A Quantum Immortal

After looking at several backup solutions for a linux-based project of mine, ranging from more advanced systems like bacula to a range of python/bash scripts, I finally found the ultra simple duplicity. Don’t get me wrong, bacula and its brethren really seem more powerful overall, but when you just need a simple solution, you can’t compete with duplicity’s simplicity.

duplicity is drop-dead simple backup system that does incremental/full backups, and supports a wide variety of backup targets from the box, including file, ftp, scp, s3, and a dozen others. The usage is simply

duplicity /folder/to/backup file:///path/to/target/folder

You can have the target folder be a local or S3-mounted folder (with the excellent s3fs), or use other supported URIs. The default is an incremental backup, by you can override by choosing a full backup. It even has support for “keep the last N full backups and delete the rest”. Update – after running some time with backups into s3fs, I recommend against it – it gave us some performance headaches. Use the native s3 option that duplicity has instead.

The only feature that I required, and duplicity didn’t have, is automatically choosing when to do full vs automatic backups. I would like to tell it “every 100 runs, do a full backup”, and this is not supported out of the box … although easily fixed with a wrapper script. Put that in crontab and you’re set. Oh, by default it requires setting a PGP key, but if you’re lazy you can skip it with the –no-enc option.

Hi all, this is your newb web developer talking again. While some of the following might be obvious to the more experienced web devs among you, this is a post that I wish I’d read when I just started using jQuery.

Write your own jQuery plugins

The word “plugin” usually entails something complicated and with some non-trivial learning curve (e.g. how many of you ever wrote a Chrome of Firefox plugin?) Well, in jQuery, this is really not the case. Here is how you write a simple jQuery plugin:

$.fn.enable = function() {
  $(this).prop("disabled", false);
};
 
$.fn.disable = function() {
  $(this).prop("disabled", true);
};

I find it useful to wrap even simple one liners such as .prop(“disabled”, false) with a plugin, because the semantics of writing $(“#foo”).disable() is much nicer than playing with properties/attributes directly. I haven’t written a lot of plugins yet, but it’s something to keep in mind as a useful tool to wrap actions on specific DOM elements.

Know the commonly used plugins
There are a ton … I still know very few of them. Here are a bunch of useful ones (and the ones I personally know and use).

A lot of plugins are very easy to use, and have good documentation and demos, so not using them and rolling your own solution is usually just a result of ignorance. Take the time to educate yourself!

UI Queues
For a long time I’ve that you can do things like $(“#mydiv”).show(), $(“#mydiv”).hide() and even $(“#mydiv”).show(1000) for a simple animation. Only recently I discovered you can actually chain these using Event Queues:

$("#mydiv")
  .hide(1000)
  .delay(500)
  .show(200)
  .fadeOut();

Each call to an animation method gets queued up and executes after the previous one.

Deferred
jQuery Deferred is a little gem. It lets you write fluent code similar to the queue example above. Here is how you use it:

$.when($.post('http://api.com/request_1'), 
       $.post('http://api.com/request_2'))
  .then(function(){alert("Got two responses")});

You can also use them with the event queue:

  $("#mydiv")
    .show(1000)
    .delay(500)
    .promise()
    .then(function(){/*do something */});

That’s all I have for now. Have any essential tips & tricks that I’m missing out on?