An Introduction to Residuality Theory - Barry O'Reilly - NDC London 2024

An Introduction to Residuality Theory - Barry O’Reilly - NDC London 2024

Why is software architecture so difficult ?

TIME, CHANGE, UNCERTAINTY

• Standard architectural representations(UML, Archimate) has no way to represent
  • Time
  • Change over time
  • Uncertainity about change

What is the unit of SWE ?

• Software Machine Punchcard Procedure Module Object Service Function Microservice Process Feature Pattern

None of these capture time, uncertainity or change. This course will introduce a new unit - The residue That has this explicit goal in mind

Order and Disorder

• Some systems are ordered :

  • Highly constrained
  • Future states can be predicted
  • They can be tested Have consistent behaviour over testing cycles = Software is ordered

• Some systems are disordered :

  • Loose constraints
  • Unpredictable
  • Changing pattern or no pattern
  • Human and business systems are disordered