从FormsAuthentication重定向到登录页面时，在Post中维护变量

Question

Here is our scenario:

1. A user logs into web site #1. Once authenticated, the site gethers some credentials about the user (a separate process that has nothing to do with this question) and POSTS this information to a page on web site #2
2. Web site #2 is protected by FormsAuthentication and redirects the user to the Login page.
3. At this point, the values that were posted by web site #1 are lost.

Question:

How do we preserve the posted values from web site #1 during the authentication/login process in web site #2.

Things we have tried:

1. We attempted to put code into the Session_Start method in Global.asmx. We wanted to save the values in session, but the session only starts (the breakpoint is hit) when the user is redirected to the Login page. By this time, we have already lost the values.
2. We tried putting some code into Application_BeginRequest, but cannot access session from that method.

We need to use POST rather than GET because the length of the data is too long to put in the querystring. Same reason why we cannot preserve the values in a cookie.

Answer 1

Can you keep track of anything (some kind of arbitrary session identifier, like a guid) throughout the steps? I would consider storing the credentials gathered in a database until step 3 is reached, and then destroying the record when the login takes place.