REAP: Delta Compression for Publish/Subscribe Web Services in MANETs

NATO has identified Web services as a key enabler for its network enabled capability, as it facilitates the use of commercial off-the-shelf components as well as easy integration and interoperability. Request/response-based Web services are widespread, but publish/subscribe-based services are gaining traction and may be especially well suited for use in mobile ad-hoc networks (MANETs). However, Soap-based Web services of all types introduce considerable communication overhead, and Web services standards for publish/subscribe, such as WS-Notification, add additional overhead. To enable use within the tactical domain and on disadvantaged grids, optimizations must be done. For MANETs on the tactical level this is especially true due to challenges with routing and convergence caused by mobility and topology changes. In this paper we present a novel proof-of-concept protocol called REAP (Reliable and Efficient Ad-hoc network publish/subscribe protocol), which builds on and extends our previous work with delta compression and epidemic publish/subscribe in ad-hoc networks. REAP allows for efficient one-to-many and many-to-many Soap-based communication in MANETs, and by not requiring any underlying routing protocol it circumvents issues associated with routing and convergence. By utilizing REAP, significantly better message compression rates was achieved for all evaluated file formats compared to Zlib in our experiments. Because message reconstruction produces exact copies of the original document, REAP supports Web service security standards based on digital signatures and content hashing, such as WS-Security. Our MANET simulator experiments show that the protocol demonstrates highly efficient data dissemination and resilience to a high degree of mobility.