Newsletter :: June 2008

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• A R T I C L E S
• db4o Announces its First Performance Contest - Win $6000 in prizes!
• Create your own db4o Distribution
• Read Committed Isolation and Pushed Updates - Revisited
• To Flush or not to Flush
• Improved Read Performance by Profiling with JProbe
• Highlighted Contributions
• Paircast of the Month
• E V E N T S
• K U D O S    O F    T H E    M O N T H
• L O O K I N G    I N T O    T H E    M I R R O R

db4o 7.4 Development Release is available for immediate download!

A R T I C L E S

db4o Announces its First Performance Contest - Win $6000 in prizes!

• As part of our commitment to improving db4o's performance we're organizing this hands-on contest where community members can contribute and benchmark patches to the db4o core and win out of 6000 USD in cash prizes
• The rules and deadlines are available in the Performance Contest page
• A full set of tools to provide for a smooth start and a "leveled playing field" has been carefully prepared for the contestants (we're providing a "Getting Started" video and a full Eclipse workspace so you can be up and running in no time).
• We encourage you to use the Performance forum for questions related to the contest

Create your own db4o Distribution

• Building a full db4o distribution will allow you to get the same db4o packages as you can get from db4o download center. However, the flexibility of the build project also allows you to get only parts of it, like only java distro, only documentation, only tests etc.
• Now you can learn how to build db4o by yourself. This will allow you to implement enhancements and come up with your custom modifications of the engine.
• The generation of db4o .NET sources is achieved through "Sharpen" which can be used for any application to automate conversion of Java sources to C# - get started using the conversion tool and give us some feedback the Sharpen forum

Read Committed Isolation and Pushed Updates - Revisited

• db4o guarantees that any query will return objects in their most recently committed state - unless they are still in memory on the client (i.e. on the reference cache)
• To help you handle this last scenario we've introduced Commited Callbacks for providing Pushed Updates (i.e. notify a client that objects have been changed via events)
• In this blog we provide code snippets for doing Pushed Updates while using db4o in embedded client-server mode (code is also compatible with the networked C/S mode)

To Flush or not to Flush

• In order to provide consistency a database must flush its data cache frequently (and db4o is no different in this sense)
• db4o used to allow users to disable the flushing via Configuration.flushFileBuffers(false) but we're now discontinuing this configuration switch and providing a brand new NonFlushingIoAdapter which makes the risk of database corruption smaller (as it used to be in db4o 6.1)
• Don't forget that there's always a trade-off between speed and consistency (to disable flushing might lead to a corrupted database file if your system is halted during the commit phase) so use the new IO adapter with care
• This new IO adapter is already available in our latest development version

Improved Read Performance by Profiling with JProbe

• In our latest paircast (a step by step video) you'll learn how to use JProbe to improve performance in your applications
• In this session you'll see how this tool helps db4o developers easily find a way to increase "read" performance by 30%
• If you have any comments about the profiling session or any performance related feedback please don't hesitate to use the Performance forum
• And don't forget that you can test drive JProbe for FREE, see JProbe's on-demand webcast and their weekly Live Demo. You might also want to check the new JProbe white papers

Highlighted Contributions

• func4: func4 allows you to use db4o for authentication through the JAAS spec for Java applications. It has been used for webapps in Tomcat 5 and Jetty 6. Currently it should be considered in beta
• db4oBackup: a community contributed tool to schedule automated backups of a db4o db. Configuration is done through a config.xml file where you specify the source and target directories. More info here (in Spanish)
• DataNucleus: 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)
• Groovy and db4o: 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  

Paircast of the Month

• "How to Build db4o" (on-line version) takes you step-by-step through the process of building db4o yourself

"Paircasts" are video recordings of "live pairing sessions" of db4o core team, designed to provide deep understanding of db4o code and practices. You can download the paircasts or see them on-line and subscribe via different services

E V E N T S

• Wednesday, July 2, 2008 - Munich, Germany
  Join the training course by db4o creator Carl Rosenberger (in German) sponsored by Ralf Westphal and Zoschke. Training will be .NET-centric, covering topics such as db4o based application development, transparent persistence, queries with LINQ, speed optimization and more...

K U D O S    O F    T H E    M O N T H

[db4o] really is a no-brainer to work with. And yet, it’s not a trite system either. Database experts will be interested to know if db4o offers multi-threading, flexible indexing, atomic transactions and other such things. The answer to these is yes; it is high performance and maintains integrity of its data.

David M Williams, 6/11, ITWire  

L O O K I N G    I N T O    T H E    M I R R O R

"db4o Sharpens its Image"
ITWire.com, May 23, 2008

"Rapid Linux apps using object databases"
ITWire.com, June 11, 2008

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With best regards

The db4objects team.

www.db4o.com
newsletter@db4o.com
Phone +1 (650) 577-2340
1900 S Norfolk Street, Suite 350
San Mateo, CA 94403 (USA)