Community News

db4o goes GPLv3

German Viscuso — Wed, 04 Nov 2009 23:43:00 GMT

Yes, we're reinforcing our commitment to the open source community and upgrading our GPL license in an effort to stay compatible with the increasing number of GPLv3 adopters. The GPL v3 license will make it easy and safe for free software developers to use db4o with the most recent license framework from the Free Software Foundation.

With more than 50% adoption GPLv3 covers new ground for the benefit of free software, with additions such as new provisions that prevent digital rights management (DRM) usage with GPLv3 licensed code, new internationalization terms (making the license more compatible globally), compatibility with the Apache 2.0 license, new terms for termination in the event of license violation and patent protections (among others).

Even though support will continue for the older license version GPLv2, we hope this move will inspire free software projects to go with GPL v3 when using db4o!

(Official announcement available here)

New to db4o? Learn & Have Fun!

German Viscuso — Wed, 21 Oct 2009 08:22:00 GMT

I just wanted to point you to a series of funny (comic style) db4o blog posts by gamlerhart which make a great way to get you started with db4o (why not having some fun while you're learning?). I think the blog posts also deal with key issues that you must have in mind if you're new to db4o (activation, object identity, etc).

So, learn and have fun!

(Thanks a lot gamlerhart!! =)

Show us what you're doing with db4o and be rewarded!

German Viscuso — Tue, 06 Oct 2009 23:23:00 GMT

We Invite You to Take Part in db4o "Cash for Cases" Program

We're always looking for new and interesting case studies of applications that took a leap forward thanks to the db4o technology.
But now you have the chance to be rewarded for your submission!
Full details for the 'Cash for Cases' program are available here:

http://developer.db4o.com/Resources/view.aspx/Community_Programs/CashForCases_Program

Note: we also accept confidential case studies which will only be used for our internal decision process

Best regards and keep them coming!

Be part of the db4o Core team!

German Viscuso — Tue, 06 Oct 2009 23:11:00 GMT

We're looking for a knowledgeable and passionate developer who would feel right at home as part of an agile team. You'll be working in the internals of a cutting edge technology with a focus on design, development and maintainance of db4o. For more details please check this post.
What are you waiting for?! =)

Repository pattern and db4o (C#)

German Viscuso — Tue, 08 Sep 2009 01:23:00 GMT

I just came across Elliott O'Hara's blog post about db4o. If you're a C# developer an you wrote at least one application where you use a repository pattern for making your domain objects persistent this might interest you. Elliot uses a Generic Repository interface and then provides a subclass Db4oRepository. Nice blog to remind us about db4o's simplcity! (source code included)

db4o based "MapMe" Now Available in the Android Market

German Viscuso — Wed, 22 Jul 2009 12:17:00 GMT

MapMe basically mimics Google Maps functionality but adds storage of location bookmarks/navpoints (including local search capabilities) via db4o.

This is a demo to show you how db4o can provide local persistence in a straight forward fully object oriented way for your Android applications.

Why db4o is cooler than SQLite? As you provide upgrades to your app you'll notice that db4o evolves the schema transparently: your users will still be able to see and edit previously stored locations even after you enhance your domain objects in new app versions.

Enter transparent upgrades for Android apps!!! =D

For more information check the MapMe Google Code site or search for the keyword "MapMe" in the Android Market or scan this QR Code with your Android device:

mdRS = mobile db4o Replication System on Google Android to any RDBMS!

German Viscuso — Tue, 21 Jul 2009 17:09:00 GMT

So you want to have a full-fledged low-footprint database on your mobile phone while being able to replicate this data (even bidirectionally) to any relational database (Oracle, MS-SQL, MySQL, PostgreSQL, DB2, etc.) or db4o? Your wait is over!

You won't believe how easy it is to set up a full fledged mobile to RDBMS replication with a cooler database on the mobile device than SQLite.

In the authors' own words: "We believe that db4o is the simplest and most powerful solution. What alternatives are out there? First of all you need a mobile phone that is able to run a database. If you choose Android you could use SQLite, send the data with any protocol (REST, SOAP?) to a server and store it in your relational database. Nevertheless we think db4o is far easier to develop while using OO languages as C# or Java, it has lots of features that SQLLite doesn't offer and the way to deal with the database is very easy"

Check the mdRS project page for more info and source code. Thanks Stefan & Roman!

New db4o demo for ADO.NET Data Services (aka Astoria)

German Viscuso — Thu, 18 Jun 2009 05:31:00 GMT

The purpose of this demo is tho show you how the .NET version of db4o can fully act as a datasource via the ADO.NET Data Services framework. This is achieved by using db4o's LINQ provider while supporting the interfaces IQueryable and IUpdatable required by Astoria to operate on the database. IQueryable allows db4o to expose entities to the Data Services framework while IUpdatable allow CRUD operations over the datastore.

ADO.NET Data Services (codename "Astoria") is a combination of the runtime and a web service for .NET which exposes data over HTTP. The data can be addressed using a REST-like URI. The Astoria service will return data when accessed via the HTTP GET method with such a URI. Updates are performed using other HTTP methods like PUT, POST or DELETE. POST can be used to create new entities, PUT for updating an entity and DELETE for deleting an entity.

If you need a universal access point to your data as a REST resource that can be easily consumed via HTTP by different kinds of clients this could be your solution. Note that right out of the box you get full browsing capability over the datastore, paging, filters, cross-linking, CRUD operations, etc just by using the HTTP protocol.

The demo is available here. Enjoy!!

ODBMS.ORG Awards for the most valuable Common Persistent Model Patterns: Public voting is open

German Viscuso — Fri, 29 May 2009 23:28:00 GMT

ODBMS.ORG, a vendor-independent non-profit group of high-profile software experts lead by Prof. Roberto V. Zicari, today announced that the Public Voting for choosing the most valuable Persistent Model Patterns among the submissions received by May 29, 2009 to ODBMS.ORG, is now open till June 20, 2009.

25 patterns comprise the set of submissions:

Matthew Barker, Director of System Engineering, Versant Corp.
Pattern: Large Persistent Collection.

Robert Greene , Vice President, Versant Corp.
Pattern: Persistent Versioned Graph Pattern.

Lenny Hoffman, Todd Stavish, Dr Nic Caine, Brian Clark. Objectivity, Inc.
Pattern: Dynamic Schemas in object database management systems (ODBMS)

Derek Laufenberg, Versant Corp.
Patterns: Back-Pointer Managed Collection.
Split Class Pattern.

Richard Lingeh, Principal Consultant, Versant
Pattern: Schema Builder

Adrian Marriott , Principal Consultant, Progress Software Inc.
Patterns: Bespoke Indexes, Compress Persistent Data, Database Manager, Evolver, Frame, Head/Body, OO Anti-Patterns, Persistent Mutex, Persistent Queue, Persistent Singleton, Query Visitor, Small Object Pool Allocator, String Table, Transaction Memento.

Eugenia Stathopoulou, Panos Vassiliadis
Patterns: Querying, Schema Modifications, Storage, Updates,

Takenori Sato
Pattern: Probabilistic Graph Model

All persistent patterns submitted are available for free download.

To vote, visit the ODBMS.ORG Public Vote site.

Public Voting takes place between June 1- 20, 2009.

The ODBMS.ORG Awards for the 3 patterns which will receive the highest votes, will be announced on June 25, 2009 at ODBMS.ORG. The Awards ceremony will take place on July 2, 2009, at the ICOODB 2009 conference in Zurich.

Second "Getting Started with db4o" Video (Java)

German Viscuso — Wed, 20 May 2009 23:42:00 GMT

It now the turn of the Java community! After the successful release of the .NET "Getting Started with db4o" video we decided to make the Java version.

This time, db4o expert Eric Falsken introduces us to db4o in a quickstart demo using Eclipse, Java and the free Object Manager Enterprise (OME) tool to browse and query the database in the example.

Note how OME becomes essential for your debugging sessions. And don't forget that it's now free!! =)
(Hint: there's no separate download of OME since it comes with the db4o download bundle, look for the "ome" directory).
For more information see the OME entry in db4o's reference documentation.

You might also want to check all previous videos (including paircasts) which are part of the official db4o video show on blip.tv

Enjoy!

Dynamic SODA

German Viscuso — Wed, 20 May 2009 18:53:00 GMT

Tino Duong just kindly contributed his "dynamic SODA" implementation. In Tino's own words:

"This project aims to provide an instrument that allows developers to dynamically create db4o query strings that can be executed without having to write and compile java code. To achieve this, the SODA querying method was extended upon, and a simple and intuitive syntax was created -- referred to as the Dynamic SODA Language or dSL. Using this syntax and the Dynamic SODA Language interpreter, a developer can quickly write and execute queries in a similar fashion to the standard SQL string.

An example dSL query is listed below.

This query string contains the necessary syntax to retrieve an object of type 'Person' who has the name 'Frank' and the age '30'. "

Take a look at the examples and source code available in the Dynamic SODA project page.

Thanks Tino for this valuable contribution (which will surely be useful to people that want to build SODA queries on the fly during runtime).

Id Generation for db4o

German Viscuso — Tue, 19 May 2009 15:47:00 GMT

I'm glad to announce dVP Tuna Toksoz just implemented an explicit POID facility for db4o (that doesn't rely on db4o's internal object id system or universal unique ids (UUIDs) used with the db4o Replication System (dRS)). Tuna managed to use the db4o callback facility as an extensibility point to hook this new external ID system so no change to db4o's core source code was necessary. The inspiration came from NHibernate POID Generators and the HiLo algorithm.

The current way of working with it looks like this:

var serverContainer = this.server.Ext().ObjectContainer();
serverContainer.IdMap(
    Map<Person>.On(x => x.Id).SetGenerator(

         new HiLoGenerator(3, typeof(Person),serverContainer)));
var person = new Person();
container.Store(person);

Full source code is available here.

Thanks Tuna for this valuable contribution to the db4o community (and also thanks to dVP Dario Quintana for also experimenting with ids on db4o).

Scala + db4o = Simplicity

German Viscuso — Mon, 18 May 2009 15:46:00 GMT

Coding with Scala? How about both getting rid of ORM and reducing your query and query result iterator to something like this?

val result = db query { person: Person => person.name.contains("t") }
for(person <- result) println(person.name)

Software developer Matthew Todd explains in this recent blog post how to code less when dealing with persistence on Scala thanks to both Scala extensibility and db4o simplicity.

"I have plenty of experience with various object relational mapping frameworks, but wanted to try an alternative framework, one which should result in clean code, with no need to have the performance hit, and configuration complexity often associated with ORM.
[...]
I think the simplicity of the API that db4o provides is certainly a good match with Scala and if the query optimisation issue can be solved, then one that is worth looking at further."

Thanks Mat! =)

A Q&A with db4o Refcard Co-Author Eric Falsken

German Viscuso — Fri, 15 May 2009 14:33:00 GMT

In coordination with the recently published db4o .NET Refcard, the guys at DZone had a chat with co-author Eric Falsken, who never hesitates to assume the role of technical evangelist on our team. A staunch supporter of Microsoft .NET, Eric enjoys coming up with new ideas for elegantly usable software, and mentoring fellow students of software.

Check the Q&A here. And if you like what you read please vote for it on DZone and/or kick it via DotNetKicks.

db4o for .NET Refcard Released

German Viscuso — Mon, 11 May 2009 13:27:00 GMT

Have you been searching for a quick reference that gets you quickly up and running in your db4o based .NET apps?

Well search no more! The db4o Refcard "Getting Started with db4o: Persisting .NET Object Data" (by Stefan Edlich and Eric Falsken) has now been released through the DZone Refcardz site and includes:

About db4o and Object Databases
Getting Started
Basic Database Operations
Queries (including the basics of LINQ queries)
Dealing with Object Activation
Hot tips and more…

So go ahead and download the db4o Refcard here and please send your comments and feedback to refcardz@dzone.com and community@db4o.com.

Important note: if you like this refcard, would like to see a Java version for it and want to help us spread the word please vote for it on DZone and/or kick it via DotNetKicks..

Enjoy!