Client Or Server-Side Processing?

Client-Side Processing

choice-yes Less latency, as the images required can be computed and fetched immediately.
choice-yes More flexibility; certain tasks (eg select alternative node in case of network problems) can only be achieved client-side. Non-JavaScript alternatives for movies exist (Flash, on-demand server-side generation of movies) but pose other problems (plugins required, lots of processing power on the server).
choice-no Support for JavaScript very browser-dependent.

Server-Side Processing

choice-yes Much greater support for browsers, no requirement for JavaScript.

What do we need/want JavaScript to do?

Proposed requirements

  • Try another node if image missing or node not available. Can use <noscript> tags to provide a working solution for browsers where JavaScript is disabled (automatic node selection would also be disabled). The client-side code can be tailored to the browser, either on the server (based on how the browser identifies itself), or better still client-side by identifying DOM capabilities (see

Wish list

  • Browse data between different dates or times without having to fetch a new HTML page. For this to work the browser is required to compute the new image location using a strftime format specifier and the time (which will be needed to use a fallback URL in image node selection) and load it, also update the text of any time-dependent text (e.g., "Data from 2006-01-1"). This does not sound like too much to ask, and for incompatible browsers PHP or JavaScript could get the browser to request a new page from the server.


  • Are there any core features in GAIA that should work without JavaScript? If so what are they?

  • Are there any features GAIA will only provide on the assumption that JavaScript is available?
    • Image mirroring.

  • For those features what are browsers we wish to support, and what JavaScript features will we need?
    • Internet Explorer (what minimum version ?)
    • Firefox (1.5+)
    • Safarai (what minimum version ?)
    • Opera (9.0 ?)
    • Konqueror?
    • Galeon?
    • any others?


  • We can have PHP provide output suitable for both client-side requests and server-side requests. Time-dependent elements (e.g., <h1>Data for 2006-01-01</h1> can be set with an appropriate style parameter, and followed with some scripting to set an object attribute with the format specifier to use when updating the text (or image src).

Topic revision: r4 - 2007-03-16 - 22:54:04 - SteveMarple
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