Community News

Users comment on O/R Impedance Mismatch

German Viscuso — Wed, 09 Jul 2008 19:26:00 GMT

ODBMS.ORG, a vendor-independent non-profit group of high-profile software experts lead by Prof. Roberto Zicari, today announced the exclusive publication of a new series of user reports on using technologies for storing and handling persistent objects:

http://www.odbms.org/downloads.html#odbms_ur

11 user reports have been published, from the following users:

Gerd Klevesaat, Siemens
Pieter van Zyl, CSIR
Philippe Roose, Liuppa
William Westlake, SAIC
Stefan Edlich, TFH Berlin
Udayan Banerjee, NIIT
Nishio Shuichi, ATR Labs
John Davies, Iona
Scott Ambler, IBM
Mike Card, Syracuse
Rich Ahrens, Merrill Lynch

Prof. Zicari asked each users a number of equal questions, among them if they had an "impedance mismatch" problem. Each time data models, e.g. relational models, are used to persistently store data and the program language used, e.g. in object-oriented Java, are different, this is referred to as the "impedance mismatch" problem.

Users confirmed in different ways the existence of such a problem.

Enjoy!

Enhanced db4o support in latest DataNucleus Access Platform 1.0 M3

German Viscuso — Sun, 06 Jul 2008 23:24:00 GMT

DataNucleus Access Platform 1.0 M3 is released (see the announcement). The main things affecting usage with db4o are :-

The original JDOQL implementation has been superceded by a new "generic" implementation supporting more of the JDOQL syntax
Support for querying via JPQL is added.

New Performance Contest - help us make db4o ultra fast!

German Viscuso — Fri, 27 Jun 2008 23:03:00 GMT

We invite you to participate in the db4o performance contest which will give away 6000 USD in prizes!

Basically participants will provide patches to the db4o core that impact on performance and then these modifications will be judged by the community to select the winners. In order to make the whole process easier we're providing the following:

Eclipse Workspace Distribution
Paircast: How to get started (this video is included in the above distribution)
Performance Forum (to provide/get help)

Ideas for possible improvements are:

A UTF-8 String encoder
Improvements to the query processor
- Removal of processed index constraints from the processor so they won't run in the SODA processor
- Class index filtering of the index results to be able to ignore the SODA processor run completely if all constraints are processed
- Index processing of ANDs and ORs over field constraints at difference hierarchy levels
Improving the BTree implementation

MRU cache for BTree pages

The Performance Costest has started already and it ends on August 15 2008.

Please hurry and submit your patch! =)

Groovy and db4o

German Viscuso — Sun, 15 Jun 2008 23:40:00 GMT

In this blog post, db4o Netbeans plugin creator Gerd Klevesaat explains how to use db4o under Groovy (through a builder implementation by the author). The post includes links to download the builder and source code examples.

Thanks Gerd!

First steps with Sharpen

German Viscuso — Sat, 14 Jun 2008 19:29:00 GMT

Well, Adriano Verona's blog post title is really "Running Sharpen Tests" but he also did a great job at introducing the first steps for trying Sharpen (db4o's conversion tool that translates Java code to C# code). As you might know the tool (which is used internally to generate the .NET version of db4o) has been released as open source. Give it a try!

DataNucleus Access Platform 1.0 M2 released with support for db4o

German Viscuso — Sun, 01 Jun 2008 01:24:00 GMT

DataNucleus Access Platform 1.0 M2 has just been released with a JDO/JPA API for db4o. Read more here

Main things of interest to db4o users in this release are:

Added support for db4o "embedded server" mode (contrib from Joe Batt)
Zip file of Access Platform specifically for db4o, including bundled db4o-6.1 (GPL)

Enjoy! (thanks Andy =)

db4o videos to watch on-line

German Viscuso — Fri, 30 May 2008 18:50:00 GMT

Hi! I just wanted to point you to the the blip.tv db4o show.

There we're hosting all db4o related videos for you to watch on-line (including our cutting-edge paircasts!). No need to download the video.

Note that you subscribe to this show via iTunes, Miro, Pando, or RSS (thanks to blip.tv the show is also available in the iTunes Store, just do a search for db4o while in iTunes and you'll get access to all our videos!).

Additionally, if you have a db4o related video which is not there we will be glad to put it in the channel (send me a private message).

Also, feel free to sindicate any of the db4o videos in your website or blog (instructions to do this are available here)

Best regards and enjoy =)

"An introduction to LINQ for db4o" by Edwin Vermeer

German Viscuso — Tue, 29 Apr 2008 19:43:00 GMT

Dutch senior web developer Edwin Vermeer just published a demo web application on The Code Project for demonstrating the power of LINQ for db4o.

In order to show the most basic operations the demo solution includes a very simple console application that creates 2 new objects and stores them in a db4o database. Before and after each save operation a list of all available objects is written to the console.

There's is also a website demo in the associated download file. The demo is not meant to be an exhaustive presentation of all the capabilities of LINQ or db4o. Instead, its objective is to show how easy it is to use db4o in an ASP.NET website. (using it in a winforms application is just as easy.) You'll learn how to use LINQ for db4o with some popular .NET databound objects. Every demo belongs to its own .aspx page and can be executed without the need of the other pages.

Thanks Edwin! Enjoy!

http://www.codeproject.com/KB/database/LINQ_for_db4o.aspx

If you would like to make the article more popular, feel free to vote here:
http://www.dzone.com/links/an_introduction_to_linq_for_db4o.html

db4o used in a Scrum tech rally

German Viscuso — Tue, 29 Apr 2008 18:51:00 GMT

At April the 4th, 2008, developers from Xebia Group (a specialist software house devoted to enterprise Java architecture, middleware, portal and integration technology) held another Tech Rally (a whole day of technical training for the whole Xebia's Software Development department).

At Xebia, previous Tech Rallies were about Ruby, Grails, CSS/Javascript/Ajax and Oracle Databases. This time it was about creating the best SCRUM tool ever. Quite a challenge for an 8 hour session!

To start with, he group was divided into smaller groups (of approx. 4 people in size) and could pick the technologies of their liking.

The "Wicket Scrum" team, originally based on Wicket, finally turned into a Groovy/Grails/db4o implementation. They focused mainly on the use of an OO database (db4o, of course =) and used the SpringBuilder form Grails to fire up their Spring config.

"Spring modules provides a module for integrating db4o and Spring, which makes integrating db4o in your project extremely easy."

http://blog.xebia.com/2008/04/22/xebia-scrum-techrally/

db4o User Survey 2008 results and prizes

German Viscuso — Tue, 15 Apr 2008 04:17:00 GMT

Thanks to your participation in the user Survey 2008 we gathered valuable feedback to guide the product roadmap.

The Results

Clearly our users vouch for even greater performance and scalability. And I must say you won't be disappointed in this respect with the upcoming db4o versions!

Given the quality of the answers and specific requests we saw a trend towards more professional db4o users. This means we will keep an eye on providing advanced resources for these users but we won't forget to help beginners get started with db4o.

The documentation was, in general, perceived as very useful by the participants while there was a clear request for more and better documentation. We will do our best to improve our comprehensive reference documentation (and to make it more accessible).

Finally, there was a boost on the percentage of embedded Java users among the participants compared to last year results. That's clearly thanks to the recently released Google Android platform. Way to go (welcome Android)!

In order to get your feedback we have started 3 forum threads on the Product Developer forum:

Please participate and state your wishes and suggestions (also let us know if your use case is an embedded device, packaged software, web, caching, etc).

The Prizes

Each of the first 25 respondents to our survey get a db4o Large Mug. And here's the list of winners:

Angsuman Chakraborty
Allan Morstein
Mauro Della Chiesa
Michael Chean
James Chen
CL Dons
Simon Treloar
Eduardo Andrés Ostertag
David Cracauer
Lester Balmaceda
Patrick Clemins
Juan Gabriel Gutierrez
Paul Bates
Shin, Soo Won
cuneyt terzi
Caidongsheng
ChenYY
Adrian Gonzalez
Brian Breneman
Alexander Stephen Cameron
Marcell Manfrin
Tiago Baptista
Ashley Aitken
Brady Anderson
Davide Angelocola

Also 10 participants get the db4o book "The Definitive Guide to db4o". This is the list:

Juan Carlos Merino Arranz
Brandon Regard
Donald Wright
Alexander Stoddard
Scott Fuelberth
Marcelo Rho
Angelo Bernrdi
Jochen Riedel
Andrea Bioli
Olivier Albiez

And finally, 3 lucky participants won an awesome Samsung Blackjack *unlocked* PDA phone:

Venelin Arnaudov
Grant Slender
Michal Minicki

Each winner will be contacted personally to arrange the details. Congratulations and...

Thanks a lot for your support!

German Viscuso
db4o community manager

UPDATE: See a review of ICOODB here:
http://best-practice-software-engineering.blogspot.com/2008/04/object-database-conference-review.html

Financial management with db4o

German Viscuso — Mon, 14 Apr 2008 18:42:00 GMT

The Loocrum project aims to create a complete, efficient and simple financial management software that helps you to control your personal finances, even if you do not have accounting and financial knowledge. Of course, the underlying persistence engine for the software is db4o.

The project is developed by volunteers and collaborators, people who work for free to make it successful and to find a great solution of finance management for everyone.

Loocrum system functionalities

Create different budget by each user.
Import Banking extract and commercial software files such as Quicken, Money, etc.
Register payments and inbound bills.
Control checks and bank accounts.
Control credit cards.
Integrate bills from diferent kinds of budgets.
Generate statistical graphics.
Generate reports.
Calculate vacation, interests, funding and so on.
Additional module to track shares around the world.
News in real time about financial world.

The development activity of the system can be followed through a roadmap, tickets and discussion groups. All these services are available on the project web site. To view the development status, access the task management system: Trac.

db4o field generation support (community contribution)

German Viscuso — Sat, 05 Apr 2008 14:06:00 GMT

Hi!

I just wanted to point you to a recent contribution by Dario Quintana. The idea is to do an interception before save/update on an object letting a (user provided) generator set a value on a given field.

Download this example and learn how to implement your own generator here.

Thanks Dario!

dUC 2008 (Berlin) synopsis

German Viscuso — Wed, 26 Mar 2008 19:31:00 GMT

The db4o User Conference 2008 held in Berlin just ended and it was a complete success! Before providing a summary of what went on in the conference I would like to thank all the attendees for making this possible (we had dVPs and db4o users from China, Germany, Brazil, Denmark, The Netherlands, South Africa, Chile, USA, Japan, Korea, Switzerland, France and more).

dDC (Developer Conference) and the Roadmap

One of the first activities was to agree on the roadmap for db4o (note that some of our dVPs participated in the process). And here's the list of top priorities:

Fast Collections - Build in Java
Pluggable indexing
Indexed Collections
Collections - Build in .NET
More paralleism in core (FSM)
FITnesse: users submit query code
Convert PolePosition to .NET
NQ Optimized
Decaf
Modularization
Public build systems
Release Sharpen & Decaf GPL
Support Aggregate Queries
Store objects on creation
Improve dRS collection support
Sync with MSFT SQL Server (build) - ADO data objects
Scalability Charts
Transparent clustering (cross db reference)

...among other features. Please note that the roadmap is agile, only a current order of priorities and subject to changes, as new market insight arises, and not bound to any dates.

What do you think? We appreciate your feedback on this!

Pairing and Paircasts

XP is in the heart of db4o, specially when it comes to pairing practices among our developers. Our Paircasts are a natural extesion to XP practices which allow a more effective sharing of knowledge among the team and the db4o community at large by making available recordings of interesting pairing sessions.

In order to let the community know about the internals of pairing sessions within db4o, Carl and Rodrigo offered a live pairing session during the conference where they implemented "delete by query" in less than an hour!

You can download the paircasts from our Paircasts blog or watch them on line at blip.tv

db4o Java IDE plugins

Gerd Klevesaat joined us in Berlin and showed us the Netbeans plugin for db4o in detail. The implementation looks great but Gerd noted that it wasn't requirement driven. So we invite you to tell us: what features would you like to see in your db4o IDE plugin? Gerd plans to add more features such as NativeQuery and SQL query support and he welcomes your feedback!

Object Manager Enterprise (OME) offering

A nice introduction to the latest commercial db4o database exploration and support tool by Tetyana Loskutova. OME provides a rock solid exploration and query tool for Eclipse or Visual Studio seamlessly integrated into db4o's support portal. Go ahead and try OME! (For more info contact sales@db4o.com)

Spring and db4o

A dynamic and right-to-the-point presentation by Chris Beams who shows how db4o can also be useful in a corporate context (e.g. SOA, rapid prototyping). The talk included details about how Spring supports db4o. "Database is no longer the integration layer", nicely put!

JPOX and db4o

Do you want to comply to Java persistence standards and still use db4o? Andy Jefferson introduced JPOX and its support for db4o. Supported standards are JPA, JDO and also there's an initial support for JDOQL. Future plans are support for SODA queries and SQL. You can reach Andy here.

LINQ adapter for db4o

JB Evain showed us how to leverage the current LINQ support on db4o. An elegant implementation to say the least (the low level query mechanism of db4o is used behind the scene (SODA) and the queries fall back transparently to LINQ for Objects when they cannot be optimized). This functionality is already available in the latest version of db4o for .NET.

Eiffel-db4o connector

Presentation of a connector that allows objects to be persisted on db4o under Eiffel for .NET. This is an excellent ongoing work provided by ETH Zurich student Ruihua Jin (supervised by Marco Piccioni). More information is available in our ProjectSpaces.

db4o Web Application

A web application demo by Victor Munzenmayer shows us how to use db4o under a .NET web environment. Web applications with db4o persistence to solve real problems are possible!

The Sovereign platform

A really interesting concept. Klaus Wuestefeld showed us how to get our freedom back while remaining tightly integrated to the Internet. From CPU sharing to a relative security system to app sharing (maybe using persistence with db4o), the Sovereign platform is a must see.

The presentations from the conference are available in our presentations section. If you want to see some photos from the event see this page.

THANK YOU guys!

German Viscuso
db4o community manager

Object-oriented database programming with db4o - Part 2 (by Buu Nguyen)

German Viscuso — Wed, 26 Mar 2008 19:27:00 GMT

Finally, I could manage some time writing up the follow-up post about other interesting features of db4o, specifically about client-server feature and transaction & concurrency support. You can read the article here: http://www.codeproject.com/KB/cs/oop_db4o_part_2.aspx.

This write-up also gives me a chance to learn about some cool new features of db4o 7.2 (currently development version) such as LINQ integration, transparent activation and transparent persistence. These are really big changes from the previous version I tried (6.3). Hope that I can find some time writing about all these features. But don’t wait for me though, just go ahead and try them yourself…

http://www.buunguyen.net/blog/object-oriented-database-programming-with-db4o-part-2.html
Buu Nguyen

Java Object Persistence: State of the Union

German Viscuso — Mon, 24 Mar 2008 19:17:00 GMT

This was a virtual panel organized by the editors of InfoQ.com (Floyd Marinescu) and ODBMS.org (Roberto V. Zicari). They asked a group of leading persistence solution architects their views on the current state of the union in persistence in the Java community. Our Chief Architect, Carl rosenberger was part of the panel.

Full list of panelists:

Mike Keith: JPA 1.0 co-spec lead, architect, Oracle TopLink and Java persistence technologies
Ted Neward: Independent consultant, often blogging on ORM and persistence topics
Carl Rosenberger: lead architect of db4objects, open source embeddable object database
Craig Russell: Spec lead of Java Data Objects (JDO) JSR, architect of entity bean engine in Sun's appservers prior to Glassfish.

Questions:

More info: http://www.infoq.com/articles/java-object-persistence-panel