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Tag Archives: Kotlin

Callback hell and Reactive patterns

One of the ways that I have better understood the usefulness of aReactive Streams based approach is how it simplifies a Non-blocking IO call. This post will be a quick walkthrough of the kind of code involved in making a synchronous remote call, then show how layering in Non-blocking IO though highly efficient in the use of resources(especially threads) introduces ...

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Extending and Overriding Flows from external CorDapps

Corda 4 was released last week (21st Feb) bringing with it a ton of new features to make Corda more enjoyable to work with. To be honest, I am kind of assuming there are a lot of new features. I had a quick browse through the changelog, mainly to see my contributions being referenced, but I remember seeing a lot ...

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Asynchronous RDBMS access with Spring Data R2DBC


Not too long ago, a reactive variant of the JDBC driver was released. Known as R2DBC. It allows data to be streamed asynchronously to any endpoints that have subscribed to it. Using a reactive driver like R2DBC together with Spring WebFlux allows you to write a full application that handles receiving and sending of data asynchronously. In this post, we ...

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Validating external data with an Oracle

I hang out in the Corda Slack channel quite a lot and try to answer questions when I can. A reasonable number of questions I have attempted to answer are related to Oracles. More specifically, when to use one. I feel like I can answer that, “Use an Oracle when you need to validate external data that can change frequently”. ...

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Native microservices with SparkJava and Graal

Microservices written with SparkJava are just plain Java code using a standard Java library. No annotation magic, just code. The advantage of this simple style of programming is that it is, well, simple. It’s so simple that the Graal native compiler just compiles it without blinking, something which is currently very difficult with more complex frameworks like Spring, for example. ...

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Java vs Kotlin for Android Development

Mobile technology is one of the most disruptive innovations in the world today. Google’s Android and Apple’s iOS, are the operating systems used primarily in mobile technology, such as smart-phones and tablets. For almost two decades, Java was the prime language to build Android applications. This language was ruling the world of Android until the birth of a new language Kotlin. A ...

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Starting Flows with trackBy

Still continuing my trend of looking at Corda Services, I have some more tips to help your CorDapp work smoothly. This time around, we will focus on using trackBy to initiate Flows from inside a Service and the discrete problem that can arise if you are not careful. This should be a relatively short post as I can lean upon ...

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Asynchronous Flow invocations with Corda Services

How can I make my Flows faster? There’s a good chance you have thought about this before if you have been working with Corda for a while. You can make reasonable tweaks to eke out performance improvements by changing a few things: transaction size, optimising queries and reducing the number of network hops required throughout the Flow’s execution. There is ...

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Use Kotlin to Build a Basic Android CRUD App

“I love writing authentication and authorization code.” ~ No Java Developer Ever. Tired of building the same login screens over and over? Try the Okta API for hosted authentication, authorization, and multi-factor auth. Kotlin was recently given official Android support status by Google, but it remains difficult to understand for many developers. The best way to start is by creating ...

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