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From Craig L Russell <Craig.Russ...@Sun.COM>
Subject Re: greetings and question about data stores
Date Sun, 05 Aug 2007 02:05:36 GMT
Sounds like there's room here for a good discussion, since JDO is the  
only standard datastore-agnostic API that might exploit something  
like MUMPS.

I'll set up a wiki where we can continue the dialog.

Craig

On Aug 4, 2007, at 6:33 PM, Richard Schilling wrote:

> 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!
>

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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