Object Database (ODBMS) for Python
Paul D. Fernhout
pdfernhout at kurtz-fernhout.com
Mon Sep 1 16:36:32 EDT 2003
Niki-
Thanks for the pointer to e4graph. I found more info about it here:
http://www.marshallbrain.com/robotic-freedom.htm
There are several similarities -- and conceptually the ideas are very
related (to the same extent the ER model is related to graphs).
A few comments on part of their blurb on that page:
"The e4Graph library allows you to model any kind of relationship
between data that can be represented by a directed graph, including
circular graphs of connections between data items. e4Graph is unique in
that it allows these circular relationships to be represented directly
rather than implicitly or through meta-data, as is necessitated by other
approaches such as relational databases. A bi-directional link between
two data items can be represented by two directed connections between
those data items."
The Pointrel Data Repository System allows circular relationships. All
links in the Pointrel System are bi-directional (well, sort of quad
directional in a way).
Differences include:
* The Pointrel System is in pure Python (e4graph is in C++ and uses a
C++ database).
* The Pointrel System suports the notion of "spaces" which could be seen
as somewhat like "graphs" -- except query operations can span spaces (or
even multiple archives for that matter).
* The Pointrel System focuses more on complete history (e.g. tracking
many versions of a linked node as it were in the e4graph metaphor).
These comments are all off the top of my head after persuing the e4graph
site for a few minutes; perhaps after looking more at e4graph I may
realize some of these comments are incorrect or there may other
important differences or similarities.
Thanks again for pointing e4graph out.
In general, the Pointrel System bears a resemblance to any system that
implements something related to Peter Chen's "Entity Relational" (ER)
model.
http://bit.csc.lsu.edu/~chen/display.html
http://www.cs.sfu.ca/CC/354/zaiane/material/notes/Chapter2/node1.html
The Pointrel System is not quite the same as pure ER in some
implementation details (e.g. it embeds the notion of a space, it focuses
on triads not arbitrary relationships, the newer version doesn't have
relations as first class objects, it doesn't seperate attributes from
relations, etc.), but otherwise has many of the same features.
--Paul Fernhout
http://www.pointrel.org
Niki Spahiev wrote:
> 8/29/2003, 19:11:51, Paul D. Fernhout wrote:
>
> [...]
> PDF> Well, to chime in here, in a "friendly" competition / cooperation sort
> PDF> of way, the Pointrel Data Repository System,
> PDF> http://sourceforge.net/projects/pointrel/
> PDF> while not quite an object database (and admittedly its case being
> PDF> easier) has a simple API in the bare minimum use case (it has more
> PDF> complex variants). Here is an example of its use (with fragments
> PDF> inspired in response to an earlier c.l.p poster's use case a few days ago):
>
> How it compares with e4graph?
>
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