Aren't the 'converted' Urls just transient? I.e. tied to a runtime
installation? So what is the danger of platform specific conversion?
sent on the move
On 15 Apr 2011 22:40, "Esteban Aliverti" <esteban.alive...@gmail.com> wrote:
> Hi Geoffrey,
> thanks for sharing your opinion!
>
> When drools-spring creates the resource from the configuration file, it
> creates it passing the class' class loader:
>
> new ClassPathResource(path, ClassPathResource.class.getClassLoader() );
>
> Internally, ClassPathResource is doing:
>
> this.classLoader = ClassLoaderUtil.getClassLoader( new ClassLoader[] {
> classLoader },null, false );
>
> So, a classloader is indeed supplied. AFAIK, the problem is that the
> provided classloader is tomcat's classloader.
>
> I know it is dangerous to store native URLs instead of the classpath, but
> after all, after you deploy drools-server, each of the resources will have
> an URL.
> If this is a problem, you can always use classpath resources. That is why
I
> thought in a new Resource type and not in modify ClassPathResource class.
>
> I have created an issue for this:
> https://issues.jboss.org/browse/JBRULES-2960
>
> Thanks again for your time!
>
> Best Regards,
>
> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>
> Esteban Aliverti
> - Developer @ http://www.plugtree.com
> - Blog @ http://ilesteban.wordpress.com
>
>
> On Fri, Apr 15, 2011 at 9:38 AM, Geoffrey De Smet
> <ge0ffrey.s...@gmail.com>wrote:
>
>> The kbuilder uses the second method of ClassPathResource
>> (getInputStream()) to get the content of the resource.
>>
>>
>> Shouldn't that also supply a ClassLoader or a Class (of which
>> Class.getClassLoader() is used)?
>>
>>
>> This resource type will let you define your resources present in your
>> classpath as usually but it will translate them to URL Resource
internally.
>>
>> It's probably dangerous to store the native URL the concept of a
classpath
>> is designed to have a map of files "that are just there" and you don't
need
>> to worry what's the OS-specific underlying details.
>> Instead, I believe, the classpath key (for example "simpler.drl") and the
>> ClassLoader (for example MyApp.class.getClassLoader()) should be stored.
>>
>> Op 15-04-11 13:52, Esteban Aliverti schreef:
>>
>> Hi Guys,
>>
>> I want to discuss a problem I have found when using the combination of
>> knowledge agent + classpathResources.
>> I will try to describe what am I doing first to give you some context.
>> I'm deploying drools-camel-server in a Tomcat 7 container. Inside the
>> WEB-INF/classes directory I have some DRL files that I want to use.
>> My knowledge-services.xml file declares the following kagent:
>>
>> <drools:kagent id="kagent1" kbase="kbase1" new-instance="false">
>> <drools:resources>
>> <drools:resource type="DRL" source="*classpath*:simple.drl"/>
>> ...
>> </drools:resources>
>> </drools:kagent>
>>
>> When spring parses this configuration file it creates a KnowledgeAgent
>> instance with a ChangeSet containing all the listed resources.
>> The next step is to start ResourceChangeNotifierService
>> and ResourceChangeScannerService.
>> So far so good.
>>
>> The problem:
>> The problem I'm having is not directly related to drools, but I think it
is
>> quite easy to provide a solution for the people that is in my same
>> situation.
>>
>> ClassPathResource is the class that represents a resource defined as "*
>> classpath:"*
>>
>> This class has 2 important methods:
>>
>> public long getLastModified(){
>> return this.classLoader.getResource( this.path
>> ).openConnection().getLastModified();
>> }
>>
>> public InputStream getInputStream(){
>> return this.classLoader.getResourceAsStream( this.path );
>> }
>>
>>
>> The first method is used by ResourceChangeScannerService to check whether
>> the resource has changed or not. It works fine. When the resource in the
>> filesystem changes, the scanner detects the change without any problem.
>> The scanner ends up notifying the kagent about the change, and the kagent
>> passes the Resource to an instance of KnowledgeBuilder.
>> An here is when things fail.
>> The kbuilder uses the second method of ClassPathResource
(getInputStream())
>> to get the content of the resource. In the case of Tomcat (and probably
some
>> other environments), it seems that the classloader (Tomcat's classloader)
is
>> using a cache. So the InputStream returned doesn't reflect the current
state
>> of the resource.
>> Long story short: the agent is notified about a change in the resource,
but
>> the change is never applied to the kbase because the kbuilder is unable
to
>> get it :P
>>
>> Solutions:
>> The first solution is not to use classpath resources :). You can use just
>> url resources like http:// or file:/. But honestly, when you have your
>> rules inside your webapp, it is much more comfortable and even manageable
to
>> avoid the use of real paths.
>>
>> What I was thinking about (I already have a working prototype) is to
>> create a new Resource type for these cases. This resource type will let
you
>> define your resources present in your classpath as usually but it will
>> translate them to URL Resource internally.
>> So, in the example above:
>>
>> <drools:resource type="DRL" source="*URLClasspath*:simple.drl"/>
>>
>> is going to be translated (internally and in a transparent way) to
>> something like:
>> file:/usr/local/apache-tomcat-7/webapps/MyWebapp/WEB-INF/simple.drl.
>>
>> Opinions?
>>
>> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>>
>> Esteban Aliverti
>> - Developer @ http://www.plugtree.com
>> - Blog @ http://ilesteban.wordpress.com
>>
>>
>> _______________________________________________
>> rules-dev mailing listrules-dev@lists.jboss.orghttps://
lists.jboss.org/mailman/listinfo/rules-dev
>>
>>
>> --
>> With kind regards,
>> Geoffrey De Smet
>>
>>
>> _______________________________________________
>> rules-dev mailing list
>> rules-dev@lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-dev
>>
>>
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