Real-Time Synchronization of Multi-Window Web-Applications : Combining SSE & XHR over HTTP/2 as an alternative to WebSockets

Abstract: Modern web-applications often need to be able to handle multi-window views that are dynamically synchronized depending on user input, as well as continuous and rapid data transfer between the client and the server. The WebSocket protocol has seen widespread industry use when it comes to bidirectional, real-time communication. However, its inherent security flaws make the prospect of other adequate alternatives highly relevant. SSE combined with XHR is a technology that has been overlooked by developers due to the shortcomings of the HTTP/1.1 protocol regarding efficiency. However, the HTTP/2 protocol expands upon and streamlines the core features of HTTP/1.1 while also providing full-duplex functionality. The introduction of the HTTP/2 protocol has given rise to speculations regarding a potential comeback for SSE as a viable contender for the WebSocket protocol. The aim is to evaluate whether the combination of SSE and XHR over HTTP/2 could be an equally or more efficient alternative to the WebSocket protocol for real-time data synchronization between multiple web-application views. This is done through the design and creation of two proof-of-concepts supported by the theoretical foundation established by conducting a literature review. The literature in this area indicates a lack of existing research concerning SSE over HTTP/2. The proof-of-concepts has produced empirical data, consisting of average data transmission times, that points to SSE/XHR performing as well as, if not better than the WebSocket counterpart. The results confirm that a combination of XHR and SSE over HTTP/2 is an adequate alternative to WebSockets within the scope of this study.