Learn 1 Thing A Day

Catching up on some reading

Sun, 06 Feb 2011 10:33:39 -0500

Today’s list

Port Knocking

Wed, 29 Sep 2010 15:58:34 -0400

http://www.portknocking.org/

Never seen this done before.

Ruby rescue learnings

Tue, 07 Sep 2010 16:45:18 -0400

Learned that rescue in Ruby does not rescue LoadErrors. You need to explicitly rescue anything that is not a subclass of StandardError

More details at http://whynotwiki.com/Ruby_/_Exception_handling

Trying out Cappuccino

Tue, 31 Aug 2010 17:43:24 -0400

Built out a demo Cappuccino application. Don’t like the Objective-J syntax much, but very cool GUI tools that may be very helpful for my current project.

Renoir and Arthritis

Sat, 28 Aug 2010 20:53:43 -0400

Went to the Late Renoir exhibit at the Philadelphia Museum of Art today. Was amazed at how arthritis crippled his hands and yet he was still able to persevere and still make beautiful things. Very motivating.

Rails / MySQL / Concurrency

Wed, 18 Aug 2010 23:07:07 -0400

Learned a lot about Rails, MySQL and concurrency. Yehuda wrote a great post on threads that was very helpful interesting. Wound up prototyping with MySqlPlus and MySQL2. I now understand why Merb was created and wished my application was based on it rather than Rails. I am not looking forward to the work that it will take to migrate to Rails 3.

if statements do not introduce scope in Ruby.

Wed, 18 Aug 2010 10:34:48 -0400

http://slideshow.rubyforge.org/ruby19.html#7

I had no idea.

The Missing Rule of Productivity

Mon, 16 Aug 2010 23:44:38 -0400

In my browsing travels today, I stumbled upon the Rules of Productivity. Really interesting presentation and many good rules of thumb. But one thing I believe they missed.

One of the key conclusions of the presentation is that working > 40 hrs per week will result in a short performance boost followed by a productivity drag. So you should always try to have your teams work 40 hour weeks, right.

Well one thing that is not considered in the presentation is that not all days can be considered equal. There are periods where pushing the team harder in the short-term can result in huge wins, even if you have to pay for it during a refractory period after the exertion. Some examples of this:

Your company has an opportunity to present at once-a-year conference/trade show coming up. A burst of productivity ahead of this may be worth sacrificing productivity from the team after
There is a scheduled vacation coming up. Should we ramp up the week before Thanksgiving or Christmas knowing that the next week is going to result in sub-optimal performance anyhow?

The Great Derangement and what I learned about Congressional earmarks.

Tue, 10 Aug 2010 08:02:00 -0400

Last night/this morning read The Great Derangement by Matt Taibbi. Taibbi is one of my favorite writers, especially when he is revealing the relationship between corporate influence buyers and politicians. What I would recommend reading in the book are his interludes on how laws actually get made (hint, not like this, which of course inspired this fantastic Simpsons clip). Learning about how earmarks actually get put into a bill, about how the Rules Committee works, was fantastic and why you want to read a book like this.

As for the overall book, very disappointed. The parts on evangelical Christians were predictable, the parts about the Truthers just sad. Reminds me much more of Malcolm Gladwell’s stuff; Taibbi has taken what would have been a fascinating 10 page magazine articles and stretched it out into a book.

Ike and the Interstate Highway System

Mon, 09 Aug 2010 09:14:00 -0400

Dwight D. Eisenhower’s experience as a member of the first 1919 Transcontinental Convoy on the Lincoln Highway and his appreciation for the German Autobahn system he gained during World War II led him to his initiate support for the Federal Aid Highway Act of 1956 and the establishment of the Interstate Highway System.

From Wikipedia…(http://en.wikipedia.org/wiki/Transcontinental_Motor_Convoy)

MySQLReport taught me much about MySQL

Fri, 06 Aug 2010 23:31:28 -0400

We are having some bizarre locking problem in our application. To try and debug it, I used mysqlreport. If you are using MySQL, I really recommend reading the user guide even if you never use the tool. I learned a bunch about the stats that are coming out of MySQL and how to tell whether your app is well tuned.

The good news was that our app does not seem to be locking at the DB level. So where could it be. MemCache? Passenger?

How to setup Amazon S3 to be your Rails asset host when deployed on EngineYard Cloud

Thu, 05 Aug 2010 21:43:00 -0400

We are using EngineYard Cloud for hosting PackLate.com. We wanted to set up an asset host for static content. This asset host needed to support both HTTP and HTTPS and we wanted to use a different, cookie-free domain. Unfortunately, the EC2 instances that EngineYard Cloud runs on only can have 1 public IP address and we are not using wildcard SSL certificates.

So we could either set up a whole new server for hosting (booo!!!), or we could try to leverage S3, which we are using for serving some images anyhow.

To do this, we used EngineYards AppCloud CLI API and created a before_symlink hook.

In this before_symlink hook, we wanted to do two things:

Generate all cached files. We use the stylesheet_link_tag and javascript_tag to create a concatenated CSS/JS scripts in the public directory.
Push all of the files in the public directory up to S3, ideally using something like rsync.

To do the first thing, what we came up with is on deployment, we fire up a Webrick instance on the app_master node prior to symlinking the newly deployed code. We then make HTTP requests to all pages that create the cached files in public. We then kill the Webrick instance.

Once the files are created, we use s3sync to sync up with a bucket on S3. This is a fantastic tool that looks at what changes and updates the appropriate nodes.

To see the scripts, check out http://gist.github.com/510683

So in a couple of hours, we had an independent, cookie-free, HTTPS supported asset host that is automatically synchronized every time we deploy.

Thanks to Jon and Kyle (via the magic of Google) for making this possible.

HTTPS and IP Addresses

Wed, 04 Aug 2010 23:16:39 -0400

Every IP address can really only support 1 SSL certificate really. And EC2 servers may only have 1 public IP address. So if you want to have 2 non-wildcard SSL certs for your site, you need 2 EC2 instances.