# Architecture ## Invite flow This implementation of Rooms 2.0 is compliant with the [Rooms 2.0 specification](https://github.com/ssbc/rooms2), but we add a few additional features and pages in order to improve user experience when their SSB app does not support [SSB URIs](https://github.com/ssbc/ssb-uri-spec). A summary can be seen in the following chart:  When the browser and operating system detects no support for opening SSB URIs, we redirect to a fallback page which presents the user with two broad options: (1) install an SSB app that supports SSB URIs, (2) link to another page where the user can manually input the user's SSB ID in a form. ## Sign-in flow This implementation is compliant with [SSB HTTP Authentication](https://github.com/ssbc/ssb-http-auth-spec), but we add a few additional features and pages in order to improve user experience. For instance, besides conventional SSB HTTP Auth, we also render a QR code to sign-in with a remote SSB app (an SSB identity not on the device that has the browser open). We also support sign-in with username/password, what we call "fallback authentication". A summary can be seen in the following chart: