usher

Simple DSL for composing decision workflows for AWS Simple Workflow

Usher

Usher enables simple, dependency based compositions of activities and decisions for AWS Simple Workflows.

In the name of simplicity, this library has strong opinions on convention, with the ability to configure and override some of these conventions.

This library can be used to implement Deciders and Activities for AWS Simple Workflow Service.

npm install usher --save

This is a simple example of 4 activities being defined to perform some tasks and returning their results. By themselves, these activities will do nothing until executed by a workflow. (To see how these activities are run, see the workflow example below.)

var usher = require('usher');
 
var activities = usher
  .activities('linear-activities', 'my-domain-name')
    .activity('activity1', '1.0.0', function (task) {
      task.success({ "key1": "value 1" });
    })
    .activity('activity2', '1.0.0', function (task) {
      task.success({ "key2": "value 2" });
    })
    .activity('activity3', '1.0.0', function (task) {
      task.success({ "key3": "value 3" });
    })
    .activity('activity4', '1.0.0', function (task) {
      task.success({ "key4": "old value 4" });
    })
    .activity('activity4', '1.1.0', function (task) {
      task.success({ "key4": "value 4" });
    });
 
activities.start();

This is a simple example of the workflow composition that will run the previously defined 4 activities in sequential order when the workflow is executed.

var usher = require('usher');
 
var workflow = usher
  .workflow('linear-workflow', 'my-domain-name')
    .version('1.0.0')
      .activity('activity1')
      .activity('activity2', ['activity1'])
      .activity('activity3', ['activity2'])
      .activity('activity4', ['activity3'], { version: '1.1.0' });
 
workflow.start();

Given the above defined linear-workflow, you could run an execution of the workflow in the following way.

var usher = require('usher');
 
// This assumes the workflow 'linerar-workflow' has already been defined previously 
var workflow = usher.workflow('linear-workflow', 'my-domain-name');
 
workflow.execute({ key: 'value '}, function (errrunIdworkflowId) {
  // once the workflow has started 
});

Copyright (c) 2014 meltmedia (mike@meltmedia.com)

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:

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