If you want to login on Salesforce from an external app, you should start creating a “connected app” within Salesforce that informs about this authentication entry point.
In a real and timeless world, SOAP is a great option. But please, before going the SOAP way, think if there is a simpler protocol that suits your needs. Remind that Web was explosive even before the advent of Web services. If XML/JSON over HTTP can possibly solve a problem, or allows a dynamic structure […]