bof #1820 -- the struts framework community the struts framework community craig mcclanahan

BOF #1820 -- The Struts Framework Community

The Struts Framework Community

Craig McClanahan

BOF #1820 -- The Struts Framework Community1

Agenda

Welcome Struts 1.1 – New Features What Does The Future Hold? Questions and Answers

Beginning


Welcome

The "Struts Community" is growing ... Users (STRUTS-USER mailing list has 1750

subscribers) Downloads (1000/day first two weeks of

March) Plug-in and Add-on technologies Publications and books Awareness (try a Google search on

"struts")

The future looks even brighter


Struts 1.1 – New Features

Jakarta Commons Libraries DynaActionForm Declarative Exception Handling Nested Tag Library PlugIn API Multiple Application Support


Jakarta Commons Libraries

COMMONS-BEANUTILS Pluggable type converters Mapped properties

contact.phone(Work) DynaBeans

Transparently supported by BeanUtils and PropertyUtils


Commons-Beanutils -- DynaBeans

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-LOGGING Wrapper around any logging API Intelligent discovery mechanism

Did I ask for a particular factory? Use it Is Log4J available? Use it Is JDK1.4 logging available? Use it Default to "no-op" logger

Simple System.err logging implementation available

Relies on underlying logging implementation for configuration



COMMONS-DBCP and COMMONS-POOL Provide javax.sql.DataSource

implementation Connection timeouts Both getConnection() methods supported Idle connections can be released

For backwards compatibility, org.apache.struts.util.GenericDataSource is a wrapper around this

Bridges the JDBC API changes in JDK 1.4


DynaActionForm – 1

A common user complaint: writing ActionForm beans is a pain

Now, in many cases you will not have to! 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


DynaActionForm – 2

<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 – 1

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): From a particular Exception class or

superclass To an application-relative path

Requires a small change to your Action to leverage this feature ...



public ActionForward execute

(ActionMapping mapping,

ActionForm form,

HttpServletRequest request,

HttpServletResponse response)

throws Exception {

...

throw new PasswordExpiredException(...);

...

}


The "Nested" Tag Library – 1

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 Except the "name" property gets set for

you automatically ...


The "Nested" Tag Library – 2

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>


Plug-In 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

public interface PlugIn {

public void destroy();

public void init(ActionServlet servlet,

ApplicationConfig config)

throws ServletException;

}


Multiple Application Support – 1

Very popular user request for large scale applications

Design goals: Support multiple independent struts-config.xml

files in the same webapp Sub-applications are identified by an

"application prefix" that follows the context path

Existing Struts-based applications should be able to be installed individually, or as a sub-application, with no changes to the pages, Actions, form beans, or other code



Implications of the design goals: "Default" sub-application with a zero-length

prefix (like the ROOT context in Tomcat) "Context-relative" paths must now be

treated as "sub-application-relative" ActionServlet initialization parameters

migrate to the struts-config.xml file Controller must identify the relevant sub-

application, and make its resources available (as request attributes)

APIs must be reviewed for assumptions about there being (for example) only one set of ActionMappings



The goals appear to have been achieved: Please download the beta and help us by

testing your apps as sub-applications

Current restrictions: All requests must flow through the

controller – no direct hyperlinks to JSP pages with Struts tags 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)


Current Status

Struts 1.1-beta-1 released on March 19, 2002 After the download counts referenced

earlier ... http://jakarta.apace.org/struts/

Please try it out with your own applications, and report any compatibility (or other) bugs: http://nagoya.apache.org/bugzilla/

I anticipate at least one more beta, but there might well be more

It will be released when we're satisfied that it works correctly


What Does The Future Hold?

In the mean time, the Java world around web applications is changing ... Servlet 2.4 (JSR-154) JSP 1.3 (JSR-152) JSP Standard Tag Library 1.0 (JSR-52) JavaServer Faces (JSR-127)

And new things are becoming popular ... Web services Portals


Servlet 2.4

Some nice additions Request lifecycle events Request dispatcher events

But not likely to affect Struts in the near term

However, is it time to migrate Struts to be based on Servlet 2.3 (and JSP 1.2)? Filters and lifecycle listeners Request and response wrappers JSP Standard Tag Library ...


JSP 1.3

Expression Language Available now in JSP Standard Tags

Library In JSP 1.3, 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 Create parameterized "custom actions"


JSP Standard Tag Library

Currently in beta, will be final in June RI implemented at Jakarta

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


JavaServer Faces – 1

The most popular question at JavaOne this year: What's the deal with Struts and

JavaServer Faces?

The short version of the answer: 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 ...



Where did Struts come from? 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 Logical name mappings in struts-config.xml View --> Controller encapsulated in a form

submit, matched to a form bean Controller --> View via RequestDispatcer



Where is JavaServer Faces coming from? 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: Event handling Validation Navigation

There needs to be enough there to beusable out of the box



So what do we do about the overlap? Use the parts that are helpful, ignore the

parts that are not

The ideal scenario: Struts provides a JSF-compliant tag library

that provides the functionality we know and love 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 We're just not done yet ...


Questions and Answers

Phew, that's a lot of information ... So, what's on your minds?

BOF #1820 -- The Struts Framework Community

bof #1820 -- the struts framework community the struts framework community craig mcclanahan

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