How to authenticate Salesforce using CL_HTTP_CLIENT

Hi experts,

I need to connect to Salesforce and for this I am thinkg of using CL_HTTP_CLIENT class. Salesforce uses 2 step authentication wherein it validates {username,pwd} and returns a token for further communication. But this class has only authenticate method and no response/token is received. Can you please let me know how to autheticate and connect to webservice in Salesforce using CL_HTTP_CLIENT. Also please let me know if there is any alternate method which can be achieved using ABAP without PI