How to connect sign in with backend (web api) services

I'm assuming it must involve some degree of cookies passing between client and server?

That is, in my `Startup.ConfigureAuth(IAppBuilder app)`, I've got this:

``` C#
// Enable the application to use a cookie to store information for the signed in user
app.UseCookieAuthentication(new CookieAuthenticationOptions
{
AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
LoginPath = new PathString("/login")
});

// Use a cookie to temporarily store information about a user logging in with a third party login provider
app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);
```

But am not entirely sure what that means. I don't want to redirect to `/login`, for instance, if I can just pass the front page sign in details, user name and/or email and password, with or without cookie, to a backend authentication service.

Then from that point forward, how to maintain some level of authentication. i.e. user id with or without session id for security reasons. That sort of thing.

Start by reading the Startup.ConfigureAuth(IAppBuilder app) configuration shown in the issue and tracing the SPA sign-in entry point. Clarify whether the intended result is an implementation or usage guidance, which backend authentication service is in scope, and how completion should be verified.

Written by the indexing model from the issue text.