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Three-tier application architecture

With the continuous development of concepts and methodologies such as object-oriented analysis, object-oriented design, object-oriented principles, design patterns and enterprise architecture patterns, according to the different functions and software structures provided, we divide application development into three layers (presentation layer, business logic layer and data access layer), commonly known as three-tier architecture.

Advantages of a three-tier application architecture

The emergence of three-tier application architecture solves the problem of complex calls between systems and unclear responsibilities, effectively reduces the dependency between layers, and becomes one of the classic modes of software architecture.

Disadvantages of three-tier application architecture

The three-tier application architecture only divides the system into three layers logically, but it is not a physical layer. We end up coupling all the code together to compile, package, deploy, and run in the same process.

With the continuous expansion of business and the continuous increase of demand functions, single-block architecture has been difficult to meet the rapidly changing needs of the business. On the one hand, the shell maintainability, expansibility and flexibility of the code are decreasing; on the other hand, the modification cost, long delivery cycle, high technology selection cost and maintenance cost of the system are significantly increased.

Characteristics of Internet application

Products in the Internet era usually have the characteristics of low innovation cost, rapid demand change and large user base.

Micro-service architecture

1. What is the micro-service architecture model

Micro-service architecture is an architectural model, which advocates dividing a single application into a group of small services, which coordinate and cooperate with each other to provide users with the ultimate value. Each service runs in its own independent process, and the service and the service communicate with each other by a lightweight communication mechanism. Each service is built around the specific business, and can be independently deployed to the production environment, class production environment. In addition, a unified and centralized service management mechanism should be avoided as far as possible. for a specific service, appropriate voice and tools should be selected according to the business context. -- taken from Martin. Mr. Fowler's blog.

2. Micro-service and SOA

SOA implements micro-services at the enterprise level, top-down implementation team level, bottom-up implementation services composed of multiple subsystems, a system with large granularity is divided into multiple services, granularity small enterprise service bus, centralized service architecture without centralized bus, loose service architecture complex (ESB/WS/SOAP) integration mode simple (HTTP/REST/JSON) monolithic architecture system Highly coupled deployment complex independent deployment of individual services

3. Micro-service application architecture

A microservice generally performs a specific function, such as order management, customer management, and so on. Each microservice is a miniature hexagonal application with its own business logic and adapter. Some micro-services will also release API to other micro-services and application clients. Other microservices complete a Web UI, and at run time, each instance may be a cloud VM or a Docker container.

This micro-service architecture model has a profound impact on the relationship between the application and the database. Unlike the traditional multiple services sharing a database, each service in the micro-service architecture has its own database. In addition, this line of thinking also affects the enterprise data schema. At the same time, this pattern means multiple pieces of data, but a unique database for each service is necessary if you want to reap the benefits of microservices, because this architecture requires this kind of loose coupling.

Advantages of micro-service architecture

1. The complexity problem is solved for multiple service methods by decomposing huge monolithic applications.

With the same function, the application is decomposed into multiple manageable branches or services. Each service has a clearly defined boundary using either RPC- or message-driven API. The micro-service architecture pattern provides a modular solution for functions that are difficult to achieve with single coding, so that a single service is easy to develop, understand and maintain.

2. This architecture allows each service to be developed by a dedicated development team.

Developers are free to choose development technologies and provide API services. Of course, many companies try to avoid confusion and offer only certain technological options. Then, this freedom means that developers do not have to be forced to use the outdated technology that was used at the beginning of a project, they can choose the current technology. Even, because the services are relatively simple, it is not very difficult to rewrite previous code with current technology.

3. The micro-service architecture model is the independent deployment of each micro-service.

Developers no longer need to coordinate the impact of other service deployments on this service. This change can speed up deployment. UI teams can use AB testing to deploy changes quickly. The micro-service architecture pattern makes continuous deployment possible.

4. The micro-service architecture pattern makes each service expand independently.

You can deploy the scale that meets the needs according to the size of each service. Even, you can use hardware that is more suitable for service resource requirements.

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