SpringCloud 2020 study notes-preface

I. Introduction

I have been using java for learning and work for a while, and I have studied roughly some time agoDubboFramework, as the first time to use the microservice framework for me, in itsService governance、Service callI am deeply moved by the function, and I also feel itMicroservicewithMonolithic applicationI like the split of its functional modules, which reduces the coupling of the overall system. This may be what everyone saidLow coupling, high cohesionThink of it. The first time I came into contact, I couldn't wait to learn about it and master it, so I decided to go to the system to learn the springcloud system. In order to improve the learning effect and deepen the learning impression, I plan to write a series of notes blog during the learning process to assist my learning and share my process, hoping to help some novices who are the same, and also hope to read The big guys who came to my article can point out my shortcomings, thank you very much (^▽)！

2. System composition

Although I just started to write study notes, I actually study onlinespringcloudThe related knowledge of has been around for a while, but this is a rough understanding of the relatively shallow knowledge, and a rough understanding of the components of this framework and the upgrading of those components, because in the previous versionspringcloudThe components have many components alsoStop and advanceNow, for a newbie like me, I need to understand its past and its present, because many components are connected, and the ideas and concepts are in the same line. Here I am also learning. Learn more about his attitude.

springcloudIt has been developing for a long time. With its rapid development, the composition of springcloud has also undergone great changes. Based on the information on the Internet, I have sorted out the old and new versions with 2020 as the dividing line.springcloudComposition of

2.1 Early composition

springCloud

We can see that the old version of the springcloud framework is mainly composed ofEureka、RIbbon、Feign、Hystrix、SpringCloud Config、SpringBootcomposition. The main modules are divided intoService registration and discovery、Service load and call、Service fusing and degradation、Service gateway、Service distributed configuration、Service development, You can see that the coverage is relatively comprehensive.

2.2 The latest composition

2020

After the rapid development of springcloud, springcloud components are also blooming. Each module has many replaceable components, and technology selection can be made according to actual business needs.

3. Registration Center

Springcloud is a very good microservice framework. To manage many services, it is necessary to govern these services, which is what we are talking aboutService governance,Service governanceThe role of is to manage the dependency between each service and each service in the traditional rpc remote invocation framework, which can realize service invocation, load balancing, service fault tolerance, and service registration and discovery.
If there are call dependencies between microservices, you need to get the service address of the target service, which is the microservice governanceService discovery. To complete service discovery, it is necessary to store service information in a carrier, and the carrier itself is the microservice governanceService Registry, And the action of storing to the carrier isService registration。
The registration centers supported by springcloud areEureka、Zookeeper、Consul、Nacos

Component name	Company	Introduction to Components
Eureka	Netflix	The earliest registration center of springcloud, has entered`Stop and advance`Up
Zookeeper	Apache	zookeeper is a distributed coordination tool that can realize the registry function
Consul	Hashicorp	Consul simplifies the registration and discovery process of services in a distributed environment, discovering through HTTP or DNS interfaces. Support external SaaS providers, etc.
Nacos	Alibaba	Nacos is committed to helping you discover, configure, and manage microservices. Nacos provides a set of simple and easy-to-use feature sets to help you quickly realize dynamic service discovery, service configuration, service metadata and traffic management.

Fourth, load balancing

Load balancing is built on the original network structure. It provides a transparent and cheap and effective way to expand the bandwidth of servers and network equipment, strengthen network data processing capabilities, increase throughput, and improve network availability and flexibility.

Currently springcloud supports two load balancing components:Ribbon、LoadBalance

Component name	Company	Introduction to Components
Ribbon	Netflix	Ribbon is a client load balancing tool based on HTTP and TCP
LoadBalancer	-	-

Five, service call

Microservices splits the traditional monolithic application into multiple microservices, and also considers how the services call each other. The old version of springcloud usesFeignTo support rpc calls, now Feign has stopped improving its dimensions, byOpenFeignService call

Component name	Company	Introduction to Components
Feign	-	-
OpenFeign	SpringCloud	It is a declarative webService client, you can use it by defining the interface and adding annotations

6. Service protection

For the current high-concurrency scenarios common on the Internet, although we can provide a cluster method to tolerate service requests, it is inevitable that we will encounter unforeseen failures, such as downtime, as a complete microservice framework. Say, springcloud considers these situations and can chooseHystrix、seilience4j、sentinelTo protect the service and provideService degradation、Service fusing、Service current limitFunction of

Component name	Company	Introduction to Components
Hystrix	Netflix	Delay and fault tolerance solutions for distributed systems have been`Stop and advance`
Resilience4j	-	`Resilience4j`It is a lightweight, easy-to-use fault-tolerant library, inspired by`Netflix Hystrix`, But designed for Java8 and functional programming, it is officially recommended`Hystrix`Alternative.
Sentinel	Alibaba	Alibaba's flow control component for distributed service architecture

Seven, service gateway

In the process of governance of numerous services in microservices, the role of service gateway can be provided in the framework of microservicesUnified entrance、Authentication check、Dynamic routing、Reduce couplingFunction of

Component name	Company	Introduction to Components
zuul	Netflix	`Stop and advance`
zuul2	Netflix	3 zuul core developers resigned, the gods fought, the way out is unknown
gateway	springcloud	A set of non-blocking network asynchronous gateways developed by springcloud

Eight, service configuration

Spring Cloud officially provides the Spring Cloud Config distributed configuration center, which provides centralized external configuration support. It is divided into two parts: client and server. The server is called the configuration center, which is an independent microservice application that is used to connect to warehouses (such as Git, Svn). The client does not provide an interface for obtaining configuration; while the client is each microservice application, and the configuration center address is specified Obtain the configuration content from the remote, and load the configuration information into the application context at startup. Because the configuration center implemented by Spring Cloud Config uses Git to store configuration information by default, version control management is also supported based on the characteristics of the Git repository itself. Currently springcloud is availablespringcloud configwithNacos

Component name	Company	Introduction to Components
Config	springcloud	Config provides server-side and client-side support for externalized configuration in distributed systems.
Nacos	Alibaba	An easy-to-use dynamic service discovery, configuration and service management platform for building cloud native applications.

Nine, service bus

Spring Cloud Bus connects distributed nodes with a lightweight message broker. It can be used to broadcast configuration file changes or communication between services, and can also be used for monitoring. This article is about using Spring Cloud Bus to realize the change of the configuration file of the notification microservice architecture.

Component name	Company	Introduction to Components
Bus	springcloud	-
Nacos	Alibaba	-

Ten, springcloud and springcloud alibaba

Spring Cloud is a set of microservice specifications designed based on Spring Boot and enhanced application context. Spring Cloud Alibaba uses Ali middleware as the foundation to implement Spring Cloud's microservice specifications.

2018-12-12 Netflix announced to stop the development of Spring Cloud related services: Ribbon, Feign, Eureka, Hystrix, continue to use it at your own risk

This article is based on my current understanding of springcloud. There must be many bad points and errors in the article. Please correct me if you see it.

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