Assorted Topics Introduction AJAX What is it? Why is it important? Examples of live applications Cloud Computing What is it? Why is virtualisation important? Security Issues

Assorted Topics What is AJAX? AJAX is an acronym that stands for “Asynchronous JavaScript and XML” It's been around since 2005 (or so) and was popularised by Google AJAX is a collection of technologies It is based on JavaScript programming, XML data requests over HTTP and “live updating” of the page through CSS

Assorted Topics Pros and Cons JavaScript can communicate asynchronously with a server, using the JavaScript XMLHttpRequest object But XMLHttpRequest is done through non-standard means Although AJAX is based on open standards, browsers do not all implement these standards perfectly AJAX is architecturally cross-platform but at the detail level there must be different code to support MSIE and the other, more standard, browsers

Assorted Topics Why is AJAX important? It helps the developer minimise the number of new full page downloads Can be faster, slicker and better than normal client- server page turnaround Applications should end up being smaller due to less network traffic Applications should run quicker and be easier to write – no more “stateless” page changes to deal with

Assorted Topics Why is AJAX important? “much of the Web's innovation and evolution during the Web 2.0 era has relied upon and benefited immensely from the capabilities of an Ajax platform” [Wikipedia, AJAX] “An Ajax application eliminates the start-stop-start- stop nature of interaction on the Web by introducing an intermediary — an Ajax engine — between the user and the server” [Adaptive Path, J.J.Garrett] “In addition Ajax works on the client and shares some work of the server, so reducing the server load” [Wikipedia, AJAX]

Assorted Topics Examples of live applications Google Maps is a good example of an AJAX application Similar precursor frameworks have been used in the past – for example, Outlook Web Access GMail is an AJAX application Parts of Flickr are based on AJAX technology Note that Java + XML, Java Applets + XML, Flash + XML and lots of other technologies have many features in common with AJAX

Assorted Topics What is “cloud computing”? Cloud computing is name for a style of grid computing “Utility computing” and the use of shared computing resources An alternative to local servers handling applications Virtualisation of computational resources Automation of many management tasks is an essential feature – otherwise we're talking about a traditional datacentre Massively parallel processing on heterogeneous nodes

Assorted Topics Strengths and weaknesses Where is the cloud? Local networks – limited size but predictable system setup and capabilities, may be relatively secure The Internet – huge but highly unpredictable, harder to secure Strengths include Can locate infrastructure in low cost areas Can share peak-load capacity among users May separate application code and data from localised hardware

Assorted Topics Security and safety issues Privacy, security and viruses are worries when online Google's online wordprocessing application is username and password protected with built-in virus scanning Google says it offers users the same level of protection as its own staff It is reported that Google employees regularly use cloud computing, including the senior executives

Assorted Topics Security in an online world Who do you trust with your documents? Where do you store (and back up) your work documents? What about personal documents? Would you be happy with cloud-based storage? Would your business be happy with cloud-based processing or storage? How important is encryption? What about identity theft?

Assorted Topics Conclusion AJAX is a flexible solution to a fundamental limitation of Web pages AJAX is very popular for highly interactive “Web 2.0” applications Cloud computing is a loose term for a fuzzy form of grid computing It's analogous to an electricity supply grid but more complex It raises issues of ownership, security, trust and reliability

Assorted Topics Optional Further Reading Ajax (programming) Ajax: A New Approach to Web Applications AJAX:Getting Started Cloud computing IBM cloud computing Cloud computing begins to emerge from the haze line/archives/2008/03/cloud_computing.html line/archives/2008/03/cloud_computing.html Cloud Computing with Red Hat Enterprise Linux