[cloud native] what is the microservice architecture?

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One 、 Why do you need a microservice Architecture

The emergence of new things will inevitably conflict with the sending of old things , And the vitality of a new thing , It depends on whether there is room for development , So micro service architecture is no exception . With the development of Internet technology , The traditional application architecture has been unable to meet the actual needs , Microservice architecture comes into being . So what are the problems with traditional application architecture ？ How to solve it ？

① Problems of traditional single application architecture

Usually, the traditional single application architecture we use is modular design , After the program is written, it will be packaged and deployed as a specific application , The format of the application depends on the corresponding application language and framework . for example : An e-commerce project ,Web The project will be hit WAR Packages are deployed in the form of Web Server , And ordinary. Java The program is marked as a Jar The form of package is contained in WAR in .

Pictured , This is our common development style , The benefits of this are conducive to development and debugging , And easy to deploy . In the case of a small number of customers , This kind of Architecture ( Single application architecture ) Fully meet the needs , But as the number of users increases , One server cannot satisfy , At this point, we will consider the horizontal expansion of the system , Usually our solution is to increase the number of servers , And copy the packaged application to different servers ( for example :Tomcat), Through the load balancer （Apache、Nginx） Easy horizontal expansion .

The problems of this architecture are as follows ：

• Application complexity increases , to update 、 Difficult to maintain
  • Simple applications are updated many times 、 Maintenance will become huge , Applications will become more complex , The development team faces many problems , The main problem is that the application is too complex , So that it is difficult for a single developer to carry out secondary development or maintenance
• It is easy to waste system resources
  • Although load balancing is used to expand the service capacity of the project horizontally across domains , However, there is only one code in the single application architecture that contains all functions WAR package , So while expanding the service capacity , You can only choose to deploy this repeatedly WAR Package to expand service capabilities , Instead of just expanding the services you need .
• Impact on development efficiency
  • When an application is bigger , The starting speed will be greatly reduced . In development and debugging , If you spend most of your time on startup , It will greatly affect the development efficiency .
• Low application reliability
  • The reliability of single application architecture is low , When a module generates BUG when , It is likely to cause the whole process to collapse , Thus affecting the whole application .
• It is not conducive to the renewal of Technology
  • Once certain technologies are selected for the traditional single application architecture , The later development and expansion will be realized on the basis of these technologies . If you need to change a technology , Then it is likely to redevelop the whole application .

② Solve the problems of traditional application architecture

Aiming at the problems of traditional monomer Architecture , Most enterprises pass SOA(Service-Oritend Architecture) Service oriented architecture solves the above problems .SOA The idea is to aggregate similar functions of applications , In the form of service , therefore SOA The application of architecture is simply understood as the combination of a number of services across domains .

• A whole project is divided into several sub projects , Different development teams are responsible for different sub projects , Improve development efficiency
• Split the module , Use interface communication , Reduce the coupling between modules
• Protect customers or service consumers from the impact of changes in service implementation

Although the use of SOA It solves the problems in the traditional monomer architecture , But most of the time ,SOA Independent services in will still be deployed to the same Tomcat For example , Similar to the single application architecture , With the increase of business functions ,SOA Services will also become complex . See the essence through the phenomenon , The problem of monomer architecture has not been solved .

In response to this problem , The architecture idea of microservice architecture also came into being , That is to decompose the application into small 、 Interconnected microservices .

Two 、 What is the microservice architecture ?

Microservice architecture is an architecture style and architecture idea , It advocates us to build on the traditional software application architecture , Split the system business more finely according to functions , Each service split is an independent application , These applications provide public API, Undertake external service responsibilities independently across domains , The software service entity developed through this idea is Microservices , And a series of architectures built around the idea of microservice ( Development 、 test 、 Deployment, etc. ) Let's call this Microservice architecture

① The advantages of microservice Architecture

• Controllable complexity
  • Finer grained application splitting , It will not become complicated with the evolution of time , Each service focuses on only one small function .
• Independently deployable
  • Because microservices have independent running processes , So each microservice can be deployed independently .
• Flexible technology selection
  • Microservices architecture , The selection of technology is diversified . Each team chooses the most suitable technology according to different needs .
• Easy fault tolerance
  • When a component sends a fault , It will only affect a small service , You can go online again by retrying .
• extensible
  • A single service application can also achieve horizontal expansion , This extension can completely complex the entire application to different nodes .
• Stable function
  • Each microservice has its own business logic and adapter , And only complete a specific function , For example, goods and services only manage goods .

② The shortcomings of microservice Architecture

• Developers have to deal with the complexity of creating distributed systems
  • Development tools are geared towards building traditional monolithic applications , Does not provide full functional support for developing distributed applications ( Typical development tools ：Eclipse)
• Testing is more difficult . In the microservices architecture , There are many services , Each service is an independent business unit , Services need to interact through interfaces .
• Implement across multiple service use cases , Requires careful coordination between teams .
• The complexity of deployment will greatly increase , This means developing 、 test 、 Operation and maintenance personnel need more solid accounting technology
• Increase memory consumption , The microservice architecture is replaced by multiple service instances 1 A single application instance , If every service is running at an increased JVM in , How many service instances are there , How many instances will have memory overhead at runtime .

③ Microservice architecture and SOA The difference between

Microservice architecture	SOA
A system is split into multiple services , fine-grained	The service consists of several subsystems , coarse-grained
Team level , Implement from bottom to top	Enterprise class , Carry out implementation from top to bottom
No centralized bus , Loose service architecture	Enterprise service bus , Centralized service architecture
Integrated way egg	The integration mode is complex
Services can be deployed independently	Services are interdependent , Can't deploy independently

3、 ... and 、 How to build a microservice Architecture

①、 Development of microservice instance

The development of micro services can choose Spring Boot

②、 Service registration and discovery

The registration and discovery of services in the architecture , Optional Spring Cloud Eureka、Apache Zookeeper、Consul（ Domestic deactivation )、Dubbo etc.

③、 Load balancing

Load balancing can be used Spring Cloud Ribbon and Dubbo etc.

④、 Service fault tolerance

The technology of service fault tolerance can use brother Hao (Hystrix) stay SpringCloud The subproject of contains

⑤、API gateway

In the architecture API Gateway service , Use Spring Cloud Zuul、Spring Reactor、Netty etc.

⑥、 Distributed configuration center

have access to Spring Cloud Config

⑦ debugging

The testing of microservice applications generally uses Swagger.Swagger It's the most popular REST API One of the document generation tools , Provides powerful page testing capabilities to debug each RESTful API

⑧ Deploy

Microservices are officially recommended Docker To package and deploy microservices .Docker Is an open source application container engine , Strong portability 、 It's fast to start , Suitable for lightweight applications