Book Chat: The Pragmatic Programmer

For a long time this had been on my list of books to buy and read with a “note to self” saying to check if there was a copy of it somewhere on my bookshelf before buying one. It felt like a book I had read at some point years ago, but that I didn’t really remember anymore. Even the woodworking plane on the cover felt familiar. It felt like it was full of ideas about creating software that you love when you encounter them but are disappointingly sparse in practice. Despite being from the year 2000 it still contains a wealth of great advice on the craft of creating software.

Since it is about the craft of software, not any specific technologies or tools or styles, it aged much better than other books. That timeless quality makes the book like a great piece of hardwood furniture, it may wear a little but it develops that patina that says these are the ideas that really matter. There is an entire chapter devoted to mastering the basic tools of the trade: your editors and debuggers, as well as the suite of command line tools available to help deal with basic automation tasks. While we’ve developed a number of specialized tools to do a lot of these tasks it is valuable to remember than you don’t need to break out a really big tool to accomplish a small but valuable task.

It’s all about the fundamentals, and mastering these sorts of skills will transfer across domains and technical stacks. It was popular enough that is spawned an entire series of books – The Pragmatic Bookshelf – and while I have only written about one of them I have read a few more and they’ve all been informative.

About two-thirds of the way through the book I realized that I had indeed read it before – I had borrowed a copy of it from a coworker at my second job. He had recommended it to me as a source he had learned a lot from. I remember having enjoyed it a lot but not really appreciating the timeless quality. Probably since that would have been around 2007, it wouldn’t have seemed as old, especially since things seemed to be moving less quickly then. Maybe I just feel that way since I didn’t know enough of the old stuff to see it changing.

If you haven’t read it, go do it.

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Changing Stacks

I had an odd realization recently – the jobs that I changed stacks for seemed to be better than the jobs where I already knew the stack. I’m not sure if it’s a common experience or something that’s unique to my experiences.

I’ve got a few theories about why this might be the case for me. First, the jobs where I changed stacks appeared more engaging to me because there was more to learn. Second, the jobs where I changed stacks felt better because they used different hiring practices, where they looked for underlying talent and skills as opposed to specific stack-related experiences. Third, relating to the second point, the diverse points of view brought together because so many colleagues were also changing stacks creates a better workplace. Fourth, the people that are willing to change stacks are the kind of people who are more open to learning going forward. Lastly, the jobs where I changed stacks happened to be better by pure chance due to small sample sizes. None of these theories is particularly provable. Several of them could be true and working together. They could all be false and it could be something completely different.

I know that from talking to some of my coworkers that they all came into their current jobs without particular experience in the Scala/Play Framework/MongoDB stack as well, although most of them came from a much more similar Java stack rather than the C# stack I came from most recently, or any of the other stacks I worked with in the past. They mentioned that we have issues recruiting in our DC office because of the pay differentials for cleared work in the area;  there are lots of places you can go and get a comfortable government contracting job and not really stretch yourself and grow. There has also been some discussion about how the stack effects our ability to recruit since it’s not as common as other stacks, and some candidates have expressed reservations since the stack isn’t really growing in popularity. There was a lot of information in the most recent Stack Overflow Developer Survey that corroborates the idea that the Scala is shrinking, but it says it is shrinking in relative of share of all votes. In absolute terms the change is less clear.

I guess that I’ve enjoyed the stack changes I’ve made. Only once did I set out with an intention of changing stacks as part of a job change. Then I wasn’t looking to go to anywhere particular, but I was looking to move away from ColdFusion since it didn’t really mesh with how I like to do development. I don’t have any intention to make another change any time soon, but I’ll definitely consider another stack change when I do just because it opens up a wider variety of options and seems to have worked out for me in the past.

Book Chat: Growing Object-Oriented Software Guided By Tests

Growing Object-Oriented Software Guided By Tests is an early text on TDD. Since it was published in 2010, the code samples are fairly dated, but the essence of TDD is there to be expressed. So, you need to look past some of the specific listings since their choice of libraries (JUnit, jMock, and something called Window Licker I had never heard of) seem to have fallen out of favor. Instead, focus on the listings where they show all of the steps and how their code evolved through building out each individual item. It’s sort of as if you are engaged in pair programming with the book, in that you see the thought process and those intermediate steps that would never show up in a commit history, sort of like this old post on refactoring but with the code intermixed.

This would have been mind blowing stuff to me in 2010, however the march of time seems to have moved three of the five parts of the book into ‘correct but commonly known’ territory. The last two parts cover what people are still having trouble with when doing TDD.

Part 4 of the book really spoke to me. It is an anti-pattern listing describing ways they had seen TDD go off the rails and options for how to try to deal with each of those issues. Some of the anti-patterns were architectural like singletons, some were specific technical ideas like patterns for making test data, and some were more social in terms of how to write the tests to make the more readable or create better failure messages.

Part 5 covers some advanced topics like how to write tests for threads or asynchronous code. I haven’t had a chance to try the strategies they are showing but they do look better than the ways I had coped with these problems in the past. There is also an awesome appendix on how to write a hamcrest matcher which when I’ve had to do it in the past was more difficult to to do the first time than it would look.

Overall if you are doing TDD and are running into issues, checking out part 4 of this book could easily help you immediately. Reading parts 1 through 3 is still a great introduction to the topic if you aren’t already familiar. I didn’t have a good recommendation book on TDD before and while this isn’t amazing in all respects I would recommend it to someone looking to get started with the ideas.

Session Fun

I’ve been working on getting a new session infrastructure set up for the web application I’m working on. We ended up going with a stateful session stored in mongoDB along with some endpoints to query the session with. This design has a couple of nice aspects – all of the logic about if a session is active or not can live inside of one specific service and a session can be terminated if needed.

Building a session infrastructure is a fairly common activity, but we are building a session that is used by multiple services and we can’t roll all of them out simultaneously. So we’ve been building a setup that can process both the new session and the old session as a way to have a backwards compatible intermediate step. This is creating some interesting flow issues. There are two specific issues I wanted to discuss: (1) how to maintain the activity of the new session during backwards compatibility and (2) processing of identity federation.

Maintaining the new session from applications that have not been updated is nuanced. Since, by rule, you haven’t made changes to the applications that haven’t been updated, you can’t add any calls. In our case there was a call made from all of the application frontends to a specific service, so we are using that to piggyback keeping the session alive. We looked into a couple of other options but didn’t find anything easy. We considered rolling out a heartbeat to the various application frontends but that would require an extra round of updates, testing, and deploys for code that was likely to all be ripped out when we were done.

The federation flow is extra complex because a federation in the new scheme is not that different from some of the session passing semantics under the old session scheme. This ends up mixing together the case where there is just a federation occurring and the case where the new session has timed out and the old session is still valid. This creates an awkward compromise; you’d like to be able to say that if the new session has timed out the entire session is expired, but if you can’t tell the difference between the two cases that’s not possible. This means that the new session expiration can’t be any longer than the old session expiration. But it also solved the problem with maintaining the new session while in applications that haven’t been updated yet.

The one problem solved the other problem which was a nice little win.

Book Chat: AWS in Action

Amazon Web Services in Action is a great introduction to the basics of AWS. It mostly discusses IaaS services, but touches on some of the PaaS services too. It also covers a good portion of what’s in the Architecting on AWS course if you were considering that. I was hoping for coverage of AWS Lambda, API Gateway and EC2 Container Service but they weren’t included. There were references to when to use AWS Cloudfront but it was never introduced like the other services were.

It’s a very quick read, even though it weighs in about 400 pages. There are lots of detailed examples including specific information about if the example was covered under the free tier of services and how to be sure to roll back everything. Lots of screenshots of consoles and the CLI interface and plenty of code samples of using the various SDKs, mostly in node.

If you are already familiar with AWS this probably isn’t the right book for you. It doesn’t cover the architecture aspect in depth, just simple examples of how to combine the various services. For my taste it doesn’t sufficiently cover how to decide when to use a PaaS solution vs rolling your own at the IaaS level. There is one little chart in the portion covering Elastic Beanstalk about the benefits of it vs other less managed options.

Overall it wasn’t the book I was looking for. But it is the sort of thing that can be helpful to lots of people who want to try and understand how to apply their existing architectural knowledge to the AWS platform.