# Spring Cloud Polaris RateLimit Example

## Project Explanation

This project shows how to use ratelimit feature of Polaris to complete Spring Cloud application's rate limit

## Example

### How to access

Before showcasing the project, let's get to know how to access Polaris rate limit component

> ** note: this chapter is to help you understand different ways to access, the codes in the example has been executed, you don't need to re-edit.**

1, first, change document `pom.xml`, introduce Polaris ratelimit starter

  ```xml
  <dependency>
      <groupId>com.tencent.cloud</groupId>
      <artifactId>spring-cloud-starter-tencent-polaris-ratelimit</artifactId>
  </dependency>
  ```

2. Launch Application

Examples provided by Polaris all support to run at IDE, or compile and run with orders

- Launch Polaris locally

- at Polaris end, through control panel, under namespace Product, add RateLimitCalleeService

- Launch callee server:

   1. Launch IDE directly: First find `RateLimitCalleeService`, execute main then launch application
   2. compile package then launch: first execute `mvn clean package` compile the package
      - then execute  `java -jar ratelimit-callee-sevice-${verion}.jar` execute the application
      - then execute  `java -jar ratelimit-caller-sevice-${verion}.jar` execute the application
   - After launching, one can watch server instance from Polaris control panel

   3. Invoke Service

  After visiting http://127.0.0.1:58080/business/invoke, one can see the following information:

   ````
  hello world for ratelimit service 1
  hello world for ratelimit service 2
  hello world for ratelimit service 3
  ...
   ````

4. Configuration rate limit and verification
   Polaris provide three wats to conduct rate limit configuration (control panel, HTTP port and local files)

   - HTTP configuration. One can figure with the following steps:

     ````
      curl -X POST -H "Content-Type:application/json" 127.0.0.1:8090/naming/v1/ratelimits  -d @rule.json
     ````

   - Configuration is done through the console, example as follows.

      ![](polaris-ratelimit-ui.png)

5. Verify rate limit result
   continue visit http://127.0.0.1:68080/business/invoke, one can see, after 10 invokes, rate limit will start:

  ````
   hello world for ratelimit service 1
   hello world for ratelimit service 2

  ````