Do and donts on REST

Today I have found an amazing REST do and donts list of StackOverFlow:

General principles for good URI design:

• Don't use query parameters to alter state
• Don't use mixed-case paths if you can help it; lowercase is best
• Don't use implementation-specific extensions in your URIs (.php, .py, .pl, etc.)
• Don't fall into RPC with your URIs
• Do limit your URI space as much as possible
• Do keep path segments short
• Do prefer either /resource or /resource/; create 301 redirects from the one you don't use
• Do use query parameters for sub-selection of a resource; i.e. pagination, search queries
• Do move stuff out of the URI that should be in an HTTP header or a body (Note: I did not say "RESTful URI design"; URIs are essentially opaque in REST.)

General principles for HTTP method choice:

• Don't ever use GET to alter state; this is a great way to have the Googlebot ruin your day
• Don't use PUT unless you are updating an entire resource
• Don't use PUT unless you can also legitimately do a GET on the same URI
• Don't use POST to retrieve information that is long-lived or that might be reasonable to cache
• Don't perform an operation that is not idempotent with PUT
• Do use GET for as much as possible
• Do use POST in preference to PUT when in doubt
• Do use POST whenever you have to do something that feels RPC-like
• Do use PUT for classes of resources that are larger or hierarchical
• Do use DELETE in preference to POST to remove resources
• Do use GET for things like calculations, unless your input is large, in which case use POST

General principles of web service design with HTTP:

• Don't put metadata in the body of a response that should be in a header
• Don't put metadata in a separate resource unless including it would create significant overhead
• Do use the appropriate status code

201 Created after creating a resource; resource must exist at the time the response is sent

202 Accepted after performing an operation successfully or creating a resource asynchronously

400 Bad Request when someone does an operation on data that's clearly bogus; for your application this could be a validation error; generally reserve

500 for uncaught exceptions

401 Unauthorized when someone accesses your API either without supplying a necessary Authorization header or when the credentials within the Authorization are invalid; don't use this response code if you aren't expecting credentials via an Authorization header.

403 Forbidden when someone accesses your API in a way that might be malicious or if they aren't authorized

405 Method Not Allowed when someone uses POST when they should have used PUT, etc

413 Request Entity Too Large when someone attempts to send you an unacceptably large file

418 I'm a teapot when attempting to brew coffee with a teapot

Do use caching headers whenever you can

• ETag headers are good when you can easily reduce a resource to a hash value

• Last-Modified should indicate to you that keeping around a timestamp of when resources are updated is a good idea

• Cache-Control and Expires should be given sensible values

• Do everything you can to honor caching headers in a request (If-None-Modified, If-Modified-Since)

*Do use redirects when they make sense, but these should be rare for a web service

SOURCE: http://stackoverflow.com/questions/1619152/how-to-create-rest-urls-without-verbs/1619677#1619677