Examples

a place to experiment and learn

Installation

Create a .env file in the root of the project. (Note the .gitignore file keeping .env files out of source control)

Streaming Server Example

Add this line to your .env file:

TIME_ON_THE_ROAD_VARIANCE=10

Usage

Open a console and navigate to the root of the project. Type:

thin start -R StreamingServerConfig.ru -p 3000

(Ctrl+C followed by Y to interrupt the server)

Open up the WebSocketsClient.html to test

WebSockets chat example using redis

Credit: https://gist.github.com/ahaedike/a7f35c0bb9cc40fdc48e

Start up Redis I am using redis-server.exe on Windows. To set up download redis-2.4.6-setup-32-bit.exe from https://github.com/rgl/redis/downloads

ruby redis_pubsub_demo.rb

Open up RedisPubsubChatClient.html in multiple browser tabs or windows to see it in action

Millsey_cycle_spambot

Credit: http://stackoverflow.com/questions/7772057/read-file-in-eventmachine-asynchronous

An Event Machine driven web sockets client that reads the GPS positions from a CSV file and sends them up to our cloud chat example where subscribes can see them as they came in (by default this is sped up by a factor of ten). The client also subscribes to the updates so you'll see them come back as well as go up.

Event Machine uses the Reactor Pattern. You'll probably get confused if you don't do at least some reading up on this pattern and the implications of blocking. To illustrate the point study the

EM.add_timer(time_to_wait/SPEED_UP_FACTOR) do
  ...
end    

block and consider the implication of replacing the delay with

sleep(time_to_wait/SPEED_UP_FACTOR) 

In itself this example is not particularly exciting. In the next example we'll replace the web chat client with a map dynamically updating with the position.

One point to note in the dataset is that there are some relatively long delays in logging a GPS position. We'll need to investigate these in the Android app to see what caused these.

Note that this example uses Pravigo::Duration which is based on ActiveSupport::Duration and will do some of the heavy lifting around durations in future examples and apps.

You can amend the following self-explanatory environment variables to run locally:

CYCLIST_HANDLE=Millsey
SPEED_UP_FACTOR=10
WEBSOCKETS_SERVER_ADDRESS=wss://pravigo-chat.herokuapp.com/
FILENAME=2015Jul12.csv

To run:

ruby millsey_cycle_spambot.rb

Contributing

Whoever tries this first please add the gem install notes to this README and delete this line. Cheers

Otherwise standard procedure:

1. Fork it ( http://github.com/pravigo/examples/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request