Content Negotiation: Difference between revisions
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# If there are common formats left, the server picks the one the client marked with the highest priority. | # If there are common formats left, the server picks the one the client marked with the highest priority. | ||
# The server then returns the content that matches the negotiated format. | # The server then returns the content that matches the negotiated format. | ||
== Wildcards == | |||
Sometimes clients want to specify general classes that they accept. This can be done by using a <code>*</code>. This allows clients to request things like imge types: (<code>image/*</code>), or anything at all: (<code>*/*</code>) | |||
== Content-Language Negotiation == | == Content-Language Negotiation == | ||
Aside from negotiating the [[Content-Type Header | Content-Type]] of the response, HTTP also allows clients to negotiate the language of the returned data. This is done in the same way as above but then with the [[Accept-Language Header]]. | Aside from negotiating the [[Content-Type Header | Content-Type]] of the response, HTTP also allows clients to negotiate the language of the returned data. This is done in the same way as above but then with the [[Accept-Language Header]]. | ||
Revision as of 07:11, 15 January 2021
A main feature of the HyperText Transfer Protocol (HTTP) is that it allows clients and servers to negotiate what kind of formats both support. They do this using the Accept Header.
This allows implementation of APIs that are Backwards Compatible using Content Negotiation Versioning. Additionally this feature can be used to serve modern image and video formats to clients that indicate support for it.
Mechanism
- When a client makes a request to a server it supplies all the formats it supports in the Accept Header:
Accept: text/html,application/xhtml+xml. - The server looks at the list the client sent and excludes all formats it does not support.
- If there are no common formats, the server either responds with 406 Not Acceptable or it picks a fallback format like
text/html. - If there are common formats left, the server picks the one the client marked with the highest priority.
- The server then returns the content that matches the negotiated format.
Wildcards
Sometimes clients want to specify general classes that they accept. This can be done by using a *. This allows clients to request things like imge types: (image/*), or anything at all: (*/*)
Content-Language Negotiation
Aside from negotiating the Content-Type of the response, HTTP also allows clients to negotiate the language of the returned data. This is done in the same way as above but then with the Accept-Language Header.