On 2/17/10 9:44 AM, Gabriel Brunstein wrote:
I didn´t know the advantages and disadvantages of Gemstone over Magma,
I've found http://gemstonesoup.wordpress.com/2009/03/09/why-glass/
with this comment:
"Denis, the most obvious difference is that magma is used from a
smalltalk image (squeak, pharo,…) as a database add-on. Gemstone _is_
the database and the image you run.
In gemstone even the system classes are in the image that are
persistent. Some parts of gemstone oodb are built in a native
language. They are optimized in more traditional way for the speed of
objects acquiry. Magma is done in pure smalltalk and should therefor
be really flexible in what you can do with it.
From the programming side they aren’t that different. You build your
object graph in both and you need to attach this graph somewhere that
it doesn’t get garbage collected. In Magma you have one database root
where you attach your stuff. In Gemstone you can attach things just
everywhere because everything is part of the persistent things.
I don’t know both that well. But Magma you can download and there you
go. It is just a piece of software you load and you have a OO
persistence layer. This is very good for deploying along with an
image. I never tested to use magma as a server. Lately magma came up
with some cool features like distributed databases, offline objects
and high availability. I like to do some stuff with it.
On the other hand gemstone you must deploy in more server like
environment. It eats a certain amount of your memory. But you get a
server that performs really well, has proven scalability, cares more
about security and user based data separation. It is something fast
and solid for me. With the remote debugging features it is the ideal
database for my purposes so that were the reasons to choose it.
I hope this helps you little bit in understanding. Magma and gemstone
are in principal the same: they are OODBS. But for me the usage
scenarios are completely different."
what do you think about it? maybe you can include something of that.
I'm using Magma on a project where there is a central server running
Seaside & Magma that is the "master" application. There are also a few
users who have a one-click Seaside & Magma image running on their local
machines that launches Mozilla Prism to the local Seaside using OSProcess.
I'm using Magma to maintain a local read-only copy of the master that
can catch itself up when online. I'm also using Gjaller-like
transactions that are generated against the domain model, and later sent
to the master server to be "applied" when the user comes online again.
I considered using Gemstone, but the problem with Gemstone for this
particular case is its "server-ness". It runs a few different processes
that all do different things (the DB, the memory caches, VMs, etc.). So
in my situation I couldn't have a nice "one-click" setup that could be
deployed on client machines that could also handle being disconnected
from the "master" database.
2010/2/17 laurent laffont <[email protected]
<mailto:[email protected]>>
Really great informations :
Scenario’s
In different situations, there are different storage needs
1. You are writing a small demonstration program to show your
customers, and want to populate the system with some
representative data. Add a class instance variable to store
the instances, and simply save the image.
2. You have a small system with a few hundred/thousand objects,
and are not dependent on external systems. A prevayler-like
system like SandstoneDB might be a perfect fit. Each object
save means a disk access, so scaling ends with disk speed. A
few old versions of the data are kept around, so backing up
or reverting is easy. If you want a readable representation,
SIXX might help.
3. You have a legacy (relational) database, with extensive
reporting written for it. Use an ORM.
4. You have a complex and large object model that has to
support changing the object model while developing. The
solution is an OODB. Gemstone is the large and proven
commercial offering. It has a free version for smaller
databases (4GB data, 1 core, 1G ram), and has proven
scalability to 500 machines. Magma is an open source OODB,
seeing active development and growing more and more advanced
functionality.
Laurent Laffont
On Wed, Feb 17, 2010 at 3:07 PM, laurent laffont
<[email protected] <mailto:[email protected]>> wrote:
No :) Thanks for the link !
Laurent Laffont
On Wed, Feb 17, 2010 at 2:23 PM, Stephan Eggermont
<[email protected] <mailto:[email protected]>> wrote:
Hello Laurent,
I assume you are aware of:
http://www.seaside.st/documentation/persistence
Stephan
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