CODEWITHSUNDEEP
javascripthtmlwebsocketraspberry-pipush
os x nerd
os x nerd

Reputation: 927

Pushing data from a server to Web based UI elements

I want to connect a bunch of weather sensors to a Raspberry PI. Writing the daemon that reads the sensors and writes the data to a database will be the easy part since I'm a systems programmer. I also want a simple cross platform UI for this device so I'd like to set my Raspberry Pi up as a WIFI hotspot that people can connect to and then just entering a URL like 'weather.local' into a browser which would take them to a web page where the weather sensor data is continually updated. I.e. I want the sensor daemon to 'push' updates to the web page.

The problem is that I'm no web developer. The solutions I can think of off the top of my head are:

  1. Flash, which is out because I want this to work on mobile browsers.
  2. Using Java script and hanging HTTP requests to a web service.
  3. HTML5 socket.io which is presumably the same as WebSocket.

If I go with option (2) even if it's a kind of polling, I'll have to incorporate some form of HTTP server into my sensor daemon and I have a fair idea of how to code that. My question, however, regards the HTML5 socket IO. Can I use this to connect directly to a TCP/IP binary socket or do I need a server side WebSocket library? Also how widely is HTML5 socket.io/WebSocket implemented on mobile browsers?

Upvotes: 0

Views: 1105

Answers (1)

Touffy
Touffy

Reputation: 6561

WebSocket always begins with an upgrade handshake over HTTP, so you do need to have basic HTTP capability. It's simple enough that you can hand-code it.

WebSockets is basically supported by all modern browsers. It is not used that widely because it's a pain to set up on traditional HTTP servers and messes up with many proxies, but that's not a problem for you. As long as the client is a recent version of anything, it'll work.

A note about option 2: browsers have a native implementation of it — that means you don't need so much JavaScript on the client. You just create the EventSource object and listen to its events.

Upvotes: 1

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