I'm looking to implement a chat room using PHP/Javascript (Jquery) with both group chat and private chat features. The problem is how to continually update the interface in a natural way and possibly also how to show 'X is typing.' Messages in private chat. The obvious way seems to be that every X seconds/milliseconds the javascript pings the server and fetches a list of new messages between the last ping and now.

CometChat readily integrates with PHP (with mySQL). You can embed CometChat in a site page or use the floating chat bar on every page of your website. Your users can initiate voice, video and text chat from anywhere, anytime. All features of CometChat including private chat, groups, games, real-time language translation and more will work effortlessly in your PHP (with mySQL) site.

However, this can make the interface seem a bit unnatural, if suddenly the chat room is flooded with 5 messages. I would rather each message appear as it is typed. Is there a way for javascript to maintain a continuous connection to the server, the server pushes any new messages to this connection, and javascript adds them to the interface so they appear simultaneously, almost as soon as the server receives them? I know there are some polling options that require you to install some apache modules etc, but I'm pretty bad of a sysadmin, therefore I'd prefer if there was a very easy to install solution on a shared hosting account, or a php/mysql only solution. Polling is not a good idea.

You need a solution that use long polling or web sockets. Is probably the best tool you can use.

It is a box that lives between the server and the browsers and manages abstractions called channels (think about an IRC channel). It is open source on github: The box is written in Python but it can easily be used with a server written in any language.

It also come with a Javascript library that is built on jsio (uses websockets, long-polling, or whatever is the best technology available on the browser) that guarantee that it uses the best technology available in the browsers.In a demo I saw a realtime chat implemented with few line of code. Hookbox’s purpose is to ease the development of real-time web applications, with an emphasis on tight integration with existing web technology. Put simply, Hookbox is a web-enabled message queue.

Browers may directly connect to Hookbox, subscribe to named channels, and publish and receive messages on those channels in real-time. An external application (typically the web application itself) may also publish messages to channels by means of the Hookbox REST interface. All authentication and authorization is performed by an external web application via designated “webhook” callbacks. Any time a user connects or operates on a channel, ( subscribe, publish, unsubscribe) Hookbox makes an http request to the web application for authorization for the action. Once subscribed to a channel, the user’s browser will receive real-time events that originate either in another browser via the javascript api, or from the web application via the REST api. They key insight is that all application development with hookbox Happens either in javascript, or in the native language of the web application itself (e.g. PHP.) You need a server that can run Python BUT you do NOT have to know Python.