For the record, this is mainly out of curiousity. I'm not trying to figure out how to hack linuxquestions or anything like that.

How does a site ilke this work? I understand basic html, and basic programming concepts, and I'm assuming that there is some kind of database that ties in with the php code. Would someone w/ more experiance than me, or perhaps jeremy, explain how this kind of site works? What exactly is AJAX, and how does it benefit this site(aside from the obvious behavior changes, replying w/out reloading the page, etc.)? Why does this site do things the way it does, code-wise?

Its mainly a php bulletin board system (called vbulletin) that runs the forums. I have little knowledge of vbulletin (compared to phpbb2) but the HCL is probably a custom coded hack added to vbulletin. The main page (linuxquestions.org) is a portal system that can display current activity on the forums. The forums basically submit information to to a SQL database. Whenever you open a thread, the php scripts connect to the database and retrieve information and the bulletin board system displays the information in a post/thread view accordingly.

EDIT: Forgot to add about AJAX. I think you'd probably learn more about than from the little I know if you search about it on the web.

so anything posted is a database entry? How do all the parts communicate? is it packets? or do they have a "customized language" for lack of a better term? I mean, I know SQL's got it's own interface, so php must use that somehow to communicate. What ties it all together?

PHP is a scripting language, kinda like Perl, or a shell script. All these can communicate with a MySQL database using typical MySQL commands. When you request the page, Apache looks for the page you're trying to access, then uses the proper commands to execute the code. If you were to "View Source" on this page, you would not see the PHP, but rather output from the PHP script - it just happens to output HTML which Apache then serves up as a webpage.

SQL does not actually have its own interface but another php program (ie phpMyAdmin) that allows you to view/edit the contents of the sql database from the web.
What happens when you post something is this. The php script say post.php takes the information in the text box and adds it to other information about the post, date, time, user of entry and formats it into a command.
It will then send to MySQL (or whatever database system) a command to enter the data into a table. There are several tables, ie. one that has the admin board configurations, one that has the rules for the forums (who can post, view, read, edit, moderate...), one that has the thread information and so on.

Commands for the database vary for tasks. Like when you click on a thread the vbulletin file (such as viewtopic.php) will send a command like (and others):
SELECT {this is a string of table entries, userid, user's post count, user email, avatars, post texts, post subject and everything else pertaining to the thread's information that you see} FROM {this is a string of tables that information is stored, ie. POSTS_TABLE, USERS_TABLE...} WHERE $topic_id = {the id of the topic you clicked on}

Thats a pretty rough and short example of what is done. There's alot more that goes on but my knowledge is way lacking to explain much.

EDIT:
If you really want to learn more, you might want to take a look at this link. It has quite a bit of information about php and sql and probably could explain it way better than I. http://dev.mysql.com/tech-resources/...s/ddws/20.html

That's actually pretty good, thanks. So how about hardware requirements for all this stuff? Do people who are logged into the site actually logged into the server? Do they have an account there? Assuming the do, I would doubt their given a home directory right? Why was PHP chosed over something like perl(or ASP, but that's kind of a given. Why would one choose PHP over ASP on a windows machine?)?

As for the language chosen, I think it is all up to who ever writes the code. People (like you and I on linuxquestions) don't have a regular user account on the machine thats hosts the site. If you've dabled with webhosting on your linux box, its kind of like that. Any computer can actually run a site, but the more people who view it and interact, the more resources are neccessary to keep it running smooth. I can't remember about PHP (I believe it just runs as a component in Apache) but SQL runs under a user account. We just connect to Apache and it does the rest. I believe that mysql.com link above actually details it.
I hope I'm correct, someone who knows correct me if I'm wrong please .

I've played around a little bit, but it was just internal(I have a dynamic IP, and my parents won't let me...). Is there anything better about one language over the other? or is it just personal preference? Hmmm...I think that's all my questions for now...I'll be back though

The site runs on the LAMP stack and at our size we use more resources than you might think. As was indicated, you don't have any kind of system or shell account, but are simply a record in the user table. As for why PHP, it's really a matter of choice. PHP is simple, clean, built for the web and does what we want. As for AJAX (Asynchronous JavaScript And XML), http://en.wikipedia.org/wiki/AJAX is a good place to start.

--jeremy

Hey jeremy, I know you're busy, but would it possible to do a write up on how linuxquestions.org works? I'm sure I'm not the only interested, and, unless there's some reason not to(security, etc.), I don't see an negative effects. Something to think about...

PHP is a good choice for lots of applications because it is very powerful but it is just so easy to learn! It's beyond easy and it has a fantastic reference. If you're site is going to be based around a forum system though, PHP is the obvious choice because vBulletin is by far the best forum software around.

Honestly, the best way to understand this is to install Apache, PHP and MySQL and teach yourself the basics of the language. It'll take you a solid weekend to get the basics down and something neato written to show off to everyone

The LAMP stack is well documented enough that I'm not sure there is much I could really add.

--jeremy

Very simply put it works like this:

1. PHP Code sitting on the server gets executed whenever a page is requested. PHP interacts with the MySQL server using PHP commands for MySQL (with the php-mysql module).

2. PHP renders output in the form of HTML to the client (end user) using the data retrieved from the MySQL server and also stores user data submitted in HTML forms into the MySQL server.

3. All data in the site, user accounts, posts, topics, forums, categories and other dynamic info are stored in the MySQL database.

Since vBulletin powers the main forum, most of the functionality is part of the vBulletin code, but of course the extra sections on this site like HCL, reviews and so on are add-ons or hacks... All of course coded in PHP.

ok, sounds good. Thanks for all the information you guys(or girls). I'll probably be back with more questions