Software performance models from system scenarios

The earliest definition of a software system may be in the form of Use Cases, which may be elaborated as scenarios. In this work, performance models are created from scenarios, to permit the earliest possible analysis of potential performance issues. Suitable forms of scenario models include Unified Modeling Language (UML) Activity or Sequence Diagrams (SD), and Use Case Maps (UCM) from the User Requirements Notation (URN) standard. They capture the causal flow of intended execution, and the operations, activities or responsibilities which may be allocated to components, with their expected resource demands. The Scenario to Performance (S2P) algorithm described here automatically transforms scenario models into performance models, and the LQNGenerator tool implements S2P to convert UCM scenario models into layered queueing performance models. S2P can, in principle, also be applied to other scenario models, including Message Sequence Charts, UML Activity Graphs (or Collaboration Diagrams, or Sequence Diagrams).