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corsmicrosoft-translator

CORS support for Microsoft Azure Translate API?

This is a question related to https://social.msdn.microsoft.com/Forums/en-US/6e856136-9a39-4b98-a53d-7f8bce08e3a6/cors-support-for-bing-translate-api

Does the Microsoft Azure Translate API support CORS now?

Solution

  • The Microsoft Translator Text API appears to at least minimally now support CORS, in that it does at least seem to send the Access-Control-Allow-Origin header in responses:

    $ curl -i -H 'Origin: http://example.com' \
  'https://api.microsofttranslator.com/v2/http.svc/Translate?appid=foo&text=hello&from=en&to=de'

HTTP/1.1 400 Bad Request
Content-Length: 220
Content-Type: text/html; charset=utf-8
Access-Control-Allow-Origin: *
Access-Control-Allow-Headers: X-MS-Trans-Info
X-MS-Trans-Info: 0642.V2_Rest.Translate.4E779D02
Date: Wed, 30 Aug 2017 09:07:34 GMT

<html><body><h1>Argument Exception</h1><p>Method: Translate()</p><p>Parameter: appId</p><p>Message: Invalid appId&#xD;
Parameter name: appId</p><code></code><p>message id=0642.V2_Rest.Translate.4E779D02</p></body></html>

    I don’t personally have a valid appid to test with—but if you do, I think you’ll find it’ll work:

    If may also work for the https://docs.microsofttranslator.com/text-translate.html POST endpoints—as long as your requests don’t use the Authorization request header or set a Content-Type.

    The problem with those headers is, they’ll trigger browsers to do a preflight OPTIONS request:

    https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS#Preflighted_requests

    And the problem with making calls to those API endpoints that trigger a preflight is, they don’t seem to respond to OPTIONS requests in a way that’ll cause browsers to see the preflight as a success.

    At https://docs.microsofttranslator.com/text-translate.html#!/default/post_TranslateArray I notice the docs say that endpoint expects a POST with an application/xml or text/xml Content-Type, so if that endpoint doesn’t respond to preflight OPTIONS in the right way, that one won’t work.

    That’s because adding an Content-Type: application/xml or Content-Type: text/xml header to a request will definitely trigger browsers to do a preflight OPTIONS before the POST.