Question

Characterize the following design purpose as creational, structural, or behavioral. Explain your conclusion clearly. We must build a human resources application dealing with the management structure at a large company. We need to represent the organization chart within the application.

Short answer

The design purpose is structural as it deals with organization hierarchy.

Step-by-step solution

Understand the Design Purposes

Design patterns in software engineering fall into three main categories: creational, structural, and behavioral. - **Creational patterns** are focused on the process of object creation. - **Structural patterns** are concerned with how classes and objects are composed to form larger structures. - **Behavioral patterns** focus on communication between objects.

Analyze the Problem Statement

The problem involves representing an organization chart in a human resources application. An organization chart illustrates the management structure and hierarchy, showing relationships between different units or roles.

Match the Problem with Appropriate Design Category

Since the objective is to model the structure of the organization hierarchy, this primarily pertains to how different components are organized and interact within the system. This aligns most closely with *structural design patterns*. These patterns help define how objects and classes are composed to create larger entities, which is exactly what organizational charts represent.

Conclusion

Based on the analysis, the design purpose of constructing an organization chart falls under structural design patterns. This is because the core focus is on representing and managing the structured relationships between various organizational roles.

Key concepts

Creational Patterns

Creational patterns play a crucial role in defining the best way to instantiate objects in a software system. These patterns are all about the process of object creation.

When developing a software application, you often need to create objects in a way that is both efficient and flexible. Creational design patterns offer solutions that encapsulate the instantiation logic, allowing for more manageable and scalable code.

For instance, if an application requires the creation of multiple instances of a class, you might employ patterns such as the Factory Method, Abstract Factory, or Builder. These patterns provide mechanisms to reduce complexity and allow for more dynamic and decoupled designs.

• The **Factory Method** allows a class to defer instantiation to subclasses.
• The **Abstract Factory** creates families of related objects without specifying their concrete classes.
• The **Builder** pattern splits the creation of a complex object into simpler, smaller steps.

By utilizing creational patterns, you ensure that your application can create objects in a systematic manner, optimizing resource utilization and enhancing flexibility.

Structural Patterns

Structural patterns focus on how classes and objects can be combined to form larger, more complex structures. When dealing with an organization chart, as outlined in the problem statement, structural patterns are essential.

These patterns define clear guidelines on how to build relationships between entities, making sure the application architecture is robust and maintainable. Specifically, structural patterns aid in composing classes or objects to form a larger whole.

• The **Adapter** pattern makes incompatible interfaces work together.
• The **Composite** pattern allows you to treat individual objects and compositions of objects uniformly.
• The **Facade** pattern provides a unified interface to a set of interfaces in a subsystem.

For an organization chart, the Composite pattern would be particularly useful. It allows for representation of hierarchies where an organization chart is essentially a recursive tree structure. You can easily represent complex parent-child relationships and manage them systematically. This aligns directly with the need to effectively and efficiently model organizational structures within a human resources application.

Behavioral Patterns

Behavioral patterns are all about how objects and classes interact in a software system. They focus on communication and the responsibilities among different entities.

These patterns help define the architecture of how objects collaborate, promoting flexible and adaptable code. When a software application needs to manage dynamic interactions, behavioral patterns are invaluable.

A few important examples include:

• The **Observer** pattern, which allows objects to be notified of changes in other objects.
• The **Strategy** pattern, which enables selecting an algorithm's behavior at runtime.
• The **Command** pattern, which encapsulates a request as an object.

In practice, behavioral patterns help manage complex chains of communication and data exchange. Within an application, using these patterns means that objects can cooperate without tight coupling, leading to systems that are easier to maintain and extend. Effective use of behavioral patterns results in code that embodies well-organized and well-structured communication protocol between different parts of the application.