1. A method of providing closed-loop analysis of a business process, the method performed by a computer-based process management subsystem of an enterprise system, the method comprising: in response to user input, selectively communicating with each of a plurality of commercial off-the-shelf software (COTS) products including at least one COTS flowcharting tool, at least one COTS simulator, at least one COTS project management tool, and at least one COTS workflow management tool, the selective communicating performable via application programming interfaces (APIs) implemented between the process management subsystem and each COTS product; making a plurality of modeling stencils available on a graphical display via one of the at least one COTS flowcharting tool, at least some of the stencils representing modeling diagram objects selectable by a user of the display to compose and display one or more extended modeling diagrams, including one or more activity diagrams, representing the business process, the modeling diagrams extended so as to be independent of proprietary tools and protocols of the plurality of COTS products; in response to user input via one or more simulation stencils made available on the display via one of the at least one COTS flowcharting tool, using one or more simulation objects represented by simulation stencils selected by a user of the display to extend a user-selected one of the one or more activity diagrams to obtain a simulation model that is independent of proprietary tools and protocols of the COTS products, and delivering the simulation model via one of the APIs to one of the at least one COTS simulator for performance of simulation; in response to user input via one of the at least one COTS flowcharting tool, generating activity duration data based on simulation output received from the at least one COTS simulator, and sending the duration data to one of the at least one COTS project management tool; and in response to user input, providing abstractions of workflow and project management for use in one or more user-selected implementations of the selected activity diagram via the at least one COTS workflow management tool and via the at least one COTS project management tool.