tapestry-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From conflue...@apache.org
Subject [CONF] Apache Tapestry > Tutorial
Date Sun, 28 Nov 2010 21:05:00 GMT
<html>
<head>
    <base href="https://cwiki.apache.org/confluence">
            <link rel="stylesheet" href="/confluence/s/1810/9/12/_/styles/combined.css?spaceKey=TAPESTRY&amp;forWysiwyg=true"
type="text/css">
    </head>
<body style="background: white;" bgcolor="white" class="email-body">
<div id="pageContent">
<div id="notificationFormat">
<div class="wiki-content">
<div class="email">
    <h2><a href="https://cwiki.apache.org/confluence/display/TAPESTRY/Tutorial">Tutorial</a></h2>
    <h4>Page <b>edited</b> by             <a href="https://cwiki.apache.org/confluence/display/~hlship">Howard
M. Lewis Ship</a>
    </h4>
        <br/>
                         <h4>Changes (5)</h4>
                                 
    
<div id="page-diffs">
            <table class="diff" cellpadding="0" cellspacing="0">
            <tr><td class="diff-deleted-lines" style="color:#999;background-color:#fdd;text-decoration:line-through;">h1.
Tapestry Tutorial: Introduction <br></td></tr>
            <tr><td class="diff-added-lines" style="background-color: #dfd;">{tutorialnav}
<br></td></tr>
            <tr><td class="diff-unchanged" > <br></td></tr>
            <tr><td class="diff-added-lines" style="background-color: #dfd;">h1.
Introduction <br> <br></td></tr>
            <tr><td class="diff-unchanged" >Welcome to Tapestry! <br> <br></td></tr>
            <tr><td class="diff-snipped" >...<br></td></tr>
            <tr><td class="diff-unchanged" >If you are reading this documentation
online, be aware that the online documentation generally represents the very latest version
of the code, termed &amp;quot;the snapshot&amp;quot;. The documentation is _written_
as if the next release is available, but may reference version numbers, or even features,
that are only available by building the latest Tapestry source. <br> <br></td></tr>
            <tr><td class="diff-deleted-lines" style="color:#999;background-color:#fdd;text-decoration:line-through;">[Continue
on to Chapter 1: Setting Up Your Environment|Setting Up Your Environment] <br></td></tr>
            <tr><td class="diff-added-lines" style="background-color: #dfd;">{tutorialnav}
<br></td></tr>
        </table>
</div>                            <h4>Full Content</h4>
                    <div class="notificationGreySide">
        <div class="children-nav"><ul><li><a href="/confluence/display/TAPESTRY/First"
title="First">First</a></li><li><a href="/confluence/display/TAPESTRY/Forms"
title="Forms">Forms</a></li><li><a href="/confluence/display/TAPESTRY/Forms2"
title="Forms2">Forms2</a></li><li><a href="/confluence/display/TAPESTRY/Hilo"
title="Hilo">Hilo</a></li><li><a href="/confluence/display/TAPESTRY/Setting+Up+Your+Environment"
title="Setting Up Your Environment">Setting Up Your Environment</a></li></ul></div>


<h1><a name="Tutorial-Introduction"></a>Introduction</h1>

<p>Welcome to Tapestry!</p>

<p>This is a tutorial for people who will be creating Tapestry 5 applications. It doesn't
matter whether you have experience with Tapestry 4 (or Tapestry 3, for that matter) or whether
you are completely new to Tapestry. In fact, in some ways, the less you know about web development
in general, and older Tapestry versions in particular, the better off you may be ... that
much less to unlearn!</p>

<p>You do need to have a reasonable understanding of HTML, a smattering of XML, and
a good understanding of basic Java language features, and a few newer things such as Java
Annotations.</p>

<h2><a name="Tutorial-TheChallengesofWebApplicationDevelopment"></a>The
Challenges of Web Application Development</h2>

<p>If you're used to developing web applications using servlets and JSPs, or with Struts,
you are simply used to a lot of pain. So much pain, you may not even understand the dire situation
you are in! These are environments with no safety net; Struts and the Servlet API has no idea
how your application is structured, or how the different pieces fit together. Any URL can
be an action and any action can forward to any view (usually a JSP) to provide an HTML response
to the web browser. The pain is the unending series of small, yet important, decisions you
have to make as a developer (and communicate to the rest of your team). What are the naming
conventions for actions, for pages, for attributes stored in the HttpSession or HttpServletRequest?
Where do cross-cutting concerns such as database transactions, caching and security get implemented
(and do you have to cut-and-paste Java or XML to make it work?) How are your packages organized
... where to the user interface classes go, and where do the data and entity objects go? 
How do you share code from one part of your application to another?</p>

<p>On top of all that, the traditional approaches thrust something most unwanted in
your face: <em>multi-threaded coding</em>. Remember back to Object Oriented Programming
101 where an object was defined as a bundle of data and operations on that data? You have
to unlearn that lesson as soon as you build a traditional web application, because web applications
are multi-threaded. An application server could be handling dozens or hundreds of requests
from individual users, each in their own thread, and each sharing the exact same objects.
Suddenly, you can't store data inside an object (a servlet or a Struts Action) because whatever
data you store for one user will be instantly overwritten by some other user.</p>

<p>Worse, your objects each have only one operation: <tt>doGet()</tt> or
<tt>doPost()</tt>.</p>

<p>Meanwhile, most of your day-to-day work involves deciding how to package up some
data already inside a particular Java object and squeeze that data into a URL's query parameters,
so that you can write more code to convert it back if the user clicks that particular link.
And don't forget editing a bunch of XML files to keep the servlet container, or the Struts
framework, aware of these decisions.</p>

<p>Just for laughs, remember that you have to rebuild, redeploy and restart your application
after virtually any change. Is any of this familiar? Then perhaps you'd appreciate something
a little <em>less</em> familiar: Tapestry.</p>

<h2><a name="Tutorial-TheTapestryWay"></a>The Tapestry Way</h2>

<p>Tapestry uses a very different model: a structured, organized world of pages, and
components within pages. Everything has a very specific name (that you provide). Once you
know the name of a page, you know the location of the Java class for that page, the location
of the template for that page, and the total structure of the page. Tapestry knows all this
as well, and can make things <b>just work</b>.</p>

<p>As we'll see in the following pages, Tapestry lets you code in terms of your objects.
You'll barely see any Tapestry classes, outside of a few Java annotations. If you have information
to store, store it as fields of your classes, not inside the HttpServletRequest or HttpSession.
If you need some code to execute, it's just a simple annotation or method naming convention
to get Tapestry to invoke that method, at the right time, with the right data. The methods
don't even have to be public!</p>

<p>Tapestry also shields you from the multi-threaded aspects of web application development.
Tapestry manages the life-cycles of your page and components objects, and manages the fields
of the pages and components in a thread-safe way. Your page and component classes always look
like simple, standard POJOs. </p>

<p>Tapestry began in January 2000, and now represents over ten years of experience of
the entire Tapestry community. Tapestry brings to the table all that experience about the
best ways to build scalable, maintainable, robust, internationalized (and more recently) Ajax-enabled
applications. Tapestry 5 represents a completely new code base designed to simplify the Tapestry
coding model while at the same time, extending the power of Tapestry and improving performance.</p>

<h2><a name="Tutorial-AboutReleasesandDocumentation"></a>About Releases
and Documentation</h2>

<p>If you are reading this documentation online, be aware that the online documentation
generally represents the very latest version of the code, termed &quot;the snapshot&quot;.
The documentation is <em>written</em> as if the next release is available, but
may reference version numbers, or even features, that are only available by building the latest
Tapestry source.</p>


<hr />
<div class="children-nav"><ul><li><a href="/confluence/display/TAPESTRY/First"
title="First">First</a></li><li><a href="/confluence/display/TAPESTRY/Forms"
title="Forms">Forms</a></li><li><a href="/confluence/display/TAPESTRY/Forms2"
title="Forms2">Forms2</a></li><li><a href="/confluence/display/TAPESTRY/Hilo"
title="Hilo">Hilo</a></li><li><a href="/confluence/display/TAPESTRY/Setting+Up+Your+Environment"
title="Setting Up Your Environment">Setting Up Your Environment</a></li></ul></div>

    </div>
        <div id="commentsSection" class="wiki-content pageSection">
        <div style="float: right;">
            <a href="https://cwiki.apache.org/confluence/users/viewnotifications.action"
class="grey">Change Notification Preferences</a>
        </div>
        <a href="https://cwiki.apache.org/confluence/display/TAPESTRY/Tutorial">View
Online</a>
        |
        <a href="https://cwiki.apache.org/confluence/pages/diffpagesbyversion.action?pageId=23340343&revisedVersion=9&originalVersion=8">View
Changes</a>
            </div>
</div>
</div>
</div>
</div>
</body>
</html>

Mime
View raw message