Errai: The browser as a platform

Friday, July 1, 2016

Errai 4.0.0.Beta2 released!


Today we're happy to announce the release of Errai 4.0.0.Beta2. This release includes lots of little fixes and enhancements including:
  • The EmbeddedWildflyLauncher for Super Dev Mode has been upgraded to use WildFly 10
  • Errai Navigation has new annotations for linking native anchors to Errai Navigation pages
  • Improved code-generation performance
  • Better support for declarative data-binding to native DOM elements
  • An injectable ManagedInstance for dynamically creating bean instances that manages the instances' life-cycles
Below we'll explain what some of these changes mean before talking about next steps.

WildFly 10 Upgrade

The EmbeddedWildflyLauncher now support WidFly 10+. Because of API changes in WildFly, it was not possible to maintain backwards compatibility with WildFly 8. That means that you have two options when upgrading Errai to 4.0.0.Beta2.

Upgrading to WildFly 10 (Recommended)

If you use the same WildFly configuration shown in the Errai Tutorial then you need only upgrade the as.version property to 10.0.0.Final. If you have any other configuration, just make sure that the errai.jboss.home system property in your Super Dev Mode configuration points to the root of a WildFly 10 installation.

Don't Upgrade errai-cdi-jboss

If you can't migrate to WildFly 10 right away, you can use an older version of errai-cdi-jboss (which contains the launcher) while still using the newest beta release for all other Errai jars.

Errai Navigation Links with Native Anchors

Errai Navigation has two new annotations that you can use on native Anchors for linking to Errai Navigation pages:
  • org.jboss.errai.ui.nav.client.local.api.TransitionTo
  • org.jboss.errai.ui.nav.client.local.api.TransitionToRole

These annotations are meant to replace the widget-based TransitionAnchor. Below we show them used in an Errai UI templated bean.

The first anchor links directly to the FAQPage while the second links to the page with the DefaultPage role. As with the previous transition anchors, Anchors with TransitionTo or TransitionToRole are validated at compile-time.

Better Data-Binding Support for Native DOM Elements

There were two issues with declarative data-binding of native elements in Errai 4.0.0.Beta1:
  • @Bound on a native element would fail in some cases for beans that were not @Templated
  • @Bound(onKeyUp=true) on an input element (TextInput, NumberInput, etc.) was not supported (and would cause compilation errors)
Both of these issues are fixed in 4.0.0.Beta2, moving Errai two small steps closer to the goal of GWT widget-free UI development.

Creating Beans Dynamically with Managed Life-Cycles

Errai supports CDI's Instance<T> for dynamically creating bean instances, but this API has some practical issues:
  • An instance created by an Instance<T> is managed by the caller. The caller is responsible for destroying the bean, which can lead to memory leaks.
  • Calling destroy on an Instance<T> destroys a bean regardless of its scope. But usually it is only desirable to destroy @Dependent beans, since @ApplicationScoped beans tend to be used throughout the entire runtime of an application.
Errai 4.0.0.Beta2 includes a new ManagedInstance<T> interface with similar methods but slightly different semantics that aim to simplify dynamic bean creation:
  • The destroy method on ManagedInstance<T> destroys @Dependent instances and is a no-op for all other scopes.
  • ManagedInstance<T> has a destroyAll method that destroys all @Dependent instances created by it.
  • When a ManagedInstance<T> is destroyed, its destroyAll method is called. A ManagedInstance<T> is destroyed when the bean it is injected into is destroyed.
In case the significance of that last point isn't immediately clear, this means that every dynamically created @Dependent instance from ManagedInstance<T> is cleaned-up when the type that injected that ManagedInstance<T> is destroyed. This avoids memory leaks and boiler-plate in short-lived components that create dynamic instances (like lists of UI elements).

Next Steps

In the coming weeks here are some of the features and tasks we will be working on:
In the interim, please try out Errai 4.0.0.Beta2 and tell us what you think.

Happy coding!

Friday, April 1, 2016

Errai 4.0.0.Beta1 released!

Greetings everyone!

As we write this, GWT and Errai are 10- and 6-years-old projects respectively. In those years, the web development community has progressed at an amazing speed, which has led some to ask the question: Is there still a place for these projects now and in the future?

We on the Errai Team continue to see huge value in our type-safe and declarative programming model for developing large projects. It is because of this value that we continue to actively develop Errai and it is because of this value that we continue to say this.

Today we're happy to announce the release of Errai 4.0.0.Beta1, targeting GWT 2.8.0-Beta1. This release brings exciting new features for working with native JavaScript and HTML, as well as improved refresh times in Super Dev Mode. In particular, 4.0.0.Beta1 includes:

  • A new Errai IoC container supporting partial code regeneration for improved refresh performance in Super Dev Mode
  • Greater compliance with CDI such as:
  • Support for injecting native JavaScript objects into IoC beans with JS interop
  • Support for injecting Errai IoC beans across separately compiled GWT scripts
  • Support for native DOM-based UI development with:
    • JS interop wrappers for common DOM elements
    • A declarative way of defining custom element wrappers available for injection in Errai IoC
    • Ability to use native DOM elements with Errai UI @DataFields, Errai Navigation @Pages, and Errai Data Binding @Bound fields

So what do all these changes mean for you?

Performance Improvements

When developing in Super Dev Mode, refreshing after modifying an IoC managed type requires generating significantly less code, decreasing the overall refresh time.
At runtime, applications with many @ApplicationScoped beans will notice decreased start-up times as @ApplicationScoped beans are now lazily instantiated by default.

Templated Beans with Native HTML Elements

In Errai 4 it's now possible to develop UI components without Widgets, and instead with thin-wrappers around native HTML elements. Here is a @Templated bean for a form using Errai UI and Data Binding.

How is this different from Errai 3?
  • Div, TextInput, and TextArea are not Widgets. Rather they are thin-wrappers around the div, input, and textarea elements respectively (using the GWT 2.8 JS Interop API)
  • The ContactForm does not extend Composite
  • The root element of the template is accessible as a @DataField. (This can be used to manually add this template to the DOM.)

Injecting Other DOM Elements

Errai 4 provides built-in thin-wrappers for most commonly used HTML elements, which you can you use in place of Widgets. The complete collection can be found in this package.
In case you wish to inject elements which do not have specific wrappers provided by Errai, you may use either of the following options.

Use the @Named Qualifier

Using the @Named qualifier, it is possible to inject an HTMLElement with any tag name. For example, here is how you could inject a nav element.

Create your own @Element

It's also very simple to declare your own thin DOM wrappers using the new @Element annotation. For example, here is a thin wrapper for the nav element that, if included in your project, can be available for injection in the IoC.

Next Steps

For those of you itching to learn more, our next blog post will take a deep dive into native JavaScript support in Errai 4, including how you can make arbitrary JavaScript objects injectable and how you can inject Errai IoC beans across separately compiled GWT scripts.
Until then you can check out our new and improved Errai Tutorial, which showcases all of the features mentioned here.

Happy coding!

Thursday, August 6, 2015

Errai 3.2.0.Final released and 4.0 in the making!

Hi everyone,

It's time for a quick update: Errai 3.2.0.Final has been released which contains a number of important fixes and quite a few new features, like runtime template support and an embedded WildFly launcher for Super Dev Mode (see the release notes for all details).

We've also just started work on Errai 4.0! In the short-term, we will be focusing on the following features and enhancements:

  • Errai IoC: Injection of types provided at runtime by dynamically loaded modules (external scripts)
  • Errai IoC: Incremental generation of our bootstrapping logic (to significantly improve refresh times)
  • Errai UI: Ease the integration of web components and allow the use of light-weight DOM wrappers instead of GWT widgets

Max Barkley is back in full force and will be leading most of this development.

What other features or enhancements would you like to see in Errai 4? We rely on your feedback so please join us on Freenode #errai, the errai-dev mailing list, or on our community forums.

Happy coding!

Thursday, February 5, 2015

Upcoming Errai talks

We're happy to announce that there will be three Errai talks this March!

Johannes Barop, a long-time Errai contributor and community member, will present at JavaLand on March, 25. You can find the details of his talk here. If you plan to attend JavaLand (and why wouldn't you? They have Java, beer, and roller coasters!) make sure to stop by and check out his talk!

Harald Pehl, core developer on Red Hat's WildFly team and long-time GWT developer, will present Errai at the Java Users Group in Frankfurt.

Finally, I am really excited and looking forward to presenting at QCon São Paulo on March, 26. The details of my talk can be found here.

Happy coding!

Monday, January 19, 2015

Errai 3.1.1.Final released!

Hi everyone,

Just a quick note that we released Errai 3.1.1.Final today. This is a maintenance release containing a few bug fixes (see the release notes for details). We have also switched master to 3.2.0-SNAPSHOT for future development. So far 3.2 contains a new feature that allows for server-side (dynamic) Errai UI templates. Please stay tuned for more information and an updated roadmap.

Everything is set for GWT.create now and I hope to see many of you in Mountain View and Munich in the coming days!

Happy coding!