Authenticates a User using a username and password, and returns its unique identifier on success.
| Method | /sites/{company-id}/ws/soap_v1.svc/AuthenticateUser | 
The request body is of type AuthenticateUser.
| Name | Description | Data Type | 
|---|---|---|
| userName | xml:string | |
| password | xml:string | 
|  | 
The response body is of type AuthenticateUserResponse.
| Name | Description | Data Type | 
|---|---|---|
| AuthenticateUserResult | guid | 
|  | 
 |