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Lightweight Ethereum Clients Using Web3j 1. Introduction This tutorial introduces Web3j, a Java implementation of the popular Web3 abstraction library. Web3j is used to interact with the Ethereum network by connecting to Ethereum nodes using JSON-RPC or familiar standards like HTTP, WebSockets, IPC. Ethereum is a whole topic unto itself so let’s first… Continue Reading web3j
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Querying Couchbase with N1QL 1. Overview In this article, we’ll be looking at querying a Couchbase Server with N1QL. In a simplified way, this is SQL for NoSQL databases – with the goal of making the transition from SQL/Relational databases to a NoSQL database system easier. There are a couple… Continue Reading n1ql-couchbase
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Java Web Weekly, Issue 167 Lots of interesting writeups on Spring stuff going on this week. Let’s jump right in… 1. Spring and Java ===== >> Spring Boot – Configure Log Level in Runtime Using Actuator Endpoint [codeleak.pl] Starting with Spring Boot 1.5, we can configure log levels at runtime… Continue Reading java-web-weekly-167
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A Simple Tagging Implementation with JPA 1. Overview Tagging is a standard design pattern that allows us to categorize and filter items in our data model. In this article, we’ll implement tagging using Spring and JPA. We’ll be using Spring Data to accomplish the task. Furthermore, this implementation will be… Continue Reading jpa-tagging
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Form Validation with AngularJS and Spring MVC 1. Overview Validation is never quite as straightforward as we expect. And of course validating the values entered by a user into an application is very important for preserving the integrity of our data. In the context of a web application, data input… Continue Reading validation-angularjs-spring-mvc
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Mapping A Hibernate Query to a Custom Class Persistence Hibernate 1. Overview When we use Hibernate to retrieve data from the database, by default, it uses the retrieved data to construct the whole object graph for the object requested. But sometimes we might want to retrieve only part of the… Continue Reading hibernate-query-to-custom-class
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Inline Classes in Kotlin 1. Overview In Kotlin 1.3+, we have an experimental new type of class, called inline class. In this tutorial, we’ll focus on the usage of inline classes and also some of their limitations. 2. Setup As we mentioned before, inline classes are an experimental feature of… Continue Reading kotlin-inline-classes
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Introduction to Clojure 1. Introduction Clojure is a functional programming language that runs entirely on the Java Virtual Machine, in a similar way to Scala and Kotlin. Clojure is considered to be a Lisp derivative and will be familiar to anyone who has experience with other Lisp languages. This tutorial… Continue Reading clojure
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Create a Custom FailureAnalyzer with Spring Boot 1. Overview A FailureAnalyzer in Spring Boot offers a way to intercept exceptions that occur during the startup of an application causing an application startup failure. The FailureAnalyzer replaces the stack trace of the exception with a more readable message represented by a… Continue Reading spring-boot-failure-analyzer
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How to Return 404 with Spring WebFlux 1. Overview With Spring Boot 2 and the new non-blocking server Netty, we don’t have the Servlet context API anymore, so let’s discuss the way how we can express different kind of HTTP status codes, using the new stack. 2. Semantic Response Status… Continue Reading spring-webflux-404
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