I have the webpage that displays "questions" and "answers" for users. Questions are created by admin. I am using PHP.
New requirement has come to update questions/answers for users in "real time" (this is not so real time like in strategy game, but I will call this real time). When admin created new question, user should see it (new question appears). When admin closes existing question, then it disappears from user point of view.
I am thinking to create it using ajax and javascript timer- to call ajax each minute and to update results. I wonder is this is the right way?
And also I wonder about usability/performance... I really do not need to update those questions for user that were not changed... What are your suggestions to determine, which questions were changed by admin (maybe I should add something like "last_update_date" for question in database and put "last_update_date into hidden field for each question" and compare?
If you do not want to implement your own logic with Socket.io (as suggested in the comments), you should have a look at some of the services available online.
I've been using Pusher.com for some time and is quite happy about it.