1. A system for developing software applications from preexisting, comprehensive, and new models, the system comprising: a hardware processor communicatively coupled to a modeling module, an application development module, and a virtualization module; the modeling module configured to: generate an integrated graphical modeler that is viewable on a display of a user device; receive input from the user device indicative of user input that specifies which of a plurality of business entities are to be used in constructing a model, wherein the user input is provided via the integrated graphical modeler that includes visual elements corresponding to the plurality of business entities; and construct the model that represents a business scenario involving the specified business entities by connecting the corresponding visual elements; the application development module configured to: express the model as one or more application programming interfaces (APIs); and deploy the model in a simulation mode so that development data necessary for development and prototyping of a software application is stored in an internal smart memory object-oriented database, wherein the development data simulates real data required by the software application upon deployment; the virtualization module configured to: retrieve and integrate real data specified as necessary by the model, wherein the real data is retrieved from one or more real storage systems; configure integration access parameters; and map the real data and the integration access parameters to the model; and a repository configured to store the model, the one or more APIs, the internal smart memory object-oriented database, the real data, or some combination thereof.