NeoDatis ODB

NeoDatis ODB

Developer(s)	NeoDatis Team
Stable release	1.9 / May 14, 2009
Development status	Under development
Written in	C#, Java
Operating system	Cross-platform
Platform	Java
Available in	English
Type	Object database
License	LGPL
Website	neodatis.org

NeoDatis ODB is an object database available the GNU Lesser General Public License, hence usable in free or commercial applications. NeoDatis ODB is available both for Java and .NET, the latter being still under development.

Features

• Support for Native Queries (see below).
• NeoDatis is simple and intuitive. Objects can be easily be added to a database, requiring no boilerplate, nor modification to already existing classes.
• ODB Explorer: a graphical tool to browse, query, create, update, and delete objects, as well as import/export the database from and to XML files.

Types of Queries

NativeQuery

To perform a native query, an object implementing a method named match is sent to the database. Such method receives each object of a determined class from the database, and returns a boolean value determining whether each one should be returned as part of the query result or not. Usage of such queries would be for example:^[1]

IQuery query = new SimpleNativeQuery() {
    public boolean match(Player player) {
        return player.getFavoriteSport().getName().toLowerCase().startsWith("volley");
    }
};

Objects<Player> players = odb.getObjects(query);

NeoDatis version 1.9x does not implement the suggested Native query analyser and performance enhancements suggested in the Cook paper,^[2] the likes of which are implemented in a more mature object database like db4o.

Therefore, NeoDatis's NativeQuery and SimpleNativeQuery have reduced performance compared to other types of queries (CriteriaQuery), since every object of a certain class in the database must be instantiated, along with its members. However, they maintain some principles of object-oriented programming (encapsulation and data abstraction), which other types of queries do not.

CriteriaQuery

A CriteriaQuery allow retrieval of objects by queries which compare object attributes. Its syntaxis is somewhat SQL-like. A simple example is:

IQuery query = new CriteriaQuery(Player.class, Where.equal("name", "olivier"));
    Objects<Player> players = odb.getObjects(query);

References

1. http://www.neodatis.org/5m-tutorial#toc7
2. http://www.cs.utexas.edu/users/wcook/papers/NativeQueries/NativeQueries8-23-05.pdf

External links

• neodatis.org

Similar databases

• db4o
• objectdb