Apache

Sometimes it is nice to set up an embedded Kafka broker for testing without the need to have Docker installed (e.g. for using testcontainers-lib). The following snippet shows, how to set up an embedded Kafka instance for testing for a Spring Boot project. Setup Using Maven, this is our Spring Boot project with dependencies needed: pom.xml <?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId>(1) <version>2.6.4</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.hascode.tutorial</groupId> <artifactId>kafka-testing</artifactId> <version>1.0.0-SNAPSHOT</version> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>17</java.version> <maven.compiler.source>${java.version}</maven.compiler.source> <maven.compiler.target>${java.version}</maven.compiler.target> <kafka.version>3.1.0</kafka.version>(2) </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.kafka</groupId> <artifactId>spring-kafka</artifactId>(3) </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.kafka</groupId> <artifactId>spring-kafka-test</artifactId>(4) <scope>test</scope> </dependency> <dependency>(5) <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-engine</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.platform</groupId> <artifactId>junit-platform-launcher</artifactId> <scope>test</scope> </dependency> [..] </project> ...

Steps Pull image and run with ports exposed: docker run --name "nifi" -p 8443:8443 -d apache/nifi:latest Fetch the generated username and password from the logs: docker logs nifi | grep -A1 "Generated Username" Generated Username [8f6d91f7-733e-40cf-b900-059ea9dccbf2] Generated Password [v7KGiiRYLJL2+HzhKOqz1rbgiPOaWz0B] Now we may enter the https://localhost:8443/nifi/login in our browser, accept the security exemption and login with the credentials from above, voila! Installing additional connectors I have found a nice summary on the following GitHub repository: ...

Capacity planning is an important task when trying to anticipate resources and scaling factors for our applications. The usl4j library offers us an easy abstraction for Neil J. Gunther’s Universal Scalability Law and allows us to build up a predictive model based on the parameters throughput, latency and concurrent operations. With a basic input set of two of these parameters, we are able to predict how these values change if we change one input parameter so that we can build our infrastructure or systems according to our SLAs. ...

When writing test for applications that interact with Kafka brokers we often need to setup a decent environment including an instance of Kafka and ZooKeeper. Though Kafka ships with some classes for testing, setting up a simple testing environment is quite easier with the kafka-unit library that offers JUnit test rule support or a fast programmatic setup within no time. In the following short example, I’d like to show how create a simple setup using Maven, Surefire and kafka-unit. ...

When writing applications that interchange information with LDAP directory services there is always the need to write integration tests for these components and services. Therefore we need a the possibility to start-up an embedded LDAP server, fill it with test-data and control its life-cycle during the test-phases. In the following tutorial I’d like to demonstrate two candidates that fulfil this purpose, the ApacheDS test integrations and a small library named embedded-ldap-junit. ...

Apache Camel not only is one of my favourite frameworks ever but it also allows the humble developer to create a full blown chat bot within a few lines of code and using the Camel XMPP component. In the following tutorial, we’re going to create a simple chat bot and since Atlassian’s HipChat basic plan is now free for unlimited users, we’re using HipChat as our play- and testing ground for the bot. ...

Recently I needed to modify some excel files and to add some aggregated formula fields to a sheet and the following snippet did the work for me. Figure 1. Modified Excel File with Formulas Dependencies Just two dependencies needed here: One for Apache POI and one for the Office Open XML Documents API. <dependency> <groupId>org.apache.poi</groupId> <artifactId>poi</artifactId> <version>3.10.1</version> </dependency> <dependency> <groupId>org.apache.poi</groupId> <artifactId>poi-ooxml</artifactId> <version>3.10.1</version> </dependency> Sample Excel File Our sample excel file is quite empty just some empty customer information and a chart that is bound to the data grid. ...

Apache Avro is a serialization framework similar to Google’s Protocol Buffers or Apache Thrift and offering features like rich data structures, a compact binary format, simple integration with dynamic languages and more. In the following short five minute tutorial, we’re going to specify a schema to serialize books in a JSON format, we’re using the Avro Maven plugin to generate the stub classes and finally we’re serializing the data into a single file. ...

Apache Pivot is a modern framework to create rich clients as desktop applications or to run in a web browser. It offers nice GUI elements, supports XML/WTKX templates, data bindings, JVM scripting languages and much more. In the following short examples I’m going to create a desktop application to open a file browser, select a file and output the selected file’s name, first using a programmatic approach to create the user interface, and afterwards using XML/WTKX templates. ...

Whenever I encounter a situation where I have to mix a blend of different services and endpoints and apply one or more of the traditional enterprise integration patterns then Apache Camel often is my weapon of choice. I simply love how easy it is to set up some datasources, add some routing magic, data transformers, load balancers, content enrichers and enjoy the result. Another thing that I’m beginning to love is Scala and so this is the perfect time to write an article about using Scala and Apache Camel together. ...