Flexibility

Question 1

Achieving Flexibility

Answer 1

Practices that enhance a designs quality will in and of themselves help to make systems more flexible

-strengthening cohesion
relaxing module coupling
streamlining intermodule dependency
improving the clarity

Additional practices include the 0,1 or infinity principle collection

isolating risk

providing support for data driven system configurability

Question 2

What is the 0,1 or infinity Principle?

Answer 2

When considering whether to support a collection of items, plan for one of three situations:

1) Support for NO instances of that item
2) Supporting EXACTLY ONE instance of that item
3) Supporting INFINITE instances of that item

Question 3

Isolating Risk

Answer 3

You can isolate risk, by isolating likely areas of functional instability with interfaces that abstract the functionality key concerns: eg(Platforms, data exchange formats, user interface designs)

Concerns: Contain “damage” to other parts of implementation due to change.

Question 4

Data Driven Configurability

Answer 4

Use a well known persistent store to parameterize variable aspects of an applications behavior.

Define a multilevel (label, value) based structure aka XML or JSON

Advantages includes the elimination of the need to revise and recompile source code to modify an applications behavior.

Disadvantages: Can be time consuming and difficult to implement.

Can be difficult to present options In user friendly ways without overwhelming users with choices