Invoke external authentication service for login

Hi ,  I'm new to the platform . I want to create a login page where my authentication service is invoked on clicking login. Validation of the user and password is done by the external service. I have used a REST call action in a micro flow to achieve this. But I want to pass user name and password as dynamic parameters. Where should I store the username and password and how to pass them dynamically. Also how to design the form so that is reads the input values. 
1 answers


Maybe its worth to take a look at the Appstore in the category Authentication