Should interactive components change the data model?

[ckhsponge]

Send messages to the UI that create a surface with an interactive TextField component backed by a data model. The user then types into the text field. When and how should the data model be updated?

Possible solutions:

1. With every keystroke a new data-model-update message should be created that keeps the data model completely in sync with what is seen in the UI.
2. Don't do anything necessarily. The UI may become out of sync with the data model. Another action like a Save button could then get the UI in sync with the data model.

I saw this in the spec:

4.1. The dataModelUpdate Message¶
This message is the only way to modify the client's data model.

so perhaps the answer is #1. In that case the other UI elements such as check boxes and sliders should create dataModelUpdate messages with every interaction as well.

Or maybe the answer is that it doesn't matter to A2UI and the render can decide for itself what to do.