Adobe esign service access token

Hoi,

I am trying to use adobe esign service rest api, as listed in https://secure.na1.echosign.com/public/docs/restapi/v5​ , an access token is required for rest api call. Because we are using the rest api in our java backend service implementation, we want to implement it without user interaction. So no user login /redirec etc. Is it possible to retrieve an access token or some api key for the rest api programmally

thanks in advance