software development

Continuous Deployment changes your mind

Posted in agile, continuous delivery, continuous integration, deployment, management, software development, testing on August 14th, 2011 by Joerg – Be the first to comment

We are practicing Continuous Deployment since about a year. When looking back I realize the dramatic way this practice changed the way we work.

Just to draw the fine line between Continuous Delivery and Continuos Deployment I use the definition I once heard from Neal Ford. Continuous Delivery allows you to deploy every commit but you don’t do it every time. With Continuous Deployment you go further and really deploy every time.

I have recently been asked what the benefits of Continuous Deployment are compared to Continuous Delivery. I think the impact on your development practice is a huge thing.

In our company we practice agile development since about 2005. During that time I can remember many discussions about agile practices like:

  • Test Driven Development
  • Definition of Done
  • Potentially Shippable Product
  • Refactoring in baby steps
  • Not committing on a red build

Many of them do not easily reveal their benefits in daily business. So it becomes difficult to use them consequently.

The Definition of Done is a great example. It is easy to declare something finished or appropriately tested when there is usually a QA department that will find your mistakes during release tests. So the common recipe is write down your definition, post it on the wall and “be more disciplined”. Force yourself to write more tests, force yourself to declare things done only if they are really done and so on. This is not easy. In my experience it seldom works.

This changes dramatically when using continuous deployment. Between your commit and the production system is only an automated deployment pipeline, that usually takes something around 30 minutes. There is no QA department that does a extensive release test. Your mistakes will only be found by automated test that you wrote yourself. Well or they will be found by your Users.

Automated tests become your safety net. This again changes the way you think about TDD. It totally makes sense to have a near full coverage of your code. It also makes sense to have integration tests on API and GUI level to make sure your deployment pipeline catches most mistakes. It will not catch any mistake, but in my experience the same is true for most QA departments.

You will think differently about Potentially Shippable Products. Every commit has to be shippable and it will (not only potentially) be shipped.

This forces working in baby steps. It is just not possible to refactor a system by destroying it for several days.

If a build is red the deployment pipeline is halted. Nobody is able to apply more changes to the system unless this problem is fixed. Again something that used to be a discipline thing becomes a necessity. You need to help your teammates to fix the problem otherwise you can’t work yourself. The same is true if there is a red build in the evening. One of my teammates even talks about an addiction to fix the build before going home. It just gives you a good feeling to finish your day in a green state.

Continuous Delivery has several immediate business benefits I might tell you about another time. But most of them don’t need every commit to be deployed.

But I think the impact of deploying every commit on your development practice huge. Many agile practices make so much more sense. They fit naturally in this environment and you follow them easily. This will then result in benefits for your business on the long term.

Continuous Delivery Slides

Posted in agile, continuous delivery, continuous integration, deployment, java, management, software development, testing, version control on July 5th, 2011 by Joerg – Be the first to comment

The last Java User Group event in Berlin was hosted at Hypoport. It was about Continuous Delivery. We had about 100 guests.

There where two talks. One by Axel Fontaine who introduced Continuous Delivery especially in a Java environment. You can find his talk on Parleys or on his Blog.

I had the pleasure to introduce our experiences with Continuous Delivery. We are currently developing a new product. Since we started about a year ago we consequently used Continuous Delivery. We learned quite some lessons on our way which I presented that evening. My Slides are available here. (As this was a german event the slides are in german)

Thanks to everyone who attended the event. It was a really nice evening. Special thanks to everybody who helped organizing it.

Learn your damn vocabulary!

Posted in agile, management, software development on January 29th, 2011 by Joerg – 2 Comments

Yesterday in a conversation with a team-mate we had the idea of a metaphor that turned out to be very useful. Learning programming has a lot in common with learning a foreign language.

We were talking about different experiences while programming. Sometimes you are in a real flow. You can just fluently express all your ideas and create hundreds of lines without stopping. Other times you need to stop every second line to google some details or ask other people.

When using foreign languages you can find situations that feel exactly the same. The tourist with a dictionary needs to lookup every second word. There is no way to start a real conversation. It’s only enough to get to the next train station. But after some years of learning he might join the natives and enjoy a conversation. He can talk fluently and does not look up words or think about the grammar.

If the situations feel so similar, what can we learn from the metaphor. We should look what it takes to become a fluent speaker in a foreign language:

  • Learning vocabulary
  • Learning grammar
  • Using the language

Vocabulary in the world of programming is similar to basic language constructs, keywords and knowing what functionality your libraries are offering. I would also include knowledge about the editor or IDE, keyboard shortcuts and version control.
So what do you need to do to get fluent in your language. Learn your damn vocabulary! You really need to memorize it. It is not enough to be able to look it up. This would be like looking up every second word in a dictionary. A fluent conversation is impossible. Now the good news is, that in a natural language about 1000 words are enough to conduct a fluent conversation. Something similar is probably true for programming. You don’t need to know every detail to be fluent.
But the guy with a vocabulary of 1000 words will probably never win a Pulitzer prize. A lot of people think if they know the basics of their programming environment it is sufficient. No! You have to constantly extend your vocabulary. I am often surprised by discovering new features of the JDK, my IDE or the libraries we are using. Often I realize that I could have saved a lot of time, if only I did know this before. So go and discover new vocabulary and don’t forget to memorize it.

Grammar is more equivalent to higher level constructs like design patterns, data structures or algorithms. When you learn a foreign language, grammar is very helpful in understanding the right way to combine the words. If you don’t know the grammar, the way you use the language usually sounds funny to native speakers. The same goes for the grammar of programming. So learn it if you don’t want to sound funny.
There is another interesting effect. A fluent user of a language usually does not think about grammar. He can often not even explain why he used the words in a certain way. It just felt right. There is a lesson in it. Learn your grammar well but after a while don’t try to think about it to much in order to talk fluently.

Last but not least in order to get fluent in a language you have to use it. You usually start in a class together with a teacher. You have a save environment where you can try your vocabulary and grammar without fear. A good way to do this for programming are code katas. You are in a save environment with peers that support you and give you feedback. You have to repeat a kata often to memorize every important vocabulary.
There are many other well known ways to use programming in order to get fluent:

  • Read other peoples code
  • Do private projects (and open source them to get feedback)
  • And of course your do your daily business

Like learning a foreign language, learning programming takes many years. In the beginning you will be like the tourist and his dictionary. Just make sure that you don’t stay the tourist.

Next time you are stuck every second line while programming try to identify what vocabulary you just did not memorize or what grammar you probably not understood. Then memorize it and repeat …

Ten years ago …

Posted in history, software development on February 14th, 2010 by Joerg – Be the first to comment

This is really a fun exercise.  Just try to remember the situation as it was ten years ago. You can do this for several topics, but as this is a technology blog I will focus on technology. Beside of fun it has some nice side effects like improving your long term memory or giving you a better feeling how fast things are really moving. That’s something which is easily missed if you only look at short term events. And if you forget this you might be surprised by things happening faster than you thought.

So here are my points. They are completely from my memory and not guaranteed to be accurate.  This will of course describe the situation where I lived, which was in Germany.

Ten years ago …


  • My private PC was a 233 Mhz Pentium with about 64 MB of Ram and a 6 GB HD. At this time it was already more than 2 years old. I think a good PC at this time would have had a 600 Mhz Pentium 2. It used Windows ME, which was still DOS based but the only possible choice if you wanted to occasionally play a game. I had a second partition with SUSE Linux, but just to experiment. Using it as the primary desktop OS would have been a masochistic experience.
  • My business Notebook was a Compaq  with something between 300 and 400 Mhz, a 13 inch Display and about 4 GB hard drive. That was pretty good at this time. Buying a notebook like this for private use was unlikely as they were priced at about 7000 Deutsche Mark (ca. 3500 Euro)  each. The Euro was not used 10 years ago, but price tags already had to include it.
  • Apple started to become popular again. The iMac (the colored one with a CRT Screen) was the first Mac that was available in general electronic stores (like Media Markt) in Germany. It still used System 9. I thought it might be a nice toy for my girlfriend, but for serious computing?
  • Speaking of CRT. This was the dominant Display technology. A 17 inch display with a screen resolution of 1024 * 768 was the standard. The first 15 inch LCD Displays were available but they were ridiculous expensive and were only useful for showing static pictures. As soon as something started to move on the screen you did know you just burned money.


  • My Internet Connection at home was an ISDN line. (64 kBit up and down) This at least allowed to get a phone call, while browsing the net at the same time.
  • I think at about this time I ordered my first DSL. I had to wait more than one year to get it. Transfer rates of 768 kBit download  and 128 kBit upload were revolutionary at this time. Even more important was the flat rate, as you usually had to pay per minute.
  • Google was the new kid on the block. Beside better search results it had a revolutionary interface. Just a search box and a logo. All other search engines (Altavista, Excite, Lycos …) tried to be portals to the internet including news, ads and much more. They sometimes took minutes to load on a dial-up connection.

Mobile technology

  • Mobile Phones just started to become popular for the masses. Until then they were seen as status symbols. I had two phones at this time a Siemens S25 as company phone and a C25 as private. The S25 even had a color display (the only one on the market). It had stunning 4 colors.
  • SMS just started too. People learnt how to use this strange 160 character message thing. It was priced 0.39 DM each. There are still phone providers today that charge 0.19 Euro, which is even a bit more expensive than 10 years ago.
  • Mobile data transfer was only possible in GSM-dailup-mode which meant 9600 bit/s up- and download. The first GPRS-phones which allowed package oriented transfer and 48.000 bit/s download were available about a year later.
  • Palm PDAs were wildly successful in Business. It was a status symbol to have one. The Palm V had a really nice design, but had a monochrome LCD Display. The latest invention was the Palm IIIc which was the first to have a color display (240*240 and 256 colors). I had one and the most annoying thing was that you could not read anything on this display when you were outside.

Consumer electronics

  • Most people used CD-Players for listening to music. Portable CD-Players were pretty common.
  • There were the first dedicated MP3 Players. But they used Flash-RAM which was very expensive. A 64 Mbyte Compact Flash card did cost about 500 Deutsche Mark (ca. 300 Dollars) and did not store more music than a CD. That was not really a competition for CD-Players or even the classic Walkman.
  • TVs were usually CRT. There were the first flatscreens based on plasma technology. But they were priced at the same range as a small car. A lot of the CRT TVs were already 16:9. But you needed several strong men to move one. Some of these monsters had more than 100 kg.

Software and Programming

  • Java was a huge hype. It was used in a lot of places, especially on the server side. It was not very successful on the desktop. (Deja vu?) Java was also recognized as being very slow. Which is funny because today many people compare new programming languages like Groovy, Scala or even Ruby to Java as the benchmark.
  • Java already had some IDEs. I think the most prominent was the Borland JBuilder. Things like automated refactoring were still unknown.
  • There were some rumors about a strange thing called Extreme Programming. Those guys were supposed to call programming the most important thing when creating software. Scary!
  • Open Source software was used in some companies. Especially as web servers. It was ok to use it for this unimportant piece of infrastructure. But using open source for some mission critical stuff would still have been a revolution.

I could write on for hours but that’s probably enough for now. I hope you enjoyed reading this as much as I enjoyed writing. Please share your own memories about ten years ago in the comments or on your own blog!

Why all programmers should blog

Posted in agile, blogging, management, software development on January 30th, 2010 by Joerg – 38 Comments

There are some obvious reasons why you should start blogging when you are a programmer. Most of them also apply to everybody else:

  • You share your knowledge. This is a benefit for all of us. If everybody would be blogging about all the little issues they had then a Google-Search would help us even more. I am sure nearly every problem in the world is already solved. It is just not written down.
  • It’s a kind of self marketing. A potential employer can get a much better picture of your abilities than he could from CVs or references. When I hire somebody it is already a huge plus for him when he has a blog at all.
  • Explaining things to other people is the best way to learn. You can only teach what you fully understand. This is at least as efficient as hands on experience.
  • You might even make some money with blogging. There are several sites about this. If you are interested look here or here.

But the main reason is something else. Some years ago I read an article about software documentation. There was a lot of wisdom in it, but one phrase sticked to my brain:

Programming is doing something weird to your brain. When you write a piece of documentation right after a programming session the result is likely to be barely readable for human beings.

If that’s true then the opposite should work too.  Blogging teaches you to write for people, which is exactly what you should do in your code. Good code needs to be easy to understand to be easy to maintain. There are whole books about this like the famous Clean Code by Uncle Bob.

I think blogging does something weird to your brain, that makes your code better readable for human beings. So:

If you want to become a better programmer, start blogging!