rest/urls

Jump to: navigation, search

Contents

URL Conventions

These are the recommended conventions for RESTful URLs, based on work pioneered by Ruby on Rails, which again is closely modelled over Atompub . Following these conventions for both HTTP method names and URL construction will allow your application to be consumed by ActiveResource, Jester, and other RESTful clients. Note that Rails 1.x used ";edit" and ";new" in place of the simpler "/edit" and "/new" recommended going forward.

Methods

One of the key aspects of REST is using the HTTP Verbs to implement the standard Create-Retrieve-Update-Delete (CRUD) database semantics. The primary ones are:

POST
Create a resource within a given collection
GET
Retrieve a resource
PUT
Update a resource
DELETE
Delete a resource

Most browsers do not currently support PUT and DELETE (HTML forms only allow "get" and "post", links are always "get"). The other methods can be emulated by providing a "method" parameter with a value of "PUT" and "DELETE", respectively.

Routing

The principal unit of operation is the "collection", which typically corresponds to a database table or (in Rails) an ActiveRecord class. For a collection named "people", the primary routes would be:

Operate on the Collection

GET /people
return a list of all records
GET /people/new
return a form for creating a new record
POST /people
submit fields for creating a new record

Operate on a Record

GET /people/1
return the first record
DELETE /people/1
destroy the first record
POST /people/1?_method=DELETE
alias for DELETE, to compensate for browser limitations
GET /people/1/edit
return a form to edit the first record
PUT /people/1
submit fields for updating the first record
POST /people/1?_method=PUT
alias for PUT, to compensate for browser limitations

Follow a Relationship

GET /people/1/phones
return the collection of phone numbers associated with the first person
GET /people/1/phones/23
return the phone number with id #23 associated with the first person
GET /people/1/phones/new
return a form for creating a new phone number for the first person
POST /people/1/phones/
submit fields for creating a new phone number for the first person

Invoke Custom Actions

It isn't always possible to map everything into CRUD. Thus, there is also a syntax for specifying custom actions:

POST /people/1/promote
run the "promote" action against the first record

These should be used sparingly, as they are unlikely to be supported by most clients.

File Formats

Data types are extremely important in REST. While it is ideal to specify the appropriate MIME type as an HTTP header, developers are encouraged to follow Rails in allowing extension-based typing, e.g.:

HTML

GET /people/1
return the first record in HTML format
GET /people/1.html
return the first record in HTML format

XML

GET /people/1.xml
return the first record in XML format

JSON

GET /people/1.json
return the first record in JSON format

While the JSON mapping should be trivially obvious, the best practice for XML is to:

  1. use the column name as the element name
  2. include an appropriate "type" field

See the Highrise reference for an example of how this works in practice.

Response Codes

Another important aspect of REST is returning the appropriate HTTP Response Codes. Some common ones are:

Successful

200 OK
The request has succeeded.
201 Created
The request has been fulfilled and resulted in a new resource being created. The newly created resource can be referenced by the URI(s) returned in the entity of the response, with the most specific URI for the resource given by a Location header field.
204 No Content
The server has fulfilled the request but does not need to return an entity-body, and might want to return updated metainformation.

Redirection

303 See Other
The response to the request can be found under a different URI and SHOULD be retrieved using a GET method on that resource. This method exists primarily to allow the output of a POST-activated script to redirect the user agent to a selected resource.

Client Error

400 Bad Request
The request could not be understood by the server due to malformed syntax.
401 Unauthorized
The request requires user authentication. The response MUST include a WWW-Authenticate header field (14.47) containing a challenge applicable to the requested resource.
404 Not Found
The requested resource could not be found(section 10.4.5).
405 Method Not Allowed
The method specified in the Request-Line is not allowed for the resource identified by the Request-URI. The response MUST include an Allow header containing a list of valid methods for the requested resource.
422 Unprocessable Entity
The server understands the media type of the request entity, but was unable to process the contained instructions.

Examples in the Wild

Ruby

PHP

Perl

Java

Python

JavaScript

rest/urls was last modified: Thursday, May 7th, 2009

Views