Fetch

Plan

Fetch is fetch.spec.whatwg.org and will define HTML fetch and CORS as a set of coherent algorithms rather than the intertwined mess we have now. It will also deal with the following:

• Deal with authentication (URLs containing username/password, servers responding with 401)
• Deal with URL processing
• Define HTTP context for data: URLs, about:blank, and file: URLs.
• Progress Events

Model

The basic model is Request -> Fetch -> Response.

Request

• Parsed URL (object)
• method (probably with restrictions as seen in XHR)
• UA headers
• author headers (maybe rename because people get upset with "author", with implicit restrictions as seen in XHR / CORS)
• entity body
• origin (object)
• referrer source (Document / URL)
• manual redirect flag
• omit credentials flag (will replace HTML fetch block cookies flag but also has other features)
• force preflight flag (set for upload progress notifications (to not reveal existence of server in case of POST I suppose; see bug 20322))
• synchronous flag
• force same-origin flag (looks identical to No CORS, fail, filed bug 20951)
• CORS mode
  • No CORS, taint (<link>, <script>, ...); still need to allow the server to opt in to CORS anyway to effectively make the resource CORS same-origin even if not requested as such (HTML does not have this feature
  • No CORS, fail (<track>)
  • Anonymous
  • Credentialed

Fetch

Have a case-switch on URL scheme. See also URL. Fetch results in a network error response unless the scheme is one of

• http / https
  • CORS only has an effect here.
  • Might result in nested Request -> Fetch -> Response chains due to redirects and CORS.
• ftp
  • This is legacy, but still works.
• file
  • This is by and large platform-specific.
• about
  • See URL schemes.
• data
  • Response object as per http://xhr.spec.whatwg.org/#data:-urls-and-http except that failing to parse needs to be added.
• blob
  • http://dev.w3.org/2006/webapi/FileAPI/#processingModel

Response

Both intermediate updates (progress, headers received, ...) and final. Also indicates network error / CORS error (exposed as network error), ...