I'm working in project where Snap framework is used on server-side to provide HTTP interface (with JSON as data format) to Redis storage where instances of models (collections of fields) are stored. Backbone.js is used to maintain ever-sync for models in client side and server side. For reactive interface Knockout is used. The two are bound via Knockback and bunch of extra code. This way we got ability to write in field and have it ever-synced to server (input events propagate to changes in Knockout ViewModel, which propagates to Backbone, which is bound to sync changes in model to server (delta-style)). Client representation may differ from what is stored on server (mapping by key-label or even more generic function), in which case custom Knockout observables (readable and writable) are installed to perform extra client—server transformations. I don't know how to do collaborative editing with that, smells like rewriting Wave.