HTTP Verbs

Question 1

HTTP GET

Answer 1

Use GET requests to retrieve resource representation/information only – and not modify it in any way

Additionally, GET APIs should be idempotent. Making multiple identical requests must produce the same result every time until another API (POST or PUT) has changed the state of the resource on the server.

Examples
HTTP GET http://www.appdomain.com/users
HTTP GET http://www.appdomain.com/users?size=20&page=5
HTTP GET http://www.appdomain.com/users/123
HTTP GET http://www.appdomain.com/users/123/address

Question 2

HTTP GET Response Codes

Answer 2

If the resource is found on the server, then it must return HTTP response code 200 (OK) – along with the response body, which is usually either XML or JSON content (due to their platform-independent nature)

In case the resource is NOT found on the server then API must return HTTP response code 404 (NOT FOUND).

Similarly, if it is determined that the GET request itself is not correctly formed then the server will return the HTTP response code 400 (BAD REQUEST).

Question 3

HTTP Post

Answer 3

When talking strictly about REST, POST methods are used to create a new resource into the collection of resources.
Use POST APIs to create new subordinate resources, e.g., a file is subordinate to a directory containing it or a row is subordinate to a database table.
Please note that POST is neither safe nor idempotent, and invoking two identical POST requests will result in two different resources containing the same information (except resource ids)

Question 4

HTTP Post Response Code

Answer 4

Many times, the action performed by the POST method might not result in a resource that can be identified by a URI. In this case, either HTTP response code 200 (OK) or 204 (No Content) is the appropriate response status.

Question 5

HTTP Post Examples

Answer 5

HTTP POST http://www.appdomain.com/users
HTTP POST http://www.appdomain.com/users/123/accounts

Question 6

HTTP Put

Answer 6

Use PUT APIs primarily to update an existing resource (if the resource does not exist, then API may decide to create a new resource or not).

Question 7

HTTP Put vs Post

Answer 7

The difference between the POST and PUT APIs can be observed in request URIs. POST requests are made on resource collections, whereas PUT requests are made on a single resource.

HTTP PUT http://www.appdomain.com/users/123
HTTP PUT http://www.appdomain.com/users/123/accounts/456

HTTP POST http://www.appdomain.com/users
HTTP POST http://www.appdomain.com/users/123/accounts

Question 8

HTTP Put Response Codes

Answer 8

If a new resource has been created by the PUT API, the origin server MUST inform the user agent via the HTTP response code 201 (Created) response.

If an existing resource is modified, either the 200 (OK) or 204 (No Content) response codes SHOULD be sent to indicate successful completion of the request.

Question 9

HTTP Delete

Answer 9

As the name applies, DELETE APIs delete the resources (identified by the Request-URI).

DELETE operations are idempotent. If you DELETE a resource, it’s removed from the collection of resources.

Some may argue that it makes the DELETE method non-idempotent. It’s a matter of discussion and personal opinion.

Question 10

HTTP Delete Response Codes

Answer 10

A successful response of DELETE requests SHOULD be an HTTP response code 200 (OK) if the response includes an entity describing the status.
The status should be 202 (Accepted) if the action has been queued.
The status should be 204 (No Content) if the action has been performed but the response does not include an entity.
Repeatedly calling DELETE API on that resource will not change the outcome – however, calling DELETE on a resource a second time will return a 404 (NOT FOUND) since it was already removed.

Question 11

HTTP DELETE Example

Answer 11

HTTP DELETE http://www.appdomain.com/users/123
HTTP DELETE http://www.appdomain.com/users/123/accounts/456