Doc: fix sidecar doc (#3296)

spring-cloud-alibaba-docs/src/main/asciidoc-zh/sidecar.adoc

@@ -40,7 +40,7 @@ Gateway的新一代Sidecar，然而官方表示并没有该计划。详见：htt
 * 目前Mesh主要使用场景在Kubernetes领域（Istio、Linkerd
 2等，大多将Kubernetes作为First
 Class支持，虽然Istio也可部署在非Kubernetes环境），而目前业界，Spring
-Cloud应用未必有试试Mesh的环境；
+Cloud应用未必有 Service Mesh 的环境；
 * 使用Alibaba
 Sidecar一个小组件就能解决问题了（核心代码不超过200行），引入整套Mesh方案，颇有点屠龙刀杀黄鳝的意思。
 
@@ -66,7 +66,7 @@ Cloud本身就是基于HTTP的；
 === 使用示例
 
 * 如使用Nacos作为服务发现组件，详见`spring-cloud-alibaba-examples/spring-cloud-alibaba-sidecar-examples/spring-cloud-alibaba-sidecar-nacos-example`
-* 如使用Consul作为服务发现组件，详见`spring-cloud-alibaba-examples/spring-cloud-alibaba-sidecar-examples/spring-cloud-alibaba-sidecar-nacos-example`
+* 如使用Consul作为服务发现组件，详见`spring-cloud-alibaba-examples/spring-cloud-alibaba-sidecar-examples/spring-cloud-alibaba-sidecar-consul-example`
 
 ==== 示例代码（以Nacos服务发现为例）
 
@@ -178,7 +178,7 @@ Gateway还可以整合Sentinel或者Hystirx、Resilience4J，所以也带有了
 === Alibaba Sidecar优缺点分析
 
 Alibaba
-Sidecar的设计和Sidecar基本一致，优缺点和Sidecar的优缺点也是一样的。
+Sidecar的设计和 Netfix Sidecar 基本一致，优缺点和 Netfix Sidecar 的优缺点也是一样的。
 
 优点：
 

spring-cloud-alibaba-docs/src/main/asciidoc/sidecar.adoc

@@ -0,0 +1,193 @@
+== Spring Cloud Alibaba Sidecar
+
+`Spring Cloud Alibaba Sidecar` is a Spring Cloud for quick and perfect integration
+with * heterogeneous microservices * framework, inspired by
+https://github.com/spring-cloud/spring-cloud-netflix/tree/master/spring-cloud-netflix-sidecar[Spring
+Cloud Netflix Sidecar]，currently supported service discovery components:
+
+* Nacos
+* Consul
+
+=== Terminology
+
+==== Heterogeneous microservice
+
+Non-spring Cloud applications are referred to as heterogeneous micro-services. Such as your legacy projects, or non-JVM applications.
+
+==== Three meanings of "perfect integration"
+
+* Take advantage of service discovery
+* There is load balancing
+* with circuit breaker
+
+=== Why or Why not?
+
+==== Why write Alibaba Sidecar?
+
+There are two reasons:
+
+* Spring Cloud subproject 'Spring Cloud Netflix Sidecar'
+It is possible to integrate heterogeneous microservices quickly. However, Sidecar only supports the use of Eureka as a service discovery, * if you use other service discovery components you are blinded *.
+* *Sidecar is based on Zuul 1.x *, Spring
+Cloud has officially stated that Zuul will be phased out in the future. Earlier this year, I gave it to Spring
+The Cloud official requested an official implementation based on the Spring Cloud
+Gateway's new Sidecar, though officials say there are no plans for it. See: https://github.com/spring-cloud/spring-cloud-gateway/issues/735
+
+Since I didn't, I wrote it myself.
+
+==== Why not use a Service Mesh?
+
+* Currently, Mesh is mainly used in Kubernetes (Istio, Linkerd
+2, etc., most of the Kubernetes as the First
+Class support, although Istio can also be deployed in non-Kubernetes environments), unlike the current industry, Spring
+Cloud applications may not have Service Mesh environments;
+* Use Alibaba
+Sidecar solves the problem in a single widget (no more than 200 lines of core code) and introduces a complete Mesh scheme, which is a bit like killing eel.
+
+=== principle
+
+* Alibaba
+Sidecar registers the IP/ port of heterogeneous micro-services to the service discovery component based on the configured IP and port of heterogeneous micro-services*
+.
+* Alibaba Sidecar implements * Health Check *, Alibaba
+Sidecar periodically checks whether heterogeneous microservices are healthy. If heterogeneous microservices are found to be unhealthy, Alibaba
+Sidecar will automatically represent the heterogeneous micro services of Alibaba
+Sidecar instance is offline. If the heterogeneous microservice recovers, it automatically goes online. The maximum delay is 30 seconds, see details
+`Alibaba SidecarChecker#check.`
+
+=== requirement
+
+* [Must] Your heterogeneous microservice needs to communicate using HTTP. This is not strictly a requirement because of Spring
+The Cloud itself is based on HTTP;
+* 【 Optional 】 If the microservice is configured with `sidecar.health-check-url`
+In this case, your heterogeneous micro service needs to implement health check (can be empty implementation, as long as an endpoint is exposed, return similar
+`{"status": "UP"}` is a string).
+
+=== Use an example
+
+* If Nacos is used as a service discovery component, See `spring-cloud-alibaba-examples/spring-cloud-alibaba-sidecar-examples/spring-cloud-alibaba-sidecar-nacos-example` for details
+* If you use Consul as a service discovery component, See `spring-cloud-alibaba-examples/spring-cloud-alibaba-sidecar-examples/spring-cloud-alibaba-sidecar-consul-example` for details
+
+==== Sample code (using Nacos service discovery as an example)
+
+* Plus dependence:
++
+[source,xml]
+----
+<dependency>
+<groupId>com.alibaba.cloud</groupId>
+<artifactId>spring-cloud-starter-alibaba-sidecar</artifactId>
+</dependency>
+----
+* Write configuration:
++
+[source,yaml]
+----
+server:
+  port: 8070
+spring:
+  cloud:
+    nacos:
+      discovery:
+        server-addr: 127.0.0.1:8848
+    gateway:
+      discovery:
+        locator:
+          enabled: true
+  application:
+    name: node-service
+sidecar:
+  # IP address of the heterogeneous microservice
+  ip: 127.0.0.1
+  # Port of the heterogeneous microservice
+  port: 8060
+  # Health check URL for heterogeneous microservices
+  health-check-url: http://localhost:8060/health.json
+management:
+endpoint:
+    health:
+      show-details: always
+----
++
+The configuration was simple, registering Alibaba Sidecar with Nacos and adding a few lines of Alibaba
+Sidecar configuration.
+
+==== Heterogeneous microservice
+
+I have prepared a simple microservice written in NodeJS.
+
+[source,javascript]
+----
+var http = require('http');
+var url = require("url");
+var path = require('path');
+
+// create server
+var server = http.createServer(function(req, res) {
+    // Get the path to the request
+    var pathname = url.parse(req.url).pathname;
+    res.writeHead(200, { 'Content-Type' : 'application/json; charset=utf-8' });
+    // Visit http://localhost:8060/ and {"index":" Welcome to Home page"}
+    if (pathname === '/') {
+        res.end(JSON.stringify({ "index" : "Welcome to Home page" }));
+    }
+    // Visit http://localhost:8060/health, will return to {" status ":" UP "}
+    else if (pathname === '/health.json') {
+        res.end(JSON.stringify({ "status" : "UP" }));
+    }
+    // In other cases, 404 is returned
+    else {
+        res.end("404");
+    }
+});
+// Create a listener and print a log
+server.listen(8060, function() {
+    console.log('listening on localhost:8060');
+});
+----
+
+==== Test
+===== Test 1: Spring Cloud microservices perfectly invoke heterogeneous microservices
+
+Integrate the Ribbon for your Spring Cloud microservice and build `http://node-service/**`
+, you can request the heterogeneous micro service `/**`.
+
+Example:
+
+Ribbon requests `http://node-service/` will request `http://localhost:8060/`
+And so on.
+
+As for the circuit breaker, normal for your Spring
+Just integrate Sentinel, Hystirx and Resilience4J with Cloud microservices.
+
+===== Test 2: Heterogeneous microservices perfectly invoke Spring Cloud microservices
+
+Alibaba Sidecar is based on the Spring Cloud Gateway, and the gateway has its own forwarding capability.
+
+Example:
+
+If you have a Spring Cloud microservice called `spring-cloud-microservice`
+Then the NodeJS application only needs to build
+`http://localhost:8070/spring-cloud-microservice/**`, Alibaba
+Sidecar then forwards the request to `spring-cloud-microservice`’s `/**` 。
+
+The Spring Cloud Gateway integrates the Ribbon to realize load balancing. Spring Cloud
+Gateway also has a circuit breaker for integrating Sentinel or Hystirx, Resilience4J.
+
+Analysis of advantages and disadvantages of Alibaba Sidecar
+
+Alibaba
+The design of Sidecar is basically the same as that of Netfix Sidecar, and the advantages and disadvantages are the same as those of Netfix Sidecar.
+
+Advantages:
+
+* Easy access, a few lines of code to integrate heterogeneous micro-services into the Spring Cloud ecosystem
+* Does not hack the original code
+
+Disadvantages:
+
+* You need to deploy an additional Alibaba for each heterogeneous microservice instance you connect to
+Sidecar instances, increasing the deployment cost (although this cost is almost negligible in a Kubernetes environment)
+Sidecar instances and heterogeneous microservices can be deployed as a Pod));
+* When a heterogeneous microservice calls a Spring Cloud microservice, it essentially takes Alibaba
+Sidecar When the gateway is in use, the gateway performance deteriorates after layer 1 forwarding.

spring-cloud-alibaba-docs/src/main/asciidoc/spring-cloud-alibaba.adoc

@@ -29,4 +29,6 @@ include::schedulerx.adoc[]
 
 include::sms.adoc[]
 
+include::sidecar.adoc[]
+
 include::graalvm.adoc[]