OAuth2 is a frequently used standard for authorization and with Spring Boot it is easy to set up authorization and resource server in no time. In the following short tutorial I’d like to demonstrate how to set up an OAuth2 authorization server as well as a connected and secured resource server within a few minutes using Java, Maven and Spring Boot. Figure 1. OAuth2 Flow with Spring Boot in Action...
Generating test suites for existing code allows us to verify the behaviour of an application before we’re making changes to its code base or for regression testing. In the following short tutorial I’d like to demonstrate how to derive test suites from an existing Java application using EvoSuite and the EvoSuite Maven plug-in. EvoSuite offers some nice features like running in a sandbox to avoid dangerous operations, virtual file-system and network and optimizing of different coverage criteria. ...
When writing tests for our software components sometimes we need to mock external services based on the HTTP protocol, might it be a RESTful web-service, an XML-RPC call or a simple GET request to some web-server. In the following short tutorial I’d like to demonstrate how to create a mock HTTP server for testing and how to bootstrap and bind it to the life-cycle of a classical build-management tool like Maven. ...
The Reactive Manifesto specifies responsive, resilient, elastic and message-driven as attributes for a reactive application. When implementing specific mechanisms to achieve this requirements, we often need to deal with timeout and retry-operations in our application and depending on our setup and environment, different tools and libraries exist to help us here. In the following short tutorial I’d like to demonstrate how to handle exceptions and operation retries on service boundaries with a lesser know, slim library named Retry4j. ...
When it comes to the field of hybrid mobile application development, Ionic and its tool-stack is often an attractive choice. Now there is Ionic Creator to speed up the development process offering an in-browser editor to create user interfaces via drag and drop and supporting basic templates for mobile applications like tabbed layouts etc. In addition, a project created with this tool may be downloaded and started with easy and that’s what I’d like to show in the following short example. ...
We all love the simplicity when chaining commands and pipes in an Unix derivative environment. UStream takes this approach and extends Java 8′s stream API to mimic some of the well known commands and apply them on streams. In the following tutorial, I’d like to share some slim examples for using UStream. Figure 1. Data pipelines with UStream Dependencies We simply need to add one dependency to our pom.xml (using Maven): io.github.benas:ustream:0.2 ...
For us developers there plenty of libraries exist helping us in deriving and generating clients for existing RESTful web-services and I have already covered some of the in this blog (e.g. the JAX-RS Client API). Nevertheless, I’d like to share my experience with another interesting lightweight library here: Netflix Feign. Feign offers a nice fluent-builder API, a rich integration for common libraries and APIs like JAX-RS, Jackson, GSON, SAX, JAX-B, OkHttp, Ribbon, Hystrix, SLF4J and more and last bot not least, it is setup easy and the service contracts are specified using interfaces and annotations. ...
Promises may help us when dealing with asynchronous code and we need to merge, pipe or track the progress and the results of single parts of computation in our applications. In the following tutorial I’d like to demonstrate a small library, JDeferred that helps us for this specific use case. Figure 1. JDeferred examples running in Eclipse IDE. Dependencies Using Maven here, we simply need to add one dependency for jdeferred-core to our pom.xml: ...
Writing tests for asynchronous applications has never been much fun as we’re always struggling with the problem how to determine state changes, handle process terminations, dealing with timeouts or failures and stuff like this. Awaitility eases this process for us offering a nice DSL, rich support for languages like Scala or Groovy and an easy-to-use syntax that’s even more fun when using it with Java 8′s lambda expressions. In the following short introduction I’d like to demonstrate writing some tests different scenarios. ...
HipChat is Atlassian’s alternative to Slack and its solution to team collaboration chats. Atlassian Connect offers developer tools to bootstrap applications, connect to Atlassian’s cloud products with easy and in combination with HipChat’s REST APIs allows us to write integrations for such a chat server in no time. In the following tutorial I’d like to show how to write an integration within a few steps using Atlassian Connect, Node.js and Express and how to connect the integration to a HipChat server. ...