[jira] [Commented] (NIFI-2909) Provide a framework mechanism for loading additional classpath resources

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/NIFI-2909?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15602762#comment-15602762 ] 

ASF GitHub Bot commented on NIFI-2909:
--------------------------------------

GitHub user bbende opened a pull request:

    https://github.com/apache/nifi/pull/1156

    NIFI-2909 and NIFI-1712 Per-Instance ClassLoading

    Thank you for submitting a contribution to Apache NiFi.
    
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    ## Summary of Changes
    
    - Introduced a new annotation for processors, reporting tasks, controller services - @RequiresInstanceClassLoading
    - Added new builder method to PropertyDescriptor dynamicallyModifiesClasspath(boolean)
    - Created a new InstanceClassLoader that maintains a child-first internal ClassLoader where classpath resources can be set, only used when component has @RequiresInstanceClassLoading
    - Added support to ExtensionManager to obtain ClassLoaders based on type + id, before we only had by type
    - If the type being requested supports instance class loading (the annotation described above) it will create an InstanceClassLoader which starts as a copy of the NAR ClassLoader for that type
    - When properties are set on a component, the framework will identify the properties that are classpath modifiers and add those resources to the InstanceClassLoader's child resources

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/bbende/nifi NIFI-1712

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/nifi/pull/1156.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #1156
    
----
commit 493a6097d3a44337ab08cfac9b6f8e24b350b2a6
Author: Bryan Bende <bb...@apache.org>
Date:   2016-10-10T13:27:57Z

    NIFI-2909 Adding per-instance class loading capability through @RequiresInstanceClassLoading annotation
    NIFI-1712 Applying per-instance class loading to HBaseClientService to allow specifying Phoenix Client JAR

----


> Provide a framework mechanism for loading additional classpath resources
> ------------------------------------------------------------------------
>
>                 Key: NIFI-2909
>                 URL: https://issues.apache.org/jira/browse/NIFI-2909
>             Project: Apache NiFi
>          Issue Type: Improvement
>            Reporter: Bryan Bende
>            Assignee: Bryan Bende
>             Fix For: 1.1.0
>
>
> We currently have several components with a property for specifying additional classpath resources (DBCP connection pool, scripting processors, JMS). Each of these components is responsible for handling this in its own way. 
> The framework should provide a more integrated solution to make it easier for component developers to deal with this scenario. Some requirements that need to be met by this solution:
> - Multiple instances of the same component with different resources added to the classpath and not interfering with each other (i.e. two DBCP connection pools using different drivers)
> - Ability to modify the actual ClassLoader of the component to deal with frameworks that use Class.forName() without passing in a ClassLoader, meaning if a processor loads class A and class A calls Class.forName(classBName), then class B needs to be available in the ClassLoader that loaded the processor's class which in turn loaded class A
> - A component developer should be able to indicate that a given PropertyDescriptor represents a classpath resource and the framework should take care of the ClassLoader manipulation



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