Designing large scale web applications

When building large scale applications you really need to plan plan plan so visio will come in handy for organising the page structure and of course your database schema. It's a lot easier to stick to your plans when coding if you have some sort of diagram in front of you.

I tackled a large web application for a client a few years back and ended up having to print the sitemap and database structure out on A0 paper so I could see it all at once! It made troubleshooting and the build stage a million times easier though.

benf;211398 wrote: I am now in the first stages of my college project. I plan to design a large scale web application.

I'm working on one of these myself, so I'll share my experience.

benf;211398 wrote: However, im not sure what sort of design techniques i should use.

1. UML
2. SSADM
3. Microsoft Visio

Nothing like it was necessary.

I did plan at a high level, to organise the big ideas and goals, such as identifying users, roles, schedules and other factors. (A paper and pencil -- without UML! -- were quite enough for that.) It may seem counterintuitive, but I left implementation decisions for later.

I figured that the application was so large, I could not know and design solutions for all of its problems beforehand. So I took a bottom-up tack. Starting from the lowest level, I built -- or borrowed -- domain-specific languages, and with them, incrementally higher level components, while exploring problems in a highly interactive, expressive environment.

Works for me.

benf;211398 wrote: How do companies design web applications?

Be careful with this question. Just because companies do things a certain way does not make it ideal for you. Not that they all do it the same way. For example, a small company (startup or one-man-band) invariably takes a radically different approach than a large company (so-called 'enterprise').

Also, you ought to distinguish between failing and successful ventures (most fail), their lifetimes and constraints, those within or outside your domain, dense and sparse teams, novel and traditional methodologies, etc, when evaluating what's better or worse.

benf;211398 wrote: They must be designed with object-orientation in mind, is php a good language for OOP?

Yeah, for a large application, object orientation, among other things, is advisable. However, there are many ways to implement OOP principles. There is no one true way, and some are better than others. PHP's is at the 'worse' end of that spectrum, imo, and it lacks various other features too.

For my project, I used Common Lisp, which lends itself very well to the approach I took. If you like OOP implementations in the Smalltalk-Java tradition instead, consider Python or Ruby. Similarly, for top-down development, look at Java or C# rather than PHP.

Btw, what is your motivation in this project? Are you trying to learn how companies engineer software, or are you trying to solve some other problem? Can you say anything more about it?

Anyway, good luck!