services.md

Services

The service is responsible for business logic and data persistence, each service controls their own data store. When registering a service it is important that the service can only listen to data events and submit/emit events from the write log. This is how it communicates with the outside world.

module.exports = service;

function service (config) {
  // manage any config info
  return function (ee) {
    ee.on('/model/verb', function(object) {
      // do stuff
      // return response
      emit('send', responseEvent);      
    });
  }
}

The above example is a service that takes in a configuration object and returns a function that is looking for a palmettoflow adapter, the adapter will emit palmettoflow events using the following json schema

{
  "title": "palmettoFlow-event",
  "type": "object",
  "properties": {
    "to": {
      "type": "string",
      "description": "for calls to service use /:domain/:category/:service/:action"
    },
    "from": {
      "type": "string",
      "description": "a unique identifier that can be used to return response"
    },
    "object": {
      "type": "object",
      "description": "the data that is needed to process the event"
    },
    "subject": {
      "type": "string",
      "description": "the name of the event"
    },
    "verb": {
      "type": "string",
      "description": "the action that event is trying to perform"
    },
    "actor": {
      "type": "object",
      "description": "the initiator of the event"
    },
    "dateSubmitted": {
      "type": "string",
      "description": "the date the event was initiated"
    },
    "duration": {
      "type": "string",
      "description": "the time in milliseconds the event took to process"
    }
  },
  "required": ["to","from","object"]
}

and just pass to the service the object and the actor. Then the service can listen based on the verb using the on method. It can do its work and then push back the results using the ee.emit('send', {}) method. The application service container would marry the response with the sent in verb, type, transaction, system.

The main goal is to have a service like widgets to be re-usable in many different applications without having to have know specific details of that application other than its piece.

Open Source Services

• Simple Queue Service
• PouchDB/CouchDB Service
• MySQL Service
• Auth0 Service