accept header in HTTP request

Question

I am trying to learn web services in general and have a small doubt.

When HTTP request is sent, if I mention a particular format (for example JSON) in Accept header and suppose server does not support that format, then will it be a network call error or server will still respond with whatever format it supports?

I know while sending a POST request, client sends another header by name "Content Type" and if that format is not supported by server, then it responds back with 415 error. (unsupported media type).

Answer 1

It's up to the server. It does not need to pay attention to the Accept header field.

A request without any Accept header field implies that the user agent will accept any media type in response. If the header field is present in a request and none of the available representations for the response have a media type that is listed as acceptable, the origin server can either honor the header field by sending a 406 (Not Acceptable) response or disregard the header field by treating the response as if it is not subject to content negotiation.

(from https://www.greenbytes.de/tech/webdav/rfc7231.html#rfc.section.5.3.2.p.7 )

Answer 2

For web services, the server will be responsible to denote the type of format that it intends to support, whether it is using JSON or XML.

Based on the data received from the client, the server should validate the format provided by the client. If it fits the specified format, then the server will respond accordingly to the intend of the end point. On the other hand, if it doesn't fit, the server should respond gracefully, indicating that the format (JSON/XML) is not supported by the web services.

I hope that answers your question. Have a nice day!