I am looking to build an web application using node.js and possibly socket.io but I am having a lots of confusion regarding whether to use socket.io or go with plain http. In the app the node.js server will be basically an api server which serves json to the javascript client or may be mobile clients too. The web app will also has chat messeneger for its users, this is where socket.io comes in.
I am not sure whether to use socket.io for the whole app or only for the chat part. Although my app itself could benefit from socket.io but its nothing that I think can't be done using plain http and client making more requests to the server.
I have read at several places that sometimes socket.io can be difficult to scale for more users.
Socket.io often crashes and specially creates probs when there are firewall in clients system.
More importantly.....I checked out socket.io user list and did not find many users, so was curious to know what kind of platform is more know chat network like facebook messenger, google talk etc are built upon, Are any built using http-ajax and continues querying to the server.
Please help me out in solving this question. Some might argue that this is a opinion based question. But what actually I am trying to figure out the implementation of socket.io and its limitation.
I would suggest serving your API over HTTP and leave the real-time business to Socket.io. If you are adverse to using Websockets, like #GeoPheonix stated, you can choose from a variety of transport methods using both socket.io and sockjs (https://github.com/sockjs/sockjs-node).
As far as scaling is concerned, I deployed a socket.io based real-time analytics/tracking service for a very large application with ana average of 400+ concurrent connections with no visible performance impact, but this may depend on the implementation and hardware.
Socket.io is faster than plain http. I recommend you to use it for all since you have to have a chat in first place.
In my case, real-time Texas Hold'em-like game can receive up to 2500 concurrent with one node process. However, if you change transport from websocket to xhr-polling, It can receive like more 10x than pure websocket. Your application is just chat so, I guess a little slow down wouldn't be a problem. If you sure you will exceed this number, yes, scale socket.io is a pain.
This problem will happen only if you open socket.io for port other than 80 and 443. If you have frontend web server with other language already, you can still use socket.io on another subdomain to be able to run on port 80 without conflict with your main frontend web server. Socket.io support cross-domain without a problem.
Have you used trello.com? If not, try it :). It's best for task management or even some Agile thing. They used socket.io. https://c9.io/ is another one. It's online IDE with google doc-like collaborative. One thing to note is xhr-polling trasport in socket.io is the same with http-ajax with long-polling (Better than general ajax). You can read more info at:
http://book.mixu.net/node/ch13.html
Related
This is a bit of a stretch, but I hope someone can help.
I'm a PHP/iOS developer who's been working on an app that has a messaging component. Front end is Obj-C, backend is PHP/MySQL currently. As I've gone further into development, I'm feeling the shortcomings of polling and I've been looking for a more realtime solution and, sure enough, I've found the answer in web sockets. PHP doesn't play too well in this domain, but I've been able to get things working locally by using Laravel + Redis + Node.js.
Next I needed to find a suitable host for the real world app deployment and this is where I'm running into my first major obstacle (or perceived obstacle?)
Heroku appears to have very low limits on the number of Redis connections allowable:
Link: https://elements.heroku.com/addons/heroku-redis
Free plan: 20 connections
$120/month: 400 connections
$1450/month: 5000 connections
The problem is, if this app does well and gains the kind of traction I want, a LOT of people will be using it at the same time all across the country and these limits have me worried. These prices seem a bit ridiculous or I'm not looking at it correctly.
So my question is, does maintaining an open web socket (one user) mean that one of the Redis connections is used? Or am I looking at this completely wrong? Trying to decide if I need to just stick to polling or if there is a cost-efficient solution to this. I do want to stick to Laravel/Redis if possible because I am not too familiar with JS and I feel that my backend will be much less secure if I try to go down that route at this point.
Proper design will use 2 Redis connections per server (or per Heroku Dyno):
One connection will be used to Subscribe (to listen) to the app's channel(s). This connection cannot be used for other functions, so...
A second connection is used for all other Redis features, such as Database use and Publishing to the app's channel(s).
I don't know if you're into Ruby, but I'm the author of the Plezi Http(REST)/Websocket framework and had to manage a solution for Plezi's scaling capabilities over Redis (which is an automated feature, you just tell Plezi the Redis server's address and you're good to go).
If you want to look over Plezi's Redis code, you will notice there are two connections and that each server registers to two channels - a global channel and a private channel: one used for application wide events and the other one allows messages to be routed to specific connections based on the server they belong to (avoiding workload on unrelated servers).
Good luck!
Most examples I have seen are are just small demo's and not full stack applications and they use websocket for messaging, but for any chat application there is more data then just messages...suppose like user profile, his contacts etc.
So should I use websockets for all communication between server and client or just use them for sending messages and do other things through http? If I am to use websocket for all communication how do url design of the app...since websockets don't have have any different urls like http.
You might be interested in WAMP, an officially registered WebSocket subprotocol that provides applications with WebSocket based
asynchronous, bidirectional remote procedure calls
real-time publish & subscribe notifications
Disclaimer: I am original author of WAMP and work for Tavendo.
Pretty sure you'll get the usual "it depends" answer, because, well, it depends!
If you are going to build a large application, to be used by a number of different clients in different network arrangements etc then I personally wouldn't recommend using WebSockets for everything. Why?
It's a new standard, so not all clients support it
In some network configurations WebSocket traffic may be filtered out, meaning you end up with no communications - not great
If you end up exposing an external API then HTTP is much better fitted for the job and will likely be easier to code against. There are a lot more tools out there to help you with it and styles that everyone is familiar with, like REST, to follow.
Use WebSockets when you require data being pushed from the server without the client having to poll for it, or when HTTP header overhead becomes a problem. And if you still decide to use it make sure you have a fallback mechanism (e.g. longpolling) so you don't end up with no comms.
I'm afraid I can't help you regarding WebSocket API design... given it's a new standard I don't believe the community has settled on anything just yet so you'll have to come out with your own message-based scheme.
Background: I am building a web app using NodeJS + Express. Most of the communication between client and server is REST (GET and POST) calls. I would typically use AJAX XMLHttpRequest like mentioned in https://developers.google.com/appengine/articles/rpc. And I don't seem to understand how to make my RESTful service being used for Socket.io as well.
My questions are
What scenarios should I use Socket.io over AJAX RPC?
Is there a straight forward way to make them work together. At least for Expressjs style REST.
Do I have real benefits of using socket.io(if websockets are used -- TCP layer) on non real time web applications. Like a tinyurl site (where users post queries and server responds and forgets).
Also I was thinking a tricky but nonsense idea. What if I use RESTful for requests from clients and close connection from server side and do socket.emit().
Thanks in advance.
Your primary problem is that WebSockets are not request/response oriented like HTTP is. You mention REST and HTTP interchangeably, keep in mind that REST is a methodology behind designing and modeling your HTTP routes.
Your questions,
1. Socket.io would be a good scenario when you don't require a request/response format. For instance if you were building a multiplayer game in which whoever could click on more buttons won, you would send the server each click from each user, not needing a response back from the server that it registered each click. As long as the WebSocket connection is open, you can assume the message is making it to the server. Another use case is when you need a server to contact a client sporadically. An analytics page would be a good use case for WebSockets as there is no uniform pattern as to when data needs to be at the client, it could happen at anytime.
The WebSocket connection is an HTTP GET request with a special header requesting the server to upgrade it to a WebSocket connection. Distinguishing different events and message on the WebSocket connection is up to your application logic and likely won't match REST style URIs and methods (otherwise you are replication HTTP request/reply in a sense).
No.
Not sure what you mean on the last bit.
I'll just explain more about when you want to use Socket.IO and leave the in-depth explanation to Tj there.
Generally you will choose Socket.IO when performance and/or latency is a major concern and you have a site that involves users polling for data often. AJAX or long-polling is by far easier to implement, however, it can have serious performance problems in high load situations. By high-load, I mean like Facebook. Imagine millions of people loading their feed, and every minute each user is asking the server for new data. That could require some serious hardware and software to make that work well. With Socket.IO, each user could instead connect and just indefinitely wait for new data from the server as it arrives, resulting in far less overall server traffic.
Also, if you have a real-time application, Socket.IO would allow for a much better user experience while maintaining a reasonable server load. A common example is a chat room. You really don't want to have to constantly poll the server for new messages. It would be much better for the server to broadcast new messages as they are received. Although you can do it with long-polling, it can be pretty expensive in terms of server resources.
I am to build a chat platform over Node.js, that in core, must be able to to provide chat screens 1-1, much like Olark provides
The chat update rate is not priority, but scalability and browser compatibility are.
My question is: Which back-end strategy and which way to transmit, would be best?
EDIT:
Thanks, #Brandon_R. It is just that I am not sure if websocket is the way to go here, I am between it and AJAX.
I want my server to be able to host multiple calls, and websocket do keep a open connection for each client; isn't it limiting?
Socket.io falls back on ajax polling/other transports if websockets are not available and is probably the way to go. You can also disable websockets/other transports if you prefer not to use them.
socket.io 0.8 also has support for "rooms" which will namespace and multiplex your sockets.
I want to use dotcloud with node.js + socket.io for realtime applications.
But they don't support websockets.
Will there be noticeable bandwidth or performance degradation by relying purely on fallbacks?
Is it worth it to use my own server? Linode or aws or whatnot.
Thanks.
I'm implementing an instant messaging system which depends completely on websocket. As the web is evolving quite fast and websocket was in the web standard, I decided to use flash websocket fallback for any browser that don't support it by default (Firefox, Opera). Here is what you may want to know:
I use websocket. I use a pure websocket server. I don't use any other protocols. I don't use socket.io. I must say that if you decide to use only websocket, you won't have benefit from socket.io lib, even the development time. It only adds unnecessary overhead to your server because of multiple transportation layers support.
At client side, I use websocket + flash websocket fallback which implements websocket specs using flash socket and I would say that there's no noticable difference. The only thing you should know that is due to the "same origin policy", you may need to serve flash socket policy request your own (run on port 843 by default) to allow the flash socket to connect in.
We're currently using private server because we have a dedicated sysadmin. However, it's better if you can just focus on doing what you intended to do, and not on unwanted things. Oh, and sometimes, it's better if you have complete control of your own server :-).
Hope it helps.