Java

A lot of features are already included in the Neo4j graph database system but sometimes we want to extends its capabilities and implement functions and procedures by ourselves that we may reuse. In the following tutorial I will demonstrate how to implement a procedure for Neo4j, how to write and run tests using JUnit and an embedded graph database and last but not least how to setup Neo4j with Docker and our stored procedure installed in no time. ...

I have written about other software system analyzing and validation tools before but today I would like to introduce a new tool named jqAssistant that supports software architects, developers and analysts in a variety of tasks like analyzing given structures, validating architectural or quality constraints and generating reports. Therefore jqAssistant analyzes given projects or artifacts and stores the gathered information – that is enriched by a variety of existing plugin-ins – in a Neo4j graph database. ...

Communicating with identity and access management systems is a common task for many web-applications exposing secured resources. Keycloak is an open source software that provides not also such authorization services but also offers a lot of features from Single-Sign-On, Identity-Brokering, Social-Login, User-Federation, multiple client-adapters up to the administration console or support for protocols like OpenID, SAML, OAuth2, Kerberos and more. I will demonstrate how to integrate a Spring Boot web application with Keycloak and configure an authentication flow that requires a two-factor-authentication with user credentials and also one-time-passwords. ...

The Java Mission Control and the Java Flight Recorder allow us to capture run-time information from our Java applications without much overhead and aggregate profiling information. I have written down the commands that I’m using the most when profiling a Java application with this tool chain in the following article. Figure 1. Java Mission Control - Report Running Java Mission Control (JMC) We may start the JMC user interface shown above using the jmc command that is shipped with Oracle’s JRockit or Java (since Java 7 update 40). ...

On the one hand adding dependencies to a project is easy, on the other hand securing a project and checking for vulnerable dependencies is way harder. The OWASP dependency check plugin for Maven allows us to scan our project’s dependencies for know vulnerabilities. I will demonstrate its usage in the following short example. Figure 1. OWASP Vulnerability Report Dependencies We just need to add one plugin-dependency to our Mavenized project’s pom.xml. ...

Writing microbenchmarks for parts of our applications is not always easy – especially when the internals of the virtual machine, the just-in-time-compiler and such things are coming into effect. Java Microbenchmark Harness is a tool that takes care of creating JVM warmup-cycles, handling benchmark-input-parameters and running benchmarks as isolated processes etc. Now following a few short examples for writing microbenchmarks with JMH. Figure 1. Java JMH Microbenchmarks running in IntelliJ...

Sometimes I need to resolve Maven dependencies programmatically. Eclipse Aether is a library for working with artifact repositories and I’ll be using it in the following example to read dependency trees from a given POM descriptor file and download each dependency from a remote Maven repository to a local directory. Figure 1. Using Eclipse Aether. Dependencies We’re adding a bunch of dependencies to our project’s pom.xml: <properties> <aetherVersion>1.1.0</aetherVersion> <mavenVersion>3.2.1</mavenVersion> </properties> ...

With JUnit 5 the possibilities to write parameterized tests have changed and improved a lot. The following short overview covers all new types of possible parameter sources for JUnit 5 tests as well as the new conversion API for test arguments. In addition we’re showing how parameterized tests were written in JUnit 4. Figure 1. Running JUnit5 in IntelliJ About We will be covering all available types of parameter sources in the following sections – all that you need as a prerequisite is Java ™, Maven and a few minutes of your time. ...

Maintaining architecture rules and constraints for a specific software project or an application is not easy as textual documentation is easily forgotten after a while and hard to verify. ArchUnit is a testing library that allows developers and software architects to write down such rules as executable tests that may be run by the development teams and the integration servers. In the following article I will demonstrate the basic features of this library by applying rules and constraints to an existing application. ...

In our tests we often need to create a bunch of test-objects that are populated with random-data. This data needs to follow specific rules as identifiers need to be unique or must be incremented, string-properties must follow special conventions and so on. In the following short tutorial I will demonstrate how to generate such test data using the Fixture Factory library. Figure 1. Fixture Factory and JUnit...