Language-integrated event notification for OSGi services
Sven De Labey, Jeroen Boydens, Eric Steegmans · Lirias · 2009
Abstract:The Open Services Gateway initiative (OSGi) is a platform for service-oriented computing in Java with support for managing service dependencies among installed bundles (i.e. application components). An important aspect of OSGi is event notification. OSGi intro-duces a specialized approach, called the Whiteboard pattern, to integrate event notification in a volatile services environment. But this mechanism strongly deviates from the Java program-ming model because it bypasses important compile-time guarantees. Furthermore, the limited expressiveness of its event constraint language makes it impossible to detect composite events, and it leads to the notification of unsollicited events. In this paper, we propose a domain specific language that allows programmers to de-fine events in a way that maximizes compile-time guarantees on event definitions and on the actions to be taken when these events arise. This extension not only raises the level of abstrac-tion for event publication, but it also supports the detection of composite events. During the transformation of our DSL to Java, all technical interactions are injected, based on information that programmers provide by means of our new language constructs. The resulting application remains compatible with OSGi. 1