book

Java and XSLT

by Eric M. Burke

September 2001

Intermediate to advanced

528 pages

13h 46m

English

O'Reilly Media, Inc.

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Audience
Java, XSLT, and the WebWhat’s Wrong with HTML?Keeping Data and Presentation SeparateThe XSLT Solution
SGML, XML, and Markup LanguagesXML SyntaxValidationJava and XMLSAXDOMJDOMJDOM and DOM interoperability
Web Development ChallengesWeb ApplicationsNonbrowser ClientsSOAPWireless

Java XSLT Processor ChoicesXTLotusXSLSAXONJAXP
XSLT IntroductionAn XSLT ExampleTrying It Out
XML Tree Data StructureRecursive Processing with TemplatesBuilt-in Template RulesA Skeleton Stylesheet
How XSLT Uses XPathAxesLocation StepsLocation PathsAbbreviated Syntax
Looping with <xsl:for-each>SortingLooping and Sorting Examples
<xsl:attribute>Attribute Value Templates<xsl:attribute-set>
Conditional Processing<xsl:if><xsl:choose>, <xsl:when>, and <xsl:otherwise>
<xsl:variable>Defining variablesUsing variables<xsl:call-template> and Named Templates<xsl:param>and <xsl:with-param>Incrementing VariablesTemplate Modes<xsl:template> Syntax Summary
<xsl:include><xsl:import>
Number FormattingText Formatting
An Example XML FileThe Identity TransformationTransforming Elements and AttributesThe Result File
Ant BasicsStylesheet FunctionalityThe Complete ExampleSpecifying XHTML outputCreating the dependency graphCleaning up dependency lists
Traditional ApproachesCGIServlets as CGI ReplacementsJSPTemplate EnginesThe Hybrid Approach
Web FrameworksModel-View-ControllerXSLT ImplementationDevelopment and Maintenance Benefits of XSLT
Tradeoffs
A Simple ExampleThe DesignXalan 1 ImplementationSAXON ImplementationSAXON, Xalan, or TrAX?
JAXP 1.1 ImplementationXSLT Plugability LayerThe Transformer ClassJAXP XSLT Design
System Identifiers, Files, and URLsJAXP I/O DesignJAXP Stream I/OJAXP DOM I/OJAXP SAX I/OThe approachDetailed CSV to SAX designWriting the custom parserUsing the parserConclusionFeeding JDOM Output into JAXPJDOM to SAX approachJDOM to DOM approachJDOM to text approach
Templates APIA Stylesheet Cache
Servlet SyntaxSplash Screen Servlet Example
WAR FilesDeployment DescriptorDeploying SplashScreenServlet to TomcatServlet API Highlights
DesignXML and StylesheetsSource CodeDeploymentHow to Compile, Deploy, and RunLocating Stylesheets with Initialization Parameters
Integration with the Stylesheet Cache
Servlet Threading ModelThread Safety TipsTip 1: Local variables are thread-safeTip 2: Immutable objects are thread-safeTip 3: Provide a single point of entryTip 4: Understand the Templates interface
Overall ProcessRequirementsScreen Flow
XHTML PrototypesXML SamplesXSLT Stylesheets
Domain ClassesData Adapter LayerJDOM XML Production
DeploymentIdeas for Enhancements
XSLT Page Layout Templates
Servlet Session-Tracking APISession Tracking with Java and XSLT
Filter OverviewXSLT Transformation FilterClosing Thoughts on Filters
XSLT Stylesheet DesignEncodingsCreating the XML and XSLTPutting It All TogetherXML dataXSLT stylesheetsWeb page and servletI18n Troubleshooting Checklist
Development EnvironmentCLASSPATH IssuesJAR hell?Sealing violationsOther exceptions and errorsJava optional packagesJava IDEsAntInstalling AntA typical Ant build fileTransforming using Ant’s style taskTomcatConfiguring Tomcat 3.2.xConfiguring Tomcat 4.0.x
JUnitAn example unit testRunning the testJAXP 1.1 Error ListenersA Custom XSLT Transformer GUIScreen shotsSource code
Stress Testing with JMeterMore Detailed MeasurementsCommercial optionsJVMPIUnit testingUsing XSLT Processors EffectivelyStylesheet cachingResult cachingWriting Effective XSLTInteracting with EJBSending XML from EJBsSending objects from EJBs
Wireless TechnologiesWhy Not HTML?Problems with HTMLLimitations of current devices
A WML ExampleWMLScript and WBMPServlets and WMLIdentifying the clientSetting the content typeMovie Theater ExampleStoryboardXML dataWML prototypes and screen shotsServlet implementationXSLT stylesheets

Content preview from Java and XSLT

Identifying the Browser

A strength of XSLT is its ability to help keep data and presentation separate. As you know, supporting different transformations is a matter of writing different XSLT stylesheets. Figuring out which stylesheet to apply is the only missing piece. For web applications, the User-Agent HTTP header offers the solution.

HTTP requests consist of a header followed by content; the header contains name/value pairs of data, allowing the client and server to exchange additional information with each other. The text shown in Example 8-7 contains the complete HTTP request issued by Netscape 6.0 when running on Windows 2000.

Example 8-7. Netscape 6 HTTP request

GET / HTTP/1.1
Host: localhost:80
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; m18) Gecko/20001108 
Netscape6/6.0
Accept: */*
Accept-Language: en
Accept-Encoding: gzip,deflate,compress,identity
Keep-Alive: 300
Connection: keep-alive

For the purposes of browser detection, the value of User-Agent must be parsed to determine what kind of browser is requesting information from the servlet. Based on this information, the servlet can select an appropriate XSLT stylesheet that supports the particular strengths and weaknesses of the browser in question.

Unfortunately, there are hundreds of variations of User-Agent, and browser vendors do not rigorously adhere to any standard format. The common browsers can be identified, however, with a small amount of parsing logic. Table 8-2 lists some of the more common ...