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

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  • AJAX

    • What is it?

    • Why is it important?

    • Examples of live applications

  • Cloud Computing

    • What is it?

    • Why is virtualisation important?

  • Security Issues

What is ajax

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

Pros and cons

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

Why is ajax important

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

Why is ajax important1

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]

Examples of live applications

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

What is cloud computing

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

Strengths and weaknesses

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

Security and safety issues

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

Security in an online world

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?



  • 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

Optional further reading

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

  • Cloud Computing with Red Hat Enterprise Linux

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