Would a Socket Connection Outperform an Intarvaled Database Sweep and Requests?

I'm building a small chat application to add to an existing framework. There will only be 20-50 users maximum at any one time.

I was wondering if I could get away with updating a cache file containing (semi) live chat data for whichever users happen to be chatting just by performing timed queries and regular AJAX r开发者_JAVA百科efreshes for new data as opposed to learning how to open and maintain a socket connection.

I'm sure there are existing chat plug-ins out there, but I just had a hell of a time installing one and I could see building the whole damn thing taking just as much time as plugging one in.

Am I off to a bad start?

Thanks in advance -J

(p.s. this is a semi closed network behind a php login so security isn't a great concern)

---

First of all, I would suggest reading up on JavaScript Long Polling to retrieve your data instantaneously.

As far as collecting and distributing your data, I would recommend you use a database that supports LISTEN and NOTIFY. (For example, Postgres provides you with pg_get_notify() in PHP)

With long-polling and a notification-enabled database like Postgres, you could easily build a real-time, scalable chat application.

Other resources and links:

• http://www.postgresql.org/docs/current/static/sql-notify.html
• http://www.postgresql.org/docs/current/static/sql-listen.html
• http://www.php.net/manual/en/function.pg-get-notify.php
• http://blog.perplexedlabs.com/2009/05/04/php-jquery-ajax-javascript-long-polling/
• http://en.wikipedia.org/wiki/Comet_%28programming%29
• http://www.webdevelopmentbits.com/avoiding-long-polling

---

I second that long polling is a good approach. However, understanding it, and doing it correctly, is far more difficult than just polling in intervals. With 20-50 users, scalability shouldn't be an issue. For a good long polling design, you should look at how you can avoid to suspend a server thread for the lifetime of an http request.

It could be wise to start out with a simple polling approach, advancing to long polling later on.