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JavaScript Library Dependencies

Alex R. Young

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server nodejs narwhal

JavaScript Library Dependencies

Posted by Alex R. Young on .
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server nodejs narwhal

JavaScript Library Dependencies

Posted by Alex R. Young on .

I've been thinking about strategies for hosting JavaScript apps. One
core part of this is dependency management -- it makes deployment as
smooth as possible, and takes away a lot of maintenance pain. But what
library dependency management options are there right now?

Require and Packages

The building block of dependency management is require.
This is specified in CommonJS
modules
, and they have unit
tests for implementors to use.

That's not enough though. Production server-side applications need to be
specific about library versions to ensure that what's deployed is tested
and safe. Yet nobody wants to waste time downloading specific versions
of scripts. This is where a package manager comes in handy.

Much like there are multiple implementations of JavaScript there can be
many package managers. Some programming languages opt to bundle one as
standard, and others allow the community to provide and support them.

Narwhal

Narwhal has tusk, which manages virtual environments and is also a package manager. Packages use a json file to express metadata like dependencies, and can include jars,
executables, C and Java source, and
engines.

The package.json files look like this:

{
    "author": "Author Name",
    "contributors": [
        "Contributor Name"
    ],
    "dependencies": [
        "narwhal"
    ],
    "jars": [
        "jars/simple-4.1.10.jar"
    ],
    "version": "0.2.2"
}

Tusk usage looks like this:

alex@mog ~/narwhal[git:master]$ tusk install jack
Updating catalog.
Downloading http://github.com/280north/narwhal/raw/master/catalog-2.json
# ... etc

Tusk installs into your own path, rather than system-wide. You could use
it to manage your own apps to ease deployment to production servers.

Kiwi

Kiwi is a package manager for node.js. You can install it like this:

git clone git://github.com/visionmedia/kiwi.git
cd kiwi
# sudo if required or available
sudo make install
# This installs into ~/.kiwi
kiwi -v install oo

A node app that uses kiwi looks like this:

var kiwi = require('kiwi'),
    sys = require('sys')

sys.p(kiwi.require('oo'))

Kiwi uses YAML seed files: