Develop Integrations with Web Services | APIs

Has anyone figured out silent login of Acumatica user? We should be able to pass the user id and pwd to specific URL and auto-login or silent login so it bypasses the login and takes you to specific page to perform certain action and then when we close it logs off, this shld be possible assuming help.acumatica.com works that way.  This feature allows to do lot of things within the framework and allows to scale for online approvals or proofing etc. Any hacks or thoughts, pls share.