Software Architecture Patterns Lecture Notes

Introduction

• Welcome to Whiteboard Programming
• Focus on simplifying programming with whiteboard videos.
• Topic: Common software architecture patterns used by enterprises globally.

What is Software Architecture Patterns?

• Definition: Pictorial representation of an IT system; serves as a blueprint.
• Purpose:
  • Manage system complexity.
  • Establish communication and coordination among components.
  • Define structured solutions for technical and operational requirements.
  • Optimize quality attributes like performance and security.
• Goal: Identify requirements that affect application structure, reduce business risks, and bridge business and technical needs.

Major Software Architecture Patterns

1. Layered Pattern

   • Structure programs into groups of subtasks at different abstraction levels.
   • Layers provide services to the next higher layer.
   • Common layers:
     • Presentation Layer (UI Layer)
     • Application Layer (Service Layer)
     • Business Logic Layer (Domain Layer)
     • Data Access Layer (Persistence Layer)
   • Used in desktop applications and e-commerce web applications.

2. Client-Server Pattern

   • Consists of a server and multiple clients.
   • Server provides services to clients; clients request services.
   • Commonly used in online applications (e.g., email, banking).

3. Master-Slave Pattern

   • Master distributes work among slave components.
   • Final result computed from slaves' outputs.
   • Employed in database replication and peripheral connections.

4. Event-Bus Pattern

   • Deals with events with four components:
     • Event Source
     • Event Listener
     • Channel
     • Event Bus
   • Sources publish messages; listeners subscribe to channels.
   • Used in Android development and notification services.

5. Pipe-Filter Pattern

   • Structures systems producing and processing data streams.
   • Each processing step enclosed in a filter; data passed through pipes.
   • Used in compilers and workflows in bioinformatics.

6. Broker Pattern

   • Structures distributed systems with decoupled components.
   • Broker coordinates communication; servers publish services.
   • Commonly used in message broker software (e.g., Apache Kafka).

7. Peer-to-Peer Pattern

   • Components (peers) can act as clients or servers.
   • Peers provide and request services from each other.
   • Used in file-sharing networks and blockchain products.

8. Model-View-Controller (MVC) Pattern

   • Divides applications into three parts:
     • Model: Core functionality and data.
     • View: Displays information to users.
     • Controller: Handles user input.
   • Decouples components, allowing efficient code reuse.
   • Foundation for web frameworks like Django and Rails.

9. Interpreter Pattern

   • Designs components that interpret programs in a dedicated language.
   • Each class corresponds to a symbol of the language.
   • Used in database query languages (e.g., SQL).

10. Blackboard Pattern

    • Useful for problems without deterministic solution strategies.
    • Components:
      • Blackboard: Global memory containing solution objects.
      • Knowledge Source: Specialized modules.
      • Control Component: Manages module execution.
    • Used in applications like speech recognition and tracking systems.

Conclusion

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