1. A computer database system for multi-model integration comprising: one or more remote client computers, each having remote client-side components provided therein, said remote client-side components comprising: a multi-model manager adapted to construct a system model from a plurality of constituent models, the plurality of constituent models created from a plurality of domain-specific modeling languages; one or more connectors providing an interface between the system model and each of the plurality of constituent models; an execution automation engine; a sandbox comprising a local copy of the system model on the remote client computer; and a version control system client; and a server connected to the one or more remote client computers via a communication medium, the server comprising: a processing unit; and a data storage for storing a multi-model database of a product system and accessible by the processing unit, said multi-model database comprising: a plurality of artifacts that define the multi-model database; and a multi-model repository that holds said artifacts under version control, wherein said artifacts comprise: a models data dataset, wherein each model represents a discrete aspect of the product system; a model registry dataset containing a list of the models in the multi-model database; a model attributes dataset corresponding to each of the models; a model interfaces dataset representing a tuple corresponding to each of the models, wherein said tuple contains a mapping operation and said model attributes; a model attribute constraints dataset associated with the input and output attributes, wherein said attribute constraints are triggers on the value of the associated attribute; a model data editing tools dataset; a notifications dataset associated with each of the models for informing the models of defined events; and a multi-model execution control dataset.