POST /api/2.0/authentication.json HTTP/1.1
Host: portal.onlyoffice.com
Accept: application/json,application/xml
Accept-Encoding: gzip, deflate
userName=yourusername&password=yourpassword

HTTP/1.1 200 Ok
Cache-Control: private
Content-Type: application/json; charset=utf-8
{
    "count": 0,
    "startIndex": 0,
    "status": 0,
    "response": {
    "token": "sdjhfskjdhkqy739459234",
    "expires": "2013-01-13T16:35:42.7564317+04:00"
    }
}