What is it?
According to IBM, the IT industry is moving towards a mixed model, with commercial tools built on top of open source frameworks. Sun Microsystems seems to agree. Both supply the same small-footprint, pure-Java, open source database.
Sun calls it Java DB and ships it with the Java Enterprise System and Solaris Enterprise System. IBM calls it Cloudscape and has added a driver for the DB2 Universal Database. It is also shipped with the Websphere application server.
Cloudscape and Java DB are full implementations of the Apache Software Foundation's Derby project. Like Derby, they can run on any system with a Java Virtual Machine, enabling developers to "write once, deploy anywhere", but both include add-ons to draw the user gently from the open source to the proprietary environment.
Where did it originate?
Cloudscape Inc was founded in 1996 to develop a Java database. In 1999 it was acquired by Informix, which was taken over by IBM in 2001. IBM developed Cloudscape as an embedded Java database, before handing it over to the Apache Software Foundation in 2004. Sun began supplying Java DB in 2006.
What's it for?
Despite its small size (about 2Mbytes), Derby/Cloudscape/Java DB has standard relational database functions, such as multi-user support, indexes, triggers, transactions and failure recovery.
It can be used as an embedded database or in client applications, being particularly suited to laptops and PDAs, where a small, robust database is needed. It is also suitable for rapid Java application development and testing. But it scales to hundreds of users, and IBM offers easy migration to DB2.
Cloudscape/Derby is also used to provide SQL functionality within applications developed under the IBM-backed Eclipse initiative.
Sun uses Java DB as an embedded application and developer platform in Java Enterprise System 4.0. It is supported by Netbeans 5.0 and Java Studio Enterprise.
What makes it special?
IBM says, "Cloudscape's simplified deployment and robust self-management features eliminate the need for a database administrator." This, along with its small size, means it can be distributed within browser-based applications that need a local data store. Implemented as a Java JAR file, Cloudscape/Derby becomes part of the application that is running it, although it is hidden from the user.
How difficult is it to master?
Straightforward for Java developers who are comfortable with SQL.
Where is it used?
In independent software suppliers that want to sell to both large and small users without having multiple databases. The same applications can be supplied with either Cloudscape or DB2, without porting. It is also used in applications requiring long-term persistence or short-term caching, such as UDDI registries and shopping carts.
What systems does it run on?
AIX, Linux, OS/400, Sun Unix, Windows, z/OS.
What's coming up?
The future of Derby will be covered at ApacheCon Europe 2007, which takes place in Amsterdam in May.
Rates of pay
Websphere developers with Cloudscape and other Java skills can earn £35,000 or more.