Tuesday, April 28, 2009


I recently wrote some utility code which we'll be using to process bundle manifests, typically to map header names to typed values. It was surprising that this code was neither available elsewhere nor completely trivial to implement.

So what was it? A map with String keys which is insensitive to the case of the keys and which preserves the case of the keys. Apache Commons has a CaseInsensitiveMap which whacks the keys to lower case on input. I was tempted to use that code, but in our environment, it's important to preserve the case of keys.

For example, the bundlor tool will eventually use this code to create bundle manifests from templates. If the user carefully spells headers in the template with mixed case, e.g. "Export-Package", they would probably be disappointed to see the headers converted to lower case in the generated manifest.

Implementing an (Apache licensed) case-preserving CaseInsensitiveMap was an interesting exercise. I saved some time by extending AbstractMap and AbstractSet (for the key and entry sets). I used an instance of ConcurrentHashMap to maintain the state. I exposed one internal type to be package visible so I could get 100% unit test coverage and made some inner classes static to stop findbugs complaining.

Why blog about this? Simply to increase your chances of finding the class if you need it.

Thursday, April 09, 2009

SpringSource dm Server 2.0 M1

As in Rob's blog, we recently shipped the first milestone of dm Server v2.0. Apart from some new function, this marks an opening up of the dm Server development process with publicly accessible subversion repositories and issue tracker.

The 2.0 roadmap is pretty exciting, and includes constructing a Reference Implementation for RFC 66 ("web container for OSGi") from the existing web components of dm Server.

I'm spending most of my time down in the dm Kernel implementing "cloning" which, roughly speaking, enables a bundle to be wired more than one way, which is not normally possible in OSGi. Cloning copies bundles into an application's scope. This enables the OSGi resolver to have another go at wiring the dependencies of the cloned bundles in a way which suits the application. More information on cloning is included in the above blog entries.

Application scopes can be thought of as an alternative to "nested" OSGi frameworks, which are being specified in the OSGi Alliance and implemented in Equinox. The contents of an application scope can "see" all the contents of the global scope which are not "shadowed" in the application scope. The contents of a nested framework can, by default, not see any of the content of the parent framework(s) unless the nested framework is explicitly defined to see some of the parents' contents.

Much of what we're learning about cloning into application scopes, such as how to calculate what needs cloning and how to manage cloned extenders, will also apply to cloning into nested frameworks if and when that becomes necessary.

Wednesday, April 08, 2009

Is JDK 7 Java?

I wonder if the JCP rules allow JDK 7 to be called "Java"? Sun appears to think so since the JDK 7 page is entitled "jdk7: Java SE 7". Apache Harmony meanwhile will presumably avoid calling itself "Java" until it can obtain and pass the JCK. Does this make Harmony the true guardian of Java? ;-)


OSGi (130) Virgo (59) Eclipse (10) Equinox (9) dm Server (8) Felix (4) WebSphere (3) Aries (2) GlassFish (2) JBoss (1) Newton (1) WebLogic (1)