The OGC Publish/Subscribe specification in the context of sensor-based applications (Solicited)

The Open Geospatial Consortium Publish/Subscribe Standards Working Group (in short, OGC PubSub SWG) was chartered in 2010 to specify a mechanism to support publish/subscribe requirements across OGC service interfaces and data types (coverage, feature, etc.) Two primary parties characterize the publish/subscribe model: a Publisher, which is publishing information, and a Subscriber, which expresses an interest in all or part of the published information. The Publish/Subscribe model is distinguished from the typical request/response model, where a client makes a request and the server responds with either the requested information or a failure. This provides relatively immediate feedback, but can be insufficient in cases where the client is waiting for a specific event (such as data arrival, server changes, or data updates). Instead, the Publish/Subscribe model is characterized by the ability for a Subscriber to specify an ongoing (persistent) expression of interest in some messages, and by the asynchronous delivery of such messages. Hence, the publish/subscribe model can be useful to reduce the latency between event occurrence and event notification, as it is the Publisher's responsibility to publish a message when the event occurs, rather than relying on clients to anticipate the occurrence. The above suggests that the OGC Publish/Subscribe specification could be successfully applied to sensor-based monitoring. This work elaborates on this technology and its possible applications in this context. The work of the OGC PubSub SWG has resulted in the definition of the Publish/Subscribe Core Interface, which defines an abstract description of the basic mandatory functionality for Publish/Subscribe, along with several optional, extended capabilities. Besides, two extensions have been defined for the underlying binding layer, independent of the Core: a SOAP binding and RESTful binding.