Interoperability for a limited class of web-based modeling and simulation (M&S) applications has traditionally been achieved through web services. However, this transactional, request/response approach is not well-suited to more interactive applications which require continuous, bi-directional updates of a large number of simulated objects.

In recent years, several new technologies and standards have been developed in the broad web community that enable highly-interactive, low-latency, and real-time web-based applications written in JavaScript. These technologies include HTML5, WebGL, WebSockets, and a variety of JavaScript rendering engines and mapping tools. Based on these technologies, it is now possible to develop web-based 2D tactical maps, 3D viewers, remote simulation managers, instructor operator stations, and even web-based flight simulators and first-person gaming applications.

However, to date there has not been a standard interoperability protocol for linking these new web-applications with each other and with traditional M&S federations in a way that is: a) high-performance enough for the needs of these applications; b) natural to use in a JavaScript environment; and c) flexible enough to support interoperability regardless of the protocol being used in the target federation, e.g., DIS (Distributed Interactive Simulation), HLA (High Level Architecture) 1.3, HLA 1516, HLA Evolved, TENA (Test and Training Enabling Architecture), etc.

This paper provides an introduction and technical overview of the WebLVC protocol - a mechanism for encoding simulation data in the JSON (JavaScript Object Notation) format, and passing the resulting messages between web-based client applications and servers over WebSockets. The WebLVC protocol is being evaluated by the WebLVC Study Group within SISO to determine its suitability as the basis for a SISO Standard. We will provide an update on the activities of the Study Group, and compare the approach to previous efforts such as HLA's WSDL (Web Service Definition Language) interface.