Why does Salesforce OAuth2 redirect me from one instance na3 for ex to another na9

Question

I am trying to build a web app that lets the customer add demo data to any Salesforce instance. My demo builder uses OAuth 2 Authorization Code Grant.

I am trying to get the switch instance portion working. However once the user connects to one instance

GET /services/oauth2/authorize?response_type=code&client_id=blabla.UKP&redirect_uri=https%3A%2F%2Fsfblademo.bla.com%2Foauth%2Fcallback HTTP/1.1 Host: na9.salesforce.com Connection: keep-alive User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_1) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/15.0.874.12 Safari/535.2 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8 Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 Cookie: cookie_bla; disco=5:00D50000000Ii39:00550000001ifEp:0|; autocomplete=1; inst=APP5

It redirects to the previous instance. Seems like its reading cookies and redirecting

HTTP/1.1 302 Found Server: Location: https://na3.salesforce.com/setup/secur/RemoteAccessAuthorizationPage.apexp?source=blablablaContent-Type: text/html Content-Length: 525 Date: Fri, 16 Sep 2011 21:46:58 GMT

The URL has moved here

Is there a way to sign out or clear the cookies salesforce has. I am not running my app on salesforce.

Thanks !

Answer 1

The API logout() call isn't going to work because that will only invalidate the API session and not the UI session stored in the browser cookie on the *.salesforce.com domain, to which your app won't have direct access. That's not to say it isn't still recommended, but to clarify that UI cookie, you'll need to redirect the end-user to /secur/logout.jsp on the instance_url of the previous session. To make it transparent to end-users, you can load it in a hidden iframe like this:

<iframe src='https://{instance_url}/secur/logout.jsp' width='0' height='0' style='display:none;'></iframe>

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