Task orchestration API and runners
Either if you are building a completely new system composed of many discreet API applications, each of them with a clearly defined area of responsibility, or in the case you are trying to assemble a collaboration channel between an heterogeneous set of totally unrelated API applications, you need a way to orchestrate interactions between these applications.
So a workflow is effectively an orchestration.
You want a workflow, because it gives you a way to decompose a complex series of operations down to a sequence of discreet tasks with a state machine.
The sequence of tasks is more complex than just a series. The tasks of course can fail, and so you need to deal with timeouts, retries, "stuck" flows, etc.
You can define a workflow and its tasks using an arbitrarily complex language. Or you can keep it simple by taking some assumptions:
This package provides a way to define re-usable
workflows using JSON and run
jobs with specific
parameters based on such
In order to execute the
jobs, at least one
WorkflowRunner must be up and
ready to take jobs. An arbitrary number of
runners can be used on any set of
hosts; configuration must match.
WorkflowRunner is provided with the package and can be started
examples directory contains the file
config.json.sample which can be
used as reference).
You can create
jobs either by using the provided REST API(s),
or by embedding this module's API into your own system(s).
The former will be easier to get up and running, but you should use the latter
The package also provides a binary file to run the
WorkflowAPI using the
same configuration file we pass to our
See demo section below for more details about both approaches.
git clone git://github.com/kusor/node-workflow.git cd node-workflow make all
make all will setup all the required dependencies, node modules and run
make check and
make test. In order to just setup node modules,
To run the Workflow API server:
To run a Job Runner:
Note that it's perfectly fine to run more than one Runner, either on the same or different machines, as far as they have access to Redis Server.
In order to run
make prepush before every commit, add the following to a file
chmod +x it:
#!/bin/sh # Run make prepush before allow commit set -e make prepush exit 0
Obviously, if you've made a change not affecting source code files but, for
example only docs, you can skip this hook by passing the option
git commit command.
The workflow-example repository contains everything needed to illustrate:
config.json.samplewhich should be renamed to
config.jsonand modified to properly match your local environment.
Remember that, in order to process any
to be initialized pointing to the aforementioned configuration file:
Also, in order to be able to run the API based example mentioned below, the
workflow-api HTTP server needs to be up and running too:
Contents for the other files within the workflow-examples repository are:
shared-workflow.js. The beginning of the aforementioned files can be useful to understand the differences when trying to create a workflow using these different approaches.
node.jswhich does exactly the same thing than the workflow/job does - create and star a gist using your github's username and password - but straight from NodeJS. This file is useful in order to understand the differences between writing code to be executed by NodeJS directly, and using it to create workflows and the associated tasks. Remember code withing tasks runs sandboxed using Node's VM API and that tasks are totally independent, and run each one on its own child process.
example.js for more options when defining workflows and the
different possibilities for tasks fallbacks, retries, timeouts ...
deps/ Git submodules and/or commited 3rd-party deps. See "node_modules/" for node.js deps. docs/ Project docs (restdown) lib/ Source files. node_modules/ Node.js deps, either populated at build time or commited. pkg/ Package lifecycle scripts test/ Test suite (using node-tap) tools/ Miscellaneous dev/upgrade/deployment tools and data. Makefile package.json npm module info README.md
The MIT License (MIT) Copyright (c) 2012 Pedro Palazón Candel
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