Embodiments of the disclosure are directed to systems and methods to process a declaratively-specified computer application by interpreting a structure and a behavior specification. Application data items are interpreted using a processing concrete model based on the structure specification. Application functionality is provided by processing the application data items in accordance to the behavior specification. The application information may further be used in an embodiment of the disclosure to perform additional processing and provide an added functionality. Various embodiments of the disclosure allow additional functions for declarative application such as performing domain activities, accessing data items, transferring application data, storing data and milestones and rendering data items.