clientservertiered

Client-server tiered, often referred to as three-tier architecture, is a software architectural pattern that separates an application into distinct layers to improve manageability, scalability, and maintainability. In this model, the term is used to describe the division of responsibilities across presentation, application logic, and data management layers.

The typical model includes a presentation tier running on the client (or a thin client in a centralized environment), a middle tier containing the application server and business logic, and a data tier hosting databases or other storage. The presentation tier handles the user interface and input, the middle tier processes requests and enforces business rules, and the data tier stores and retrieves information.

Communication between tiers usually occurs over network protocols such as HTTP, REST, SOAP, or RPC. The middle tier is often designed to be stateless, with data access components centralized for security and consistency. Security is implemented at multiple layers, including client authentication, access control in the middle tier, and database permissions in the data tier.

Benefits of client-server tiered architectures include improved scalability, easier maintenance, and a clear separation of concerns that enables independent development and deployment of user interfaces, business logic, and data components. They also support centralized data management and easier testing.

Drawbacks can include added architectural complexity, potential latency from multiple network hops, and greater development and debugging overhead. Performance tuning may require load balancing, caching, and careful data access optimization.

Variants of this pattern include N-tier architectures with additional layers, such as API gateways or service layers. Modern distributed systems, including service-oriented architectures and microservices, often implement the core ideas of client-server tiered while distributing responsibilities across multiple independent services.