Best Practices for Application Layering: Alibaba's Architecture Guidelines and Optimized Design

1. Background

Many developers treat application layering superficially, often mixing responsibilities across controller, service, and mapper layers, which leads to tangled code, poor reusability, and difficult maintenance.

2. Alibaba's Layer Specification

Open Interface Layer : Exposes Service methods as RPC or HTTP interfaces, handling gateway security and traffic control.

Terminal Display Layer : Handles template rendering for various clients (Velocity, JS, JSP, mobile).

Web Layer : Performs request routing, basic parameter validation, and simple non‑reusable business processing.

Service Layer : Contains concrete business logic with relatively low reusability.

Manager Layer : Provides reusable logic such as cache, MQ, or composite operations, and may handle data conversion for HTTP/ RPC managers.

DAO Layer : Direct data access to databases like MySQL, Oracle, HBase.

3. Optimized Layering (Considering Thrift RPC)

The added Thrift layer functions similarly to a controller. Recommended structure:

Controller/TService : Light business logic, parameter validation, exception handling.

Service : Core business processing; each controller method should map to a distinct service method to avoid duplicated orchestration logic.

Manager : Reusable logic, possibly aggregating multiple managers.

DAO : Database access, only invoked by its corresponding service.

4. Domain Model Conversions

Alibaba's guidelines define several model types:

DO (Data Object): Directly maps to database tables.

DTO (Data Transfer Object): Used for data transfer between Service/Manager and external callers.

BO (Business Object): Encapsulates business logic output from Service.

AO (Application Object): Near‑presentation layer, low reuse.

VO (View Object): Passed to view/template engines.

Query: Encapsulates query parameters, avoiding Map usage for >2 parameters.

Excessive conversions across layers can lead to performance overhead and maintenance burden.

5. Recommendations

Allow Service/Manager layers to operate on domain models, handling business logic and data assembly.

Prevent Controller/TService from passing its models directly to DAO, preserving responsibility boundaries.

Similarly, DAO should not receive models from Controller/TService.

6. Conclusion

A well‑designed layering scheme enhances code reuse, clarifies responsibilities, and simplifies maintenance, though teams may adapt the guidelines to fit their specific development practices.