1. A computer system tangibly operating in an information technology hardware and software environment, comprising: a knowledge base model for representation and storage of regulatory knowledge, the regulatory knowledge including the following knowledge base model entities: regulations, procedures, parameters, concepts, decisions, rules, service calls, and their features and relationships to other knowledge base model entities; a data interface model for representation and storage of regulatory data, the regulatory data including the following groups of data interface model entities: simple transactional events, complex events, referential entities, profiles, and their features and their relationships to other data interface model entities and their relationships to knowledge base model entities; a reasoning session data model for representation and storage of the reasoning session data, the reasoning session data including the following reasoning session data model entities: reasoning sessions, session events, and their features and their relationships to other session data model entities and their relationships to data interface model entities and their relationships to knowledge base model entities; an interface configured to receive a request in the form of a structured or semi-structured message from an external source, to pass the received message to a reasoning session controller, and upon receiving a response from the reasoning session controller, pass that response to the external source; a reasoning session controller configured to receive an input request from the interface and to match the input request to a decision record from the knowledge base model decision entity, execute programmable instructions from the decision record, perform post-processing tasks after execution of the programmable instructions is completed, and select a next new session event for execution; a library of procedures configured to be invoked by a service call, take a subset of parameters established by a reasoning session and use those parameters to call external services, and place results returned by the external services in a data interface repository.