Question

php script for names of users online - possible to work with session ID ?

Asked by: xberry

Would like to show on a website names of active users online.
Thought that not to be a problem, since only needed to show users that are logged in
and to control if a user is logged in, for a vaild login a session_id() is saved in the mysql
users profile table. Problem is, that if a user does not a proper log out (lets say he simply closes the browsers window)
then the session_id is still saved in database even if user is no longer online.
Is there a method to check if a user has left the site, so in that case it would set session_id in database
back to Null and I could simply retrieve from database all users whose session_ids are not set to Null ?

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Asked On
2009-03-08 at 05:44:54ID24210007
Tags

php

,

mysql

Topics

PHP Scripting Language

,

WebApplications

Participating Experts
2
Points
500
Comments
7

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Answers

 

by: cxrPosted on 2009-03-08 at 07:21:02ID: 23829471

This won't happen automatically, you would have to write code to set those columns to NULL. I would put a new column in the user profile table: last_seen. For every click done by logged in users, update this column with the current timestamp. When the timestamp is more than X minutes old, you can consider the user as "logged out", and set the session_id to NULL, or you can let the session_id live forever, but use the timestamp when you make your list of online users.

 

by: xberryPosted on 2009-03-08 at 07:59:56ID: 23829592

>> For every click done by logged in users update this column with the current timestamp

How to record clicks with php ?  if users are participating in a chat on site or just went away for a cup of tea
but will come back within minutes then if the user is still online and logged in, I'd like to count him as
'online'

short, I've seen sites they have written under their list of online users 'updated' every five minutes. Would be ok with me.
However, how is this done? how to check if user still online?  





 

by: cxrPosted on 2009-03-08 at 08:54:18ID: 23829775

>> How to record clicks with php ?

mysql_query("update userprofile set last_seen=now() where session_id=$session_id")

If as user has left for a cup of tea, or has left for good, you can't know the difference. Only when he actually comes back and does another click, you can know for sure he has not left for good. This is why you need a timestamp: when the timestamp is more than X minutes old, the user has actually left. What X is depends on your situation, banking sites use a low X, like 5 minutes, while less secure sites use a higher X for instance 60 or 120 or even 240 (4 hours).

>> how to check if user still online?  

Decide a suitable X for your site, and list online users like this:

select * from userprofile where last_seen > now() - interval X minute

 

by: vickatlinuxPosted on 2009-03-08 at 08:55:13ID: 23829777

System can never guess whether the user has gone away for a cup of tea or having sweet dreams without logging his session out. If session's expiry reached n hez still not there, he should be counted as logged out. There is nothing wrong with it. He wouldnt mind cz he knows that system is just doing wt is natural for it to do.

 

by: xberryPosted on 2009-03-08 at 11:15:22ID: 23830507

>> mysql_query("update userprofile set last_seen=now() where session_id=$session_id")

hmm, well, somehow my logical brain seems to have gone for holidays - this explains to me how
to set timestamp, but where would I put this piece of code, . i.e. when would it execcuted ?
Don't  tell me to put this on every page of the site ?

 

by: cxrPosted on 2009-03-08 at 11:41:21ID: 23830675

Yes, it must be on every page that is used for logged in users.

You probably have a file that you include on every page to check if a user is logged in? If so, you can put it in there. If you have a common header.php or footer.php file, you can put it in there.

If you don't have any common file, you must either put it in all pages, or you can use the auto_prepend_file feature, described here:

http://php.net/ini.core

 

by: xberryPosted on 2009-03-10 at 07:08:11ID: 31555500

Thanks.

20120131-EE-VQP-002

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