Principles of Modeling
  1. First, The choice of what models to create has a profound influence on how a problem is attacked and how a solution is shaped.
  2. Second, Every model may be expressed at different levels of precision.
  3. Third, The best models are connected to reality.
  4. Fourth,No single model or view is sufficient. Every nontrivial system is best approached through a small set of nearly independent models with multiple viewpoints.
Three major elements:
  1. the UML's basic building blocks
  2. the rules that dictate how those building blocks may be put together
  3. some common mechanisms that apply throughout the UML
The vocabulary of the UML encompasses three kinds of building blocks:
  1. Things
  2. Relationships
  3. Diagrams
Three kinds of relationships that are most important: dependencies, generalizations, and associations.
  1. Dependencies are using relationships. For example, pipes depend on the water heater to heat the water they carry.
  2. Associations are structural relationships among instances. For example, rooms consist of walls and other things; walls themselves may have embedded doors and windows; pipes may pass through walls.
  3. Generalizations connect generalized classes to more-specialized ones in what is known as subclass/superclass or child/parent relationships. For example, a picture window is a kind of window with very large, fixed panes; a patio window is a kind of window with panes that open side to side.