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Archive for the ‘twitter’ Category

Pivotal Tracker: Fantastic app, shame it’s free

I’ve been digging around for a decent agile PM tool for a while, and stumbled across Pivotal Tracker on Twitter a couple of days ago.

Within about thirty minutes of trying it out, I was totally hooked. We’ve rolled our own basic project management tool internally, but we’ve yet to get the time to put proper iterative development support into the app. Pivotal Tracker just works. With a clean UI and some great reporting tools, it’s all I need to run an agile project.

The one big downside is this: it’s completely free.

Wait, you say: surely that’s a good thing? Well, yes and no.

Why great software should cost money

When I pay for an app on the net, I expect a few things:

  • It’s going to be up pretty much all the time.
  • It’s not going to vanish tomorrow.
  • It’s not going to suddenly cost a fortune.

With Pivotal Tracker, I’ve no idea when they’re going to take the software down for maintenance. I’ve seen reports of it going down without notices for 15 minutes here and there, which is fine if it’s a non-critical service. It is however most definitely not fine when my client is trying to comment on features. I also have no guarantee that it’s not going to suddenly disappear into the night, taking all my stories and possibly the project itself with it.

The other issue is that if I’m paying $20/month for it, I’ve a reasonable expectation that it’s not going to cost say $200/month next month. It’s well within Pivotal’s rights to withdraw the free service and charge what they like for the paying version, without any notice.

Are we going to use it anyway? Yes we are: it’s too good to ignore. However, we’ve put in place the following cron job to mitigate the risk:

*/20 * * * * curl -H "X-TrackerToken: " -H
 "Content-type: application/xml" -X GET
 https://www.pivotaltracker.com/services/v2/projects/39382/stories
 > stories-backup.xml

This little piece of magic copies all our stories in XML form to our backup server every 20 minutes, so we’re not screwed if the site vanishes without notice. It would only take us about an hour to import this XML into our old system should we need to. That takes care of the main risk for me.

The conclusions: Some software shouldn’t be free. If you’re using Pivotal Tracker or any other free service in anger, make sure you’ve got a backup plan.

Posted on: Monday, March 16th, 2009 Posted in bdd, business, code, twitter | 12 Comments »

Twitter integration from your Rails app

We’ve learnt a bit about Twitter from writing ykyat.com.

I particularly want to write about how we fetch Twitter user icons. The icons are stored on AWS (Amazon Web Services) and cannot be deduced from the user name. You have to go through the Twitter API to find the image location.

The first thing I tried was the Twitter4R library. This seems to be a very powerful library, and if you were writing a full Twitter client in Ruby you’d definitely want to consider it. It was simple to get the user icons, but the library just felt a little over-the-top for our needs.

Twitter4R seemed to require authentication with every request, and we soon hit the API limit. I realised this is odd because you really don’t need to authenticate to look at the XML or JSON data about a Twitter user. I decided to go back to basics and do it myself. This is the code for parsing the JSON data and picking up the user icon URL:

def icon_url_for_user(username)
  require 'open-uri'
  require 'json'
  buffer = open("http://twitter.com/users/show/#{username}.json").read
  result = JSON.parse(buffer)
  result['profile_image_url']
end

See! Easy!

Most people don’t change their user icon very often, so once we know where to find a user’s icon, we don’t need to ask Twitter for it again for an arbitrary amount of time. A week seems quite sensible. To that end, we created a lookup table in our database to match Twitter user names to their user icon URL. We added an index to the user name column because it acts as the primary key lookup.

When we want to know a user’s icon, we first look up in our table. If we don’t yet have it, or if the updated_at date is more than a week ago, we check with Twitter for the image location. Otherwise we use our cached location.

Fast and easy! :)

Posted on: Thursday, February 26th, 2009 Posted in code, how-to, twitter, ykyat | 11 Comments »