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From Craig L Russell <Craig.Russ...@Sun.COM>
Subject Re: greetings and question about data stores
Date Sat, 04 Aug 2007 18:55:57 GMT
Hi Richard,

If you're interested in the non-RDBMS side of JDO, I've had for a  
long time an interest in upgrading the FOStore piece to use a more  
modern key/value store like a modern version of Berkeley DB.

The sticking point for many of the non-RDBMS stores in the public  
domain is the lack of query capability. And much of this is due to  
the lack of schema for the values. In MDR, the key is not-quite- 
opaque. You can see this in the special treatment of keys in the  
FOStore key-generation. We'd have liked to use a simple long as a key  
but MDR doesn't support them. And the value is truly opaque. In  
FOStore we simply "serialize" the objects for storage replacing  
objects with true FOStore object references.

Anyway, if you're interested in upgrading FOStore to use a better  
store than MDR, perhaps we can start a wiki to discuss this.



On Aug 4, 2007, at 10:46 AM, Richard Schilling wrote:

> Looking some more this morning, I also found the source code  
> repository for netbeans b-tree implementation:
> http://mdr.netbeans.org/source/browse/mdr/src/org/netbeans/mdr/ 
> persistence/btreeimpl/?only_with_tag=release60_m4
> And lo and behold, I also found an old CORBA module I didn't know  
> existed.  This is going to get interesting.... :-)
> Richard
> Craig L Russell wrote:
>> Hi Richard,
>> Sorry about that. The FOStore implementation had just a bit of  
>> documentation which I've tried to locate for you but can't seem to  
>> find just now. When I find it I'll post it on the JDO site and put  
>> a link here.
>> Craig
>> On Aug 3, 2007, at 11:07 PM, Richard Schilling wrote:
>>> Here is the posting I had way back in March of 2006, which didn't  
>>> get much response - if any at all:
>>> http://www.webservertalk.com/archive383-2006-3-1437593.html
>>> Never did find out the answers to these questions, but this  
>>> explains what I'm up to.
>>> After just looking, I find this on the netbeans site:
>>> http://mdr.netbeans.org/architecture.html#persistence
>>> This explains MDR, the use of b-tree (which the JDO reference  
>>> implementation uses) in much more detail than I saw in the past.
>>> FYI.
>>> Cheers!
>>> Richard Schilling
>>> Craig L Russell wrote:
>>>> Hi Richard,
>>>> The fostore project at Apache JDO is an implementation that you  
>>>> could study for insights as to how the various components  
>>>> interact. There's a separation of an abstract StoreManager  
>>>> responsible for storing data to a specific datastore, a  
>>>> StateManager responsible for managing the state of individual  
>>>> instances, and a PersistenceManager whose API is pretty much  
>>>> defined in the JDO specification.
>>>> Regards,
>>>> Craig
>>>> On Jul 31, 2007, at 3:23 PM, Richard Schilling wrote:
>>>>> I did realize that the JDO API and the model in the apache code  
>>>>> was just the implementation of the spec.  What I'm after is to  
>>>>> make sure I understand what parts of the API (which interfaces)  
>>>>> are used by a specific implementation to cause classes to be  
>>>>> committed to the data store.  It looks like the transactions  
>>>>> defined in the spec serve this purpose, but there's so much  
>>>>> information I can't be sure.
>>>>> Thanks ... still getting my head around the JDO spec - I've  
>>>>> even read the JDO book which I have.
>>>>> Cheers.
>>>>> Richard
>>>>> Matthew T. Adams wrote:
>>>>>> Hi Richard,
>>>>>> Apache JDO is the home of the JDO API (the interface & class
>>>>>> files of the
>>>>>> specification) & TCK (the code that tests whether a JDO  
>>>>>> implementation is
>>>>>> compliant with the specification); none of the code here  
>>>>>> actually writes to
>>>>>> a database*.  The reference implementation for JDO 2.0 is JPOX
>>>>>> (www.jpox.org) -- it is an implementation of the JDO 2.0 API.   
>>>>>> There are
>>>>>> also many other implementations of JDO out there.
>>>>>> HTH,
>>>>>> Matthew
>>>>>> *:  There is a legacy reference implementation called FOStore  
>>>>>> (pronounced
>>>>>> like "foster") that was used as the JDO 1.0, but I don't think  
>>>>>> that's used
>>>>>> much anymore.  Others can comment on that.
>>>>>> -----Original Message-----
>>>>>> From: Richard Schilling [mailto:rschilling@cognitiongroup.biz]  
>>>>>> Sent: Tuesday, July 31, 2007 10:22 AM
>>>>>> To: jdo-dev@db.apache.org
>>>>>> Subject: greetings and question about data stores
>>>>>> Greetings.  This is my first post to the list.
>>>>>> I would like to know about the code base itself.  There is not  
>>>>>> any documentation that discusses the structure of the code  
>>>>>> itself and how the software interacts with the data store.
>>>>>> Can any one tell me what source code files actually contain  
>>>>>> the code that writes to the data store?
>>>>>> Thanks!
>>>>>> Richard Schilling
>>>> Craig Russell
>>>> Architect, Sun Java Enterprise System http://java.sun.com/ 
>>>> products/jdo
>>>> 408 276-5638 mailto:Craig.Russell@sun.com
>>>> P.S. A good JDO? O, Gasp!
>> Craig Russell
>> Architect, Sun Java Enterprise System http://java.sun.com/products/ 
>> jdo
>> 408 276-5638 mailto:Craig.Russell@sun.com
>> P.S. A good JDO? O, Gasp!

Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:Craig.Russell@sun.com
P.S. A good JDO? O, Gasp!

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