Transcript people.apache.org

What's New In Struts 1.1
Session TU07 – 11/19/2002 – 13:30-14:30
Craig R. McClanahan
Senior Staff Engineer
Sun Microsystems, Inc.
Session Outline
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Welcome
New Features In Struts 1.1
What Does The Future Hold?
Q&A
Welcome
Welcome
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I'm assuming you are familiar with Struts 1.0
For an introduction, please attend session
WE06 tomorrow at 1:30pm: “Building Web
Applications With Struts”
Two BOFs tonight will also be of interest:
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8pm – Struts After 1.1 – Where Do We Go From
Here?
9pm – JSP New And Improved – The JSP 2.0
Specification
Welcome
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Struts 1.0:
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Original Release: June 2001
Version 1.0.2: February 2002
Struts 1.1:
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Version 1.1-b1: March 2002
Version 1.1-b2: September 2002
Version 1.1 Final: “Real Soon Now”
Welcome
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The “Struts community” is growing
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Users
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Downloads:
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October 2002: 29,199
Tomcat runs 80k-100k per month
Articles and Books:
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STRUTS-USER has 2399 subscribers
Second only to TOMCAT-USER (2454)
Five recently published
http://jakarta.apache.org/struts/resources/
So What's New In Struts 1.1?
New Features In Struts 1.1
New Features In Struts 1.1
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Jakarta Commons Libraries
DynaActionForm
Declarative Exception Handling
PlugIn API
STRUTS-NESTED Tag Library
STRUTS-EL Tag Library (Contrib)
Application Module Support
Jakarta Commons Libraries
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Small, tightly focused, class libraries
Several originated in Struts 1.0
Included Libraries:
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Beanutils – JavaBean manipulation
Collections – Extensions to JDK collections
Dbcp – JDBC connection pools
Digester – XML file parsing
Fileupload – HTML file upload support
Lang – Extensions to JDK class libraries
Logging – Wrapper around log
implementations
Pool – Object pools (used by DBCP)
Validator – Field validation framework
COMMONS-BEANUTILS
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Generic JavaBean property manipulation
Originally from Struts 1.0
New features:
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Pluggable type converters
Mapped properties:
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Contact.phone(Work)
DynaBean interface and basic
implementations
Dynamically defined sets of properties
BeanUtils and PropertyUtils transparently support
DynaBeans and standard JavaBeans
● Struts implementation: DynaActionForm
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COMMONS-BEANUTILS
public interface DynaBean {
public Object get(String name);
public Object get(String name, int index);
public Object get(String name, String key);
public void set(String name, Object value);
public void set(String name, int index,
Object value);
public void set(String name, String key,
Object value);
}
COMMONS-DBCP
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Provides javax.sql.DataSource (connection
pool) implementation
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Connection timeouts
Both getConnection() methods supported
Idle connections can be released
Validation query tests connection before return
For backwards compatibility,
org.apache.struts.util.GenericDataSource is a
wrapper around DBCP.
FYI: Tomcat 4.1 also uses this
implementation.
COMMONS-FILEUPLOAD
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Original code from Turbine
Supports file uploads as defined by RFC
1867.
For backwards compatibility,
org.apache.struts.upload.MultipartUploadHand
ler implementations wrap this.
COMMONS-LOGGING
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Wrapper around any logging API
Intelligent discovery mechanism
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Did I ask for a specific factory? Use it.
Is Log4J available? Use it.
Is JDK 1.4 logging available? Use it.
Fallback to default logger
Simple System.err logging implementation is
available
Relies on underlying logging implementation
for configuration
COMMONS-VALIDATOR
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Original code from Struts
General framework for validating input data
against defined rules
Struts Integration:
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ValidatorActionForm and
DynaValidatorActionForm
Configure Validator via Plug-In Architecture
DynaActionForm
A common user complaint: writing ActionForm
beans is a pain
●Now, in many cases you will not have to!
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Only necessary to provide non-default reset() and/or
validate() methods
Configure the properties and their types in your
struts-config.xml file
●Transparently supported by all of the existing
Struts machinery
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DynaActionForm
<form-bean
name="logonForm"
type="org.apache.struts.action.DynaActionForm">
<form-property name="username"
type="java.lang.String"/>
<form-property name="password"
type="java.lang.String"/>
</form-bean>
Declarative Exception Handling
Previously, an Action had to deal with all
business logic exceptions itself
●Now, you can choose to delegate exception
handling to other application resources
●Global and per-Action mapping declared in
struts-config.xml (like forwards):
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From a particular Exception class or superclass
To an application-relative path
Requires a small change to your Action to
leverage this feature ...
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Declarative Exception Handling
public ActionForward execute
(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {
...
throw new PasswordExpiredException(...);
...
}
Declarative Exception Handling
<action path="/logon" ...>
...
<exception key="expired.password"
type="o.a.s.w.e.ExpiredPasswordException"
path="/changePassword.jsp"/>
...
</action>
PlugIn API
Before, you had to subclass ActionServlet (or
define a separate servlet) to initialize application
resources at startup time
●Now, you can declare a PlugIn that receives
notification of application startup and
shutdown
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public interface PlugIn {
public void destroy();
public void init(ActionServlet servlet,
ApplicationConfig config)
throws ServletException;
}
STRUTS-NESTED Tag Library
If you ever programmed in Pascal, you might
remember the "with" statement ...
●Nested tags allow you to establish a default
bean for nested property references
●1:1 correspondence, and identical functionality,
of other Struts tags
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Except the "name" property gets set for you
automatically ...
STRUTS-NESTED Tag Library
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Before using the nested tags:
<bean:write property="address.city"/>
<bean:write property="address.state"/>
<bean:write property="address.zip"/>
●After
using the nested tags:
<nested:nest property="address">
<nested:write property="city"/>
<nested:write property="state"/>
<nested:write property="zip"/>
</nested:nest>
STRUTS-EL Tag Library
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Inspired by the expression language that is
available in the JSP Standard Tag Library.
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${customer.address}
${customer.address[0].city}
${cusotmer.addressMap['Postal']}
Includes “EL-ized” versions of all Struts tags
that do not have natural replacements in the
JSTL tag library.
Nearly every tag attribute supports EL.
Shipped in the “contrib” subdirectory, not
currently integrated into Struts core.
STRUTS-EL Tag Library
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Requires a Servlet 2.3 / JSP 1.2 container
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Such as Tomcat 4.x or later
Requires the “standard” taglib from the Jakarta
Taglibs project
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http://jakarta.apache.org/taglibs/doc/standarddoc/intro.html
Application Module Support
Very popular user request for large scale
applications
●Design goals:
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Support multiple independent struts-config.xml files
in the same webapp
Modules are identified by an "module prefix" that
follows the context path
Existing Struts-based applications should be able to
be installed individually, or as a module, with no
changes to the pages, Actions, form beans, or
other code
Application Module Support
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Implications of the design goals:
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"Default" module with a zero-length prefix (like the
ROOT context in Tomcat)
"Context-relative" paths must now be treated as
"module-relative"
ActionServlet initialization parameters migrate to the
struts-config.xml file
Controller must identify the relevant module, and
make its resources available (as request attributes)
Application Module Support
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The goals appear to have been achieved:
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Please download the latest nightly build and help us
by testing your apps as modules
Current restrictions:
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All requests must flow through the controller –
no direct hyperlinks to JSP pages with Struts
tags
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Can be lifted by implementing the controller as a Filter
in Servlet 2.3
Works only for extension-mapped paths to the
controller servlet (*.do)
What Does The Future Hold?
What Does The Future Hold?
In the mean time, the Java world around web
applications is changing ...
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Servlet 2.4 (JSR-154)
JSP 2.0 (JSR-152)
JSP Standard Tag Library 1.0 (JSR-52)
JavaServer Faces (JSR-127)
And new things are becoming popular ...
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Web services
Portals
Servlet 2.4
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Some nice additions
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Request lifecycle events
Request dispatcher events
But not likely to affect Struts in the near term
●However, it may soon be time to migrate
Struts to be based on Servlet 2.3 (and JSP
1.2) or later
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Filters and lifecycle listeners
Request and response wrappers
JSP Standard Tag Library ...
JavaServer Pages (JSP) 2.0
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Expression Language
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Available now in JSP Standard Tag Library
In JSP 2.0, can use in all tag attributes, as well as
in template text
We can help the transition by supporting this in
Struts tags
JSP Fragments
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Create parameterized "custom actions"
JSP Standard Tag Library (JSTL) 1.0
Version 1.0 released, June 2002
●RI based on code from Jakarta
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http://jakarta.apache.org/taglibs/
Core library has familiar functionality
●URL, XML, and I18N tags also very useful
●Expression language allows for much simpler
tags
●JSP containers can optimize performance
●Struts users should definitely plan
on utilizing these tag libraries
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JavaServer Faces
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A frequently asked question this year:
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What's the deal with Struts and JavaServer
Faces?
The short version of the answer:
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JavaServer Faces will be a useful mechanism to
build the UI for Struts-based web applications
For the longer version of the answer, let's go
back into history for a moment ...
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JavaServer Faces
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Where did Struts come from?
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Two years of discussion about MVC and Model 1
versus Model 2
My experience building a large scale web
application that was fully internationalized
The key feature – separation of concerns
The key technologies enforcing separation
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Logical name mappings in struts-config.xml
View --> Controller encapsulated in a form
submit, matched to a form bean
Controller --> View via RequestDispatcer
JavaServer Faces
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Where is JavaServer Faces coming from?
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The need to provide rich UI components to page
developers
The need for a standard set of components to
ease learning (and enable tools support)
But UI components are not enough by
themselves:
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Event handling
Validation
Navigation
There needs to be enough there to be
usable out of the box
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JavaServer Faces
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So what do we do about the overlap?
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Use the parts that are helpful, ignore the parts that
are not
The planned scenario:
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Struts provides a JSF-compliant tag library that
provides the functionality we know and love
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Context-relative paths, URL rewriting, ...
Struts applications can migrate their UI to use
Faces, one page at a time, with no changes to the
Actions, form beans, or business logic
This is an entirely feasible endgame
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Will be available with next EA release of JSF ...
Resources
Struts Resources
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The Struts and Commons Web Sites:
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http://jakarta.apache.org/struts/
http://jakarta.apache.org/commons/
Recent Books About Struts:
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Cavaness, Chuck; Programming Jakarta Struts;
O'Reilly
Goodwill, James; Mastering Jakarta Struts; John
Wiley
Husted, Ted; Java Web Development With Struts;
Manning
Spielman, Sue; The Struts Framework: Practical
Guide for Programmers; Morgan Kaufman
Turner, James; Struts Kick Start; Sams
Q&A