REST & WOA Wiki

In a Nutshell

In REST there are no objects or methods.  Instead, everything is a resource. Sometimes REST is also referred to as “resource-orientation.”  REST is designed to leverage intermediaries, which participate in the exchange.  By giving intermediaries more insight into the exchange, they can respond on behalf of the resource, short-circuiting communication and offloading the resource server.  For example in WOA, an application of REST to the Web, these intermediaries are corporate proxies or content delivery networks, such as Akamai.  REST also requires decoupling of knowledge between the resource and the agent acting upon it.  This separation of concerns is achieved by having a semantically rich representation to describe to the agent how it can act upon the resource and discover other resources.  For example in WOA, common representations are (X)HTML, Atom, and RDF.

In a RESTful system, an agent communicates with a resource using its location, a verb that describes the operation, and a representation of the desired state.  The resource location must be universally comprehensible and describe at most one resource.  In WOA, the location is a URI.  Intermediaries use the location to route the message, but also to determine if a cached response already exists.  This step would not be possible if the intermediary could not identify with certainty the resource in question.  Similarly, the operation verb is taken from a known vocabulary.  The verb tells intermediaries the nature of the exchange and if it invalidates existing information about the resource.  The verb does not tell what the effect of the exchange will be, only that there might be one, if any.  In WOA, the verbs correspond to the HTTP methods GET, POST, PUT and DELETE.

The representation of the resource must instruct the agent how it can act upon the resource.  For example in WOA, HTML <form> elements are used to describe how new requests are constructed, what parameters to submit, and where to submit them to.  This enables the resource author to modify the set of parameters, how they are embedded into a request, or where they are sent to without requiring a change in the agent.  This level of decoupling enables independent evolution of agent and resource while maintaining compatibility.