S3 REST API PUT POST method

Question

I ve manged to sign in  with AWS S3 Rest API. When I use correct REST verb for creating resource, namely POST, I encounter this error '405 method not allowed'. Same request works fine with method PUT and creates resource.

Am I doing something wrong?

Answer 1

This where I feel is the problem lies that is while mapping CRUD to HTTP methods.

Understand this, POST may not be the best method to create resource. This is because semantics of other methods are determined by the HTTP protocol, but the semantics of POST are determined by the target media type itself. 

POST is used for creation, but can be used for updates.  It's wrong to use POST for retrieval, since you have GET standardized for that, but it's fine to use POST for creating a resource when the client can't use PUT for some reason.

PUT on the other hand is not the "correct method for updating resource". 

PUT is the method used to replace a resource completely, ignoring its current state. It's not right to use PUT for partial updates, because you're asking for the server to consider the current state of the resource. PATCH is the method to do that.

These are the definitions:

• POST: Takes in data, applies it to the resource identified by the given URI, here the rules you documented for the resource media type are followed.

• PUT: It will replace whatever is identified by the given URI with this data, and ignore whatever is in there already, if anything.

• PATCH: if the resource identified by the given URI still has the same state it had the last time, apply this diff to it.

It is possible to create with POST and PUT, but not PATCH, because it is dependent on current state. You can update with any of them, but with PATCH you have an update conditional to the state you want to update from, with PUT you update by replacing the whole entity, so it's an idempotent operation, and with POST you ask the server to do it according to predefined rules.

Answer 2

From the http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html

POST:

The posted entity is subordinate to the URI in the same way that a file is subordinate to a directory containing it, a news article is subordinate to a newsgroup to which it is posted, or a record is subordinate to a database

The action performed by the POST method might not result in a resource that can be identified by a URI. In this case, either 200 (OK) or 204 (No Content) is the appropriate response status, depending on whether or not the response includes an entity that describes the result

If a resource has been created on the origin server, the response SHOULD be 201 (Created)

PUT:

The PUT method requests that the enclosed entity be stored under the supplied Request-URI. If the Request-URI refers to an already existing resource, the enclosed entity SHOULD be considered as a modified version of the one residing on the origin server. If the Request-URI does not point to an existing resource, and that URI is capable of being defined as a new resource by the requesting user agent, the origin server can create the resource with that URI. If a new resource is created, the origin server MUST inform the user agent via the 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

Answer 3

The HTTP methods POST and PUT, they both serve a different purpose. It's quite possible, valid and even preferred in some occasions, to use PUT to create resources, or use POST to update resources.

Use PUT when you can update a resource completely through a specific resource.

If you do not know the actual resource location, for instance, when you add a new article, but do not have any idea where to store it, you can POST it to an URL, and let the server decide the actual URL.

Answer 4

The POST verb is most-often utilized to **create** new resources. In particular, it's used to create subordinate resources.

PUT is most-often utilized for **update** capabilities, PUT-ing to a known resource URI with the request body containing the newly-updated representation of the original resource.