Is ReST over websockets possible?

I am planning to develop a web based chat application which takes in ReSTful requests, translate them to XMPP and deliver them to an XMPP server.

Using websockets for this kind of chat based application looked promising as the events (or responses) can be delivered asynchronously. But if I use websockets as the underlying protocol for transferring the requests from the browser, can this still be considered as a ReSTful design? If yes, how are the URIs, verbs (GET, POST...), parameters represented in the websocket message? Wrap them in an xml/json and send it?

Also, ReSTful architecture states that no session state will be stored on the server. But here in this case when an XMPP client session is created, the state of this session will be stored on the server (violating the stateless constraint)

REST is an architectural style that does not impose a protocol. So yes, you can do REST with Web Sockets, REST with HTTP and REST with FTP if you like.

The main reason to use HTTP is that it is easy and fairly simple to communicate with any component or programming language via HTTP and also because HTTP supports distributed environments with multiple intermediaries: proxies, firewalls...; So you can deploy your service on any topology and anyone will be able to access it.

My rant: If you are a RESTliban and Roy Fielding’s dissertation is the source of truth, verbs are never acknowledged as part of the semantic. URIs are the semantic. The usage of different verbs for different actions has been an elegant evolution of REST over HTTP, but not part of the "truth". You can check the scenario of rest over HTTP evaluated by Roy in chapter six of his dissertation. No mention to verbs. And notice it is an evaluation scenario, not the specification.

TLDR;

If you need realtime two way communications via the internet and the client is a web browser, the best choice is Web Sockets. You could then implement an application level protocol on top of web sockets to implement a RESTful Web Service.

Yes. You can use REST over WebSocket with library like https://github.com/wordnik/swaggersocket" > SwaggerSocket.

Why would you want to build a REST API on top of socket? IMHO the benefit of a REST API is to leverage standard HTTP protocol possibilities like stateless requests, semantic verbs like GET, DELETE to build an API that can be easily understood by (client) developers. Since sockets do not offer HTTP verbs and so on, you would build some kind of HTTP layer for sockets which is IMHO not reasonable.

In case you would really build such a thing, I'd recommend to use the HTTP protocol as a blueprint and implement the socket protocol like HTTP.

REST architectural style mostly presumes 2 entities viz. client and server.

As we move more towards real time web and development of reactive systems WebSocket would prominently start replacing usage of REST API's.

WS allows data push and pull which dismisses the concept of server and client.

STOMP,AMQP ,XMPP can be used as messaging protocols.

The data itself maybe JSON or Google protocol buffers or maybe Apache Avro.

WebSockets is not tied to web servers but can be developed in stand alone apps like mobile apps or desktop apps too.

I don't understand why you would convert XMPP into REST and then run REST over WS. The point of WebSocket is to take the XMPP protocol directly to the browser, thereby avoiding all of the translation issues.

There are JavaScript libraries that can talk XMPP from the browser to the server. All you need is to proxy the XMPP traffic from WS over into TCP and then straight into your XMPP server. Kaazing has a gateway that allows you to do this.

If you want to use open source, you will need to write a JavaScript XMPP library. There are examples that show how to write a JS library for simple protocols. You just have to find one and extend the concept to the XMPP protocol.

So to recap, here are the way the architecture would look:

Your XMPP Client code <-> XMPP JavaScript Library <-> WebSocket over http <-> WebSocket to TCP Proxy <-> XMPP Server

where the XMPP Client code and the XMPP JavaScript Library runs in the browser, and the WS to TCP proxy along with the XMPP server are all server-side.

I understand this post is really old, but wanted to interject a bit further on the notion that "So if I choose a REST architecture I forfeit the ability for real-time communications?".

In a word, no. A number of REST style implementations I have had experience with leverage REST for compatibility, discoverability, and as a means to scale across different devices in the shadow of IoT.

However, in addition to using WS in addition to REST to facilitate near real-time transmission. There are also a number of abstractions which really help with this and allow you to focus on building your API and deciding how the RT components of the consuming applications should operate.

I would suggest taking a look at things like Tibco Smart-Sockets, or SignalR if you're looking to build a REST API and would like to avoid re-creating the wheel for your RT needs.

I created a project that adds callbacks to the web socket send function: https://github.com/ModernEdgeSoftware/WebSocketR2

Message IDs are established so the client can implement callbacks. It handles message retries after timeouts as well as reconnects to the server if the connection gets dropped. You can then structure you payload to be as RESTful as you want by adding verbs and paths.

This is similar to when a video game studio uses UDP to achieve the speeds they need, but their net code implements a lot of TCP like features for reliability.

I just spot new topic on the blog of one company who providing cloud solution and "Server-end/Service as a Platform" (SaaS) for games.

I'm not advertising this company, nor I used them, so I don't even know how good or bad they are.

However, they very clearly explain reasons and what are the benefits of using WebSockets in REST Have a read on their blog