Just for the sake of argument. Both are http request (xhr), and its at least partially untrue it uses more server resources (depends totally on technology, will explain later). Short polling. Lot of request that are processed as they come on server. Creates a lot of traffic (uses resources, but frees them as soon as … Read more
1) Why is the WebSockets protocol better? WebSockets is better for situations that involve low-latency communication especially for low latency for client to server messages. For server to client data you can get fairly low latency using long-held connections and chunked transfer. However, this doesn’t help with client to server latency which requires a new … Read more
Agreeing/expanding what has already been said, I don’t think FastCGI will solve the problem. Apache Each request into Apache will use one worker thread until the request completes, which may be a long time for COMET requests. This article on Ajaxian mentions using COMET on Apache, and that it is difficult. The problem isn’t specific … Read more
Comet is challenging to scale with IIS because of comet’s persistent connectivity, but there is a team looking at Comet scenarios now. Also look at Aaron Lerch’s blog as I believe he’s done some early Comet work in ASP.NET.
Yes, what you’re looking for is COMET http://en.wikipedia.org/wiki/Comet_(programming). Other good Google terms to search for are AJAX-push and reverse-ajax.
I wrote the plugin mentioned by Till. The plugin is an implementation of the Bayeux protocol and currently supports long-polling (local server via AJAX) and callback-polling (remote server via XSS). There is a Bayeux implementation for Python called cometd-twisted that I have heard my plugin works with, but I have not verified this. I have … Read more
The way Facebook does this is pretty interesting. A common method of doing such notifications is to poll a script on the server (using AJAX) on a given interval (perhaps every few seconds), to check if something has happened. However, this can be pretty network intensive, and you often make pointless requests, because nothing has … Read more
In the examples below the client is the browser and the server is the webserver hosting the website. Before you can understand these technologies, you have to understand classic HTTP web traffic first. Regular HTTP: A client requests a webpage from a server. The server calculates the response The server sends the response to the … Read more
It’s simpler than I initially thought.. Basically you have a page that does nothing, until the data you want to send is available (say, a new message arrives). Here is a really basic example, which sends a simple string after 2-10 seconds. 1 in 3 chance of returning an error 404 (to show error handling … Read more