vw-server

A node wrapper around vowpal_wabbit that provides a more accessible server.

Quickstart

• Install vw
• Download vw-server: $ git clone git@github.com:yhat/vw-server.git
• Install vw-server: $ npm install -g
• Start the server!

$ vw-server

Data Structure

• features - Data you're using to predict a label. Needs to be a key/value. The features are not order dependent (vw remembers the names), so be sure to maintain consistent feature names.
• label - Result/Outcome you're trying to predict.

Training Data

{
  "features": {
    "x": 1,
    "y": 2,
    "z": 4
  },
  "label": 1
}

Prediction Data

{
  "features": {
    "x": 1,
    "y": 2,
    "z": 4
  }
}

Endpoints

There are 2 ways to interact with vw-server: REST and WebSockets. Both accept the same basic data structure, so it's a matter of personal preference as to which one you use.

REST

/train

$ curl -X POST -d '{"features": {"x": 1, "y": 2}, "label": 1 }' localhost:3000/train
$ curl -X POST -d '{"features": {"x": 0, "y": 1.5}, "label": 2 }' localhost:3000/train
$ curl -X POST -d '{"features": {"x": 1, "y": 1.7}, "label": 1 }' localhost:3000/train

/predict

$ curl -X POST -d '{"features": {"x": 1, "y": 2}}' localhost:3000/predict
$ curl -X POST -d '{"features": {"x": 0, "y": 1.5}}' localhost:3000/predict
$ curl -X POST -d '{"features": {"x": 1, "y": 1.7}}' localhost:3000/predict

WebSockets

train

var socket = io.connect();

# sending to the server
socket.emit("train", {"x": 1, "y": 2}, "label": 0});
socket.emit("train", {"x": 1, "y": 4}, "label": 1});
// coming back from the server
socket.on("train", function(data) {
  console.log(data);
});

predict

var socket = io.connect();
// sending to the server
socket.emit("predict", {"x": 1, "y": 2});
socket.emit("predict", {"x": 1, "y": 4});
// coming back from the server
socket.on("predict", function(data) {
  console.log(data);
});

Tuning vw

You can pass arguemnts to vw-server the same as you would with vw.

$ vw-server --csoaa 3
$ vw-server --adaptive

Misc

You can set the port by using an environment variable:

$ export PORT=5000
$ vw-server
# starting vw:
#   vw --adaptive --normalized -p /dev/stdout
# listening on port 5000