- NodeJS >= 0.8
- An active AWS account with Access Keys
- Basic understanding of AWS SimpleWorkflow concepts
npm install aws-swf
- aws-swf-toolkit: Node.js Framework for workflows on Amazon SWF
- aws-swf-activities: A collection of Node.js activity workers for Amazon SWF
aws-swf uses the official Node.js aws-sdk for the low-level API calls. You can find the full API reference here
aws-swf provide classes to wrap higher-level concepts of the AWS SWF API :
- ActivityPoller
- ActivityTask
- Decider
- DecisionTask
- Workflow
- WorkflowExecution
Don't hardcode your Amazon credentials :
If no config is passed to createClient (see below), aws-swf will walk up the directory hierarchy until it finds a .aws-swf.json file.
{
"accessKeyId": "xxxxxx",
"secretAccessKey": "xxxxxx",
"region": "us-east-1",
"defaultDomain": "aws-swf-test-domain",
"defaultTasklist": "aws-swf-tasklist"
}
var swf = require("aws-swf");
var swfClient = swf.createClient({
accessKeyId: "... access key id here ...",
secretAccessKey: "... secret key here ...",
region: "us-east-1"
});or using the global configuration file :
var swf = require("aws-swf"),
swfClient = swf.createClient();An ActivityPoller polls Amazon SWF for new tasks to be done.
An ActivityTask is instantiated by an ActivityPoller when it receives a task from SWF.
It is passed to your callback and adds the respondCompleted() and respondFailed() methods.
Example :
var swf = require('aws-swf');
var activityPoller = new swf.ActivityPoller({
domain: 'test-domain',
taskList: { name: 'my-workflow-tasklist' },
identity: 'simple poller ' + process.pid
});
activityPoller.on('activityTask', function(task) {
console.log("Received new activity task !");
var output = task.input;
task.respondCompleted(output, function (err) {
if(err) {
console.log(err);
return;
}
console.log("responded with some data !");
});
});
activityPoller.on('poll', function(d) {
console.log("polling for activity tasks...", d);
});
// Start polling
activityPoller.start();It is not recommanded to stop the poller in the middle of a long-polling request, because SWF might schedule an ActivityTask to this poller anyway, which will obviously timeout. The .stop() method will wait for the end of the current polling request, eventually wait for a last activity execution, then stop properly :
// on SIGINT event, close the poller properly
process.on('SIGINT', function () {
console.log('Got SIGINT ! Stopping activity poller after this request...please wait...');
activityPoller.stop();
});A Decider will poll Amazon SWF for new decision tasks.
A DecisionTask is instantiated by a Decider when it receives a decision task from SWF.
var swf = require('aws-swf');
var myDecider = new swf.Decider({
"domain": "test-domain",
"taskList": {"name": "my-workflow-tasklist"},
"identity": "Decider-01",
"maximumPageSize": 500,
"reverseOrder": false // IMPORTANT: must replay events in the right order, ie. from the start
});
myDecider.on('decisionTask', function (decisionTask) {
console.log("Got a new decision task !");
if(!decisionTask.eventList.scheduled('step1')) {
decisionTask.response.schedule({
name: 'step1',
activity: 'simple-activity'
});
}
else {
decisionTask.response.stop({
result: "some workflow output data"
});
}
decisionTask.response.respondCompleted(decisionTask.response.decisions, function(err, result) {
if(err) {
console.log(err);
return;
}
console.log("responded with some data !");
});
});
myDecider.on('poll', function(d) {
//console.log(_this.config.identity + ": polling for decision tasks...");
console.log("polling for tasks...", d);
});
// Start polling
myDecider.start();It is not recommanded to stop the poller in the middle of a long-polling request, because SWF might schedule an ActivityTask to this poller anyway, which will obviously timeout. The .stop() method will wait for the end of the current polling request, eventually wait for a last activity execution, then stop properly :
// on SIGINT event, close the poller properly
process.on('SIGINT', function () {
console.log('Got SIGINT ! Stopping decider poller after this request...please wait...');
myDecider.stop();
});var swf = require("aws-swf");
var workflow = new swf.Workflow(swfClient, {
"domain": "test-domain",
"workflowType": {
"name": name,
"version": version
},
"taskList": { "name": "my-workflow-tasklist" },
"executionStartToCloseTimeout": "1800",
"taskStartToCloseTimeout": "1800",
"tagList": ["music purchase", "digital"],
"childPolicy": "TERMINATE"
});To start a new workflowExecution :
var workflowExecution = workflow.start({ input: "{}"}, function (err, runId) {
if (err) {
console.log("Cannot start workflow : ", err);
return;
}
console.log("Workflow started, runId: " +runId);
});Those examples should be executed in order :
-
TODO: decider helper methods to make it easier to query the event history (dt.completed('step1'), dt.failed('step1'), dt.results('step1'))
if (dt.failed()) { ... dt.scheduled() }
-
... to schedule tasks/timer/workflows etc... dt.schedule({ ... })
-
to stop, or signal, or ...
jsdoc lib/*.js README.md