The ASF is made up of nearly 150 top level projects which cover a wide range of technologies. Chances are if you are looking for a rewarding experience in Open Source, you are going to find it here.
Apache Airavata is a distributed system software framework to manage simple to composite applications with complex execution and workflow patterns on diverse computational resources.
Apache Airavata is a micro-service architecture based software framework for executing and managing computational jobs and workflows on distributed computing resources including local clusters, supercomputers, national grids, academic and commercial clouds. Airavata is dominantly used to build Web-based science gateways and assist to compose, manage, execute, and monitor large scale applications (wrapped as Web services) and workflows composed of these services.
Jelly is a Java and XML based scripting engine. Jelly combines the best ideas from JSTL, Velocity, DVSL, Ant and Cocoon all together in a simple yet powerful scripting engine.
OSGi framework implementation in C.
Celix is an implementation of the OSGi specification adapted to C. It will follow the API as close as possible, but since the OSGi specification is written primarily for Java, there will be differences (Java is OO, C is procedural). An important aspect of the implementation is interoperability between Java and C. This interoperability is achieved by porting and implementing the Remote Services specification in Celix.