Behavioral Pattern

What is a Behavioral Pattern?

In software engineering, a behavioral pattern is a type of design pattern concerned with algorithms and the assignment of responsibilities between objects. Behavioral patterns focus on how objects interact and distribute work among themselves rather than emphasizing the objects themselves (structural patterns) or how they are instantiated (creational patterns). These patterns help make the interactions between objects easier, more flexible, and more dynamic.

Role and Purpose of Behavioral Patterns

The primary role of behavioral patterns is to manage complex control flow in software designs by handling communication between objects in a system. Their purpose includes:

• Managing Inter-object Communications: Facilitating how objects interact and communicate data.
• Encapsulating Requests: Hiding the details of operations performed and the communication mechanism.
• Increasing Flexibility: Allowing loose coupling between objects, which can change their interaction independently from other interacting objects.

Usage of Behavioral Patterns

Behavioral patterns are used in various scenarios in software development:

• Command Pattern: Used to encapsulate all details of an operation in a separate object. This pattern allows for parameterizing objects with operations, queuing requests, and implementing various communication schemas between objects.
• Observer Pattern: Used to subscribe and notify multiple objects about any changes to the state of an object, which is particularly useful in implementing distributed event-handling systems.
• Strategy Pattern: Used to define a family of algorithms, encapsulate each one, and make them interchangeable. This pattern lets the algorithm vary independently from clients that use it.
• Iterator Pattern: Used to provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation.

Importance of Behavioral Patterns

Behavioral patterns are important because they help manage how objects are interconnected and how they communicate, which can greatly influence the complexity and performance of software applications. They offer important benefits in terms of:

• Improved Communication: Enhancing how components communicate and cooperate.
• Flexibility and Reusability: Encouraging loose coupling and easy reconfiguration of components without requiring extensive code changes.

Benefits of Behavioral Patterns

Using behavioral patterns in software design can lead to several benefits:

• Scalability: Easier management of growing systems with many interacting components.
• Maintainability: Simpler maintenance and update of the system’s behavior without major changes to the codebase.
• Robustness: Better handling of new or changing requirements due to encapsulated behaviors that can be modified independently.
• Reusability: Components can be reused across different programs if they encapsulate behavior that is sufficiently general.

Examples of Behavioral Patterns

• Mediator Pattern: In a GUI application, the mediator pattern can manage communication between various user interface components, like buttons, text fields, and lists, without needing to know about each other.
• State Pattern: Used in applications where the behavior of an object changes depending on its state, such as a TCP connection that behaves differently if it's in the established, listening, or closed state.
• Visitor Pattern: Useful in operations on objects with differing classes. It can provide a new operation without changing the classes of the elements on which it operates.

Behavioral patterns are essential for designing highly cohesive, loosely coupled systems with complex interactions between objects, significantly improving the adaptability and robustness of software applications.

See Also

• Design Pattern: An overview of common design patterns in software engineering, distinguishing between structural, creational, and behavioral patterns.
• Software Architecture: Discussing broader concepts in software architecture where behavioral patterns are crucial in defining how software components interact.
• Observer Pattern: Detailing a specific behavioral pattern to manage complex dependencies between objects, allowing for efficient communication and updates.
• Strategy Pattern: Explaining how this pattern allows the algorithm’s behavior to be selected at runtime, which is a key example of a behavioral pattern in action.
• State Pattern: Describing how this pattern allows an object to alter its behavior when its internal state changes, appearing as if the object has changed its class.
• Command Pattern: Covering the command pattern, which encapsulates a command request as an object, thereby allowing parameterization of clients with different requests.
• Iterator Pattern: Discussing how this pattern provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation.
• Template Method Pattern: Explaining how this pattern defines the program skeleton of an algorithm in a method, deferring some steps to subclasses.
• Mediator Pattern: Detailing how this pattern reduces complexity by enabling objects to communicate through a mediator object instead of directly with each other.
• Chain of Responsibility Pattern: Discussing how this pattern creates a chain of receiver objects for a request, allowing several objects to handle the request without knowing the receiver explicitly.