plugin

Compatibility

Pomelo plugins were introduced in version 0.6.

Plugin Structure

Pomelo plugins are divided into two sections: components (required) and events (optional):

In Pomelo, a component is a reusable factory where each instance provides a service. For more in-depth information on Pomelo component architecture, see What is a component.

Each plugin can have several components, and for each component developers can implement different life-cycle callbacks (e.g. start, afterStart, stop, etc.).

Each plugin dispatches the following events:

• 'add_servers'： event parameter is an Array of server information.
• 'remove_servers': event parameter is an Array of server information.
• 'replace_servers': internal server disconnect and reconnect event. Parameter is an Array of server information which have not disconnected.
• 'bind_session': session has been bound. Parameter is the session object.
• 'close_session': close session event (including connection error). Parameter is the session object.

Using a Plugin

Most plugin configuration will occur in your app.js file.

####app.use(plugin, options);

• 'plugin': plugin definition
• 'options': plugin options

Example:

var statusPlugin = require('pomelo-status-plugin');
...
app.use(statusPlugin, {
  status: {
    host: '127.0.0.1',
    port: 6379
  }
});
...

##Building a Plugin

First, create a plugin project with directory structure like so:

Second, you need to configure the components and events in index.js:

module.exports = {
  components: __dirname + '/lib/components/',
  events: __dirname + '/lib/events/'
};

Finally, you can add your components and events. For components, you need to export its constructor, the example code is as follow:

module.exports = function(app, opts) {
  return new Component(app, opts);
};

var Component = function(app, opts) {
  //do construction
};

Component.prototype.start = function(cb) {
  // do something application start
};

Component.prototype.afterStart = function(cb) {
  // do something after application started
};

Component.prototype.stop = function(cb) {
  // do something on application stop
};

Events are similar:

module.exports = function(app) {
  return new Event(app, opts);
};

var Event = function(app) {
  //do construction
};

Event.prototype.add_servers = function(servers) {
  //do something when application add servers
};

Event.prototype.remove_servers = function(ids) {
  //do something when application remove servers
};

Event.prototype.replace_servers = function(servers) {
  //do something when server reconnected
};

Event.prototype.bind_session = function(session) {
  //do something when session binded
};

Event.prototype.close_session = function(session) {
  //do something when session closed
};