bajo-emitter

Plugin name: bajoEmitter, alias: emitter

Attention: I do NOT accept any pull request at the moment, thanks!

Event emitter and message broker for Bajo based on the excellent EventEmitter2.

Installation

Goto your <bajo-base-dir> and type:

$ npm install bajo-emitter

Now open your <bajo-data-dir>/config/.plugins and add bajo-emitter in it

Configuration

Open/create <bajo-data-dir>/config/bajoEmitter.json:

| Key | Type | Required | Default | Description | | --- | ---- | -------- | ------- | ----------- | | maxListeners | integer | no | 100 | Max number of listeners that can be assigned to an event | | verboseMemoryLeak | boolean | no | false | Show event name in memory leak message when more than maximum amount of listeners is assigned | | ignoreErrors | boolean | no | false | Disable throwing uncaughtException if an error event is emitted and it has no listeners | | broadcastPools | array | no | [] | Broadcast pools | |   name | string | no | default | Pool name | |   from | string/array of string | yes || Source address(es) | |   to | string/array of string | no || Destinatin address(es) | |   handler | string | no || If not empty, messages are handled by this plugin helper instead of simply routed to to address(es) |

Note:

• Only incoming messages from connections marked for broadcast will be processed
• from should be one or more addresses with format <connection>@<plugin>. Only messages coming from one of these addresses are handled by this pool
• to should be one or more addresses with format [subject:]<connection>@<plugin>
• handler is a plugin helper name with format <plugin>:<helper>. If you use .js config file, you can attach a custom function instead.

Helper

function addressSplit (address)

• A valid address should be in [<subject>:]<connection>@<plugin>
• This helper destructs address into their components.
• Returns object with the following keys:
  • plugin
  • connection
  • subject

function addressVerify (address, options)

• Validate address of its components correctness. All options are optional:
  • skipConnectionCheck: won't check whether the connection is valid or not. Default: false
• Returns true if address is valid, otherwise false

function emit (event, ...params)

• Emit message as event named event
• Zero, one or more parameters to emit
• Returns none

function broadcast (params)

• Send message as a broadcast
• Parameters
  • msg: message to send
  • from: address from where message is originated
  • to: address to where message will be sent
  • subject: message subject
• Returns none

Event Handling

To consume event emitted you should do these steps:

• Create bajoEmitter/event/<eventType> directory inside your <bajo-plugin-dir>. Event type could be one of on, once and off
• Create a file named [<plugin>@]<event>.js inside directory you just created above. <plugin> is optional, if not supplied, it defaults to current plugin
• <event> is the name of event emitted. Name is then camel cased to form a valid event name
• Write <bajo-handler> inside the above file

As an example, I use main plugin here and try to consume message event of bajoMqtt

1. Directory structure:

   ...
   app
   |-- main
   |   |-- bajoEmitter
   |       |-- event
   |           |-- on
   |               |-- [email protected]
   ...

2. Inside [email protected]:

   async function onBajoMqttMessage (conn, ...params) {
     const [topic, msg] = params
     console.log(topic, msg.toString())
   }
   
   export default onBajoMqttMessage

License

MIT