Java News from Monday, December 4, 2006

The Apache Jakarta Project has released Commons Discovery 0.4, an open source class library that

The Discovery component is about discovering, or finding, implementations for pluggable interfaces. It provides facilities for instantiating classes in general, and for lifecycle management of singleton (factory) classes.

Fundamentally, Discovery locates classes that implement a given Java interface. The discovery pattern, though not necessarily this package, is used in many projects including JAXP (SaxParserFactory and others) and commons-logging (LogFactory). By extracting this pattern, other projects can (re)use it and take advantage of improvements to the pattern as Discovery evolves.

Discovery improves over previous implementations by establishing facilities for working within managed environments. These allow configuration and property overrides without appealing to the global System properties (which are scoped across an entire JVM).

According to Henri Yandell, "Discovery 0.4 is a long overdue release (0.3 failed at the last hurdle to actually be released). Discovery is not an actively developed component, so this release is chiefly to mark a stable point that the users of discovery can depend on. "