I have a collaborative website where I need different sessions from different users to talk to each other (all sessions run php scripts on the same server). I was thinking of updating a "status" field in the mysql database and having other sessions from other users probing this field every second (using php).
Is there any potential issue with using such an approach (database caching etc...). Is there a better solution? thank you
Unless you want to have your users' browsers reload the entire page each second, you should use something like ajax to poll the server.
For the states, you could have your server update a json file that your clients can download periodically.
For inter-session communication, you could have a system with a message queue whereby messages are either transmitted specifically to a particular user or broadcast to all.