Node.js chat without Socket.IO

Question

I just started learning Node.js and as I was learning about the fs.watchFile() method, I was wondering if a chat website could be efficiently built with it (and fs.writeFile() ), against for example Socket.IO which is stable, but I believe not 100% stable (several fallbacks, including flash).

Using fs.watchFile could perhaps also be used to keep histories of the chats quite simply (as JSON would be used on the spot).

The chat files could be formatted in JSON in such a way that only the last chatter's message is brought up to the DOM (or whatever to make it efficient to 'fetch' messages when the file gets updated).

I haven't tried it yet as I still need to learn more about Node, and even more to be able to compare it with Socket.IO, but what's your opinion about it? Could it be an efficient/stable way of doing chats?

Answer 1

fs.watchFile() can be used to watch changes to the file in the local filesystem (on the server). This will not solve your need to update all clients chat messages in their browsers. You'll still need web sockets, AJAX or Flash for that (or socket.io, which handles all of those).

What you could typically do in the client is to try to use Web Sockets. If browser does not support them, try to use XMLHttpRequest. If that fails, fallback to Flash. It's a lot of programming to do, and it has to be handled by node.js server as well. Socket.io does that for you.

Also, socket.io is pretty stable. Fallback to Flash is not due to it's instability but due to lack of browser support for better solutions (like Web Sockets).

Answer 2

Storing chat files in flatfile JSON is not a good idea, because if you are going to manipulating the files, you would have to parse and serialize entire JSON objects, which would become very slow as the size of the JSON object increased. The watch methods for the filesystem module also don't work on all operating systems.

You also can't compare Node.js to Socket.IO because they are entirely different things. Socket.IO is a Node module for realtime transport between the browser and the server. What you need is dependent on what you're doing. If you need chat history, then you should be using a database such as MongoDB or MySQL. Watching files for changes is not an efficient way and you should just send messages as they received.

In conclusion no, using fs.watchFile() and fs.writeFile() is a very bad idea, because race conditions would occur due to concurrent file writes, besides that fs.watchFile() uses polling to check if a file has changed. You should instead use Socket.IO and push messages to other clients / store them in a database as they are received .

Answer 3

You can use long pooling method using javascript setTimeout and setInterval

long pooling

basically long pooling working on Ajax reqest and server responce time.

server will respond after a certain time (like after 50 seconds ) if there is not notification or message else it will respond with data and from client side when client gets response client javascript makes another request for new update and wait till response this process is endless until server is running