Structural Design Pattern: Facade Design Pattern

Define Facade Design Pattern

The facade pattern hides the system's complexities and provides the client with an interface through which to access the system. This pattern uses a single wrapper class with a set of members requested by the client. These members use the system on behalf of the facade client and cover the implementation specifics. Provides a higher-level interface, making the subsystem easier to use. It aggregates items to make the procedure easier.

Examples of Facade Design Patterns

Examples of Facade design patterns are:

• User Registration Process
• Process An Order
• Creating User Follower Workflow

Facade Design Pattern with UML diagram

The UML class diagram above defines the following classes, interfaces, and objects:

• Complex System: A collection of subsystems.
• SubsystemA, SubsystemB, and SubsystemC: These are classes inside a complicated system that perform certain operations.
• Facade: This is a wrapper class that contains the client's needed members.
• Client: This is a class that handles high-level activities in the Facade.

When to use Facade Design Patterns?

• The facade design pattern is beneficial when a simple interface is needed to access a complicated system.
• A subsystem's abstractions and implementations are tightly connected.
• Each level of stacked software requires its access point.
• The facade design pattern is particularly useful when a system is exceedingly complex or difficult to understand because the system has a large number of interrelated classes or its source code is unavailable.

Advantages of the Facade Design Pattern

• Simplified Interface: Provides a single, simplified interface for complicated subsystems, making them easier to utilize.
• Reduced Complexity: Clients engage with a single unified interface rather than directly with complicated components, lowering the system's perceived complexity.
• Isolation: Provides some separation from the complicated subsystems, which might be useful when there are frequent subsystem changes.
• Improved Testability & Maintainability: Facade can make testing easier by reducing interdependencies and focusing on system interfaces.