Archive for the ‘eclipselink’ Category
Modular development with OSGI about to be very, very popular – finally.
Monday, March 2nd, 2009
Posted in: J2EE, JPA, OSGI, System architecture, eclipselink, java, open source, spring.
It’s quite exciting to see the tremendous progress in development tools, patterns, frameworks and libraries since the release of JAVA 1.0 in 1996.
Within just thirteen years, development improved from the first applets, from the dark ages of the first EJB standardization attempts and a lack of suitable development processes into an age where aspect oriented programming, dependency injection and a freely available range of lightweight yet extremely powerful frameworks, libraries and API’s finally permitted the humble programmer to do what he always wanted to do – analyze problems, and elegantly write them down without spending all of his precious time on the syntax.
I would even go as far as saying that there was no object orientation before programming crosscutting concerns and using dependency injection became established mechanisms.
Think about it: The original goal of OO is not to use inheritance, encapsulation, identity and polymorphism, but to express the real world of things – our reality – using an abstract world of things, while preserving most of the properties and relationships we observe in reality.
Before AOP, before being able to separate the description of things from creating, configurating and connecting concrete instances through dependency injection frameworks, this goal was hard to achieve.
Modules larger than classes with OSGI
Now however, we are about to reach a new stage in development of object orientation in JAVA: Developing modules that are larger than classes, modules which can, once properly identified, be developed independently using all the wonderful technology described beforehand. The technology used to achieve this has a name: OSGI. This technology has quite a long history of development, but a certain lack of elegance and light-weightiness barred this component model from becoming a real hit in the worldwide development community. This is about to change.
Read the rest of “Modular development with OSGI about to be very, very popular – finally.”
Solving the eclipselink (former toplink) issue with HSQLDB
Tuesday, August 12th, 2008
Posted in: J2EE, JPA, eclipselink, java.
When using the great hypersonic java database (hsql) with eclipselink 1.0, i stumbled upon a schema generation (ddl generation) issue. It appears as though eclipselink generates “CREATE TABLE…” statements containing UNIQUE keywords which are incompatible with HSQLDB.
As it turned out, there already is an issue filed for the problem (240618).
The resulting exceptions look like this:
[EL Warning]: 2008.08.12 11:01:13.134--ServerSession(28607378)--Exception [EclipseLink-4002] (Eclipse Persistence Services - 1.0 (Build 1.0 - 20080707)): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLException: Unexpected token: UNIQUE in statement [CREATE TABLE ... (ID INTEGER UNIQUE]
Error Code: -11
Read the rest of “Solving the eclipselink (former toplink) issue with HSQLDB”
