Re: Logging user's movements

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H
On 4 Feb 2005, at 08:13, ben syverson wrote:

> Hello,
>
> I'm curious how the "pros" would approach an interesting system design  
> problem I'm facing. I'm building a system which keeps track of user's  
> movements through a collection of information (for the sake of  
> argument, a Wiki). For example, if John moves from the "dinosaur" page  
> to the "bird" page, the system logs it -- but only once a day per  
> connection between nodes per user. That is, if Jane then travels from  
> "dinosaur" to "bird," it will log it, but if "John" travels moves back  
> to "dinosaur" from "bird," it won't be logged. The result is a log of  
> every unique connection made by every user that day.
>
> The question is, how would you do this with the least amount of strain  
> on the server?
>
I think the standard approach for user tracking is a 1x1 gif, there are  
lots of ways of doing it, here are 2:

Javascript + Logs - update tracking when logs are processed
------------------------------------------------------------------------ 
---------

Use javascript to set a cookie (session or 24 hours) - if there isn't  
already one. Then use javascript to do a document write to the gif.

so /tracker/c.gif?c=<user_session_id>&page=dinosaur

It should then be fast (no live processing) and fairly easy to extract  
this information from the logs and into a db.

Mod_perl - live db updates
-------------------------------------
Alternatively if you need live updates create a mod_perl handle that  
sits at /tracker/c.gif, processes the parameters and puts them into a  
database, then returns a gif (I do this, read the gif in and store it  
as a global when the module starts so it just stays in memory). It's  
fast and means you can still get the benefits of caching with squid or  
what ever.

I get about half a million hits a day to my gif.

I think the main point is you should separate it from your main content  
handler if you want it to be flexible and still allow other levels of  
caching.

Cheers

Leo