Modular application development, in which a set of loosely coupled modules can be integrated into one large application, has been one of the most successful software development practices. The term “loosely coupled” highlights the fact that the modules are both independent and can communicate with one another. OSGI (the Open Services Gateway Initiative), a dynamic module system for Java, defines one such architecture for modular application development. The SDN controller OpenDaylight (ODL), which we will be discussing in this article, is one such controller (apart from Beacon/Floodlight) that is based on the OSGi architecture. ODL is an open-source collaborative project that focuses on building a multi-vendor, multi-project ecosystem to encourage innovation and an open/transparent approach toward SDN. We need to look at these terms, “open,” “multi-vendor,” “multi-project,” “innovation,” etc., in detail to really appreciate the strengths of ODL.
ODL is managed by the Linux Foundation and boasts broad industry support, with memberships covering over 40 companies, such as Cisco, IBM, NEC, etc. Projects focus on adding specific features to the controller. ODL is often touted as an open-source framework designed to “shape the future of SDN” – mainly because it provides an open platform for developers to contribute, use, and, in fact, even build commercial products. As put nicely by David Meyer of Brocade:
OpenDaylight can do for networking what Linux has done for the computing industry.