Programming Jakarta Struts, 2nd Edition [Electronic resources] نسخه متنی

1.7 Alternatives to Struts

Although this book is dedicated to the Jakarta Struts framework,
Struts is far from the only Java Web
framework available. There are quite a few available, each with their
own proponents and evangelists.

Because framework versions and features may change with each new
release, it's not always practical to compare and
contrast Struts simply by reading these descriptions; you should
conduct your own research with the latest stable versions of
framework alternatives. This list is by no means exhaustive, but it
will provide you with a launching pad.

Note that only solutions based on or around the Java platform are
listed here. Microsoft also offers a competing technology based on
Active Server Pages (ASP). Although the goal of ASP is similar to
that of JSP, ASP and ASP+ are not discussed
herethey're better left for a book on JSP and
servlets. Furthermore, the Struts framework goes well beyond what is
offered by JSP alone, and comparing ASP or other technologies similar
to Struts wouldn't make sense.

Microsoft also has also introduced an "Application
Block" called User Interface Process (UIP). UIP
shares some of the same goals as MVC frameworks like Struts, but is
meant for use with for the .NET programming model. Although
interesting, it won't be presented here either.

1.7.1 Building Your Own Framework

At first, it might seem strange to include
building your own framework as an
alternative to using Struts. Why would you want to build frameworks
from scratch when they already exist in readily-available products?
The answer is the same reason that other open source or commercial
products are developed. The available selection of products just
might not be close enough to your desired framework, and it might be
preferable to build it in-house.

The best advice I can give regarding building your own framework is
to ask yourself several questions:

1. Have I taken the time to inspect what's available
   and build a prototype using an available framework?

2. What does my application need that doesn't exist in
   one of the available frameworks?

3. Can I extend an existing framework to suit my needs or find what I
   need at another source and add it?

4. Do I know enough about building this type of framework to be able to
   meet my requirements?

5. Am I willing to provide support for bug fixes and feature
   enhancements for my framework for at least one year?

Depending on the honest answers to these questions, you might find
that building your own framework isn't the best
decision. A good guideline to which many in the software-development
industry subscribe is that if it pertains to your core business, you
should build it in-house. However, if the software component is not
directly related to your core business, it might be wise to get it
elsewhere. Play to your team's strengths and
minimize its weaknesses.

1.7.2 Barracuda

The Barracuda
presentation framework is a type of Model 2 architecture similar to
Struts, but it goes a step further and provides a model
event-notification mechanism. Unlike a strictly JSP approach, the
Barracuda framework has created a template engine component, which is
supposed to allow for more flexibility and extensibility. The
framework leverages code-content separation provided by the XMLC
approach of creating user interfaces. XMLC is a Java-based
compiler that uses either an HTML or XML document and creates Java
classes that can recreate the document when executed. The generated
Java classes can be used to insert dynamic content into the document
at runtime by manipulating Document Object Model (DOM) interfaces.
The separation of markup and application logic allows web designers
to focus on markup and programmers to focus on coding. It also
includes a Form mapping and Validation package for taking HTML form
data and automatically validating it.

The available documentation for Barracuda is abundant, which makes it
easy to get started. You can find more information on the Barracuda
presentation framework at http://barracudamvc.org/Barracuda/indexl.

1.7.3 Cocoon

Stefano
Mazzocchi founded the
Cocoon
project in January 1999 as an open source project under the ASF. The
goal of Cocoon is to help separate the content style, logic, and
management functions for XML-based web sites. Cocoon leverages XML,
Extensible Stylesheet Language Transformations (XSLT), and Simple API
for XML (SAX) technologies to help create, deploy, and maintain XML
server applications. With the release of 2.0, Cocoon has been raised
to a higher level by providing a pipeline-style of assembling
components. This allows for easier assembly of its various components
and allows Cocoon to fit inside your existing web architecture.

Most types of data sources, including RDBMS, LDAP, and File Systems,
are supported. More information on Cocoon can be found at http://cocoon.apache.org.

1.7.4 Expresso

The Expresso
framework from Jcorporate is an application development framework
that provides a component-based framework for developing
applications. It provides a set of core components, compatible with
both EJB and non-EJB applications alike. Although completely
independent of Struts and other frameworks, the Expresso components
can also be integrated into Struts in order to add security
capabilities, object-to-relational mapping, background job handling
and scheduling, and many other features. More information on the
Expresso framework can be found at http://www.jcorporate.com.

1.7.5 Freemarker, Velocity, and WebMacro

These three products are grouped together because they all represent
similar types of template engines.

Freemarker
is an open source HTML template engine for Java
servlets. With Freemarker, you store
the HTML in templates, which eventually get compiled into template
objects. These template objects then generate HTML dynamically, using
data provided by servlets. Freemarker uses its own template language
and claims speeds approaching those of static HTML pages. The
software is free and licensed under a BSD-style License. You can find
more information about Freemarker at http://freemarker.sourceforge.net.

Velocity is
another Jakarta project like Struts.
It is a Java-based
template engine that is similar in many ways to Freemarker, but it is
capable of more than just creating dynamic content for web sites.
Velocity can generate SQL, PostScript, and XML from templates, for
example, and can be used either as a standalone utility for
generating source code and reports or as an integrated component of
other systems. Velocity also provides template services for the
Turbine web application framework. Many other frameworks either
support the Velocity scripting syntax or actually depend on it. For
more information on Velocity, go to http://jakarta.apache.org/velocity.

WebMacro is an
open source Java servlet framework used by several large web sites.
The WebMacro framework uses a lightweight scripting language that
allows separation of how a page looks from the page logic. WebMacro
can be run in standalone mode or with a servlet container. More
information about WebMacro can be found at http://www.webmacro.org.

1.7.6 Maverick

The Maverick
MVC framework offers the ability to render views using JSP, the
Velocity scripting language, or XSLT. Maverick is an MVC-type
architecture, but it actually provides a view template mechanism. One
neat feature of Maverick is that it can use reflection on JavaBeans
in the presentation layer to create a DOM interface, so no XML
generation or parsing is required. This allows for a little less
clutter and probably better performance when using XSLT to generate
the views. You can find more information on the Maverick framework at
http://mav.sourceforge.net.

1.7.7 SiteMesh

SiteMesh is a
web page layout and integration system that makes it easier to create
web sites that need a consistent look and feel. SiteMesh intercepts
requests to any web page, whether it's static or
dynamically generated, parses the content, and generates a final
page. This process is based on the well-known
Decorator
pattern.^[4]

^[4] The Decorator pattern is a structural design
pattern mentioned in the book Design Patterns
(Addison Wesley), by Gamma, Helm, Johnson, and Vlissides,
affectionately known as the "gang of
four."

SiteMesh is built with Servlet, JSP, and XML technologies, which
makes it appropriate for J2EE applications. However, it also claims
to be easy to integrate with other web technologies, such as CGI.
More information on SiteMesh can be found at
http://www.opensymphony.com/sitemesh.

1.7.8 Jakarta Turbine

Turbine
is a servlet-based framework and an open source Jakarta project.

Turbine appears to be focused on providing a collection of reusable
components. A large set of components is included with the framework,
including components for using relational databases, security, and
schedulingjust to name a few. More information on Turbine can
be found at http://jakarta.apache.org/turbine.

1.7.9 WebWork

WebWork
has now moved under the umbrella project known as
OpenSymphony.
OpenSymphony is a SourceForge project dedicated to providing open
source J2EE applications and components. You can find information on
OpenSymphony at http://www.opensymphony.com.

WebWork is a web application framework that uses the
Pull Hierarchical Model View
Controller (HMVC) design. With a standard MVC design, changes made to
the model are pushed to the view. In the case of WebWork, the views
pull the data when they need it. Interestingly, WebWork
doesn't seem to be tied to a servlet; therefore, it
can support other types of clients such as Swing. More information on
the WebWork framework can be found at
http://www.opensymphony.com/webwork.

1.7.10 Spring Framework

Spring
is a relatively new J2EE application framework developed by Rod
Johnson and included in his J2EE design book. Spring is not just a
web frameworkit's strength lies in the
ability be integrated with other disparate components. More
information on Spring can be found at http://www.springframework.org.

1.7.11 JavaServer Faces

In 2001, a new Java Specification Request (JSR)
was issued for a new Java technology called
JavaServer Faces (JSF). The goal of this
JSR is to lessen the burden on Servlet and JSP developers by
providing a standard set of JSP Tags and classes to aid in the
management of complicated HTML forms, event handling, and
presentation state. The proposal also attempts to account for various
platforms and client types by allowing pluggable rendering kits.

The JSR defines the architecture and a set of APIs for the creation
and maintenance of Java server web
applicationsit's simply a set of standard
APIs, not an actual implementation. Vendors can create their own
implementations, so developers have more than one implementation to
choose from.

The JSR indicates that the creators of JSF are aware that other
projects (such as Struts) already have addressed many of the problems
that this specification attempts to solve. The JSR is aimed at
creating a standard that will help unify this fragmented area. Keep
your eye on this specification, as it may have a huge impact on
Struts and the entire web application area as a whole. The good news
for Jakarta Struts users is that one of the primary authors of
Struts, Craig McClanahan, is co-specification lead
for JavaServer Faces. His influence will surely help ensure a smooth
transition for the Struts framework.

At the time of this writing, the Java Specification Request (JSR) has
moved past the 2nd public review and a final specification is
expected in the near future. More information on the specification
can be found in Chapter 18 and online at
http://www.jcp.org/jsr/detail/127.jsp.