Heimdall Client

Library to easily use the Heimdall global events system within a project

See Diagram

Installing the NPM Module

You need to be logged into NPM to use this private module.

npm login
npm install @satthief/heimdall-client --add

Quick Use

const heimdall = require('@satthief/heimdall-client');

//make a client to interact with
var hdc_config = {
  'host':'192.168.113.15',
  'user':'test',
  'pass':'test'
};


heimdall.connect(hdc_config,function(err,hdc){

  //Example trigger handler config - DYNAMIC QUEUE - Beware!
  var handler_config_dynamic = {
    'dynamic':true,
    'topic':'example-heimdall-client-app',
    'handler_function':function(data,cb){
      console.log('handler got',data);
      return cb();
    }
  };

  //Example trigger handler config - STATIC QUEUE - Need to bind manually on RabbitMQ
  var handler_config_static = {
    'dynamic':false,
    'queue':'my-manually-bound-queue',
    'handler_function':function(data,cb){
      console.log('handler got',data);
      return cb();
    }
  };

  //Example of registering for trigger on an event global.test.werner
  var regtrigger = {
    'uuid':'88888888-2343-2325-2523-888888888888',
    'registration':{
      "events": {
          "test_event": {
              "path": "global.test.werner",
              "mechanism": "evt"
          }
      }
    },
    'trigger': {
        "on_trigger": {
            "default_deregister": true
        },
        "system": {
            "type": "rabbitmq",
            "exchange": "/exchange/ex-heimdall-triggers",
            "topic": "example-heimdall-client-app",
            "server": "mq01",
            "data_method":"inject_into_triggerdata",
            "triggerdata_inject_path":"eventdata_here",
        },
        "triggerdata": {
            "eventdata_here": {
            },
            "test_trigger_obj":{
              "bla":"dee"
            }
        }
    }
  };

  //Example of an event to emit
  var event = {
    "path": "global.test.werner",
    "mechanism":"evt",
    "eventdata": {
        "girl": "monalisa"
    }
  };

  //Do all 3 actions in series - Callback method
  hdc.setup_trigger_handler(handler_config,function(err){
    console.log('Back from setup_trigger_handler');
    hdc.register_trigger(regtrigger,function(err){
      console.log('Back from register_trigger');
      true ? hdc.emit_event(event,function(err){
        console.log('Back from emit_event');
      }) : false;
    });
  });


});

Notes and Links

Choose 1 of 2 methods for receiving triggers

1. explicit queue setup you setup a queue on RabbitMQ for your application and then bind the queue via a topic to ex-heimdall-triggers, then use this queue in your trigger handler config

2. dynamic queue you specify dynamic and a topic in the heimdall trigger handler config, this connects to RabbitMQ and makes a dynamic subscription, it is linked to the exchange

• disadvantages of this method are that when you disconnect the queue gets removed and triggers will go missing
• each instance of the app will have its own queue, duplicates are possible ??
• see more at https://www.rabbitmq.com/stomp.html#d.ed

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