Calculating number of online visitors?

i need to show the number of online visitors, but there is a problem with selecting algoritm to do it! maybe i must create a table in DB, where i'll store ip addresses of visitors and time of visit! by so i can show the count of ip addresses, which's time >= NOW() - 10 minutes, for example...("now()-10 minutes" is just to show the logic, i know that this is not a function:)

is this goog wa开发者_如何转开发y to go?

please give me an idea.

Thanks

This is good tutorial. Note that mysql (i believe youll use it) online users table should be typed as MEMORY.

I'm not really sure how you would use AJAX to store the data...

I personally use the database solution.

I store user_id, last_seen, IP and location in the site (but that's not necessary to just get the count).

When the user requests a page refresh the last_seen column and delete all the entries with NOW()-last_seen greater than x minutes.

Keeping track of "visitors" (as opposed to raw page requests, which the web server should track on its own) is a complex art.

You could store IP addresses, as you described, but what about a visitor who's using a proxy that rotates their IP as frequently as every page load? What about a set of visitors all using the same proxy that uses the same IP for all of them?

My recommendation: don't bother doing any of it yourself, and use Google's free Analytics service. It tracks visitors, browsers, traffic sources, and just about anything else you could possibly want to know about who's looking at your site.

Yes, the algorithm is o.k. in general but with some corrections

May be you want to delete all outdated records first, and then just count the rest.
10 minutes is too much. 1-3 is the average time user spend on the page.
AJAX project is funny, but it has nothing to do with storage. You need more education of terms of client-server application. AJAX is the transport, not storage.

If you expect the website will have a lot of visitors, the query could make the page for one user every 10 minutes pretty slow...

If so, I would suggest to write an CLI script that will clean the old entries and run it in a cronjob. That way the user wouldn't notice any delay, as the parsetime will be spent on the CLI.