Home > Articles > Web Services > XML

Sams Teach Yourself XML in 21 Days

Sep 16, 2005

📄 Contents

␡

⎙ Print

< Back Page 191 of 288 Next >

Recommended Book 

Sams Teach Yourself XML in 21 Days, 3rd Edition

Learn More Buy

Introducing XForms

Like the other elements in today's discussion, XForms come from a parallel construct in HTML—Web forms. A Web form lets us display controls such as buttons or list boxes in an HTML page, and XForms are intended to do the same thing in XML. XForms 1.0 is in candidate recommendation form, and you can find the specification at http://www.w3.org/TR/xforms/. XForms were originally designed to work with XHTML, but they've been extended to any XML document.

XForms not only bring forms to XML, but they're also designed to improve them. As with style sheets, the emphasis is on separating presentation from data. Here's what W3C says about XForms:

The current design of Web forms doesn't separate the purpose from the presentation of a form. XForms, in contrast, are comprised of separate sections that describe what the form does, and how the form looks. This allows for flexible presentation options, including classic XHTML forms, to be attached to an XML form definition.

Listing 14.5 shows an example to help you see how XForms work.

Example 14.5. Using XForms (`ch14_05.xml`)

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ev="http://www.w3.org/2001/xml-events"
    xmlns:xforms="http://www.w3.org/2002/xforms/cr">

    <head>
        <xforms:model>
            <xforms:submission localfile="data.xml"/>
            <xforms:instance>
                <data xmlns="">
                    <input>Hello!</input>
                    <select>1</select>
                    <selectboolean>true</selectboolean>
                    <message>Hello!</message>
                </data>
            </xforms:instance>
        </xforms:model>
    </head>

    <body>
        <h1>Using XForms</h1>
        <p>Input Control</p>
        <xforms:input ref="/data/input"></xforms:input>

        <p>Select Control</p>
        <xforms:select appearance="full" ref="/data/select">
            <xforms:item>
                <xforms:value>1</xforms:value>
                <xforms:label>Item 1</xforms:label>
            </xforms:item>
            <xforms:item>
                <xforms:value>2</xforms:value>
                <xforms:label>Item 2</xforms:label>
            </xforms:item>
            <xforms:item>
                <xforms:value>3</xforms:value>
                <xforms:label>Item 3</xforms:label>
            </xforms:item>
        </xforms:select>

        <p>Button</p>
        <xforms:trigger>
            <xforms:label>Click Me</xforms:label>
            <xforms:message ev:event="click" level="ephemeral"
                ref="/data/message"/>
        </xforms:trigger>

        <p>Select Boolean</p>
        <xforms:selectboolean ref="/data/selectboolean">
            <xforms:label>Click Me</xforms:label>
        </xforms:selectboolean>

        <p>Submit and Reset Buttons</p>
        <xforms:submit>
            <xforms:label>Submit</xforms:label>
        </xforms:submit>

        <xforms:trigger>
            <xforms:label>Reset</xforms:label>
            <xforms:reset ev:event="DOMActivate"/>
        </xforms:trigger>
    </body>
</html>

A number of software packages support XForms to some extent; here's a sampling:

X-Smiles (http://www.x-smiles.org)— X-Smiles is a Java-based XML browser from Helsinki University of Technology. X-Smiles has good support for the XForms Candidate Recommendation version, and it uses XForms together with XHTML, SMIL, SVG, and XSL-FO.
Mozquito XForms (http://www.mozquito.com)— Mozquito XForms is an XForms implementation written in ActionScript for Flash 6.
FormsPlayer (http://www.FormsPlayer.com)— FormsPlayer is an XForms processor plug-in for Internet Explorer 6, Service Pack 1.
Novell XForms (http://www.novell.com/xforms)— Novell XForms is a Java application that is designed to provide developers with a hands-on introduction to XForms.
LiquidOffice (http://www.cardiff.com/LiquidOffice)— LiquidOffice provides support for XForms.
Chiba project (http://sourceforge.net/projects/chiba)— Chiba is an implementation of the W3C XForms standard that supports generic, XML-based form processing for the Web.
NMatrix (http://sourceforge.net/projects/dotnetopensrc)— NMatrix provides some support for XForms.
XMLForm (http://xml.apache.org/cocoon/userdocs/concepts/xmlform.html)— XMLForm is an open-source, server-side implementation of a subset of XForms that is integrated into Apache Cocoon.
TrustForm System (http://trustform.comsquare.co.kr)— TrustForm System is a client-side implementation that is based on the XForms Working Draft.
AchieveForms (http://www.achieveforms.com)— AchieveForms is a server-based XForms designer with a Web browser interface that can output forms as XForms and can process completed forms from an XForms browser to email recipients and databases and can forward XML files of completed form data.
jXForms (http://jxforms.cybernd.at)— jXForms supports working with XForms inside Java-based applications.
XServerForms (http://sourceforge.net/projects/xserverforms)— XServerForms is an open-source framework for building Web applications that includes support for XForms.
Xero (http://typeasoft.com/product/xero)— Xero is a client-side XForms processor that works in Internet Explorer 6.0 and later.
XML Forms Package (http://www.alphaworks.ibm.com/tech/xmlforms)— The IBM XML Forms Package consists of two main components: the data model component and the client component. The data model component supports creating, accessing, and modifying XForms data models. The client component supports an XForms processor control and a Java XForms compiler.
FormFaces (http://www.formfaces.com)— FormFaces is a server-side translator to HTML and JavaScript.

Today you'll use the XSmiles XML browser, which you can get for free from http://www.x-smiles.org. Figure 14.3 shows ch14_05.xml in the XSmiles browser.

Figure 14.3 An XForms example in the XSmiles browser.

Figure 14.3 shows the various controls you'll work with in this example—an input control (like an HTML text field), a select control (like the HTML select controls), a button, and a select Boolean control (like an HTML check box). When the user makes selections in this XForm and clicks the Submit button at the bottom, a new XML document with the data from those controls is generated, as you can see in Figure 14.4.

Figure 14.4 Data from the XForms example.

Here's what that XML data from the XForm looks like:

<?xml version="1.0" encoding="ISO-8859-1"?>
<data xmlns="" xmlns:ev="http://www.w3.org/2001/xml-events"
    xmlns:xforms="http://www.w3.org/2002/xforms/cr">
    <input>Hello!</input>
    <select>2</select>
    <selectboolean>true</selectboolean>
    <message>Hello!</message>
</data>

Note that the <input> element contains the text data from the input control, the <select> element contains the number of the selection the user made in the select control, and the <selectboolean> element contains the setting of the select Boolean control, which is true because it displays a check mark.

An XForm displays controls that you can use, and when you click a Submit button, that data is made accessible to you. Here are the controls you can use in XForms:

input control— Acts like an HTML text field.
secret control— Acts like an HTML hidden field.
textarea control— Acts like an HTML text area control.
output control— Displays output.
upload control— Acts like an HTML upload control.
range control— Allows selection from a sequential range of values.
trigger control— Acts like an HTML <button> element.
submit control— Acts like an HTML submit button.
select control— Acts like an HTML select control.
select1 control— Acts like an HTML single-selection HTML control.

To see what's going on here, let's take apart the XForms example ch14_05.xml in the following sections.

Writing XForms

XForms are used in XML documents, typically in XHTML, so each one needs to start off with an XML declaration, like this:

<?xml version="1.0" encoding="UTF-8"?>

If the document is written in XHTML, as this example is, you can include an XHTML <!DOCTYPE> element:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"

   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
        .
        .
        .

In this example, however, you're going to omit the XHTML <!DOCTYPE> element for the sake of brevity (so XSmiles won't have to download the entire XHTML 1.0 DTD and check it against the document each time the document is loaded). The next element, the document element, is the <html> element, and you use it to put everything into the XHTML namespace and define two other namespaces—ev for XForms events (such as button clicks) and xforms for XForms elements:

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"

       xmlns:ev="http://www.w3.org/2001/xml-events"

       xmlns:xforms="http://www.w3.org/2002/xforms/cr">

           .

           .

           .

   </html>

Separating Data from a Presentation

A major feature of XForms is the separation of data from presentation; this means that the data for the controls in an XForm is stored separately from the presentation part. You use the <xforms:model> element to specify what data an XForm should hold. For example, you can create an XForms model in the document's <head> element:

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ev="http://www.w3.org/2001/xml-events"
    xmlns:xforms="http://www.w3.org/2002/xforms/cr">

    <head>

           <xforms:model>

           .

           .

           .

           </xforms:model>

       </head>

</html>

Inside the model, you specify the submission mechanism for the data in an <xforms:submission> element. Although you could have the data from the XForm sent to a general URI, in this case you should have it stored in a local data file, data.xml:

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ev="http://www.w3.org/2001/xml-events"
    xmlns:xforms="http://www.w3.org/2002/xforms/cr">

    <head>
        <xforms:model>
            <xforms:submission localfile="data.xml"/>
        .
        .
        .
        </xforms:model>
    </head>

</html>

You store the actual data in an <xforms:instance> element. In this example you'll have an input control whose data will be stored in an <input> element, a select control whose data will be stored in a <select> element, and so on. Here's what that looks like, with the default data for the controls stored:

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ev="http://www.w3.org/2001/xml-events"
    xmlns:xforms="http://www.w3.org/2002/xforms/cr">

    <head>
        <xforms:model>
            <xforms:submission localfile="data.xml"/>
            <xforms:instance>

                   <data xmlns="">

                       <input>Hello!</input>

                       <select>1</select>

                       <selectboolean>true</selectboolean>

                       <message>Hello!</message>

                   </data>

               </xforms:instance>
        </xforms:model>
    </head>
        .
        .
        .
</html>

You have now completed the <head> section of the example, where the data is stored. In the <body> section, you'll start creating the controls you'll use, starting with the input control.

Creating Input Controls

You create an input control, much as you do an HTML text field, by using the <input> element. You tie this control to the data you've stored in the <input> element in the <head> element by using the ref attribute, which you'll set to "/data/input" in this example:

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ev="http://www.w3.org/2001/xml-events"
    xmlns:xforms="http://www.w3.org/2002/xforms/cr">

    <head>
        .
        .
        .
    </head>

    <body>
        <h1>Using XForms</h1>
        <p>Input Control</p>

           <xforms:input ref="/data/input"></xforms:input>
        .
        .
        .
    </body>
</html>

Now when the input control first appears, it will display the initial text in the <data> element, "Hello!", as shown in Figure 14.3. If the user changes that text and clicks the Submit button, the new text will be stored in that <data> element in the resulting XML file that the XForm creates, data.xml.

Creating Select Controls

Besides input controls, you can also display select controls, which look much like HTML select controls. A select control can display either a list of items to choose from or a drop-down list, and you create these controls by using the <select> element or the <select1> element (which creates single-selection select controls). In the case of our example, you need to store the current selection number in the select control in the <data> element's <select> element by assigning the select control's ref attribute to "/data/select", and you should display a list of all items in the control by setting the appearance attribute to "full".

To create the items in the select control, you use the <item> element; to label the item, you use the <label> element; and to assign a value to each item, you use the <value> element. When the user selects an item, that item's value is stored in the <select> element in the head's <data> element. Here's what the select control looks like (refer to Figure 14.3):

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ev="http://www.w3.org/2001/xml-events"
    xmlns:xforms="http://www.w3.org/2002/xforms/cr">

    <head>
        .
        .
        .
    </head>

    <body>
        <h1>Using XForms</h1>
        .
        .
        .
        <p>Select Control</p>

           <xforms:select appearance="full" ref="/data/select">

               <xforms:item>

                   <xforms:value>1</xforms:value>

                   <xforms:label>Item 1</xforms:label>

               </xforms:item>

               <xforms:item>

                   <xforms:value>2</xforms:value>

                   <xforms:label>Item 2</xforms:label>

               </xforms:item>

               <xforms:item>

                   <xforms:value>3</xforms:value>

                   <xforms:label>Item 3</xforms:label>

               </xforms:item>

           </xforms:select>
        .
        .
        .
    </body>
</html>

Creating Buttons

XForms also support buttons; in our example, clicking the Click Me button displays a message box that shows the text stored in the <message> element in the document head's <data> element:

<xforms:instance>
    <data xmlns="">
        <input>Hello!</input>
        <select>1</select>
        <selectboolean>true</selectboolean>
        <message>Hello!</message>
    </data>
</xforms:instance>

To display the text "Hello!" in a message box, you can use the XForms <message> element. To display the Click Me button, you use a <trigger> element and give it a caption by using the <label> element. To display a message box when the button is clicked, you set the <message> element's event attribute to "click"; to display the message, you set the message box's ref attribute to "/data/message". To make the message box disappear automatically after a few seconds, you can set its level attribute to "ephemeral":

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ev="http://www.w3.org/2001/xml-events"
    xmlns:xforms="http://www.w3.org/2002/xforms/cr">

    <head>
        .
        .
        .
    </head>

    <body>
        <h1>Using XForms</h1>
        .
        .
        .
        <p>Button</p>

           <xforms:trigger>

               <xforms:label>Click Me</xforms:label>

               <xforms:message ev:event="click" level="ephemeral"

                   ref="/data/message"/>

           </xforms:trigger>
        .
        .
        .
    </body>
</html>

You can see the results in Figure 14.5. When the user clicks the button, the message box shown in the figure displays the message for a few seconds and then disappears.

Figure 14.5 Creating XForms buttons.

Creating Select Booleans

XForms select Booleans are much like HTML check boxes. They are easy to use: You just use the <selectboolean> element to create one and a <label> element to give it a label. You can connect the select Boolean to the data in the <data> element's <selectboolean> element by using the ref attribute, like this:

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ev="http://www.w3.org/2001/xml-events"
    xmlns:xforms="http://www.w3.org/2002/xforms/cr">

    <head>
        .
        .
        .
    </head>

    <body>
        <h1>Using XForms</h1>
        .
        .
        .
        <p>Select Boolean</p>

           <xforms:selectboolean ref="/data/selectboolean">

               <xforms:label>Click Me</xforms:label>

           </xforms:selectboolean>
        .
        .
        .
    </body>
</html>

You can see the results in Figure 14.3, where the select Boolean displays a check box. The setting of this control, true or false, is stored in the <selectboolean> element of the resulting XML document, data.xml.

Creating Submit and Reset Buttons

The final controls for the XForms example are Submit and Reset buttons; the Submit button submits the XForm and stores its data in data.xml, and the Reset button resets the data in the XForm back to its original value. These controls are supported by their own elements: <submit> and <reset>. Here's how to use them:

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ev="http://www.w3.org/2001/xml-events"
    xmlns:xforms="http://www.w3.org/2002/xforms/cr">

    <head>
        .
        .
        .
    </head>

    <body>
        <h1>Using XForms</h1>
        .
        .
        .
        <p>Submit and Reset Buttons</p>

           <xforms:submit>

               <xforms:label>Submit</xforms:label>

           </xforms:submit>


           <xforms:trigger>

               <xforms:label>Reset</xforms:label>

               <xforms:reset ev:event="DOMActivate"/>

           </xforms:trigger>
    </body>
</html>

Figure 14.3 shows the Submit and Reset buttons, at the bottom. Clicking the Submit button stores the controls' data in the local file data.xml, as you've seen.

That completes your look at XForms and our discussion for today. Tomorrow, you're going to start working with XML and JavaScript.

< Back Page 191 of 288 Next >

🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Privacy Notice

Overview

Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security

Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children

This site is not directed to children under the age of 13.

Marketing

Pearson may send or direct marketing communications to users, provided that

Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
Such marketing is consistent with applicable law and Pearson's legal obligations.
Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out

Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

As required by law.
With the consent of the individual (or their parent, if the individual is a minor)
In response to a subpoena, court order or legal process, to the extent permitted or required by law
To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
To investigate or address actual or suspected fraud or other illegal activities
To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links

This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020

Email Address