Using Query Requests to Call Amazon EMR APIs

Query requests are HTTP or HTTPS requests that use the HTTP verb GET or POST and a Query parameter named Action or Operation that specifies the API you are calling. Action is used throughout this documentation, although Operation is also supported for backward compatibility with other AWS Query APIs.

Calling the API using a Query request is the most direct way to access the web service, but requires that your application handle low-level details such as generating the hash to sign the request, and error handling. The benefit of calling the service using a Query request is that you are assured of having access to the complete functionality of the API.

	Note
	The Query interface used by AWS is similar to REST, but does not adhere completely to the REST principles.