How to use SOAP / HTTP POST to authenticate user in CI?

Is this from a remote site? If the user is on YOUR website and needs to be authenticated, why not just create accounts for them and have them log in before they can see the data? Like how you have to log into this form before you can edit your user profile or post messages?

I'm just not clear on the need to use SOAP services for this based on your description. Sounds like you just need a regular login system?