Nacos - service discovery

Translation source of notes ： Dark horse Nacos

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One 、 Monomer architecture and microservices

1、 Monomer architecture

Use the same database for all functional modules , meanwhile , It also provides API perhaps UI Access to the Web Module etc. , Eventually, it will be packaged and deployed as a single application , This method deploys all functions in one Web The system running in the container is called monomer architecture

advantage
1	High development efficiency
2	Easy to test
3	Easy to deploy
shortcoming
1	The complexity is getting higher , The maintainability of the giant sword is getting worse
2	The falling speed of the version gradually slows down
3	Hinder technological innovation
4	Can't scale on demand

2、 Microservices

         Each business module uses independent services to complete , This microservice architecture pattern also affects the relationship between applications and databases , Unlike traditional methods, multiple business modules share a database , Microservice architecture each service has its own database .

benefits
1	Divide and rule , Single responsibility ; Easy to develop 、 Understanding and maintenance 、 Facilitate the splitting and management of the team ;
2	Telescopic ; It can scale the specified service separately ;
3	Local modification , Easy to replace , Easy to deploy , Conducive to continuous integration and rapid iteration
4	Not limited to any technology stack

Two 、 Service discovery

         In microservices , Services collaborate to achieve business goals . Remote calls between services are also required in microservices , Then you need to know the network location of the service 【IP And port number 】, Then you need to achieve the following .

        ①、 You need to report your network location to the service discovery center when each service is started .

        ②、 The service discovery client will periodically synchronize the service registry from the service discovery center , And cache on the client

        ③、 When a service needs to be requested , The service instance passes through the registry , Locate the target service network address . If the target service has multiple network addresses , Then the load balancing algorithm is used to select one from multiple service instances , Then make a request .

        summary ： In microservice , Because the network address of the service running instance is constantly changing , Dynamic changes in the number of service instances , Therefore, a fixed configuration file cannot be used to record the provider's network address , Dynamic service discovery mechanism must be used to realize mutual perception between microservices . Each service instance will report its own network address , In this way, the service center forms a complete service registry , Each service instance will obtain the network address of the target service through the service discovery center , So as to realize the mechanism of service discovery . 

3、 ... and 、 Comparison between mainstream service discovery and configuration center

Comparison items	Nacos	Eureka	Consul	Zookeeper
Agreement of conformity	Support AP and CP Model	AP Model	CP Model	CP Model
health examination	TCP/HTTP/MYSQL/Client Beat	Client Beat	TCP/HTTP/gRPC/Cmd	Keep Alive
Load balancing strategy	The weight /metadata/Selector	Ribbon	Fabil	-
Avalanche protection	Yes	Yes	nothing	nothing
Auto logout instance	Support	Support	I won't support it	Support
access protocol	HTTP/DNS	HTTP	HTTP/DNS	TCP
Monitor support	Support	Support	Support	Support
Multi-data center	Support	Support	Support	I won't support it
Sync across registries	Support	I won't support it	Support	I won't support it
SpringCloud Integrate	Support	Support	Support	I won't support it
Dubbo Integrate	Support	I won't support it	I won't support it	Support
k8s Integrate	Support	I won't support it	Support	I won't support it

Four 、Spring Cloud Service collaboration process