Abstract: Specifying content using data-driven systems is described, including creating a definition, the definition having a type and a property, instantiating the property, deriving a property value for the property using a linkage, and synchronously pushing an update to the property value over the linkage. Also described are building an object and a backing class, the object having a definition and a property for the definition, relating the backing class to the object based on the definition, and identifying a relationship between the object and another object, the object and the another object being related based on the backing class.