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From ruchi goel <Ruchi.G...@Sun.COM>
Subject Re: use of jcr mapping for JSR170, in graffito
Date Tue, 29 Aug 2006 06:47:55 GMT
Hi Dan,
   Thanks for detailed response . I  will  try this out  and let you 
know my experiences.  Don't you think that the cms model should be 
directly talking to jcr mapping tool  at least for the services which 
are part of jsr170 (Workflow is exception).

Another question : Is workflow implemented as a service ? I don't see 
anything in the source tree ?

Thanks,
Ruchi

Dan Connelly wrote:

>  Hi Ruchi:
>
> I am also a newcomer to Graffito (and a refugee from Eclipse Apogee).
>
> What I did  to get started with jcr mapping is to Check Out the 
> jcr-mapping code (under jcr folder) as a project in Eclipse.   With 
> Eclispe SVN Repository perspective, the project creation is automatic 
> on the Check Out..   A no-brainer.    (Note:  mapping itself does not 
> require anything else from Graffito.)
>
> Then you will try to run the JUnit tests (in Eclipse) from your jcr 
> mapping project.    The tests are in the download.
>
> You will need to fetch a bunch of libraries to get rid of the initial 
> errors in this testing.   An easy way to get these libraries (most of 
> them anyway) is to import the Jackrabbit server war (as an Eclipse 
> Dynamic Web project) and ref its jars from your mapping project.
>
> You do NOT need the graffito api at all.    The Graffito jcr mapping 
> uses Jackrabbit directly (as far as I can tell).
>
> ---------------------------
> 2 hints:
>
> 1) A small change is needed in custom_nodetypes.xml in the test 
> config.  Move  graffito:documentstream ahead of  graffito:documentimpl 
> in this file.
>
> 2)  Get the Jackrabbit core source and put this in a third Eclipse 
> project.    Reference this project from your jcr mapping project.   
> This is not a requirement but it will make Eclipse's debug traces a 
> lot easier to follow.
>
> -----------------------------
> 3 observations:
>
> 1)  The object mapping itself is a pretty simple affair, maybe too 
> simple. (Jury is still out on this.)  You must create the mapping by 
> hand, but this is much easier than for Hibernate or JPOX mappings.   
> However, the Graffito documentation is somewhat behind its code.    
> For instance, you need to read the comments in the mapping DTD and 
> look at the code to figure out inheritance mapping.   Also, it appears 
> that for non-containment references, you need to program these 
> references as JCR Paths.   Simple object constraints (like no dangling 
> references), may be missing from Graffito.    JCR versioning may 
> mitigate (or exacerbate?) the dangling ref problem.   This is still a 
> mystery for me.
>
> 2)  Jackrabbit transaction locking is still new territory for me 
> too.   However, with or without transactions, any object updates are 
> "very" slow.   Concurrency, too, may be limited if big chunks of 
> content get locked during a transaction.    If you want frequent, 
> transactional updates on objects and you want high concurrency (like 
> optimistic locking), it may be that you need to stick with Hibernate 
> over a RDBMS.  On the other hand, if your applications are mainly 
> read-only (like a business reporting tool) then jcr mapping may 
> provide much better access control than you would get using 
> Hibernate.   (Jury is still out here, too.)
>
> 3.  Multiple inheritance is a valid association of objects in a model 
> (though Java does not support it well).      Ideally jcr mapping 
> should deal with such a model.    It does not appear to so at this 
> time.    With mixin types available in JCR, I had hoped for more.    
> ("Mixin" being C++ slang for multiple inheritance.)
>
>    -- Dan Connelly
>
>
>
> ruchi goel wrote:
>
>> Hi,
>>   I am a  newcommer  to graffito area and  am in process of 
>> evaluating graffito for integration with our portal server.
>>
>> I am mainly interested in knowing the navigation  as to how graffito 
>> stores its java objects in JSR170 compliant repository. I understand 
>> that graffito uses Jackrabbit. I have gone through the documentation 
>> on graffito's web site and my understanding is that graffito is 
>> mapping a java object to a jcr node (via mapping's file) , and then 
>> use JSR170 on the node to talk to Jackrabbbit repository.
>>
>> I have downloaded the latest bits  , build, installed and deployed on 
>> jetspeed. I use debugger to check the flow , but I am finding  that  
>> it uses GraffitoOJBStore .
>>
>> *Is the jcr mapping layer not being used in the current code to talk 
>> to JSR170 repository. ?*
>>
>> Though I see the code in place in the source tree : packages 
>> org.apache.portals.graffito.jcr
>>
>>
>> Help appreciated.
>>
>> Thanks,
>> Ruchi
>>
>


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