There should be several ways of entry, for example continuing with the material where Joe left off the last time, or new publications (via RSS), or personal direct messages (e-mail), or search, or by typing an identifier (not in a nice way yet), or by scanning a QR code, or by visiting a certain location in physical space. There are mechanisms to present what he can look at, and if he chooses to look at something, under the hood, the following happens: his client sends a request. How does the client do it?