Joshua Hansen wrote a nice example of how to create custom meta data constraints and display dedicated validation error messages with RIFE. He also shows how easy it is to make RIFE/Crud display your validation errors for beans that use your custom constraints.

Read the article in the RIFE wiki.

In case you want to learn more about RIFE, ask questions, chat a bit about what you've done, share experiences, etc., feel free to come the the BOF tonight that I'm organizing during the QCon conference in San Francisco. You can find all the details here:

http://qcon.infoq.com/sanfrancisco/conference/

The address is:
Westin San Francisco Market Street
50 Third Street
San Francisco
California 94103

The BOF will be from 8:30pm - 9:30pm in the 'City' room.

We are also organizing a Terracotta BOF right before it, so if you're interested in that, you can come from 7:30pm - 8:30pm to the 'Stanford' room.

See you there!

I'm speaking at NFJS in London at the end of this month about RIFE and Terracotta. You can find the abstract of my session quoted below. The schedule looks very interesting and I'm excited that NFJS is finally taking place in Europe too.

If you're interested in going, you might want to click on the banner to the right or to use the promotion code NFJS-RIF660. This will give you a free Nintendo Wii with your registration (woohooo, I love my Wii!).

See you at NFJS Europe.

I also have another session about Terracotta in the real-world.

Cutting-edge productivity with RIFE and Web Continuations

RIFE is a full-stack, open-source Java web application framework, offering fast results with the promise of maintainability and code clarity. This session will review the novel ideas in Java web application development that RIFE has introduced to the development community.

Through a real-world demonstration of the development process with RIFE, learn how RIFE makes developing easier with features such as: instant reloads and centralized declarations, meta programming through constraints and meta data merging, run-time POJO-driven CRUD generation, bi-directional logic-less templates, automatic context-aware components, and the integration of a content management framework.

The second part will focus on state management, which has always been a complex and tricky part of web application development. Native Java web continuations simplify this and automatically allow you to create a one-to-one conversation between users and a web application. State preservation and flow control no longer need to be handled manually, bringing you back to the simplicity of single user console applications. Remember 'scanf()'?

Continuations will be introduced from general principles, followed by practical examples that explain how they benefit web application development and their frequent usage patterns. Finally, automatic and non-intrusive fail-over and scalability will be demonstrated through the integration with Terracotta.

In this article, Jonas Bonér and me discuss how the RIFE Web framework helps you become productive and efficient in building conversational Web applications. Productivity with RIFE is in large part due to RIFE's unique approach to Web development—its use of continuations for conversational logic, and complete integration of meta-programming to minimize boilerplate code.

We also introduce you to Terracotta and it's JVM-level clustering technology, and show you how Terracotta and RIFE can work together to create an application stack that allows you to scale out and ensure high-availability for your applications, but without sacrificing simplicity and productivity. This means working with POJOs, and minimal boilerplate and infrastructure code.

You can read it at Artima.

Frank Sommers of Artima has started a discussion about template engines and asks what you find important in them.

Template engines seem to be one of the most stagnant technologies in Java, many adopt the design that mixes content and logic but implement it differently (PHP, JSP, Velocity, Freemarker, ...). It's a good thing that Terrence Parr (of ANTLR fame) created StringTemplate which seems to move in a similar direction as what we've been doing with our template engine in RIFE. He acknowledges the push model that injects values and text into a template instance instead of pulling them in with an expression language. While I prefer our approach where there really is no logic in the template at all, I really appreciates what Terrence says in his docs:

This goes back to a less-is-more philosophy where you build what is needed to comfortably use a technology in trivial and advanced situations, and nothing more. RIFE's template engine does the same. Instead of including a whole collection of additional features, we rely on you making a mental shift to adapt your development habits towards the new capabilities and characteristics of our template engine. In my case its not language theory, but rather lots of very complex HTML layouts and other uses of our template engine that gets me to say that our template engine is powerful enough to allow you to comfortably build anything you want, without compromising on context separation and reusability.

Have you ever tried out another template engine besides the classic pull model in anger? What did you think of it?