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From Richard Schilling <rschill...@cognitiongroup.biz>
Subject Re: greetings and question about data stores
Date Sun, 05 Aug 2007 01:33:49 GMT
I think an upgrade for FOStore is definitely feasible, but it should be 
redesigned.  There's no reason I can think of why a robust b-tree type 
implementation could not be managed.  The Berkeley DB sets are O.K., but 
they typically work well for small data sets.  Where we have large data 
sets, performance I think is pretty degraded.

Having said that, I think there's a lot to be learned from an old, but 
very quick and very robust MUMPS data store.  It's underlying structure 
is essentially a b-tree, and works very well.  We could take a similar 
design approach.

Richard Schilling

Craig L Russell wrote:
> 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.
> Best,
> Craig
> 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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