Back to basics


Resiliency in cloud applications

My mind has been thinking about a few events that happened during the past week at work. These events range from Amazon AWS S3 going down to some errors in our application that was causing a “this should never happen” to.. happen. I have been catching up MSDN’s Cloud Design Patterns to see what can we do about it because all the events had the same basic problem - how do we deal with services going down?

Resiliency is an easy thing to forget partially because we are accustomed to incredibly high uptimes in our infrastructure. But even some of the best in the industry make mistakes, and network outages, database downtime, and failures still happen. Our code must be able to catch and deal with these issues.

I am reminded about how difficult it is to code to that. It is not something that can be solved in a design pattern. It is about inspecting every point of your system that makes an external call and saying “what if this calls fails?” and being able to recover from that. It’s incredibly tedius. You will inevitably try to convince yourself that the odds are extremely low. The truth is it’s almost certainly going to happen. Luck is never on your side when the enemy is time.

I also reflect on how important it is to think about this early in the process because dealing with failure gracefully might require building things differently.


Single speed bicycle

Early this year I was the victum of bike theft. I typically leave my bicycle in the visitors parking of my condo unit during the winter, and it was sadly stolen.

I was in the market for a new bicycle, and with the warmer weather coming up, I needed to make a decision. There were some things that I didn’t like about my previous bicycle that I was hoping to solve with a new bicycle:

  1. My bike was heavy. Though this was rare, I sometimes needed to lift my bicycle when parking/removing my bike from visitors parking because of the layout of bicycle parking.
  2. Adjusting the gears and derailler was time consuming

Except for flat tyres, the most common issues I had with my bike had to do with the derailler/gears. I’ve had the chain end up stuck behind the cogset a few times. If the derailler is not adjusted properly, it may cause gears to be skipped or the chain starts rubbing up against stuff. Not great stuff.

I wanted some more simplicity. My other options were single-speed or something called internal hub. I haven’t heard of internal hub before, but it seems allows you to have a smaller range of gears in an internal component that cuts down on maintenance. You don’t get the flexibility of 21 gears, but you can shift while stopping. Unforunately, the major downside I found is that taking off the wheel (to, for example, change the tyre) is quite a bit of work as is demonstrated by this nearly 8 minute unfluffed youtube video.

In the end I decided on a single-speed bicycle. I haven’t had much practice with it yet, but it is rather difficult/tiring in stop and go traffic. My commute to work does have quite a few stop signs/stop lights.

###Update###

Hey I haven’t posted this, oops! That was written in early March of 2016.

After 5 months of almost daily riding, here are some of the cons I found of single-speed bicycles:


Ras Midas - Rain and Fire

I see rain I see fire.
I see rain I see fire
This is the time of tribulation.
The publican claims its inflation.
Iron sharpeneth iron.
The Sadducees them don’t know.
That I and I a lion.
I and I a lion.
I and I a lion.

I see the Messiah From the tribe of Judeah
Selassie I is the Trinity.
Oh, three in one
and one in three.
Is the Trinity,
the Trinity.

Said I read it in the Prophecy.
Read it children
Seven years of plenty, yeah.
Seven years of famine.
That I never see on this earth before.

Seven years of plenty, yeah.
Seven years of famine.
That I never see on this earth before.

He that is on the housetop.
Won’t have time to come down.
He that leave his tool in the fields.
Won’t have time to pick it up.
For tribulation and inflation.
Cover this land.
It’s only Jah Jah.
Can solve this pollution

I see rain I see fire.
I see rain I see fire

- “Rain and Fire” by Ras Midas [YouTube]


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