Intelligent Subject - Adapting Observer with push model and filters to handle divergent update needs

The OBSERVER design pattern is one of the most widely used patterns from the original GoF book [1]. With the proliferation of mobile devices in worklife and information systems serving data to such devices is paramount to maintaining data integrity in a work process. The idiosyncracies of mobile devices have placed new requirements on the mechanisms for updating resource limited clients with an OBSERVER style solution. This work provides an adapted pattern named INTELLIGENT SUBJECT that allows for a SUBJECT side filtering mechanism to avoid propagating all updates to all OBSERVERS if the cost of notification is high. This cost could be either due to resource or network constraints. OBSERVERS define threshold values, and are only notified when the data value is changed beyond their individual threshold. The pattern introduces slightly more complexity, but allows for a separation of concerns on the SUBJECT side and a life of blissful ignorance on the OBSERVER side.