I will let Steve analyze all the code in detail, but to me it looks like you
are 'raping' Merlin, and it doesn't want to play along. It is also likely
that none of the code is 'compatibility friendly'.
Violating the AF4 lifecycle contract is not going to bring you anywhere but
possibly broken code in the future. What is happening in your code is pretty
obvious, the m_kernel == null is executed during the m_kernel =
factory.create(), and fully expected.
IIUC, you just want to instantiate an empty kernel and add the components
later. Is that correct?
If so, there is a much easier way, which is supported.
1. Start up the kernel the normal way, embedded or not.
2a. If not embedded, have a single component that has the composition model
(ContainmentModel) context entry requirement declared, and look it up in
contextualize();
2b. If embedded, you may have the bootstrapper get hold of the composition
model (ContainmentModel), but it is less generic.
3. Call the ContainmentModel.addModel() method, with the URL of a block
containing any block of the components you want loaded.
See the DeployCmd and UndeployCmd in the planet/facilities/console/impl for
details on the deployment and undeployment sequence.
Cheers
Niclas
On Friday 08 October 2004 08:48, Harvinder Singh wrote:
> Hi All,
>
> I am getting an IllegalStateException::kernel does not exist, when I am
> trying to lookup for a component.
> Here is the scenario of what I am trying to do:
> I am using Merlin in a embedded way. There are components which I have
> developed and some of them are having dependencies amongst each other.
> Their xinfo files have the correct dependencies defined.
>
> The part of embedding is as follows :
>
> ClassLoader classloader = Framework.class.getClassLoader();
>
> File repository = new File( getMavenHome(), "repository" );
> File basedir = getBaseDirectory();
>
> Map criteria = null;
> org.apache.avalon.repository.provider.Factory factory = null;
> try {
> Artifact artifact =
> DefaultBuilder.createImplementationArtifact(
> classloader,
> getMerlinHome(),
> basedir,
> MERLIN_PROPERTIES,
> IMPLEMENTATION_KEY );
>
> InitialContextFactory icFactory =
> new DefaultInitialContextFactory( "merlin", basedir );
> icFactory.setCacheDirectory( repository );
> InitialContext context = icFactory.createInitialContext();
>
> Builder builder = new DefaultBuilder( context, artifact );
> m_classloader = builder.getClassLoader();
> factory = builder.getFactory();
> criteria = factory.createDefaultCriteria();
> } catch (IOException e) {
> e.printStackTrace();
> } catch (Exception e) {
> e.printStackTrace();
> }
> if (singleton == null) {
> singleton = new Framework();
> }
> else
> {
> singleton.getLogger().debug(
> "Framework Already Initialized - Attempt Ignored");
> }
> try {
> m_kernel = factory.create( criteria );
> m_shutdown =
> m_kernel.getClass().getMethod(
> "shutdown",
> new Class[0] );
> Method method =
> m_kernel.getClass().getMethod(
> "getModel",
> new Class[0] );
> m_root = method.invoke( m_kernel, new Object[0] );
> m_locate =
> m_root.getClass().getMethod(
> "getModel",
> new Class[]{ String.class } );
> Class modelClass =
> m_classloader.loadClass( DEPLOYMENT_MODEL_CLASSNAME );
> m_resolve =
> modelClass.getMethod( "resolve", new Class[0] );
> initialized = true;
>
>
>
> Normally we try to look up the dependent components using the service
> manager in the service() method. But in the case of embeddding Merlin, I do
> not want to use the service() method to look up for the dependent
> components. Due to some design constraints, I am doing a lookup in the
> configure() method itself without using the service manager since I am
> havng my own manager class. Now here comes the problem:
>
> When Merlin is embedded, the factory.create(Map) method instantiates the
> container and then commissions all the components in the container. While
> trying to do so, it also reads the configure method of each component (got
> to know when I ran with debug option as true).
> Remember that uptill now, my kernel has not been initialized (it is in the
> process of initializing).
> In my component's configure() method, I look up for the dependent
> components, In my getComponent method, I try to invoke the compoennt by
> using reflection. as shown below:
>
> public Component getComponent(String path ) throws
> ComponentNotFoundException {
> AbstractObject abstractObject;
> try {
> abstractObject = resolve(path);
> } catch (Exception e) {
> // TODO Auto-generated catch block
> throw new ComponentNotFoundException(getLogger(),
> path,"Exception in
> getting Component .Exception is "+e);
> }
> return
> (Component)Proxy.newProxyInstance(Component.class.getClassLoader(),
> abstractObject.getclasses(),new
> InvocationHandlerImpl(abstractObject.getObj()));
> }
>
>
>
> public AbstractObject resolve( String path ) throws Exception
> {
> if( null == m_kernel )
> throw new IllegalStateException( "kernel does not exist" );
>
> try
> {
> Object model = m_locate.invoke( m_root, new Object[]{ path }
> );
>
> Class objClass = model.getClass();
>
> Method method = objClass.getMethod("getServices", null);
>
> ServiceDescriptor[] serviceDescriptors =
> (ServiceDescriptor[])method.invoke(model,new Object[0]);
> Class[] classes = new Class[serviceDescriptors.length+1];
> classes[serviceDescriptors.length] = Component.class;
> for(int i = 0 ; i < serviceDescriptors.length ; i++ ){
> classes[i] =
> Class.forName(serviceDescriptors[i].getReference().getClassname());
> }
>
>
> //()model
> Object obj = m_resolve.invoke( model, new Object[0] );
> return new AbstractObject(obj,classes);
> //return
> (Component)Proxy.newProxyInstance(Component.class.getClassLoader(),
> classes,new ComponentImpl(obj));
> }
> catch( InvocationTargetException ite )
> {
> Throwable cause = ite.getTargetException();
> final String error = ExceptionHelper.packException( cause,
> true );
> throw new Exception( error );
> }
> catch( Throwable e )
> {
> final String error = ExceptionHelper.packException( e, true );
> throw new Exception( error );
> }
> }
>
> As you notice, in the very first step the kewrnel is checked for null and
> since it has not been initalized uptill now, it throws an
> IllegalStateException. Infact other objects, such as m_root and methods
> m_locate are all unitialized as well. Thus the operation has entered in a
> loop i.e. while trying to initialize the kernel, somewhere down the line in
> some component's configure method, it is trying to use the uninitialzed
> kernel. I want to know whether the way I am using for resolving the
> component is ok or needs to be changed. Whether there is any other way
> where I can initialize the empty kernel completely and then commission all
> the components to it.
>
> I tried to reproduce this error for Normal Merlin conditions (not
> embedding). I passed the service Manager into the component's contructor
> directly and then used the service manager in the configure() method to
> lookup the components and it worked.
> So what should we do during the embedding scenario for this to work ?
>
> Please provide some pointers on this regard
>
> Regards,
> Harvinder
>
>
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