Understanding Software Architecture: Concepts, Classifications, and the COLA Framework

1. What is architecture? Architecture is an abstract description of the entities in a system and the relationships among them, originating from building design and used to split a system according to principles that enable parallel work by different roles.

2. Why is architecture needed? Any system, from an aircraft to a single e‑commerce feature, requires a well‑designed architecture to control complexity; a well‑structured design yields better outcomes than ad‑hoc development.

3. Responsibilities of an architect An architect should simplify complexity, producing understandable structures that allow designers, implementers and operators to grasp the system easily.

Software architecture definition It is a high‑level sketch of a system, describing abstract components, their interactions, and, during implementation, mapping these components to concrete classes or objects. Its core value is controlling complexity, not a specific layering or methodology.

Classification of software architecture The article distinguishes several types: business architecture, application architecture, distributed system architecture, data architecture, physical architecture, and operations architecture, each addressing different concerns such as domain modeling, service interfaces, scalability, data governance, hardware deployment, and operational tooling.

Typical application architectures

Layered architecture – a common practice of separating responsibilities into presentation, application, domain, and infrastructure layers.

CQRS (Command‑Query Separation) – separates commands that change state from queries that read state.

Hexagonal (port‑adapter) architecture – isolates the core business logic from external technical details.

Onion architecture – builds on hexagonal ideas, adding multiple domain‑driven layers (application, domain service, domain model, infrastructure) with strict inward‑only dependencies.

COLA framework COLA (Component‑Oriented Lightweight Architecture) is an open‑source Alibaba framework that incorporates the above ideas. Its layered design improves the classic three‑tier model by splitting the business layer into presentation, application, domain, and infrastructure layers. The framework defines extension points identified by a business identity (BizCode) and an extension coordinate, enabling multi‑tenant and multi‑scenario customization.

Extension design Business identity uniquely marks a scenario, while extension points allow plug‑in implementations. The combination forms an extension coordinate that the framework resolves at runtime.

Standardization COLA enforces conventions for module structure, package naming, and component organization to reduce ad‑hoc decisions and maintain consistency across projects.

Core mission of application architecture Across all discussed styles, the unifying goal is to separate core business logic from technical details, allowing the former to be stable, testable, and replaceable while the latter can evolve independently.