Real-Time Monitoring using AJAX and WebSockets

Asynchronous JavaScript and XML (AJAX) is the primary method for enabling asynchronous communication over the Web. Although AJAX is providing warranted real-time capabilities to the Web, it requires unconventional programming methods at the expense of extensive resource usage. WebSockets, which is an emerging protocol, has the potential to address many challenges with implementing asynchronous communication over the Web. However, there has been no independent study that quantitatively compares AJAX and WebSockets.This paper therefore provides two contributions to integrating Web technologies in real-time systems. First, it provides an experience report for adding real-time monitoring support over the Web to the Open-source Architecture of Software Instrumentation of Systems (OASIS), which is an open-source real-time instrumentation middleware for distributed real-time and embedded (DRE) systems. Secondly, its quantitatively compares using AJAX and WebSockets to stream collected instrumentation data over the Web. Results from our study show that a WebSockets server consumes 50% less network bandwidth than an AJAX server; a WebSockets client consumes memory at constant rate, not at an increasing rate; and WebSockets can send up to 215.44% more data samples when consuming the same amount network bandwidth as AJAX.