taskflow

An isomorphic library to implement task flows

Installation

Node

$ npm install --save taskflow

Browser

Copy the file taskflow.min.js in the dist folder and refer to it in your HTML:

<script src="/js/taskflow.min.js"></script>

taskflow will now be available via window.taskflow.

Usage

retryable(fn, [options], [thisArg])

Wraps the specified callback-style async function to be tried multiple times if it fails.

Parameters:

• fn - the callback-style function to be made retryable
• options - an optional object that provides options to the retryable operation
• thisArg - an optional object which will be made the context to execute the function

Example

var retryable = require('taskflow').retryable;

// target callback-style function
function errorProneAsyncOp(a, callback) {
  // function logic
}

// wrap errorProneAsyncOp() to be retryable 4 times
var retryableErrorProneAsyncOp = taskflow.retryable(errorProneAsyncOp, { times: 4 });

retryableErrorProneAsyncOp('my input', function (err, result) {
  if (err) return handleError(err);          // error is indicated after 4 retries
  doSomethingWith(result)
});

promisable(fn, [thisArg])

Wraps the specified callback-style async function with another that returns a promise when invoked.

Parameters:

• fn - the callback-style function to be made retryable
• options - an optional object that provides options to the retryable operation
• thisArg - an optional object which will be made the context to execute the function

Example

var promisable = require('taskflow').promisable;

// target callback-style function
function asyncOp(a, callback) {
  // function logic
}

// wrap asyncOp() to be promisable
var promisableAsyncOp = promisable(asyncOp);

retryableErrorProneAsyncOp('my input')
  .then(function (result) {
    doSomethingWith(result);
  }, function (err) {
    handleError(err);  
  });

Using Them Together

Below is an example of using retryable and promisable utilities together:

var taskflow = require('taskflow'),
    retryable = taskflow.retryable,
    promisable = taskflow.promisable;

// target callback-style function
function asyncOp(a, callback) {
  // function logic
}

// wrap asyncOp() to be promisable
var p = promisable(retryable(asyncOp, { times: 4 }));

retryableErrorProneAsyncOp('my input')
  .then(function (result) {
    doSomethingWith(result);
  }, function (err) {
    handleError(err);       // invoked if asyncOp failed 4 times
  });

Above example wraps asyncOp() method with the retryable utility to retry 4 times. We then wrap the retryable operation with the promisable utility which returns us a promise which would only fail after retrying asyncOp() at least 4 times.

License

Copyright (c) 2015, intuitivcloud Systems <engineering@intuitivcloud.com> All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

• Neither the name of signalman nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.