I'm having a hard time understanding the authentication model for the Exact Target APIs. The REST API requires a clientId and a clientSecret to obtain an access token for subsequent requests. Yet the SOAP API requires a username and password. I did see this regarding passing the token as a SOAP Header, but it doesn't work. It ALWAYS fails with soap:Server: "Unplanned Outage". Passing a username/password in a SOAP header and the API calls work fine.
First question, is someone able to explain the authentication disparity between the two APIs? Second question, does the method of passing the oauth token in a SOAP header not work?