Question

Currently I am working on web based application. I want to know what are the key factors a designer should take care while designing scalable web based application ?

Answer 1

That’s a fairly vague and broad question and something you could write books about. How far do you take it? At some point the performance of SQL JOINs breaks down and you have to implement some sharding/partitioning strategy. Is that the level you mean?

General principles are:

• Cache and version all static content (images, CSS, Javascript);
• Put such content on another domain to stop needless cookie traffic;
• GZip/deflate everything;
• Only execute required Javascript;
• Never do with Javascript what you can do on the serverside (eg style table rows with CSS rather than using fancy jQuery odd/even tricks, which can be a real time killer);
• Keep external HTTP requests to a minimum. That means very few CSS, Javascript and image files. That may mean implementing some form of CSS spriting and/or combining CSS or JS files;
• Use serverside caching where necessary but only after you find there’s a problem. Memory is an expensive but often effective tradeoff for more performance;
• Test and tune all database queries;
• Minimize redirects.