What is the "accept" part for?

Question

When connecting to a website using Net::HTTP you can parse the URL and output each of the URL headers by using #.each_header. I understand what the encoding and the user agent and such means, but not what the "accept"=>["*/*"] part is. Is this the accepted payload? Or is it something else?

require 'net/http'

uri = URI('http://www.bible-history.com/subcat.php?id=2')
http://www.bible-history.com/subcat.php?id=2>
http_request = Net::HTTP::Get.new(uri)
http_request.each_header { |header| puts header }

# => {"accept-encoding"=>["gzip;q=1.0,deflate;q=0.6,identity;q=0.3"], "accept"=>["*/*"], "user-agent"=>["Ruby"], "host"=>["www.bible-history.com"]}

Answer 1

From https://www.w3.org/Protocols/HTTP/HTRQ_Headers.html#z3

This field contains a semicolon-separated list of representation schemes ( Content-Type metainformation values) which will be accepted in the response to this request.

Basically, it specifies what kinds of content you can read back. If you write an api client, you may only be interested in application/json, for example (and you couldn't care less about text/html).

In this case, your header would look like this:

Accept: application/json

And the app will know not to send any html your way.

Answer 2

Using the Accept header, the client can specify MIME types they are willing to accept for the requested URL. If the requested resource is e.g. available in multiple representations (e.g an image as PNG, JPG or SVG), the user agent can specify that they want the PNG version only. It is up to the server to honor this request.

In your example, the request header specifies that you are willing to accept any content type.

The header is defined in RFC 2616.