What Problem Does This Solve?

A user with an account but who is not currently signed in wants to participate by contributing something.

When to Use This Pattern

Use this pattern when authentication is required for participation in a community. Forms of participation include (but are not limited to) comments, votes, ratings, tags, posts to blogs or forums, and so on.

What's the Solution?

• When the user attempts to comment (or take similar action) remind them of the need to sign in first and deliver them to the sign in flow.
• When the user has successfully signed in, return them to the context they were in when they were about to comment or take similar action.
• When handling the submission of information, preserve any data that has been entered prior to the login procedure.

Why Use This Pattern?

It's important that the sign-in requirement does not present an undue barrier to participation for the user.

Special Cases

Should paranoid concerns (such as cross-site scripting issues, and possible cross-domain issues) require that the flow be interrupted or even that the user be returned to a home page, then at least insert an alert message with a clear call to action to resume the moment of participation.

This message might include a link to the last known location, a pre-populated form or a message indicating a redirect in x seconds.

Another Example

Kayak asks the user to sign-in with an in-page overlay, without leaving the current context.