My GSoC 2017 - Slush-vertx

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Creating a scaffolder for vertx projects

slush-vertx is a project created by Paulo Lopes born to simplify build tools configurations for Vert.x. I totally refactored slush-vertx to create a multi purpose code generator for simplify various configurations of Vert.x powered projects.

Multi purpose and simple to enlarge

When I designed the new slush-vertx, I tried to create a Vert.x project generator for every configuration needed, not only an OpenAPI 3 server or OpenAPI 3 client. Another important variable of my project is create a generator that generates code for different languages and different build tools.

Now slush-vertx It’s like a “code generation hub”: It contains a set of project generators, based on what type of Vert.x project are you going to scaffold. At the moment I’m writing this post, slush-vertx contains:

  • Vert.x Starter project generator: Based on original Paulo’s project, generates an empty project configured for Vert.x 3 Framework
  • Vert.x Web Server Starter generator: Generates a skeleton with sources and tests for Vert.x 3 Web powered REST server
  • Vert.x Web Server OpenAPI project generator: Generates a skeleton based on Swagger 2/OpenAPI 3 specification with sources and tests for Vert.x 3 Web powered REST server
  • Vert.x Web Client OpenAPI project generator: Generates a client based on a Swagger 2/OpenAPI 3 specification and Vert.x 3 Web Client

I hope it will grow in the future, creating a tool that can help people to connect with Vert.x world.

How it works

Behind the scenes

slush-vertx is metadata and template driven code generator. This means:

  • For every language/build tool it has a set of metadata, that can be extended with user inputs
  • It uses a template engine to generate code, based on metadata

If you want a complete scenario of behaviours of slush-vertx, give a look at this wiki page

But, why that complexity behind a code generator? I mean, It’s only a code generator! Yes, It’s only a code generator, but I wanted to create a tool simple to extend with new generators routines, giving to Eclipse Vert.x a powerful tool.

Generate unit tests

So, if you have a powerful build tool that generates pretty everything you want, why don’t take advantage of it doing things that you don’t want to do? And this is what I’ve done! Copy-pasting code from other generators I’ve created, I builded a unit test generator for vertx-web-api-contract-openapi. This generator takes all operations declared in this oas 3 spec and generates a specific test to validate the correct parsing of parameters on server side. This is the final result: OpenAPI3ParametersUnitTest.java. This unit tests helped me a lot to complete the vertx-web-api-contract-openapi module.

With some small changes this can be a complete server libraries/frameworks compatibility test tool for OpenAPI 3

And now?

Now use it! Follow the readme inside GitHub repository to install and start using it.

You can also contribute to this project adding new generators and updating existing ones with new languages