A few years ago, a company I worked for was suffering from quality problems. We were expanding into new areas, pushing the product in new directions, and releasing new features quickly. As we pushed out new and evolved products, quality declined. Everything came to a head when customers began openly complaining about software quality. Our CTO stepped in with a mandate to solve the quality problem. His approach? The Zero Bug Policy — no-one was allowed to work on new features until the number of bugs in the product backlog was zero. ...

Note: To make this easier to read (and write), h1 may be used in place of HTTP/1, and h2 may used in place of HTTP/2. HTTP/1 has a long and storied history. Originally developed as a sixty page specification documented in RFC 1945, it was designed to handle text-based pages that leverage hypermedia to connect documents to each other. Typical web pages would kilobytes of data. For example, the first web page was a simple text file with web links to other text documents. Now, the web is made up of media-rich sites containing images, scripts, stylesheets, fonts, and more. The size of a typical web page is measured in megabytes rather than kilobytes, and the number of requests required to assemble a full page can be over one hundred. The reality of how web pages are built today does not match the reality that HTTP/1 was designed to support. ...

Building and running a successful company requires an immense amount of work and talent. It also requires focus. Companies cannot try and solve problems with new and innovative techniques everywhere they operate. It is important to understand the areas your company should innovate in, and outside of that scope, use existing standards and off-the-shelf software as much as possible. There is only so much innovation that a company (or the market) is willing to bear and walking that line is a key factor in developing a successful product on time and budget. ...

In a microservices architecture, an API gateway can help address a number of challenges: providing a stable endpoint for clients to call, allowing an easy process for releasing new endpoints, or handling SSL termination on behalf of services, to name a few. So how do we decide what features of an API gateway to adopt, and which to leave behind? This article highlights the key functions that an API gateway can provide, suggests the scope of problem that API gateways are well-suited to solve, and cautions against the features that make API gateways too ambitious. ...

The Research and Development department would appear to give equal weight to both research and development by virtue of naming, yet there are few engineers who would claim that research is a primary responsibility of their job. Between working on product features, planning sprints, fixing bugs, and attending meetings there is little time left for research. But what is the cost of foregoing research in favour of development? In this article, I consider the economic cost of ignoring research and argue that focusing solely on development is harmful to both product and engineering. ...

While microservices have become the defacto architectural pattern for building modern systems, they come with their own set of challenges. Key among them is ensuring application data consistency when data is spread over multiple databases. This article discusses one solution to this problem, distributed sagas. Distributed sagas provide consistency guarantees for systems spanning multiple databases in the face of failure using a clear and manageable implementation pattern. A saga is highly related to a finite state machines that moves consistently through a set of states, ensuring at each step that some conditions hold. ...

Infrastructure is undergoing a significant paradigm shift. At my first job as a software developer, scaling our infrastructure meant buying a physical machine and installing it in a rack, setting up the system images and base software by hand, configuring the network using some shell scripts, and finally, making it available for developers to install software. Now, with the advent of cloud computing, the same capabilities — installing and running software — are available on-demand. ...

Alpha conversion (also written \(\alpha\)-conversion) is a way of removing name clashes in expressions. A name clash arises when a \(\beta\)-reduction places an expression with a free variable in the scope of a bound variable with the same name as the free variable. — Greg Michaelson, An Introduction to Functional Programming Through Lambda Calculus When we are performing a \(beta\)-reduction it is possible that the variable name in an inner expression is the same as a variable name in an outer expression. For example, consider ...

Formally, beta reduction (also written \(\beta\)-reduction) is the replacement of a bound variable in a function body with a function argument. The purpose of \(\beta\)-reduction is to compute the result of a function by function application using specific rules. More formally, the beta reduction rule states that a function application of the form \((\lambda x.t)s\) reduces to the term \(t[x := s]\). The term \(t[x := s]\) means that all instances of \(x\) in \(t\) are replaced with \(s\). The \(\rightarrow\) syntax is used as a shorthand for beta reduction. We can specify beta-reduction explicitly using the notation \((\lambda x.t)s \rightarrow t[x := s]\), which means that the beta reduction of \((\lambda x.t)s)\) is \(t[x := s]\). The beta reduction removes the \(\lambda\) symbol and resolves to the function’s body with the argument \(s\) substituted into the body. ...

The Kubernetes sweet-spot is running stateless microservices that can scale horizontally. By keeping state out of your application, Kubernetes can seamlessly add, remove, or restart pods to keep your service healthy and scalable. Developing a stateless application is, without question, the easiest way to ensure that your app can scale with Kubernetes. However, there are some workloads that do not run effectively in a stateless way, and for that, Kubernetes offers a few tools for developing stateful applications: leader election, StatefulSets and session affinity. ...