Add static/custom attribute with ACS Url

[Cantor, Scott]

> We are expecting an url like this (May be I am wrong)

You are wrong.

> Is it possible to configure an url like above for their IDP ACS? And will that
> help us to serve our purpose?

No, and no. You don't have a problem, you're just misunderstanding how all of this works, and you haven't articulated a question that could be answered because you aren't describing the problem accurately. So there's no way to help you until that changes.

Your SP doesn't need to care about how the login is initiated, that has no impact on how your system works.

If you need to know which IdP is the source of a session, you have that information, and it has nothing to do with any parameters to a URL. It's just one of the variables the SP provides to applications. You shouldn't rely on that anyway, you should base any decisions on the attributes you get about the user.

-- Scott