Pattern-Oriented Software Architecture For Dummies

Chapter 17

Decomposing the System's Structure

In This Chapter

• Seeing how to create more than the sum of the parts
• Structuring your application

In this chapter, I tell you about the Whole-Part pattern, which describes how to build your system from parts so that the whole is greater than the sum of its parts. The assembled whole entity has its own properties, which are distinct from the sum of the properties of the parts. When the aggregation can do new things that aren't possible with just the parts, the resulting behavior is called emergent behavior. The Whole-Part pattern creates an efficient structure to unleash this emergent behavior.

The properties associated with the parts may be different from one application to another because the properties of the parts are constrained by the whole in which the parts are included.