JBoss.orgCommunity Documentation
This documentation is work in progress, thus some mistakes or incompleteness is possible
Copyright © 2008 Red Hat
The major benefit of the JSF framework is a component based architecture. The component in JSF is not just a set of HTML code rendered and interpreted by a browser. The JSF component is a combination of a client-side widget coupled with the server-side object that represents component behavior including data validation, events handling, business layers bean binding, etc.
Comparing to a page-oriented development approach, JSF allows to use a component-oriented paradigm to build a well-designed, highly customizable UI interface based on reusable components.
However, there is not yet enough sets of rich components on the market that might enable the rapid application development. One of the most important problems is a time-consuming and very complicated process of the component creation. Even the very primitive JSF component requires the UIComponent class, Renderer class, Tag class and a faces configuration file (faces-config.xml) to be written.
In order to use the component library in a Facelets environment, you should add the *.taglib.xml file to this checklist.
Creation of the rich component takes even more time. You have to provide the ListenerTagHandler class, a class for creating a listener interface, an event processing method name in a listener interface, an event class, render specific classes for each possible render kit used with the component.
Therefore, the process of JSF component creation is pretty complicated but repeatable. Jonas Jacobi and John R. Fallows in their "Pro JSF and Ajax Bulling Rich Internet Components" book describe the process in details. This description and used approaches are very similar to our own experience and have been used as a methodology for Component Development Kit (CDK) - a sub-project of RichFaces that allows you to easily create rich components with built-in Ajax support.
The significant features of the Component Development Kit (CDK) are:
Quick development start. A new component development starts from a pre-generated component project template. It contains the whole required infrastructure and necessary files generated. It's necessary only to have a Maven installed. All other required stuff will be loaded and configured automatically. For more information about how to work with Maven on JBoss projects explore corresponding articles at JBoss portal.
Declarative approach for a component development. It's necessary only to specify meta-data and a code specific for your component. All other required artifacts are generated for you.
Independent development life-cycle. Component Development Kit (CDK) presumes development of each component isolated from each other with further assembling them into the component library. Hence, this allows to organize a continuous process when one component is already in production condition, but another is just started.
Possibility to create a first-class rich components with built-in Ajax functionality and add Ajax capability to the existing JSF applications.
Facility for automatic testing. At the moment of generating the initial project structure, the Unit Test classes are also generated. The RichFaces also provides the Mock-test facility that allows to emulate a run-time environment and automatically test components before their are gathered into the result library.
Optimization for different JSF implementations. As soon as the most part of a result code is generated, the Component Development Kit (CDK) becomes able to generate an implementation specific code along with a universal code. It makes sense if it's necessary to optimize a result code using features specific for the particular implementation. For example, for using with JSF 1.2 only.
Create a modern rich user interface look-and-feel with JSP-like templates and skins-based technology. RichFaces comes with a number of predefined skins to get you started, but you can also easily create your own custom skins.
This document is aimed to describe components development with the Component Development Kit (CDK) and its features.
In order to be successful in Component Development Kit (CDK) usage and components development, it's necessary to be acquainted with Java Server Faces and RichFaces framework. To read more on these topics, please, follow the links:
In order to start working with the Component Development Kit (CDK) and to create your rich component, it's necessary to have the following installed:
Browser (on the client side)
After the Maven is installed you should configure it. In this case, please, go to the directory where you've just installed Maven, open a conf/settings.xml file for editing and add to the profiles section this code:
...
<profile>
<id>cdk</id>
<repositories>
<repository>
<id>maven2-repository.dev.java.net</id>
<name>Java.net Repository for Maven</name>
<url>http://download.java.net/maven/1</url>
<layout>legacy</layout>
</repository>
<repository>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
<updatePolicy>never</updatePolicy>
</snapshots>
<id>repository.jboss.com</id>
<name>Jboss Repository for Maven</name>
<url>http://repository.jboss.com/maven2/</url>
<layout>default</layout>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>maven.jboss.org</id>
<name>JBoss Repository for Maven Snapshots</name>
<url>http://snapshots.jboss.org/maven2/</url>
<releases>
<enabled>false</enabled>
</releases>
<snapshots>
<enabled>true</enabled>
<updatePolicy>always</updatePolicy>
</snapshots>
</pluginRepository>
<pluginRepository>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
<updatePolicy>never</updatePolicy>
</snapshots>
<id>repository.jboss.com</id>
<name>Jboss Repository for Maven</name>
<url>http://repository.jboss.com/maven2/ </url>
<layout>default</layout>
</pluginRepository>
</pluginRepositories>
</profile>
...
In order to activate a new profile, add the following after the profiles section:
...
<activeProfiles>
<activeProfile>cdk</activeProfile>
</activeProfiles>
...
Note:
In order to work with Maven from Eclipse, it's possible to download and install the Maven plugin. Please, follow the instruction at Eclipse plugins for Maven page
The environment is set up now to use the Component Development Kit (CDK).
We are going to create two components throughout the RichFaces CDK Developer Guide, but at first you need take the following steps to set up the Project and create your library:
Create a new directory where all the components will be stored (for example Sandbox).
Create a file named pom.xml in the directory with the following content:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.mycompany</groupId>
<artifactId>sandbox</artifactId>
<url>http://mycompany.org</url>
<version>1.0-SNAPSHOT</version>
<packaging>pom</packaging>
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.4</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jsp-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.faces</groupId>
<artifactId>jsf-api</artifactId>
<version>1.2_07</version>
</dependency>
<dependency>
<groupId>javax.faces</groupId>
<artifactId>jsf-impl</artifactId>
<version>1.2_07</version>
</dependency>
<dependency>
<groupId>javax.el</groupId>
<artifactId>el-api</artifactId>
<version>1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>el-impl</groupId>
<artifactId>el-impl</artifactId>
<version>1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.annotation</groupId>
<artifactId>jsr250-api</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>org.richfaces.ui</groupId>
<artifactId>richfaces-ui</artifactId>
<version>3.3.0.GA</version>
</dependency>
</dependencies>
</project>
Close the file
Here are some of these elements with descriptions:
Table 3.1. The POM elements
| Element | Description |
|---|---|
| groupId | Prefix for the Java package structure of your library |
| url | Namespace for your library to be used in the TLD file |
| version | Version of your library |
| scope | Dependency scope is used to limit the transitivity of a depedency, and also to affect the classpath used for various build tasks. "Provided" scope indicates you expect the JDK or a container to provide the dependency at runtime. For example, when you build a web application with RichFaces, you would set the dependency on the Servlet API and related libraries to scope "provided" because the web container provides those classes. |
We a going to create the <inputDate> component that can take a value, process that value, and then push it back to the underlying model as a strongly typed Date object.
The <inputDate> component allows to attach a converter in order to set the desired date format such as mm/dd/yyyy. So the component could convert and validate the date entered by user.
At first we need to create a project for the component itself. In the library directory Sandbox you just created, launch the following command (all in one line):
mvn archetype:create -DarchetypeGroupId=org.richfaces.cdk -DarchetypeArtifactId=maven-archetype-jsf-component -DarchetypeVersion=3.3.0.GA -DartifactId=inputDate
As is easy to see a new directory with the name inputDate will be created. It does not have any components in it yet, but it has this predefined structure:
Here are the main directories with descriptions:
Table 4.1. The project structure
| Directory | Description |
|---|---|
| src/main/config | Contains the metadata for the components |
| src/main/java | Contains Java code (both pre-generated and created by you) |
| src/main/resources | Used to store resource files, such as pictures, JavaScript and CSS files |
| src/main/templates | Used to contain the JSP-like templates that define the component layout |
It is necessary to extend a predefined structure with the following directories:
Table 4.2. The project structure
| Directory | Description |
|---|---|
| src/main/config/resources | Contains the resource-config.xml file for the resources registration |
| src/main/java/org/mycompany/renderkit | Contains Renderer Base class |
| src/main/resources/org/mycompany/renderkit/html/css | Used to store CSS files |
| src/main/resources/org/mycompany/renderkit/html/images | Used to store images |
| src/main/templates/org/mycompany | Used to contain the JSP-like template |
Now you should add maven-compiler-plugin to the plugins section in the inputDate/pom.xml file:
...
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<inherited>true</inherited>
<configuration>
<source>1.5</source>
<target>1.5</target>
</configuration>
</plugin>
...
Finally your inputDate/pom.xml should look like this one:
<?xml version="1.0"?>
<project>
<parent>
<artifactId>sandbox</artifactId>
<groupId>org.mycompany</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<groupId>org.mycompany</groupId>
<artifactId>inputDate</artifactId>
<name>inputDate</name>
<version>1.0-SNAPSHOT</version>
<build>
<plugins>
<plugin>
<groupId>org.richfaces.cdk</groupId>
<artifactId>maven-cdk-plugin</artifactId>
<version>3.3.0.GA</version>
<executions>
<execution>
<phase>generate-sources</phase>
<goals>
<goal>generate</goal>
</goals>
</execution>
</executions>
<configuration>
<library>
<prefix>org.mycompany</prefix>
<taglib>
<shortName>inputDate</shortName>
</taglib>
</library>
</configuration>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<inherited>true</inherited>
<configuration>
<source>1.5</source>
<target>1.5</target>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.richfaces.framework</groupId>
<artifactId>richfaces-impl</artifactId>
<version>3.3.0.GA</version>
</dependency>
</dependencies>
</project>
Let's create a skeleton for the <inputDate> component.
You need to go to the inputDate directory and then launch the following command:
mvn cdk:create -Dname=inputDate
As a result three artifacts will be created:
An XML configuration file for the metadata
A UI class
A JSP-like template
In order to build the component you should stay in the inputDate directory and launch the following command:
mvn install
This command generates and compiles the library and then creates a result JAR file. A directory named target will be created along with a src directory. If you get a file named target/inputDate-1.0-SNAPSHOT.jar, everything is set up successfully.
If you want to rebuild the component you could use the following command:
mvn clean install
It is a good idea to create at first a prototype of the intended markup. You will find out which markup elements the component has to generate and also which renderer-specific attributes are needed in order to parameterize the generated markup.
The
<inputDate>
component consists of an HTML form <input> element, an
<img> element, and <div> element:
...
<div title="Date Field Component">
<input name="dateField" value="01 January 2008" />
<img class="overlay" src="inputDateOverlay.png" />
</div>
...
All information about styles applied to the <inputDate> component is provided in the following chapter.
This is the result of your prototype which shows a simple page with an input field and an icon indicating that this is a date field:
Component functionality typically centers around two actions: decoding and encoding data. Decoding is the process of converting incoming request parameters to the values of the component. Encoding is the process of converting the current values of the component into the corresponding markup. In the following figure you can see decoding and encoding occur in the JSF lifecycle:
Thus, JSF components consist of two parts: the component class and the renderer. The component class is responsible for the state and behavior of a UI component and will be discussed later in the "Configuring component" section.
The Renderer is responsible for the JSF component representation. It generates the
appropriate client-side markup, such as HTML, WML, XUL, etc. Renderer is also
responsible for the converting information coming from the client to the proper type
for the component (for example, a string value from the request is converted to a
strongly type Date object).
It is necessary to create following renderer classes for the <inputDate> component:
InputDateRendererclass where you should overrideencode()methods for encoding the markup and resourcesInputDateRendererBaseclass where you should overridedecode()method. You could also define associated converter in this class.
You could actually implement the renderer-specific component subclass that
exposes client-side attributes such as
"style"
,
"class"
, etc. It is common practice to implement the client-specific component
subclass to make some aspects of application development easier, but in our case we
do not need to do it. The
<inputDate>
is a simple UIInput component, therefore
InputDateRenderer class generates all the markup itself.
It is a time to start creating the InputDateRenderer class.
The smartest way to create the InputDateRenderer class is a Templating mechanism,
one of the most convenient features of the Component Development Kit (CDK).
The Component Development Kit (CDK) allows to use templates for generation Renderer class.
Templates are JSP-like markup pages with special tags that are converted into Renderer by a build script.
It's possible to use evaluated expressions in components templates with the help of scriptlets. It's also possible to create the base class for a template to implement additional functions in it, so as the functions could be called from the template. Hence, in the generated Renderer class there are corresponding function calls on the place of these elements.
Let's create the template for HTML 4.0 markup. At first you should proceed to the inputDate/src/main/templates/org/mycompany directory where htmlInputDate.jspx template file is stored. This file contains a Template Skeleton like this one:
<?xml version="1.0" encoding="UTF-8"?>
<f:root
xmlns:f="http://ajax4jsf.org/cdk/template"
xmlns:c=" http://java.sun.com/jsf/core"
xmlns:ui=" http://ajax4jsf.org/cdk/ui"
xmlns:u=" http://ajax4jsf.org/cdk/u"
xmlns:x=" http://ajax4jsf.org/cdk/x"
class="org.mycompany.renderkit.html.InputDateRenderer"
baseclass="org.ajax4jsf.renderkit.AjaxComponentRendererBase"
component="org.mycompany.component.UIInputDate"
>
<f:clientid var="clientId"/>
<div id="#{clientId}"
x:passThruWithExclusions="value,name,type,id"
>
</div>
</f:root>
According to the created UI prototype you need to extend Template Skeleton with proper elements:
<div>-wrapper element with "title", "id" attributes and with the"caption" facet
...
<div id="#{clientId}" title="#{value}" x:passThruWithExclusions="value,name,type,id">
...
</div>
...
<input> element with "id", "value", "name", "type", "class", "style" attributes. It is possible to use the "icon" facet in order to redefine a default icon of the component.
...
<input id="#{clientId}"
name="#{clientId}"
type="text"
value="#{this:getValueAsString(context, component)}"
class="my-inputDate-input #{component.attributes['inputClass']}"
style="#{component.attributes['inputStyle']}"/>
...
<img> element with "src", "class", "style" attributes which defines a default icon of the component. In order to add an image to the Template you should register it with the help of <f:resource> template tag and bind to a variable specified by the "var" attribute:
...
<f:resource name="/org/mycompany/renderkit/html/images/inputDate.png" var="icon" />
...
<img src="#{icon}" class="my-inputDate-icon #{component.attributes['iconClass']}" style="#{component.attributes['iconStyle']}"/>
...
The <inputDate> component uses styles that should be defined in the template with the help of <h:styles> tag:
...
<h:styles>/org/mycompany/renderkit/html/css/inputDate.xcss</h:styles>
...
How to register all resources is explained in the "Component resources registration" chapter.
Important:
Don't forget to add namespace xmlns:h=" http://ajax4jsf.org/cdk/h" to the
<f:root> element:
<?xml version="1.0" encoding="UTF-8"?>
<f:root
...
xmlns:h=" http://ajax4jsf.org/cdk/h"
...
>
...
</f:root>
Here is a full example of the template for the <inputDate> component: htmlInputDate.jspx.
Note:
As it is seen in the Template Skeleton the Renderer Baseclass is org.ajax4jsf.renderkit.AjaxComponentRendererBase.
You need to define Renderer Base class special for the <inputDate> component.
In the next section "Creating a Renderer Base class"
we will create Renderer Base class org.mycompany.renderkit.InputDateRendererBase.
All the Template tags you could find in the "Template tags overview" chapter.
After the component tree is restored on the Restore View Phase ,
each component in the tree extracts its new value from the request parameters
by using its decode() method. Then the value is stored locally on the component.
In order to create InputDateRendererBase class you should proceed to the
src/main/java/org/mycompany/renderkit
directory and create this class there:
package org.mycompany.renderkit;
import java.io.IOException;
import java.util.Map;
import java.util.TimeZone;
import javax.faces.component.UIComponent;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.ConverterException;
import javax.faces.convert.DateTimeConverter;
import org.ajax4jsf.renderkit.HeaderResourcesRendererBase;
import org.mycompany.component.UIInputDate;
public abstract class InputDateRendererBase extends HeaderResourcesRendererBase {
...
}
The InputDateRendererBase class extends a HeaderResourcesRendererBase
class. In the HeaderResourcesRendererBase class all the encode() methods for
the right resources encoding
are already implemented, so in the InputDateRendererBase class you need to override
the decode() method only:
...
public void decode(FacesContext context, UIComponent component){
ExternalContext external = context.getExternalContext();
Map requestParams = external.getRequestParameterMap();
UIInputDate inputDate = (UIInputDate)component;
String clientId = inputDate.getClientId(context);
String submittedValue = (String)requestParams