How do you create a Consume Rest Web Service with the POST Method that uses a message structure in a

I have been requested to create a Consume Rest Web Service with the POST Method.  The message structure for the Request and Response needs to be application/Json format.  The body of the message should be in the following format.  I am looking for an example of how to create this service operation and the peoplecode to publish the message. 

{"sysparm_quantity":"1","variables":{"u_first_name":"Bob", "u_last_name":"Smith", "u_edison_id":"ED987654321", "u_candidate_department":"STS", "u_reports_to":"Jimmy Dole", "u_location":"19", "u_effective_date":"09/30/2017 08:00:00", "u_title":"ITSM Specialist 4"}}