GWT Training for Java Developers with GWT Boot

I'm always a fan of "one language solution with Java to rule them all", here are sofar my opinions about Polyglot Programming:

• Why "Polyglot Programming" or "Do It Yourself Programming Languages" or "Language Oriented Programming" sucks?
• Warum Polyglot Programming nicht praxistauglich ist
• Java als universelle Programmiersprache

Until today nobody can excite me about Polyglot Programming. My points are getting another big support after I read the "Rise of Polyglot at Netflix" presentation which says that Polyglot is expensive, also for company in the category of Netflix. At the end of the day we need to be productive. Our applications should have a high quality standard and the total costs (TCO) of our software development should be manageable and low. To be able to reach this goal we have Java with Spring Boot or JakartaEE on the server-side which offers REST interfaces. So logically for user interface development on the client-side I always bet on GWT which is a Java to JavaScript compiler / transpiler. In this architecture you will have Java on the both side, removing the need of Polyglotting.

In this week I carried out a training for seven internal Java developers, who are experts in Java but don't really have a real training in GWT yet. Within two days I managed to get through following slides http://bit.ly/2IKg9bg:

• Introduction to GWT
• Your first GWT App
• UI Frameworks for GWT
• Dependency Injection with Gin and Dagger2

This is also the first time that I could use GWT Boot to be able to let them doing their tasks. GWT Boot Starters are a set of convenient dependency descriptors that you can include in your application. You get a one-stop-shop for all the GWT and related technology that you need without having to hunt through sample code and copy paste loads of dependency descriptors. For example, if you want to get started using GWT and Domino UI for your Material Design and Elemental2 just include the spring-boot-starter-ui-domino dependency in your project, and you are good to go. Here are what I found using GWT Boot sofar:

• To show the developers how to create an example project with Maven and GWT Boot is quite easy for me. The pom.xml is very short, very easy to understand and to extend. No need to let them copy&paste a lot of Maven dependencies in their pom.xml project.
• The idea of generating the real GWT module file from module.gwt.xml is a bit difficult to understand. But this is not a show stopper.
• The start would be a lot more easier if I could offer them something like Spring Boot Initializr. It is definitely a must to also offer GWT Boot Initializr for GWT community.
• All in all it is great to have GWT Boot Starters. It is definitely easier for Java developers to start their own GWT project with their chosen UI framework, as you have lot of choices for UI frameworks in the GWT environment.

Second thing which is actually always a disadvantage of GWT - at least I always think it was - is the documentation and here are my findings:

• Wow, the documentation of GWT is actually really good, especially the "core" functionalities of GWT. I could find every single core aspects in GWT easily: 
• Compiler / transpiler
• Emulated Java Runtime
• Interoperability Layer to JavaScript (JSNI and JsInterop)
• Development artifacts:
• HTML host pages
• Standard directory and package layout
• GWT modules: units of configuration
• I have to admit that the documentation of tools and UI component frameworks is not good. But as I only use GWT Boot, everything is quite simple. No need to install plugin, just Maven. So the one page below is the only tools I need to develop with GWT productively.

Tools for GWT development

Very interesting to hear from the Java developers is what kind of UI component frameworks are interesting for them and easy to understand for them. Here are the categories of UI component frameworks which can be used in GWT:

• Widget-based (Standard GWT, GWTBootstrap3, GWTMaterialDesign, ...)
• Elemental2-based (DominoUI, Elemento, VueGWT, GWTReact, React4Java, ...)
• Canvas-based (I only show the idea and an example: Animatron)

Almost all of them like the idea of Widget-based components and from Elemental2-based they prefer Elemento and DominoUI which is also based on Elemento. One developer who already knows React could not directly understand the idea of GWTReact and VueGWT. All other Java developers are not fond of the idea working with VueGWT and GWTReact. It seems that the basic idea of VueGWT and GWTReact is too different in compare with Java UI components framework like Swing or JSF.

I still have one day with the training in which I will talk about advanced topics like: 

• Interoperability with JavaScript 
• Client/Server Communication
• GWT Architectural Patterns
• GWT Best Practices

But sofar my conclusion is that using GWT for Java developers is a great idea. You don't need to introduce new tools and IDEs. No new language like JavaScript or TypeScript is necessary, so that you as a Java developer can be very productive directly in the beginning, doing programming for the Web browser within your familiar development environment. To all Java developers: you could participate to lower the TCO of your software development costs. With GWT you don't need to stay on the server with Java, you can also have fun on the client with your Web browser.

Enjoy my slides: http://bit.ly/2IKg9bg!

This article is now published by DZone: No Polyglotting: First Experience with GWT Boot