Category: Kotlin

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 ...

Testing exceptions in Kotlin with assertFailsWith

I wanted to write this short post to highlight the assertFailsWith function available to Kotlin that makes testing exceptions a bit easier. Testing exceptions isn't something fancy or new to JVM languages (from now on I will use Java for comparisons) but Kotlin comes with the nice extra benefit of providing this functionality as part ...

https://pixabay.com/en/chainlink-fence-metal-wire-690503/

Storing when block subject in a variable

Super short post, on a change introduced in Kotlin 1.3 (yes I know it has been out for a while now). We will take a quick look at capturing the subject of a when block into a scoped variable. This is a quality of life improvement that saves a line or so of code while ...

https://pixabay.com/en/sydney-opera-house-opera-house-3381786/

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 ...

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 ...

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 ...

Corda Services 101

I'm in the mood to write a short and to the point post today. I'm actually curious how quickly I can get this published. So let's go. This post is about Corda Services (using Corda version 3.2). What are they? As a developer that uses Spring a lot, I would personally say they are like ...