Methods

Methods are defined in the methods entry of a resource’s resource-model.

Only methods that are known to yada can appear in a resource’s definition. Each method corresponds to a type that extends the yada.methods.Method protocol. This design also makes it possible to add new methods to yada, as required.

The responsibility of each method type is to encode the semantics of the corresponding method as it is defined in HTTP standards, such as responding with the correct HTTP status codes (most other web frameworks delegate this responsibility to developers).

Some methods can be implemented entirely by yada itself (HEAD, OPTIONS, TRACE etc.). Most methods, however, delegate to some function or functions declared in the method’s declaration in the resource-model.

Method semantics, by method

Each HTTP method has defined semantics. Often these semantics are defined in the HTTP standards, other RFCs or, in the case of custom methods, by you.

These semantics are important because they allow other web agents, such as browsers and proxies, to inter-operate with your site.

Below is an explanation of the semantics for every method yada currently supports and your responsibilities should you choose to provide the method for a resource.

GET

Specify a function in :response that will be called during the GET method processing.

If the resource exists, the single-arity function will be called with the request context as its only argument.

It should return the response’s body, which should satisfy yada.body.MessageBody determining how exactly the response’s body will be returned.

{:methods
  {:*
    {:response (fn [ctx] …)}}}

Custom methods

Custom methods can be added by defining new types that extend the yada.methods.Method protocol.

BREW

BREW is an example of a custom method you might want to create, especially if you are building a networked coffee maker compliant with RFC.

(require '[yada.methods Method])

(deftype BrewMethod [])

(extend-protocol Method
  BrewMethod
  (keyword-binding [_] :brew)
  (safe? [_] false)
  (idempotent? [_] false)
  (request [this ctx] …))

Method semantics, by method

GET

PUT

POST

DELETE

HEAD

OPTIONS

TRACE

PATCH

Handling all methods

Custom methods

BREW