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.

The diploma thesis deals with design and implementation of cooperative work on documents in the application TEXonWeb. The diploma theses includes the analysis of competitive solutions and key technologies for implementation. The cooperative work on documents is a functionality which allows users to cooperate simply on one document in real-time. Text of the thesis describes the process of implementation using the technology which is described in the initial analysis. The diploma theses also includes some ideas for next possible development.

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.

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.