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package.json is a simple tracking mechanism for transport statistics.


Websockets and various Comet style fallbacks create the ability for the server to push data to web clients, enabling a whole new catagory of realtime applicaitons. However each transport (e.g websocket, flashsocket, xhr-polling) comes with it's own advantages and disadvantages. For example, websockets are arguably the most efficient transport but their use can be riddled with network related issues such as incompatability with proxies, firewalls, etc. was created to better understand the characteristics of the transports leveraged by to make more informed decisions as to what transports to support in your applications.

My hope is that through community, we can generate enough diverse test data to more accurately assess the sitution.


The probe test can be run directly or embedded into any web page with a single line javascript include like this:

<script src="" type="text/javascript" defer="defer"></script>

The probe will attempt to run the following transports in your browser:

'websocket', 'xhr-polling', 'flashsocket', 'htmlfile', 'jsonp-polling'

In most cases, will only attempt to run a subset of this list for each browser based on feature detection and browser capabilities.

The probe captures the following data:

  • time to connect
  • time to disconnect
  • average rount trip time (RTT) to send a ping and pong messages, client -> server, server -> client
  • time to push 10 small messages serially from server -> client
  • total time of the test
  • browser user agent details
  • client IP (to be used in the future to estimate geographical physical distance from client to server)

Note IE6 is not supported

Data and Statistics

The probe publishes it's results back to the server via an image beacon. These results are currently being stored in CouchDB database, generously hosted by IrisCouch for free. All of the data is open and accessible, and through Couch, you can easily replicate the data as well.

Basic aggregate statistics can be viewed here.


  • Calculate estimated geographical distance
  • Improve error detection when transports fail
  • Additional charts
  • Add a more real world scenario to the probe tests
  • Track transport selection and fallback attempts.