Prepares to subscribe an endpoint by sending the endpoint a confirmation message.
            
 Declaration Syntax
 Declaration Syntax| C# | 
public SubscribeResponse Subscribe( SubscribeRequest request )
 Parameters
 Parameters- request (SubscribeRequest)
- Subscribe request
 Return Value
 Return ValueSubscribe  Response from the service
 Remarks
 Remarks
            To actually create a subscription, the endpoint owner must call the ConfirmSubscription
            action with the token from the confirmation message. Confirmation tokens are valid for three days.