General questions
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How do I get started with Tapestry?
The easiest way to get started is to use Apache Maven to create your initial project; Maven can use an archetype (a kind of project template) to create a bare-bones Tapestry application for you. See the Getting Started page for more details.
Even without Maven, Tapestry is quite easy to set up. You just need to download the binaries and setup your build to place them inside your WAR's WEB-INF/lib folder. The rest is just some one-time configuration of the web.xml deployment descriptor.
Why does Tapestry use Prototype? Why not insert favorite JavaScript library here?
An important goal for Tapestry is seamless DHTML and Ajax integration. To serve that goal, it was important that the built in components be capable of Ajax operations, such as dynamically re-rendering parts of the page. Because of that, it made sense to bundle a well-known JavaScript library as part of Tapestry.
At the time (this would be 2006-ish), Prototype and Scriptaculous were well known and well documented, and jQuery was just getting started.
The intent has always been to make this aspect of Tapestry pluggable. This is work expected in Tapestry 5.3, where a kind of adapter layer will be introduced so that Tapestry can be easily customized to work with any of the major JavaScript libraries.
Why does Tapestry have its own Inversion of Control Container? Why not Spring or Guice?
An Inversion of Control Container is the key piece of Tapestry's infrastructure. It is absolutely necessary to create software as robust, performant and extensible as Tapestry.
Tapestry IoC includes a number of features that distinguish itself from other containers:
- Configured in code, not XML
- Built-in extension mechanism for services: configurations and contributions
- Built-in aspect oriented programming model (service decorations and advice)
- Easy modularization
- Best-of-breed exception reporting
Because Tapestry is implemented on top of its IoC container, and because the container makes it easy to extend or replace any service inside the container, it is possible to make the small changes to Tapestry needed to customize it to any project's needs.
How do I upgrade from Tapestry 4 to Tapestry 5?
There is no existing tool that supports upgrading from Tapestry 4 to Tapestry 5; Tapestry 5 is a complete rewrite.
Many of the basic concepts in Tapestry 4 are still present in Tapestry 5, but refactored, improved, streamlined, and simplified. The basic concept of pages, templates and components are largely the same. Other aspects, such as server-side event handling, is markedly different.
Why are there both Request and HttpServletRequest?
Tapestry's Request interface is very close to the standard HttpServletRequest interface. It differs in a few ways, omitting some unneeded methods, and adding a couple of new methods (such as isXHR()), as well as changing how some existing methods operate. For example, getParameterNames() returns a sorted List of Strings; HttpServletRequest returns an Enumeration, which is a very dated approach.
However, the stronger reason for Request (and the related interfaces Response and Session) is to enable the support for Portlets at some point in the future. By writing code in terms of Tapestry's Request, and not HttpServletRequest, you can be assured that the same code will operate in both Servlet Tapestry and Portlet Tapestry.