@mswaleh, I am working on something similar, but due to the Salesforce requirements, the logging in then retrieving the authorization token, etc., I am finding it easier to use an intermediate server running on Rackspace or Google. Expose the REST service there, then have it do the login to Salesforce and send the request to the REST service I exposed there.
In addition I don’t want the login information stored on the Spark or in the Spark cloud.
In the end I think it will be a lot more interesting once the Event’s are supported by Spark.