3. Complexity

• Most fundamental problem in software development is complexity.

• Dealing with complexity: divide and conquer!

  • Two sub-problems are more than half-solved by their separation!

• For both people and programs, separation is easy.

• This simple principle can be applied in an amazing variety of ways.

  • implementations are connected only by a well-defined set of interfaces

  • processes are broken into distinct activities

  • interactions are well-defined between the people using the system.

• Most experience is required when

  • selecting parts

  • specifying the interfaces between parts.