Archive: November 2019

Prevent ResponseEntity being generated as OpenAPI model

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Tom de Vroomen

When using Springfox you can annotate your endpoints to automatically generate OpenAPI docs for your clients.
This blogpost will show how you can prevent Springfox generating a model on an endpoint with ResponseEntity as return type.
I’ll also cover how to prevent generating default responses.

Take an endpoint like below.
You want to return ResponseEntity because you want control over the status and body which is returned within your endpoint code.

Click to see the Spingfox configuration used for this example

Now your generated OpenAPI doc contains responses with a $ref to ResponseEntity.

Springfox will also generate default responses for 201, 202, 400, 401, 403, 404, which you may never need.

Click to see the generated definition for ResponseEntity (it is quite long)

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Adding Spring Security

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Tim te Beek

Adding Spring Security to an existing application can be quite a daunting prospect. Merely adding the required dependencies to your project sets off a chain of events which can break your application and tests.

Maybe you’re suddenly shown a login prompt which expects a generated password logged on startup.
Maybe your tests now get the dreaded 401 Unauthorized, or a subsequently a 403 Forbidden.
Maybe you get a ClassCastException when trying to use your Authentication#getPrincipal().
Either way, this post is here to help!

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Using ZIO's Ref to ensure a singleton in the Environment

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Chiel van de Steeg

In a previous post I’ve shown how to use ZIO environments to provide your program with dependencies, or modules. While using environments at the customer I’m currently working for, we found out that the logic to get a database session object using a module would run over and again. This makes sense, since a ZIO[R, E, A] is a prescribed way of getting an A, and the result is not cached. Our application was reading configuration files and creating SQL sessions on every module call, while the resulting object was obviously constructed from the same underlying values. There are multiple ways to solve this:

  • Creating the singleton objects before running you application logic.

  • Caching the result of the loading code in a reference.

In this post I’ve chosen the latter, because I wanted to show the use of ZIO’s Ref. Also, I like how semantically the desired data and the logic of retrieving it belong together.

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Spring Cloud Gateway with OpenID Connect and Token Relay

Posted on by  
Tim te Beek

When combined with Spring Security 5.2+ and an OpenID Provider such as Keycloak, one can rapidly setup and secure Spring Cloud Gateway for OAuth2 resource servers.

Spring Cloud Gateway aims to provide a simple, yet effective way to route to APIs and provide cross cutting concerns to them such as: security, monitoring/metrics, and resiliency.

We consider this combination a promising standards-based gateway solution, with desirable characteristics such as hiding tokens from the client, while keeping complexity to a minimum.

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HotSpot JVM optimizations

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Christophe Hesters

This is an overview of some optimization techniques used by Hotspot JVM to increase performance. I will start by giving a small example of how I ran into these optimizations while writing a naive benchmark. Each optimization is then explained with a short example and ends with some pointers on how to analyze your own code.

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