Introduction and use of gateway

Preface ：
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Gateway introduction

gateway (Gateway) also called Internetwork connector 、 Protocol converter . The default gateway realizes network interconnection above the network layer , Is the most complex network interconnection device , It is only used for interconnection of two high-level protocols . The structure of the gateway is similar to that of the router , The difference is the interconnection layer . Gateway can be used for WAN interconnection , Can also be used for LAN interconnection .

Gateway is a kind of computer system or device that acts as the task of transformation . Use in different communication protocols 、 Data format or language , Even between two systems with completely different architectures , The gateway is a translator . It's different from a bridge that simply conveys information , The gateway should repackage the received information , To meet the needs of the target system . Same layer – application layer .

So to sum up ：

gateway （Gateway） It is a device that connects two network segments using different protocols .
The gateway is simultaneous interpreting and translating data from two network segments using different transport protocols. .

Gateway Gateway is the gatekeeper of our service , A unified portal for all microservices .

Gateway implementation

stay SpringCloud The implementation of gateway in mainly includes two kinds ：gateway and zuul

Zuul Is based on Servlet The implementation of the , It belongs to blocking programming . and SpringCloudGateway Is based on Spring5 Provided in WebFlux, It belongs to the implementation of responsive programming , Better performance .

Gateway Use

Gateway The use steps of the gateway are as follows ：

1. establish SpringBoot engineering gateway, Introducing gateway dependencies
2. Write the startup class
3. Write basic configuration and routing rules
4. Start the gateway service for testing

First step , Introduce dependencies

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>
<!--nacos Our services depend on -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>

The second step , Write the startup class

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class GatewayApplication {
    

	public static void main(String[] args) {
    
		SpringApplication.run(GatewayApplication.class, args);
	}
}

The third step , stay ymal Write configurations and rules

server:
  port: 10010 #  Gateway port 
spring:
  application:
    name: gateway #  Name of service 
  cloud:
    nacos:
      server-addr: localhost:8848 # nacos The address of 
    gateway:
      routes: #  Gateway routing configuration 
        - id: user-service #  route id, Customize , As long as it's the only one 
          # uri: http://127.0.0.1:8081 #  The destination address of the route  http It's a fixed address 
          uri: lb://userservice #  The destination address of the route  lb It's load balancing , Followed by the service name 
          predicates: #  Route assertion , That is, judge whether the request meets the conditions of routing rules 
            - Path=/user/** #  This is matched according to the path , As long as /user/ Meet the requirements at the beginning 

We will conform to Path All requests of the rules , All agents arrive at uri The address specified by the parameter .

Summary of gateway entry

summary ：

Gateway building steps ：

1. Create project , introduce nacos Service discovery and gateway rely on

2. To configure application.yml, Including basic service information 、nacos Address 、 route

Routing configuration includes ：

1. route id： The unique identifier of the route

2. Routing destination （uri）： The destination address of the route ,http Represents a fixed address ,lb Represents load balancing based on service name

3. Route assertion （predicates）： Rules for judging routing ,

4. Routing filter （filters）： To process a request or response

The factory

Spring Cloud Gateway Many routing assertion factories are built in , It can be used directly through configuration , You can also combine multiple routing assertion factories .

for example ：
Path Route assertion factory
Path The routing assertion factory receives a parameter , according to Path Well defined rules to determine the access URI match .

```yaml
spring:
  cloud:
    gateway:
      routes:
        - id: host_route
    uri: http://example.test
    predicates:
      - Path=/blog/detail/{
    segment}

Method Route assertion factory
Method The routing assertion factory receives a parameter , That is to match HTTP Method .

spring:
  cloud:
    gateway:
      routes:
        - id: method_route
  uri: http://baidu.com
  predicates:
    - Method=GET

Cookie Route assertion factory
adopt cookie And a regular expression as a routing factory for assertion conditions , As long as this condition is met, you can access the address .

spring:
cloud:
gateway:
routes:
- id: between_route #  route  Id, only 
uri: https://example.org #  The goal is  URI,  The address routed to the microservice 
predicates:
- Cookie=chocolate, ch.p #  Use Cookie Route assertion factory , To configure cookie, Regular expressions ( There can be no )

Configuration interpretation ： This route will match with a named chocolate Of cookie Request , The cookie The value of matches ch.p Regular expressions

Of course, there are more than a dozen factories , We just need to master Path This routing project is OK .
There are also other factories , Our next article will discuss .

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