When comparing Play vs Vaadin, the Slant community recommends Vaadin for most people. In the question“What are the best JVM web frameworks?” Vaadin is ranked 1st while Play is ranked 4th. The most important reason people chose Vaadin is:
Ranked in these QuestionsQuestion Ranking
Pro Good documentation and a great community
Play has quite a large community which provides numerous tutorials and videos related to developing with Play.
The Play official documentation covers many things, such as the framework itself but also specific stuff such as Akka, SBT and Netty.
There are also many big companies that base their main sites around Play, one of them is LinkedIn which provides third-party documentation on a regular basis.
Pro Simple for beginners
Play is very simple to get started. The documentation is very helpful for beginners and advanced users alike and the official website has a great "Getting Started" tutorial to begin developing with Play.
Pro Readable code
Play framework's convention over configuration methodology makes most Play projects have a very similar structure. This means that the code written for the framework is very readable. This enables a developer to switch between applications without having to relearn the ecosystem for every project. The built-in templating system also helps with code and makes it possible to have a very low count of lines of code.
Pro Play feautures Non-blocking I/O by default
Play Framework is asynchronous from the bottom up: asynchronous is default in Play API.
Pro Play is an extensive ecosystem
Play uses Akka for concurrency, Scala for a templating engine, Netty as a client-server framework and SBT (Simple Build Tool) for building. And they all come out of the box.
Play also comes with the option to scaffold your applications. Play is an all-embracing ecosystem designed to increase developer productivity and shorten development times.
Pro Easy to use
Vaadin has a 'design mode' which allows developers to drag and drop components into a canvas and then provide the logic for every component. There are also a lot of third party tutorials and guides which help with the initial learning curve.
Pro Top notch documentation
The book of Vaadin is a must have for every developer that uses Vaadin to make web apps. It is an excellent reference manual and all around a great tool for every Vaadin related need. You can find and download the pdf online or get it for free in almost any Vaadin sponsored conference.
The online documentation is also very good. It has some tutorials and video guides.
There is also a vibrant community which sorround Vaadin, for any problem you may have there is a big chance that someone has already asked and answered that question on StackOverflow or in the Vaadin forums. If not, it will probably be answered quickly if you ask it.
Pro Modern, configurable theming
Vaadin comes with the Valo Theme, a Sass-based theme and engine that calculates styles based on configurable variables and making it easy to define a completely new theme with a few lines of SCSS.
Pro Easy to develop prototypes quickly
Vaadin has what is called the Vaadin Directory which is a repository of downloadable Vaadin components which can be easily used for development. To use something from the repository, you need to download the JAR file and add it to the project.
Con Backward incompatibility
The jump from Play 1 to Play 2.x caused a lot of confusion. While it is important to have some kind of evolution, sometimes it causes backward incompatibility which can create some problems. It makes tutorials or modules made for the old version obsolete. This can make it hard for beginners to find useful resources. The template engine which used Groovy now uses Scala.
Con Awkward, non-idiomatic Java API
Con Weak scalability
Since Vaadin stores the UI state and logic in the server, this means that for every user interaction a request needs to be sent to the server and the client needs to wait so it can know how to react. This leads to higher traffic and load times.