Bandwidth optimizations for standards-based publish/subscribe in disadvantaged grids

NATO has identified Web services as a key enabler for its network enabled capability. Web services facilitate interoperability, easy integration and use of commercial off-the-shelf components, and while request/response-based schemes have hitherto been predominant, publish/subscribe-based services are gaining ground. SOAP-based Web services, however, introduce considerable communication overhead, and optimization must be done to enable use on the tactical level. Data compression is one such optimization, and it works well for large messages. We claim that the inherent characteristics of publish/subscribe-based Web services are such that using difference-based compression will allow effective compression also for small messages. In this paper we present the design and implementation of a proof-of-concept mechanism called ZDiff, which we have tested on several types of military data formats. Together with our SOAP-based proxy system it can be used together with commercial off-the-shelf Web services software. The results show that difference-based compression outperforms traditional compression for small messages, at the same time as it never performs worse than traditional compression for larger messages.