Common Software Architecture Patterns: Layered, Multi‑Layer, Pipe‑Filter, Client‑Server, MVC, Event‑Driven, and Microservices

Architecture patterns provide reusable solutions to recurring design problems in software systems. This article introduces seven major patterns: Layered (n‑tier) architecture, Multi‑layer architecture, Pipe‑Filter architecture, Client‑Server architecture, Model‑View‑Controller (MVC), Event‑Driven architecture, and Microservices architecture.

Layered Architecture divides a system into distinct layers—typically presentation, business, persistence, and database—enforcing a one‑way dependency flow. It promotes separation of concerns, easier maintenance, and modular development, but adds runtime overhead and can degrade performance for high‑throughput applications.

Multi‑layer Architecture extends the layered concept by adding more logical groupings, often used in distributed systems such as consumer‑site J2EE applications. It helps organize complex systems into manageable sections, though it also increases initial cost and complexity.

Pipe‑Filter Architecture processes data through a series of independent filters connected by pipes. Typical components are: • source (producer) – the start of the pipeline. • map (transformer) – transforms data. • reduce (tester) – evaluates conditions. • sink (consumer) – the end point. It enables reusable, loosely‑coupled processing but can be unsuitable for highly interactive systems and may introduce performance penalties due to excessive parsing.

Client‑Server Architecture separates responsibilities between clients that request services and servers that fulfill them. It simplifies resource sharing and centralizes control, yet the server can become a performance bottleneck and a single point of failure, making relocation decisions costly.

Model‑View‑Controller (MVC) splits an application into three components: the Model (data), the View (user interface), and the Controller (mediator). This separation aids UI flexibility and testability, but for simple interfaces the added complexity may not be justified, and some UI toolkits may not map cleanly to MVC.

Event‑Driven Architecture handles asynchronous events by routing them through queues to dedicated processors. It scales well with increasing load, but can suffer from performance and error‑recovery challenges. Example workflow: an Order Service emits an OrderCreated event, a Customer Service processes it and may emit CreditReserved or CreditLimitExceeded, and the Order Service updates the order status accordingly.

Microservices Architecture decomposes an application into independently deployable services, each with its own API and data store. This improves scalability and allows heterogeneous technology stacks, but introduces operational overhead such as service monitoring, orchestration, and higher costs.