As the web browser becomes an increasingly powerful tool for the average web user, with more features and capabilities being developed constantly, the necessity to determine which features perform better than others in the same area becomes more important. This thesis investigates the performance of three separate technologies used to achieve full-duplex real time communication over the web: short polling using Ajax, server-sent events and the WebSocket protocol. An experiment was conducted measuring the performance over three custom-built web applications (one per technology being tested), comparing latency and number of HTTP requests over 100 messages being sent through the application. Additionally, the latency measurements were made over three separate network conditions. The experiment results suggest the WebSocket protocol outperforms both short polling using Ajax and server-sent events by large margins, varying slightly depending on network conditions.

As the web browser becomes an increasingly powerful tool for the average web user, with more features and capabilities being developed constantly, the necessity to determine which features perform better than others in the same area becomes more important. This thesis investigates the performance of three separate technologies used to achieve full-duplex real time communication over the web: short polling using Ajax, server-sent events and the WebSocket protocol. An experiment was conducted measuring the performance over three custom-built web applications (one per technology being tested), comparing latency and number of HTTP requests over 100 messages being sent through the application. Additionally, the latency measurements were made over three separate network conditions. The experiment results suggest the WebSocket protocol outperforms both short polling using Ajax and server-sent events by large margins, varying slightly depending on network conditions.

The advent of HTML5 (Hyper Text Markup Language revision 5) technologies are re-standardizing the web and paving the way for a new breed of real-time web applications. This has great potential for mobile browsers that are now supporting protocols such as WebSocket and Server-Sent Events (SSE). These protocols can provide ecient real-time communication in a scalable manner, especially for \always-on" applications requiring persistent connections that are now widely used. Mobile devices are inherently restricted due to their limited battery power and require frequent charging. Therefore, experimentation that potentially promotes breakthroughs in mobile energy eciency is useful at this time. Extensive measurements were conducted over 3G, 4G, and WiFi networks to analyze the performance of WebSocket and SSE across a variety of popular mobile devices, browsers, and platforms. Devices were connected to a power monitor for a precise understanding of the energetic effects of keep-alive mechanisms and their overall effects on long-lasting connectivity. The results reveal that application level keep-alive mechanisms are not necessary to sustain the connections indefinitely, given proper server and network congurations. However, to avoid timeouts and to detect prematurely disconnected clients, keep-alive exchanges are necessary and useful in practice. The effects of short and long keep-alive interval values are examined in detail for all devices. Browser performance varies widely as no browser was completely successful for both WebSocket and SSE tests. Further improvements in mobile browser support for these technologies will be necessary to reach the full potential of real-time applications in the future. / Tillkomsten av HTML5 (Hyper Text Markup Language revision 5) teknik är åter standardisera webben och bana väg för en ny typ av realtid webbapplikationer. Detta har stor potential för mobila webbläsare som nu stödjer protokoll såsom WebSocket och Server-Sent Events (SSE). Dessa protokoll kan ge effektiv kommunikation i realtid på ett skalbart sätt, särskilt för \alltid-på" applikationer som kräver beständiga anslutningar som nu används i stor utsträckning. Mobila enheter är i sig begränsade på grund av deras begränsade batteri och kräver frekvent laddning. Därför är experiment som potentiellt främjar genombrott i mobil energie ektivitet användbar vid denna tid. Omfattande mätningar utfördes över 3G, 4G och WiFi-nätverk för att analysera resultatet for Web-Socket och SSE över en variation av populära mobila enheter, webbläsare och plattformar. Enheter var ansluten till en monitor för en exakt förståelse av de energiska effekter keep-alive-mekanismer och deras samlade effekter på långvarig anslutning. Resultaten visar att applikationsnivå keep-alive-mekanismerna är inte nödvändigt att upprätthålla anslutningarna på obestämd tid, ges rätt server och konfigurationer nätverk. Men för att undvika timeout och att upptäcka tidigt frånkopplade klienter, keep-alive-börser är nödvändiga och användbara i praktiken. Effekterna av korta och långa keep-alive intervallvärdena granskas i detalj för alla enheter. Browser prestanda varierar kraftigt eftersom ingen webbläsare var helt lyckat för både WebSocket och SSE tester. Ytterligare förbättringar av mobila webbläsare stöd för denna teknik kommer att vara nödvändigt för att uppnå den fulla potentialen av realtidsapplikationer i framtiden.

Collecting and deploying online games made by inexperienced developers can behard. This is something KTH (Royal Institute of Technology) has a problem withpertaining to a course involving SDL and SDL_Net programming. A good solutionto this problem is to host these games on a website. An easy-to-use way of compilingand deploying multiplayer games and game-servers written in C as web applicationsand web servers was needed. Specifically for games written in C using SDL andSDL_net libraries. The compiler toolchain Emscripten was used to compile gameand server code from C to WebAssembly, that could then be used through the generated JavaScript functions. Communication between the client and the server washandled by WebSockets. As much of the Emscripten specific functions were to behidden behind C libraries, emulating the format of SDL_Net. The finished solutionsthat emulated the format of SDL_Net, consisted of two new libraries, one for theserver and the other for the client. The libraries successfully emulated the TCP partsof SDL_Net library. The browsers event scheduler necessitates applications to beable to return control back to it. This meant that the game codes endlessly loopingfunctions had to be rewritten to enable rendering in the browser. / Det kan vara svårt att samla in och distribuera onlinespel gjorda av oerfarnautvecklare. Detta är något som KTH (Kungliga Tekniska Högskolan) har problemmed i en kurs som involverar SDL och SDL_Net programmering. En bra lösning pådetta problem är att köra dessa spel på en webbsida. Ett lättanvänt sätt att kompileraoch distribuera multiplayer-spel och spelservrar skrivna i C till webbapplikationeroch webbservrar behövdes. Specifikt för spel skrivna i C med SDL och SDL_netbiblioteken. Kompileringsverktyget Emscripten användes för att kompilera spel- ochserverkod från C till WebAssembly, som sedan kunde användas genom degenererade JavaScript-funktionerna. Kommunikationen mellan klienten ochservern sköttes av WebSockets. I största möjliga mån skulle Emscripten specifikafunktioner döljas bakom C-bibliotek som emulerade formatet av SDL_Net. Defärdiga lösningarna som emulerar formatet av SDL_Net bestod av två nya bibliotek,ett för servern och det andra för klienten. De emulerade framgångsrikt TCP-delarnaav SDL_Net biblioteket. Webbläsarens händelseschemaläggare kräver attapplikationer har möjligheten att återge kontroll till den. Detta gjorde att spelkodensoändligt loopande funktioner behövdes skrivas om för att kunna rendera i webbläsaren.

Linnaeus University is aiming at implementing a Data Stream Centre to provide streaming of accumulated data from the websites’ newspapers and articles in order to help its scientists of University to have faster and easier access to the mentioned data. This mentioned project consists of multiple parts and the part we are responsible to research about is first nominating some text streaming protocols based on the criteria that are important for Linnaeus University and then evaluating them. Those protocols are responsible to transfer text stream from the robots (that read articles from the websites) to the data stream center and from them to the scientists. Some KPIs (Key Performance Indicators) are defined and the protocols are evaluated based on those KPIs. In this study we address evaluation of network streaming protocol by starting to read about the protocol’s specifications and nominating four protocols including TCP, HTTP1.1, Server-Sent Events and Websocket. Then, fake robot and server are implemented by each protocol to simulate the functionality of real robots, servers and scientists in LNU data stream center project. Later, the evaluation is done in the mentioned simulated environment using RawCAP, Wireshark and Message Analyzer. The results of this study indicated that the best suited protocols for transferring text stream data from robot to data stream center and from data stream center to scientist are TCP and Server-Sent Events, respectively. In the concluding part, other protocols are also suggested in the order of priority.

Möjligheterna på webben blir hela tiden större. Teknologier för webbaserade spel börjar dyka upp som tillåter animationer och realtidskommunikationskrav till den standard som spel gjorda för desktops idag har. I detta arbete testas WebRTC och Websockets mot varandra för att ta fram underlag för vilken lösning som presterar bäst i olika scenarion. Ett experiment utfördes och resultatet pekade på att WebRTC klarade av fler scenarion bättre än Websockets till en nivå som relaterad forskningslitteratur pekar på är acceptabla nivåer av nätverksfördröjning för att uppnå kraven för realtidskommunikation. Experimentet gick ut på att simulera nätverksfördröjning vid olika antal samtida användare i ett webbaserat spel. För framtida arbete spekuleras det kring användning av andra webbläsare, enheter och kopplingar till Internet of all things.

Goal of this master thesis is to analyze existing algorithms for ensuring consistency in real-time synchronization of vector graphics between server and multiple clients, testing them, describe main differences and selection of the best for this purpose. The theoretical part is devoted to realtime comunication over HTTP, to WebSockets, to concurrency algorithms and to basics of application architecture. The practical part describes the technology used in this thesis, as well as actual application design a its implementation. The result of this thesis is an overview of concurrency algorithms, the choise of technology for real-time communication between server and multiple clients and implementation of selected technologies and algorithms in Node.js application.

The problematics of gigabit optical networks as well as web technologies suitable for a web tool implementation were studied within this thesis. An experimental web application for monitoring GPON frames is developed based on the proposed system architecture. The frontend is implemented using ReactJS and the Tornado web framework is used for backend implementation. Data for analysis are read from the stream using the Kafka platform.

Generally, the term gateway (gateway) in computer networks holds a node that connects two networks with different protocols. This thesis deals with the translation between two protocols, SIP protocol and WebSocket. This translation is the work first described theoretically and then work deals with the way this translation solutions using tools available on the Internet.

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.