Programming Amazon Web Services

Interfaces: REST and Query Versus SOAP

AWS infrastructure services are made available through three separate APIs: REST, Query, and SOAP. In this book we will focus only on the REST and Query APIs and will not demonstrate how to use the SOAP APIs. We have a number of reasons for doing this, reasons which will become clearer after a brief explanation of the differences between the interfaces.

REST interfaces

The REST interfaces offered by AWS use only the standard components of HTTP request messages to represent the API action that is being performed. These components include:

• HTTP method: describes the action the request will perform

• Universal Resource Identifier (URI): path and query elements that indicate the resource on which the action will be performed

• Request Headers: pieces of metadata that provide more information about the request itself or the requester

• Request Body: the data on which the service will perform an action

Web services that use these components to describe operations are often termed RESTful services, a categorization for services that use the HTTP protocol as it was originally intended.

Query interfaces

The Query interfaces offered by AWS also use the standard components of the HTTP protocol to represent API actions; however these interfaces use them in a different way. Query requests rely on parameters, simple name and value pairs, to express both the action the service will perform and the data the action will be performed on. When you are using a Query interface, ...