBUG" ); // "debug" does not work either
lContext.put( "urn:merlin:home", lHome );
lContext.put(
"urn:merlin:classloader.common", this.getClass( ).getClassLoader( ) );
lContext.put(
"urn:merlin:classloader.system", this.getClass( ).getClassLoader( ) );
lContext.put( "urn:merlin:kernel.profile", lProfile );
lContext.makeReadOnly( );
Configuration lConfig = lConfig = getConfiguration( lProfile );
m_kernel.contextualize( lContext );
m_kernel.configure( lConfig );
m_kernel.initialize( );
m_kernel.start( );
================ snap ===============
A grep through the sandbox code did not show any occurence of "urn:merlin:debug" ...
when did you implement this?
> Apart from that you can control logging priority for any appliance or
> block declared in your blocks.xml file using the
> <categories/> element.
>
> <categories priority="WARN"/>
>
> The above declaration set the logging priority for whateve is
> enclosing it to the declared level. In the following example
> the logging level is set to INFO and a child logger called
> my-sub-channel is set to DEBUG.
>
> <categories priority="INFO"/>
> <category name="/my-sub-channel" priority="DEBUG"/>
> </categories>
>
> Here is a practical example in which I'm setting different logging
> levels at the block and appliance levels.
>
> <block name="demo">
>
> <implementation>
>
> <!-- set the logging level for the root block to WARN-->
> <categories priority="WARN"/>
>
> <appliance name="standard"
> class="org.apache.avalon.playground.StandardComponent"
> activation="startup">
> <!-- set the logging level for this component to DEBUG -->
> <categories priority="DEBUG"/>
> </appliance>
>
> <container name="test">
> <!-- set the logging level for this container to ERROR-->
> <categories priority="ERROR"/>
> <appliance name="standard"
>
> class="org.apache.avalon.playground.StandardComponent"
> activation="startup">
> <!-- set the logging level for this component to INFO -->
> <categories priority="INFO"/>
> <context
> class="org.apache.avalon.playground.StandardContextImp"/>
> <configuration>
> <message>Standard component inside a nested
> block.</message>
> </configuration>
> </appliance>
> </container>
>
> </implementation>
>
> </block>
Hmm. I tried the entry within the root block, but no effect, I do not get debug output
:(
Here is the output:
====================== snip ======================
[INFO ] (sys): initialization from: C:\Work\demo\head\src on localhost
[WARN ] (sys): directory scanning not supported: file:/C:/demo/head/bin/
[WARN ] (sys): directory scanning not supported: file:/C:/demo/head/bin/
[INFO ] (sys):
commencing block construction phase
[INFO ] (sys): block count = 1
[ERROR ] (sys): Message: Block installation phase failure.
===================================================================
Exception: org.apache.avalon.merlin.block.BlockException
Error during block deployment for block: 1 [test]
Cause: org.apache.avalon.merlin.block.BlockException
Cannot build the container descriptor: test
Cause: org.apache.avalon.merlin.container.ContainerException
Root container in block: test contains an profile that references an unknown type:
demo.service.HelloWorld
Cause: org.apache.avalon.assembly.engine.type.UnknownTypeException
demo.service.HelloWorld
====================== snap ======================
And here the current block.xml:
====================== snip ======================
<block>
<implementation>
<categories priority="DEBUG" />
<appliance name="standard"
class="demo.service.HelloWorld" activation="startup">
<configuration>
<message>Hello World block descriptor.</message>
</configuration>
</appliance>
</implementation>
</block>
====================== snap ======================
Quite strange.
> No problem - the feedback makes it worthwhile ;-)
It is really welcome :)
Regards,
J�rg
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