What's Pier? Pier is a CMS and application development framework. The basic problem space is a configurable Wiki tool. Magritte is a generic framework for describing classes and their instances (dynamically).

Magritte lets you build views, reports and editors. Also data validation, querying, and for object persistence. It's a meta object framework for those things.

How do they work together? Magritte is a meta-model that is used by Lukas for building Pier with Seaside. You can build web apps using Pier, and have a layer riding on top of Seaside. Pier started life as SmallWiki (a contributed piece in VW at this point). In 2005 he switched to Squeak. The name changed because it's neither Small nor simply a Wiki any longer :)

With the changes, Lukas cleanly separated the view and model from each other. Seaside is the default view in use. Also started getting serious about testing and test coverage. He also added a storage framework, but it's not really in use - he's still saving the image and storing "transactions" as change sets. He's working on a binary persistence solution, and other people are working on plugging in prevlayer.

Now Lukas is doing a small demo of Pier - you can install the code into a Squeak image from SqueakMap. His eding capabilities look similar to things I've seen on Wikipedia - you can have links point either to new pages, or to new sections embedded in an existing page. Since he's using Seaside, that lets you make use of extant Seaside widgets, but in a way that's natural within the editing structure of Pier.

The UI view is all stylesheet driven, so it's as easy to "skin" as any other web application.

On to Magritte - "Describe once, get everywhere"

An example of the dynamic capabilities - the various editors in Pier (that are used for page creation) are created on the fly by Magritte. Lukas uses some naming conventions with class methods in order to get the descriptions picked up.

Where is Magritte used? Certainly in Pier. Also in a product called Aare, a workflow definition and runtime engine. Also used by the Seaside hosting business, and in Conrad, a conference registration system (used by ESUG?).

A general fear - auto-generation frameworks can feel like a straightjacket. Lukas has tried to deal with this by allowing for widegt pluggability (of course, on the web, CSS solves a fair bit of that).

Interesting question came up on the form editor, as to whether any of the data could be pulled from a DB. That would involve a new project to plug in.

Advantages of Magritte:

• Change description, all editors catch it
• Automatically builds views and editors, handles queries, etc
• Extensibility of all classes ensured
• Fully customizable - auto-generated stuff is replaceable

For more info, visit Lukas' websites - Magritte and Pier. Magritte is under the MIT license.