[jira] Commented: (CONFIGURATION-394) Providing BeanDiff(or ConfigurationDiff), BeanBatchUpdateListener, and some merge facility for Configuration(Specially for HierarchialConfiguration) to implement two-phase-commit-like protocol to alter entire configuration hierarchy in atomic manner.

["Java Developer (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CONFIGURATION-394?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12893964#action_12893964 ] 

Java Developer commented on CONFIGURATION-394:
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I admit it is out of scope of Apache commons configuration project. But as interested java developer I know there is so much effort to model configuration data which must be effective in web development and also application development. So I completed the implementation and provided a generator framework which generate configuration classes from XML file.

I thought this is best way to close this issue and also provide a way for googlers to find some useful code to follow it. I actually have no time to spend for new project. So I hope you still accept this last upload and let google searchers use the space of Apache project to find interesting stuff.

Just as a short description for interested developers I should say:

1- I've attached a eclipse project (FinalConfigClasses.zip) which contains all code of framework.
2- The artifact of this project is an ant task which gets the XML input file as description of config-classes and
    its output is a generated config-classes into "com.fanava.psp.cfg.sample" package.
3- You can inspect classes of  "com.fanava.psp.cfg.sample" package to find out how this framework
     would generate useful config-classes that you can use in serious business applications.
4- The concurrency equipments of generated classes are much simpler than previous upload.
5- So just execute ant target inside build.xml to see generated class files. You must fix absolute paths also.
6- Just as a note I've used "Jacobe" code beautifuler to format generated classes. You can download it from http://www.tiobe.com/index.php/content/products/jacobe/Jacobe.html .

I hope this topic provides new ideas for both java developers and also for Apache commons configuration framework. May be we could place some useful part of this project into Apache commons configuration code.

Anyway thanks for patient.

> Providing BeanDiff(or ConfigurationDiff), BeanBatchUpdateListener, and some merge facility for Configuration(Specially for HierarchialConfiguration) to implement two-phase-commit-like protocol to alter entire configuration hierarchy in atomic manner.
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: CONFIGURATION-394
>                 URL: https://issues.apache.org/jira/browse/CONFIGURATION-394
>             Project: Commons Configuration
>          Issue Type: Improvement
>            Reporter: Java Developer
>         Attachments: BeanDiff.zip, cfggenengine.jar, ConfigFramework.zip, FinalConfigClasses.zip
>
>   Original Estimate: 2016h
>  Remaining Estimate: 2016h
>
> Sorry for English and for such a generic summary:
> If you have ever worked with Weblogic AdminConsole(Weblogic 10.3 in my case) you would find out that it save your changes temporary and finally by clicking "Apply changes" it would save all changes in configurations. If one of the changes is failed then Weblogic would rollback all changes of configurations. Something like database transaction.
> The general idea could be that you create a clone of your entire or some parts of your configuration hierarchy, then change the cloned version, and finally apply back the cloned version on original version of hierarchy. Here when you ask the original configuration hierarchy to accept new changes then the original hierarchy would compute the Diff between itself and cloned version and deliver the changes to all listeners that have registered for configuration changes. If any of listeners are not agree with new changes then all process of applying configuration would be rolled back!
> Here in this scenario you need some facility to be added to Apache Commons Config and also to Apache Commons BeanUtils:
> 1- A BeanDiff class(http://issues.apache.org/jira/browse/BEANUTILS-304) that can compute the difference between two JavaBeans. These JavaBeans are custom classes that programmers write for application configuration (e.g. CacheConfiguration class). These custom configuration classes would use the apache common config classes to to store and retrieve the configuration from any source. It can be extended to have ConfigurationDiff that would represent the changes between two Configuration(shows which properties are altered)
> 2- Cloning entire hierarchy of configuration, I actually do not know whether currently Apache Commons Config support this feature.
> 3- The most important part is adding some method to Configuration interface which enables Configuration interface to accept a whole configuration hierarchy and then apply that hierarchy to itself. The apply process consist of traversing the hierarchy and visiting each node, then computing ConfigurationDiff for each node and then notifying the registered listeners of that node for all updates that node has. If one of listeners reject the update then the process would call rollback method of listeners.
> 4- Some class like ConfigurationUpdateListener(or BeanUpdateListener)  that has some method like :
> public abstract void prepareUpdate(ConfigurationUpdateEvent updateevent)
>         throws ConfigurationUpdateRejectedException;
>     public abstract void activateUpdate(ConfigurationUpdateEvent updateevent)
>         throws ConfigurationUpdateFailedException;
>     public abstract void rollbackUpdate(ConfigurationUpdateEvent updateevent);
> All classes that are interested in configuration changes(batch changes not just one property changes) can implement this class and register themselves in Configuration node in hierarchy.
> ------------------------------
> After some research! in Weblogic classes and jar files you can find the "com.bea.core.descriptor_1.4.0.0.jar" in "BEA_HOME\modules" folder.
> After another research you can find some interesting classes like BeanUpdateListener, BeanUpdateEvent, DescriptorBean, Descriptor inside "weblogic.descriptor" package. And also another interesting class "weblogic.descriptor.internal.BeanDiff" class. Looking at  them is useful!!
> I could not completely understand the model that Weblogic works but that point are what I understood about it.
> I some useful features can be added to Apache Commons Config by looking at weblogic works. It also can ease the process of writing ConfigurationMBeans for applications.

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