Nicolas Fränkel

This week, I’d like to tackle an interesting approach that is quite useful. Design by contract prescribes that developers should define preconditions, postconditions and invariants. These specifications are referred to as 'contracts'.

I started developing on the Java EE platform 15 years ago (yep, you read that right). At that time, the only way to authenticate in a webapp was through a callback. Recent Java EE versions offer alternatives. This post aims at describing both, how they work and their respective benefits.

This is the 5th post in the Starting Ethereum focus series. This post is part of a series dedicated on starting development with the Ethereum blockchain. Last week, we finally developed a contract providing some value in the form of a rough-around-the-edges voting application. Ethereum comes with no tools aimed at state-of-the-art software development out-of-the-box. Since this is a huge issue, there’s third-party tooling available in the form of the Truffle framework.

This is the 4th post in the Starting Ethereum focus series. This post is the 4th in a series dedicated on starting development with the Ethereum blockchain. Let’s face it. For a smart contract, implementing an addition of two integers is not very smart.

This is the 3rd post in the Starting Ethereum focus series. The last weeks saw us setting up the tooling and writing a contract. It’s definitely time to deploy a contract for real and run it. Thanks to the Ethereum wallet, deploying and running a contract is trivial.

In web applications, it’s necessary to prevent impatient users from POSTing the same data over and over again. For example, to avoid the pain of putting the same item into the basket multiple times because of a browser refresh. To implement that, there’s a good practice, called the Post/Redirect/Get pattern.

I have devoted a significant portion of my time thinking about designing and writing tests of all kinds. I believe my perspective can bring something to the table. In the rest of this post, I’ll follow the terminology proposed in the article.

This is the 2nd post in the Starting Ethereum focus series. In the latest post, the required infrastructure to do something on Ethereum was set up. Now is the time to roll up our sleeves and start writing some code on it. In this post, I’ll show how to write a trivial contract.

This is the 1st post in the Starting Ethereum focus series. Many people know about Bitcoin, because of its recent rise (and soon crash?). However, Bitcoin is just a currency, albeit a crypto one. As such, it’s of very limited interest to me. But it’s based on the concept of blockchain and that seems to be much more interesting. While there are a lot of resources available on the Web regarding blockchain, they mainly focus on the concept of blockchain, or how it works internally, not s

If you already had to manage some degree of randomness on Java, chances are you got acquainted with the Math.random() methods. However, the previous method returns a double. Beyond very basic use-cases, another option has to be considered, in the form of the java.util.Random class. Random An instance of this class is used to generate a stream of pseudorandom numbers. — JavaDoc https://docs.oracle.com/javase/8/docs/api/java/util/Random.html This root class provides basic random num