Home > Articles > Programming > Java

  • Print
  • + Share This
This chapter is from the book

This chapter is from the book

Adding New Template Rules

The style sheets presented thus far have used <value-of> to retrieve the content of top-level elements and attributes. However, the XML document instance in Listing 2.1 also contains subelements, namely, the address element:

<invoice num="2317" invoiceDate="07-09-01">
  ...
  <address>
    <streetAddress>123 Fourth Street</streetAddress>
    <city>Sometown</city>
    <state>CA</state>
    <zip>12345</zip>
    <province />
    <country>USA</country>
  </address>
  ...
</invoice>

To retrieve the content from, say, <streetAddress>, you could assign a step pattern in the select attribute of a <value-of> element. That might look something like:

<xsl:value-of select="invoice/address/streetAddress" />

This approach works fine for this example because the <invoice> element has a well-defined structure. That is, you know that there's one and only one occurrence of <streetAddress> and that it is a subelement of <address>. However, not all documents are so well structured.

The XML document in Listing 2.6, which represents a magazine article, is an example where the order and number of occurrences of elements is unknown.

Listing 2.6 This Magazine Article Is an Example of a Document with an Unpredictable Structure Where Both the Ordering of Elements and Number of Occurrences for a Given Element Are Unpredictable

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="article1.xsl"?>


<article>
  <logo href="/rocket/images/logo.gif" />

  <headline> Blowing XML Bubbles</headline>
  <deck>When will the bubble burst?</deck>
  <byline href="http://www.beyondhtml.com/default.asp?/rocket/bio.xml">
  Michael Floyd</byline>
  <pubDate>March 2000</pubDate>

  <aBody>
   <para>
     <dropCap>A</dropCap>t one time or another, everyone from marketing 
     professors to analyst companies has proposed various models to 
     describe the cycle of high-flying technologies. Most picture a seed 
     point followed by a phase of tremendous hyping, typically followed 
     by a period of depression usually caused by the overhyping.
   </para>
   <para>Such a model prompted me to predict, on the <bold>editorial 
   page</bold> of the <bold>June 1996 issue of <italic>Web Techniques
   </italic></bold>, a cooling period for the Web. Well, so much for 
   forecasting. In fact, I've applied this model to technologies 
   including <bullet>Artificial Intelligence (AI)</bullet>, 
   <bullet>object-oriented programming</bullet>, and <bullet>Java</bullet>.
   </para>
   <para>The point of such an exercise is really to determine if a 
   technology is just the <ital>"tech de jour"</ital> or whether it will 
   be around long enough to have a lasting impact on the industry. 
   Unfortunately, these models more often than not fail miserably in 
   making such predictions.
   </para>
   <para>Thus, I would like to propose something I call <italic>Floyd's 
   Bubble</italic>. It works much like blowing a very large soap bubble. 
   You start with a technology, and huff and puff until you get a sizable 
   bubble. Soon, others notice your bubble, and join in the huff and puff. 
   You lose ownership of the bubble-perhaps retaining 20 percent of the 
   bubble's equity if you're lucky-but the bubble grows far bigger than any
   bubble you could have blown on your own. Eventually, though, your bubble
   reaches its elastic limit and it pops. Whatever is left is the true 
   value of your bubble. It's this true value that determines whether a 
   technology will succeed or whether everyone will walk over to the next 
   bubble wand.
   </para>
   <para>...
   </para>

   <para>Michael is the publisher of BeyondHTML.com and <italic>Web 
   Techniques'</italic> editor at large.
   </para>
  </aBody>
  <copyright>Copyright Michael Floyd. 1998-2000. All Rights 
  Reserved. </copyright>
</article>

In this document, you'll notice that the article element contains several <para> elements. A <para> element may contain a drop cap, bold, italics, and bullet elements. The problem is, you don't know exactly when these elements will occur, or how many times they may occur. In one instance, an italic is embedded within an bold. In other cases, bold elements just contain text. You don't even know how many paragraph elements will occur from one document to the next.

Using the <value-of> element to retrieve text in a situation like this is all but impossible. The solution is to create additional template rules that describe the handling of these individual elements. For instance, you can create a template rule to handle all bold elements.

<xsl:template match="bold">
  <B>
   <xsl:apply-templates/>
  </B>
</xsl:template>

This rule would be placed after the root template rule in the style sheet. The template rule says, whenever the rule matches with a <bold> element, add an HTML <B> tag. The <xsl:apply-templates/> element instructs the XSL processor to apply any other matching template rules that may be in the style sheet. One such template rule is built into to XSL, and it says whenever a text node is found, retrieve its content. This built-in template rule is the equivalent of writing

<xsl:value-of select="text()" />

So, when the <apply-templates> element is invoked, it will return any text in the current node, then look in the style sheet for any other template rules to process.

If you are using an older version of Microsoft's XML parser (before version 3.0) or you are experiencing problems displaying text from your style sheet, see "Displaying Text with MSXML" in the "Troubleshooting" section at the end of this chapter.

By including <apply-templates> in this template rule, you're also able to process the content for subelements of the element being processed. For example, the XML document instance includes the following markup:

<bold>June 1996 issue of <italic>Web Techniques</italic></bold>

Notice that the <bold> element contains <italic> as a subelement. When <apply-templates /> is invoked from the <xsl:template match="bold"> rule, it looks for additional template rules. If there's a template rule to process the <italic> element, it will be instantiated. Here's a template rule to process the <italic> element:

<xsl:template match="italic">
  <I>
   <xsl:apply-templates/>
  </I>
</xsl:template>

Likewise, you will add template rules to transform any element type you want. Each template rule should usually include its own <apply-templates> element. If you don't include it, no more rules will be searched and processing will end.

So, how does processing get started in the first place? When a style sheet is loaded, the root template rule is processed automatically. To search additional template rules, you must place an <apply-templates/> element somewhere near the bottom of the root template rule. This instance is what starts the process.

Finally, Listing 2.7 presents a complete style sheet demonstrating these concepts.

Listing 2.7 Using Additional Template Rules, You Can Handle Elements as They Occur in Your Document

<?xml version="1.0"?> 

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="html" />

 <!-- Root template -->
 <xsl:template match="/">
  <HTML>
   <HEAD>
   <TITLE>
    <xsl:value-of select="article/headline"/>
   </TITLE>
   </HEAD>
   <BODY>
       <P><H1> 
        <xsl:value-of select="article/headline"/>
       </H1></P><BR></BR>

       <P><H2>
        <xsl:value-of select="article/deck"/>
       </H2></P>
       <BR></BR>

       <P>        
        <xsl:apply-templates select="article/byline"/>
       </P>
       <BR></BR>
       <P>
        <P><xsl:apply-templates select="article/aBody"/></P>
       </P>
  <HR></HR>
  <P ALIGN="CENTER"><FONT SIZE="-1">
    <xsl:value-of select="article/copyright"/>
  </FONT>
  </P>
   </BODY>
  </HTML>
 </xsl:template>

 <xsl:template match="byline">
   <P>
    <I>By <xsl:apply-templates/>
    </I>
   </P>
 </xsl:template>

 <xsl:template match="aBody">
   <P>
    <xsl:apply-templates/>
   </P>
 </xsl:template>
 <xsl:template match="para">
   <P>
    <xsl:apply-templates/>
   </P>
 </xsl:template>

 <xsl:template match="dropCap">
   <FONT Size="+4" COLOR="Navy"><B>
    <xsl:apply-templates />
   </B></FONT>
 </xsl:template>

 <xsl:template match="bullet">
   <LI>
    <xsl:apply-templates />
   </LI>
 </xsl:template>

 <xsl:template match="bold">
   <B>
    <xsl:apply-templates/>
   </B>
 </xsl:template>

 <xsl:template match="italic">
   <I>
    <xsl:apply-templates/>
   </I>
 </xsl:template>
</xsl:stylesheet>

The resulting transformation as rendered in Internet Explorer is shown in Figure 2.4.

Figure 2.4 The result of the transformation in Listing 2.7, as rendered in Internet Explorer.

  • + Share This
  • 🔖 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.

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