I Basic concepts

Simply take a study note , Bli bli has a video on it .

1. Microservices

Microservice architecture style , Is to take a Separate applications Develop into a set Little service , every last Little service It's all a separate process . And use lightweight communication to maintain communication between services , Usually HTTP. These services are built around business capabilities , And deploy independently through a fully automated deployment mechanism . These services can be written in different languages , And different data storage technologies , And maintain the lowest degree of centralized management .
In short ： Reject large single application , Service micro splitting based on business boundary , Each service runs and deploys independently .

2. colony & Distributed & node

Clusters are physical forms , Distributed is a way of working .
Just a bunch of machines , It can be called a cluster , Are they working together , No one knows this .
《 Principles and specifications of distributed systems 》 Definition ：
“ Distributed systems are collections of nogan independent of computers , These computers are like a single related system to users ”
A distributed system is a software system built on a network .
(1) Distributed means that different businesses are distributed in different places
(2) Clustering refers to putting several servers together , Achieve the same business
(3) Every node in the distribution , Can be called a cluster . Cluster is not necessarily distributed

3. The remote invocation

In distributed systems , Each service may be on a different host , But services inevitably need to call each other , We call it remote call .
SpringCloud Use in HTTP + JSON To complete the remote call in the same way .

4. Load balancing

     Distributed system ,A The service needs to call B service ,B Services exist on multiple machines ,A Calling any server can complete the function .
     In order not to be too busy or too busy for every server , We can load balance each server , Improve the performance of the website .
Common load balancing algorithms ：
     polling ： Select the first back-end server in the health pool for the first request , Then select one time later in order , Until the last one , Then the cycle .
     The minimum connection ： Give priority to the least number of connections , The back-end server with the least pressure , In conversation
     hash ： According to the request source IP Hash of （hash） To select the server to forward . This way can ensure that specific users can connect to the same server to some extent . If your application needs to handle state and require users to be able to connect to the same server as before , Think about it this way .

5. Service registration / Find out & Registry Center

A The service call B service ,A I don't know about the service B Which servers does the service currently have , What's normal , Which services have been offline . To solve this problem, we can introduce the registry .

6. Configuration center

Each service eventually has a large number of configurations , And each service may be deployed on multiple machines . We often need to change the configuration , We can let each service get its own configuration in the configuration center .

7. Service failure & service degradation

8. API gateway

In the microservices architecture ,API Gateway As an important component of the overall architecture , it It abstracts the public functions required in microservices , At the same time, the client is provided Load balancing , The service fuses automatically , Grayscale Publishing , Unified certification , Current limiting flow control , Log statistics And other rich functions , Help us solve many problems API Management problems .

Guli structure diagram