Turning Clockwise: Using UML in the Real-Time Domain “You mustn’t forget one thing,” the fairy godmother said. “Do not stay past midnight, for when the hour strikes, everything will return to the way it was before. “I promise,” said Cinderella.

A Brief History of UML Rumbaugh joins Booch at Rational Software Corporation. The UML effort officially starts in October The version 0.8 draft of the Unified Method (as it was then called) releases in October UML consortium established. Partners contributing to the UML 1.0 definition include DEC, I-Logix, Intellicorp, IBM, ICON Computing, MCI Systemhouse, Microsoft among others UML 1.0 was offered for standardization to the Object Management Group (OMG) in January 1997

Real-Time Systems and the Object Paradigm A real-time system is a software system that maintains an ongoing and timely interaction with its environment.

Requirements for Modeling Real- Time Systems Infrastructure modeling requirements Behavior modeling requirements Structure modeling requirements

Infrastructure Modeling Requirements Engineering Infrastructure –Networks –Processors –Logical Devices –Scheduling –Timing –Memory Management

Behavior Modeling Requirements Event-driven Time-driven

Structure Modeling Requirements Peer Relationships Containment Relationships Layering Relationships

Using UML for Modeling Real- Time Systems

Model A model is a simplification of reality Models help us visualize a system as it is or as we want it to be Models permit us to specify the structure or behavior of a system Models give us template that guides us in constructing a system Models document the decisions we have made

Modeling the Engineering Infrastructure Modeling resources and system services. Element-to-resource mapping. Resource-to-value mapping. Modeling time and timing facilities.

Modeling Real-Time Behavior Event-driven (reactive) behavior modeling Time-driven behavior modeling Object interaction modeling

Modeling Real-Time Structure Architectural Modeling

Strengths –UML stereotypes has enabled to capture real- time concepts and allowed smooth integration of already proven techniques developed in previous generations of real-time methods. –This allows for creation and exploitation of complicated software. –Traditional engineering techniques applied to UML, and hence to real-time systems.

Weaknesses UML still in its infancy. Real-time systems model physical reality. Not always possible to capture the complexities of nature through a modeling language.

... And they lived happily forever.