Application architecture refers to the high-level structure of an application - how components organise and interact. Good architecture improves maintainability, scalability, and development productivity.
Architecture decisions made early in development significantly impact long-term project success.
Layered Architecture
Layered architecture organises applications into horizontal layers, each handling specific concerns:
Presentation Layer: User interfaces. Web interfaces use HTML/CSS/JavaScript. Mobile applications use native or cross-platform frameworks.
Business Logic Layer: Application rules and workflows. Calculations, validations, and business processes live here.
Data Access Layer: Database interactions. The data access layer abstracts database details from business logic.
Database Layer: Where data persists.
Benefits include separation of concerns and testability. Disadvantages include performance overhead from crossing layers and difficulty handling cross-cutting concerns.
Model-View-Controller (MVC)
MVC separates applications into three components:
Model: Data and business logic. Models interact with databases.
View: Presentation. Views display models to users.
Controller: Handles user input, updates models, and selects views.
MVC is widely used in web frameworks including Rails, Django, and Laravel.
Model-View-ViewModel (MVVM)
MVVM separates applications differently:
Model: Data and business logic.
View: User interface.
ViewModel: Exposes model data suitable for views.
MVVM is popular for desktop and mobile applications using modern frameworks.
Clean Architecture
Clean architecture emphasises independence from frameworks and external dependencies. Business logic lives at the centre, isolated from external concerns.
Layers include:
- Entities: Core business objects
- Use Cases: Application-specific business rules
- Interface Adapters: Translate between use cases and external systems
- Frameworks & Drivers: External systems
Clean architecture improves testability and flexibility.
Hexagonal Architecture
Hexagonal architecture, also called ports and adapters, isolates business logic from external systems. Hexagonal architecture explicitly models interactions with external systems through ports and adapters.
Benefits include testability and reduced coupling to external systems.
CQRS
Command Query Responsibility Segregation (CQRS) separates commands (writes) from queries (reads). Write models and read models can be optimised differently.
CQRS benefits applications with complex queries or differing read/write patterns. It introduces complexity not all applications need.
Event Sourcing
Event sourcing stores all changes to application state as immutable events. Current state is derived by replaying events.
Benefits include complete audit trails and ability to reconstruct state at any point in time. Complexity is a significant disadvantage.
Database Patterns
SQL vs NoSQL: SQL databases handle structured relational data. NoSQL handles flexible, document-oriented data.
Normalisation: Reducing data duplication in databases. Trade-off between redundancy and query complexity.
Sharding: Distributing data across databases. Enables scaling but introduces complexity.
Caching Strategies
In-Memory Caching: Redis and Memcached cache frequently accessed data in memory.
Database Query Caching: Caching query results.
HTTP Caching: Using HTTP cache headers for web performance.
Scalability Patterns
Horizontal Scaling: Adding more servers. Easier for stateless systems.
Vertical Scaling: More powerful servers. Simpler but limited.
Load Balancing: Distributing traffic across servers.
Database Replication: Copying databases for redundancy and read scaling.
Resilience Patterns
Circuit Breaker: Failing fast when services are unhealthy.
Retry: Retrying failed operations with backoff.
Timeout: Not waiting indefinitely for responses.
Bulkhead: Isolating resources preventing cascading failures.
PixelForce's Architectural Approach
PixelForce designs application architectures balancing simplicity with scalability. Early decisions reflect anticipated growth. Architecture evolves as requirements become clearer.
Technology Selection
Architectural decisions include technology choices. Selecting databases, caching systems, and other technologies should align with architectural requirements.
The Future of Architecture
Architecture patterns continue evolving. Serverless architectures challenge traditional patterns. Event-driven architectures gain popularity.
Choosing appropriate architecture is crucial for application success. Overly complex architecture wastes resources. Insufficiently sophisticated architecture becomes a bottleneck.