11 LAWSON Copyright – Harold Lawson; Software Engineering in the Systems Context Is SEMAT addressing the Root Causes of Complex IT Systems? Harold “Bud” Lawson

22 LAWSON Copyright – Harold Lawson; Two Overlapping System Contexts The Infrastructure Systems Context which enables Software Systems to be Developed, Operated and Maintained. Hardware, Operating Systems, Middleware, Programming Languages-Compilers, Databases The Application Environment Context Enabling Systems, Cooperating Systems, Environmental Requirements and Influences

33 LAWSON Copyright – Harold Lawson; Infrastructure Systems Continue to suffer from deep root cause problems in function distribution. The System/360 ISA – OS and Systems Software Mismatch – March into the Black Hole of Complexity The Estridge- Gates agreement giving Microsoft free license to drive the World Deeper into the Black Hole of Complexity. (Wintel cycle) Finally – DARPA Clean Slate Program

44 LAWSON Copyright – Harold Lawson; Application Environment Software Systems always exist in a wider Systems Environment ISO/IEC (Identified Need for a System Standard) ISO/IEC (Growing Utilization) Narrow System of Interest, Wider System of Interest, Environment and Wider Environment Enabling Systems, Cooperating Systems, Culture, History, Laws, Regulations, etc. The System Context(s) adds many complexities We need to “Think” and “Act” in terms of Systems (Travel in the Systems Landscape)

55 LAWSON Copyright – Harold Lawson; Why do we create Man-Made Systems? SYSTEM COUPLING DIAGRAM

66 LAWSON Copyright – Harold Lawson; We give names to these Systems Project Program Task Mission Experiment Natural Man-Made Mixed (Thematic) Facilities Instruments Theory Knowledge Methods Tools Processes Thinking – “Understanding” Acting – “Creating Solutions”

77 LAWSON Copyright – Harold Lawson; Balancing Architecture, Processes, Methods and Tools

88 LAWSON Copyright – Harold Lawson; Balance between Processes – Enterprise and Competence Heroes

99 LAWSON Copyright – Harold Lawson; Some Relevant References “Function Distribution in Computer System Architectures”, Invited paper appearing in the Proceedings of the Third Annual Symposium on Computer Architecture, Clearwater, Florida, January “Philosophies for Engineering Computer Based Systems”, IEEE Computer, Vol. 23, No. 12, pp , December, “Salvation from System Complexity”, IEEE Computer, Vol. 31, No. 2, Feb 1998, pp “Infrastructure Risk Reduction”, Communications of the ACM, Vol. 40, No. 6, June 1998, pp120. From Busyware to Stableware”, IEEE Computer, Vol. 31, No. 10, Oct 1998, pp “Rebirth of the Computer Industry”. Communications fo the ACM June 2002/Vol. 45, No. 6. “A Journey Through the Systems Landscape”, College Publications, Kings College, UK, ISBN

10 LAWSON Copyright – Harold Lawson; Personal Experiences of Architecture Driving Concepts Pointer Variable (1964) based upon Linked Lists, Data Schema and Indirect Addressing Flexible Central Processing Unit (1971) based upon Semaphore Variables, Asynchronism, High-Level Microcode and Language Boards Control of High Voltage Power Dispatching (1974) based upon Monitors and Asynchronism Automatic Train Control (1976) based upon Time Determinism, Software Circuits and Black-Board Memory ISO/IEC (2002) based on System-of-Interest, Recursive Decomposition, Enabling Systems, Processes, Stages and Life Cycle Models