AsyncAPI 试用

AsyncAPI 提供了类似openapi的代码生成，以下demo，来自官方，只是目前官方的generator有些问题以下
同时说明运行中的一些问题

环境准备

主要是安装依赖组件

npm install -g asyncapi-generator mqtt

定义AsyncAPI

稍有改动，主要是channel（mqtt 的topic）

• yaml 文件

asyncapi: '2.0.0'

info:

  title: Streetlights API

  version: '1.0.0'

  description: |

    The Smartylighting Streetlights API allows you

    to remotely manage the city lights.

  license:

    name: Apache 2.0

    url: 'https://www.apache.org/licenses/LICENSE-2.0'

​

servers:

  mosquitto:

    url: test.mosquitto.org

    protocol: mqtt

​

channels:

  dalong/measured:

    publish:

      summary: Inform about environmental lighting conditions for a particular streetlight.

      message:

        payload:

          type: object

          properties:

            id:

              type: integer

              minimum: 0

              description: Id of the streetlight.

            lumens:

              type: integer

              minimum: 0

              description: Light intensity measured in lumens.

            sentAt:

              type: string

              format: date-time

              description: Date and time when the message was sent.

​

• 生成代码命令

ag asyncapi.yaml nodejs -p server=mosquitto

• 简单说明
  如果直接使用url test.mosquitto.org 会有解析的问题，如下：

 

Something went wrong:

Template render error: (unknown path) [Line 29, Column 36]

  TypeError [ERR_INVALID_URL]: Invalid URL: test.mosquitto.org

    at Object._prettifyError (/usr/local/lib/node_modules/asyncapi-generator/node_modules/nunjucks/src/lib.js:36:11)

    at /usr/local/lib/node_modules/asyncapi-generator/node_modules/nunjucks/src/environment.js:567:19

    at Template.root [as rootRenderFunc] (eval at _compile (/usr/local/lib/node_modules/asyncapi-generator/node_modules/nunjucks/src/environmen

t.js:637:18), <anonymous>:83:3)

    at Template.render (/usr/local/lib/node_modules/asyncapi-generator/node_modules/nunjucks/src/environment.js:556:10)

    at Environment.renderString (/usr/local/lib/node_modules/asyncapi-generator/node_modules/nunjucks/src/environment.js:380:17)

    at Promise (/usr/local/lib/node_modules/asyncapi-generator/lib/generator.js:507:21)

    at new Promise (<anonymous>)

    at Generator.renderString (/usr/local/lib/node_modules/asyncapi-generator/lib/generator.js:506:12)

    at Generator.renderFile (/usr/local/lib/node_modules/asyncapi-generator/lib/generator.js:531:19)

    at <anonymous>

 

解决方法：临时修改为一个url 格式的比如test.mosquitto.org:1883 生成代码之后再修改回来

• 生成效果

Done! ✨

Check out your shiny new generated files at /Users/dalong/mylearning/asyncapi-learning/first/streetlights.

 

• 修改几处生成的代码
  配置文件：
  config/common.yml:
  如下：

 

default:

  app:

    name: Streetlights API

    version: 1.0.0

​

  broker:

    mqtt:

      url: mqtt://test.mosquitto.org

      topics: ["dalong/measured"]

      qos:

      protocol: mqtt

      retain:

      subscribe: true

​

development:

​

test:

​

staging:

​

production:

​

 

 

路由以及handler修改：
路由：

随便些一个名字，注意后边handler 需要和这个一样

启动&&测试

• 安装npm依赖

 

yarn

• 启动

yarn start

• 模拟消息发送

mqtt pub -t 'dalong/measured' -h 'test.mosquitto.org' -m '{"id": 1111, "lumens": 3, "sentAt": "2019-10-06T12:34:32.000Z"}'

• 效果

说明

以上是一个简单的试用，以及在使用中碰到的问题，AsyncAPI 是一个很不错的编写事件驱动应用的指南

参考资料

https://www.asyncapi.com/docs/tutorials/streetlights/
https://github.com/asyncapi/generator
http://test.mosquitto.org/
https://github.com/rongfengliang/asyncapi-streetlights-demo