quartz/content/notes/uml.md

UML

A standard set of model constructs and notation defined by the object management group

specify what not how

• activity diagrams
  • high level for business prcesses workflows
  • low level for dtailed business logic
• advantages
  • describe workflows
  • specify relative processing rder of activites
  • simple
  • can be shown to stakeholders for checking and confirmation

enables implementation-independent specification of:

• user/system interactions
• partitioning of responsibility
• integration with larger or existing systems
• data flow and dependency
• order of operations (algorithms and processes)
• concurrent operations

1 why is is useful

• helps develop efficient effective correct designs
• better communication with project stakeholders
• gives a big picture view of the project system
• independent of specific programming languages or development processes
• de facto standard for modelling OO systems

2 what it is not

• visual modelling software
• a programming languages
• a software development process, method, or methodology

3 Types of diagram

3.1 structural

3.2 behavioural

3.3 Linked diagrams

each digram type models a dfiferenct aspect of the system many of the diagrams link to each other

• e.g., use case, sequence, activity
• e.g., object, communication

e.g.,

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3.4 Activites and transitions

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• activities

  • take place over some pariod of time
  • linked by transitions (arrows)
  • only one starting point potentaily many ending conditions

• Transitions

  • have guard conditions that must be satisfied before the transition can occur

3.5 Decision points

• represent conditional branching
• two or more alternative transitions depending on condition
• every transiiton exiting the decision point must have a guard condition

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3.6 Synchonisation bars

• represents two or more activites running in parallel
• transitions can be split into mutiple paths and recombined later
• if a workflow is split then it must be recombined on the same diagram

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3.7 swim lanes

• same as BPMN
• show who is responsible for a process
• can represent
  • business organisations
  • depts
  • people (actors)
• can simplify processes

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3.8 relationships to use cases

• use case diagrams show the high level interactions between actors and cases
• high level activity diagrams show the sequence of use cases within a workflow

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3.8.1 example

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3.9 Example producing a book

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