Let's say I have an Account object. Suppose one tile updates a field on that Account object. How do I persist that change across all tiles without sending a message to tiles and having them subscribe to it?
The Concepts sample contains five different sample applications which demonstrate various ways tiles can communicate. Besides message passing, tiles can access a context or a resource on the Experience Server.
Installing the samples is described as part of the "Installing ADEP Experience Services" documentation (step 5)
Under the covers it'll do the plumbing of the event for you. We're still working on a public sample for it.