Orchestrator

A module for sequencing and executing tasks and dependencies in maximum concurrency

Usage

1. Get a reference:

var Orchestrator = require('orchestrator');
var orchestrator = new Orchestrator();

2. Load it up with stuff to do:

A synchronous task:

orchestrator.add('thing1', function(){
  // do stuff
});

An asynchronous task:

orchestrator.add('thing2', function(callback){
  // do stuff
  callback(err);
});

An asynchronous task using promises:

var Q = require('q');

orchestrator.add('thing3', function(){
  var deferred = Q.defer();

  // do async stuff
  setTimeout(function () {
    deferred.resolve();
  }, 1);

  return deferred.promise;
});

An asynchronous task using streams: (task is marked complete when stream ends)

var es = require('event-stream');

orchestrator.add('thing4', function(){
  var stream = es.map(function (args, cb) {
    cb(null, args);
  });
  // do stream stuff
  return stream;
});

A task that requires other tasks be done first:

orchestrator.add('thing4', ['thing1','thing2','thing3'], function(){
  // do stuff
});

3. Run the tasks:

Start the tasks you want to run:

orchestrator.start('thing1','thing2','thing3', 'thing4');

or start all the tasks:

orchestrator.start();

or specify a callback for when all tasks are complete:

orchestrator.start('thing1', function (err) {
  // all done
});

FRAGILE: Orchestrator catches exceptions on sync runs to pass to your callback but doesn't hook to process.uncaughtException so it can't pass those exceptions to your callback

FRAGILE: Orchestrator will ensure each task and each dependency is run once during an orchestration run even if you specify it to run more than once. (e.g. orchestrator.start('thing1', 'thing1') will only run 'thing1' once.) If you need it to run a task multiple times, wait for the orchestration to end (start's callback) then call start again. (e.g. orchestrator.start('thing1', function () {orchestrator.start('thing1');}).) Alternatively create a second orchestrator instance.

4. Optionally listen to it's internals

orchestrator.on('task_start', function (e) {
  // e.message is the log message
  // e.task is the task name if the message applies to a task else `undefined`
  // e.err is the error if event is 'err' else `undefined`
});
// for task_end and task_err:
orchestrator.on('task_stop', function (e) {
  // e is the same object from task_start
  // e.message is updated to show how the task ended
  // e.duration is the task run duration (in seconds)
});

Events include:

• start: from start() method, shows you the task sequence
• stop: from stop() method, the queue finished successfully
• err: from stop() method, the queue was aborted due to a task error
• task_start: from _runTask() method, task was started
• task_stop: from _runTask() method, task completed successfully
• task_err: from _runTask() method, task errored

Note: fires either *stop or *err but not both.

Listen to all events

orchestrator.onAll(orchestrator, function (e) {
  // e is the original event args
  // e.src is event name
});

5. Enjoy!

LICENSE

(MIT License)

Copyright (c) 2013 Richardson & Sons, LLC

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.