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:[EMAIL PROTECTED]
Sent: Tuesday, July 31, 2007 10:22 AM
To: [email protected]
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:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!
Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!
Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!
