-----Original Message-----
From: Jason Chaffee [mailto:[EMAIL PROTECTED]]
Sent: 28. elokuuta 2001 21:58
To: '[EMAIL PROTECTED]'
Subject: RE: Barracuda vs. Struts [LONG]Ted, could you point us to the reports you mentioned in your Reflection section. I would be very interested in reading about these new performance findings.
Thanks,
-----Original Message-----
From: Ted Husted [mailto:[EMAIL PROTECTED]]
Sent: Monday, August 27, 2001 6:32 PM
To: [EMAIL PROTECTED]
Subject: Re: Barracuda vs. Struts [LONG]
First, this is a very impressive document, Chris. I personally consider
"Surveying the MVC Landscape" required reading (along with Jason Hunters
"The Problems with JSP"), and am glad to see that the tradition of
high-quality documentation continues at Barracuda.Though, I personally can't justify the idea that Struts is page-centric
framework. It is not the case that Struts encourages developers to write
tags that access the model. Quite the opposite. The Struts tags are
designed to obtain data from JavaBeans, or from the Controller's
mappings. When people on the list mention using tags that access the
view, most of will make a point of mentioning that it is not considered
the best practice.The "Struts approach" is for developers to use the Action to obtain
information from the model, encapsulate it in a bean, and pass it to the
view. We do not encourage the view to access the model directly.Given this, I would say that Struts today is primarily a developer's
framework. It is our hope that as GUIs like DreamWeaver and Homebase
increase their support for Custom Tags, it will blossom as a
team-players framework. Developers will expose the model to Page Authors
through standard and custom tags that will be supported directly by the
Page Author's GUI.Here are some specifics for your consideration. These will only make
sense if you have a copy of the article handy.2. Struts
In the diagram, replace "Struts-config.xml" with a box labeled Action
Mappings. These are accessed by the Controller and the View via tags.
Disconnect the arrow from the Model to the view, since Struts does not
encourage this (although our comrades at Jakarta Taglibs might).2.1 Controller.
+ uses a XML configuration file to map URIs ..., (the default name is
struts-config.xml, but its not
hardwired).+ when a requestis received, route it to the appropriate Action
- identify from the URI the appropriate mapping for this request
- use this mapping to select the corresponding action class
- if this is the first request for the action class, instantiate the an
instance of that class and cache it or future use
- ...
- call the perform() method of the action object, passing on a reference
to the mapping that was used, and the request and response objects. The
action also has access to the underlying ActionServlet and
ServletContext.
+ Actions may take data from the request, may access the Model, handle
any errors, and return a forwarding to the Controller. The forwarding
may be a page, another Action, or be redirected to a URL.
+ The Controller returns the Response to the container, which may invoke
a JSP, fetch a HTML page, or whatever else is required.
+ The JSP may display data from a JavaBean in the request, or from the
session context, access the Struts mappings to render a URL, and/or
access message resource to display internationalized text.3. View ... Views are typically rendered with JSPs, which use Java
Taglibs to pull data from JavaBeans in the request or session contexts,
and insert it into the page.4. Localization - Struts uses the standard Java localization mechanism,
augmented with a standard Message Resource that can be accessed by
various custom tags. The tags can automatically display the appropriate
text for the user's locale.Collections - (The collections have been migrated to the Commons. You
might want to skip mentioning them altogether.)Digester - You might mention that "The digester is now available through
the Jakarta Commons project as a standalone utility. "5. Future Directions. A "ValidatorForm" is being integrated with Struts
that offers client and server side validations from the same XML
configuration. It is now available as a plug-in.An advanced templating package called "Tiles" that is appropriate for
building portals and other complex layouts1. UI Issues -
6. It would be better to say this sooner, or later, and cleanly separate
the criticisms of JSP from the "comparisons" with Struts. To quote Jon
Stevens: "If you must use JSP, use it with Struts". It's my feeling that
Struts demonstrates how JSP can be used responsibly. Which is to say,
JSPs don't violate Model 2, developers do ;-)1. Personally, I don't see being able to use scriptlets as a "flaw".
Developers should have the freedom of choice. Many of us choose to say
no, but it's nice to have the option if we need it.2. References to taglibs in a JSP are VIRTUAL and defined in the
web.xml. Many developers simply use the same path for the location and
the URI, but any reference can be used. The taglibs can be moved
anyplace on the server without changing the JSP. It is not a reference
to the server-side unless you want it to be.3. Respectfully, this is gibberish. The Struts tags are "minimalistic"
and do not support or encourage looping and other such programming
constructs.4. Custom tags are valid markup, and provide a TLD to prove it ;-)
5. I would say that the given even the minimal support provided by
DreamWeaver and UltraDev, custom tags are as easy for HTML authors as
anything else. The developers do not need to work on the same file as
the authors, developers simply need to provide an API for the custom
tags.2. Page Design
Barracuda - While most editors and clients will ignore the Barracuda
extensions, this doesn't make it "valid" markup. I would argue that
Taglibs+HTML do constitute a valid markup, since the syntax for both are
defined, and can be independantly validated.7. Support for skins
The template package bundled with Struts can be used for this, and the
capabilities are enhanced in the Tiles package.8. Client capabilities.
Struts itself does not provide any specific features that address this
area.Reflection
Every recent report I've seen says reflection is no longer a point of
concern. Ditto for object creation and garbage collection. The latest
advice is that is can be more expensive to cache an object that recreate
it.Syncronization - Also minimal in Struts.
---
Anyway, keep up the excellent work, Chris. As mentioned, I think
Barracuda is an important project, and has a lot to offer to the
development community.
-- Ted Husted, Husted dot Com, Fairport NY USA.
-- Custom Software ~ Technical Services.
-- Tel +1 716 737-3463
-- http://www.husted.com/about/struts/
Title: RE: Barracuda vs. Struts [LONG]
Is it
possible to use an error page in an Action, in such way that in the "perform"
method I just throw a ServletException, and the servlet container will forward
to my "error.jsp" page.. I specified an "error-page" in the web.xml, but it
doesn't seem to work.
Thanks,
Juha
Paananen
- RE: Using the "error page" in an Action Juha Paananen
- RE: Using the "error page" in an Action John Schroeder
