It’s quite common in a microservice style architecture to provide a type-safe client library that other services can use to communicate with your service. This can be package with a Retrofit client published to nexus by the maintainer of the service. Some projects might also generate that code from a OpenAPI spec or a gRPC proto file.

However, when we expose some of these APIs to the frontend, we lose the types. In this post I suggest a way to publish your backend API types as an NPM package. The frontend can then depend on these typings. Using typescript you now have compile time type safety and code completion. To see a sneak peak, scroll to the end :).

Since MapStruct version 1.3.0.Final is out, we are able to better integrate with Lombok Builder pattern. MapStruct is a library that takes away a lot of boilerplate code for mapping between POJO’s. With MapStruct there is no need for implementing the real mapping itself.

With Lombok we can use a Builder pattern and mark an object as a Value(Object). It will result in an immutable object. This blog post shows how we can use MapStruct to use the Builder pattern of Lombok.

A big part of the fun of starting a new project is making a design and choosing an appropriate technology stack. If you are a Java developer and need to access a SQL database, a common choice is to use JPA with an ORM framework such as Hibernate. This adds a lot of complexity to your project for multiple reasons. In my experience, writing performing queries requires careful analysis. Writing custom queries is possible but more complex. For starters, JPQL/HQL queries are parsed at runtime and the criteria API is far from user friendly. Moreover, the extensive use of annotations makes it harder to quickly see how the database is structured.

Kotlin Exposed is a lightweight SQL library on top of JDBC that could serve as a good alternative. When using Kotlin Exposed you start by describing your database structure using plain Kotlin code. The code resembles SQL DDL statements very closely and does not require any annotations or reflection! You can use these descriptions to write type safe queries. These queries can be written in two flavors: DSL and/or DAO. This post focuses on the DSL flavor.

After my last post, it would be a good time to do a bit more of a technical story. The goal will be to set up a Hello World application using the Play framework, a front-end based on Angular running on a Docker image, deployed in your local running Kubernetes!
So let’s play!

Nowadays you can’t walk into an IT department without hearing discussions about containerization. Should we move to OpenStack or OpenShift? Do we want to use Pivotal Cloud Foundry? What about Docker Swarm or Kubernetes? How to integrate our new kubernetes cluster into our CI/CD pipelines?

Keep in mind that DevOps using unmanaged infra adds an extra layer of complexity to the development teams. In the end, you might save money on an Ops team, but the tasks still need to be executed, leaving the work for the development team. As an example, when you create some new code, make a pull-request, the CI/CD pipeline kicks in to automatically build your code, perform (unit) tests, deploy to the next environment, etc. When an error occurs, the pull request would be rejected, leaving the developer to fix any possible issues, even infra.