ITiCSE 2003 Tutorial on

Using XML and XSL with JavaServer Pages

presented by Jesse Heines, University of Massachusetts Lowell

Contents

• Tutorial Description (PDF File)
• Instructions for Activities (PDF File)
• Links
  • Samples and Starter Code for Activities
  • Additional Resources
  • Participant File Areas
• Technical Notes
  • XML - eXtensible Markup Language
  • XSL - XML Stylesheet Language
  • JSP - JavaServer^TM Pages

Samples and Starter Code for Activities

XML and XSL files without explicit stylesheets attached will display as document trees in Internet Explorer Version 6.0+ and Mozilla Version 1.3+

• Activity 2
  • Listing for starter.xsl
    • actual file (left-click to display, right-click and select “Save Target As...” to download)
• Activity 3
  • Listing for tutorialRoster.xml
    • actual file (left-click to display, right-click to download)
  • N.B.  This XML file is linked to tutorialRoster.xsl via an xsl-stylesheet processing instruction, so left-clicking the link will display the result of applying the XSL file to the XML file.
  • Listing for tutorialRoster.xsl
    • actual file (left-click to display, right-click to download)
  • Version 2 (includes responses to pre-tutorial e-mail query on participants’ familiarities with various technologies)
    • tutorialRoster2.xml actual file (left-click to display as formatted by XSL stylesheet, right-click to download)
    • tutorialRoster2.xsl actual file (left-click to display, right-click to download)
• Activity 4
  • Listing for minimum.jsp
    • actual file (left-click to run on a Java-enabled Web server, right-click to download)
• Activity 5
  • Listing for onthefly.jsp
    • actual file (left-click to run on a Java-enabled Web server, right-click to download)
• Activity 6
  • Listing for xsl_query.jsp
    • actual file (left-click to run on a Java-enabled Web server, right-click to download)
  • Listing for xsl_functions.jsp
    • actual file (this file cannot be run on its own -- right-click to download only)

Additional Resources

• Mulberry Technologies XML Syntax Quick Reference (PDF file)
• Mulberry Technologies XSLT and XPath Quick Reference (PDF file)
• Microsoft XSLT Reference Page (live Web link)
• Internet Encyclopedia XSL paper, to be published in The Internet Encyclopedia, ed. Hossein Bidgoli, December 2003 (PDF file)
• Creating and Maintaining Data-Drive Course Web Sites invited paper, E-Learn 2002, October 2002 (PDF file)
• UltraEdit Version 10.00c (ZIP file)

Links to Participant File Areas

• Adams, Elizabeth
• Eyfrosynh, Grousouzakou
• Haddow, John
• Meyerowitz, Jane
• Or-Bach, Rachel
• Pothering, George
• Psarri, Dimitra
• Stalvey, RoxAnn
• Walker, Henry

HTML vs. XML

HTML	XML
Tags pertain to data formatting	Tags pertain to data structure
Tag names are predefined	Tag names are user-defined
Tags have specific meanings for specific formatting constructs	Tags have no predefined meaning (they can denote whatever the user desires)
Tags have a loose hierarchical structure	Tags have a strict hierarchical structure
Tag names are not case-sensitive	Tag names are case-sensitive
Some tags can stand alone, such as <hr> and <br>	All tags must consist of a start and end tag pair
A browser can display an HTML file because it contains formatting information as well as data	A browser cannot display an XML file without further formatting information
HTML content can be manipulated by scripts	XML content can also be manipulated by scripts
HTML cannot be extended by the user,  that is, users cannot invent new tags	XML, as its name implies, is an “eXtensible” technology; users can define new tags

Displaying XML in Internet Explorer

• with no errors = “well-formed”
  • note that this is not a direct display of the underlying XML file
  • it is the Internet Explorer rendition of the XML data it has read and stored internally

• with errors = not “well-formed”
  • all end tags must match start tags
  • start and end tags must be properly nested
  • note that tags are case-sensitive
  • see additional rules above

Well-Formedness of XML Documents

HTML’s Loose Document Structure

• Consider the following HTML code:

  1  <html>
2    <body>
3      This is the first line of text.
4      <p>This text begins in a new paragraph.
5         <Br>This text begins on a new line.
6      <p>This paragraph contains both <b>bold
7         <i>and</b> italic</i> text.
8    </body>
9  </html>

• Now look at how this code is rendered in Internet Explorer 5 and Netscape Navigator 4.7

XML’s Strict Document Structure

• Unlike HTML, the structure of XML documents is very strictly defined
• An XML document’s structure must conform to specific rules
• These rules are spelled out in excruciating detail in the W3C Recommendation entitled Extensible Markup Language (XML) 1.0 dated February 10, 1998
  • Document No. REC-xml-19980210
  • Posted at http://www.w3.org/TR/REC-xml.html
• XML documents that conform to these rules are said to be “well-formed”
• XML documents that are not well-formed will not load into a browser and cannot be parsed by any XML parser

XML Document Structure

An XML document consists of two main parts

• Prolog - the declaration that this is an XML document and the specification of the version of XML to which it complies
  • In the example we looked at in Module 1 on page 1-6 (repeated below), the prolog is line 1:

    <?xml version="1.0"?>

  • At the time of this writing there is only one version: 1.0
• Root Element - the main element that encloses all other elements
  • An element is enclosed within a matching pair of start and end tags
  • In the example below, Homeowners is the root element
  • The root element is the first element after the prolog
  • The root element contains all other elements
  • It is the first element opened (line 2) and the last element closed (line 19)

 1  <?xml version="1.0" ?> «– prolog
 2  <Homeowners> «– root element start tag
 3    <Resident>
 4      <LastName>Armstrong</LastName>
 5      <FirstName>George</FirstName>
 6      <HouseNumber>31</HouseNumber>
 7      <StreetName>St. Andrews Way</StreetName>
 8      <ClosingDate>
 9        <Month>5</Month>
10        <Day>13</Day>
11        <Year>1999</Year>
12      </ClosingDate>
13    </Resident>
14    <Resident>
15      ···
16    </Resident>
17    ···
18  </Homeowners> «– root element end tag

Elements in Plain English

• A matching pair of start and end tags forms an element
• The information between matching start and end tags is that element’s content
  • For example, the following is a “Species” element that contains “Homo Sapiens” as its content:

    <Species>Homo Sapiens</Species>

1. All start tags must have complementary end tags
   • For example, <tagName> … </tagName>
   • Stand-alone HTML tags like <Br> are not allowed in XML
   • If there is no content in between the start and end tags of an element, the start and end tags may be combined as follows:

     <tagName/>  note the forward slash before the greater-than sign

2. All tags are case-sensitive

   <TAGNAME> does not match <tagName>

3. Tags cannot begin with numbers

   <1st_name> is not a legal tag

4. Tags cannot contain spaces in or around the tag name

   <First Name>  is not a legal tag
< FirstName > is not a legal tag
</ FirstName> is not a legal tag
< /FirstName> is not a legal tag

5. All tags must be properly nested
   • On page 2-4 we saw problems generated by the following nesting:

     ... both <b>bold <i>and</b> italic</i> text ...

   • XML parsers would not allow such nesting
   • Tags must be closed in the reverse order from that in which they were opened
   • Thus if we wanted to reliably achieve the result we saw in Internet Explorer in all browsers:

     … both bold and italic text …

   • we would have to code it as follows:

     ... both <b>bold <i>and</i></b> <i>italic</i> text ...

6.  In general, multiple white space in content is ignored
   • It is possible to make multiple white space in content significant, but by default it is not

Attributes

• An attribute name cannot stand alone; it must be followed by an equals sign and an attribute value
• Attribute values must be enclosed in double quotes
• HTML allows:

  <hr width=60%> and <hr width="60%">

• XML would allow only:

  <Name First="John" Last="Smith">

• Attribute values cannot contain the characters < and &
  • & can only be used as part of an entity or character reference
• Attributes cannot appear in end tags

Comments  (handout p. 2-18)

• Use liberally to explain your document’s structure to others who may have to maintain it
  • Or even to explain it to yourself six months from now…
• Formal definition
  • Begin with <!--
  • Follow with 0 or more occurrences of any character except a hyphen (-) or a hyphen followed by any character except a hyphen
  • End with -->
• Thus a comment cannot contain two hyphens in a row

Legal Comments	Illegal Comments
<!-- root element -->	<!---- root element -->
<!--- root element -->	<!-- root element --->
<!-- root-element -->	<!-- root--element -->
<!-- root- -element -->	<!-- root---element -->

Built-In Entity References  (handout p. 2-19)

• Used to insert characters that would otherwise result in non-well-formed documents

Entity Reference	Character Inserted	Name or Description
&	&	ampersand
'	'	apostrophe (single quote)
>	>	greater-than sign
&lt;	<	less-than sign
&quot;	"	quotation mark (double quote)

• All entity references begin with an ampersand and end with a semi-colon

• Examples

1  <Name>Jesse &amp; Bonnie</Name>
2  <Name>George Herman &quot;Babe&quot; Ruth</Name>
3  <Name>Bill O&apos;Malley</Name>
4  <Formula>(x &gt; y) AND (x &lt; z)</Formula>

• Note that these five are the only built-in entity references
  • One cannot use the standard HTML references (like – and — and  )
  • One can, however, use the &#nnnn; syntax (where nnnn is a decimal number) to insert special characters
    • For example, “ is a left double quote (“), ” is a right double quote (”), and   is a non-breaking space
• We will see how to define our own entity references later if we have time

Character Data Sections

• Used to insert a section containing text that should not be processed by the XML parser
  • All data with this section is simply read as characters
• Syntax: <![CDATA[your text]]>
• Can be used in place of built-in entity references

  <Name>Bill <![CDATA[O'Malley]]></Name>

• Particularly useful for larger sections

 1  <Example>
 2    A member record has the following format:
 3    <![CDATA[
 4      <Member>
 5        <Name First="Robert" Last="Boyle"></Name>
 6        <Address>
 7          <Street>13 Paris Road</Street>
 8          <City>Chelmsford</City>
 9          <State ZIP="01863">Massachusetts</State>
10         </Address>
11       </Member>
12     ]]>
13   </Example>

• Note that white space is preserved in CDATA sections, so you may want to format your entry accordingly

CSS “Decorates” While XSL “Transforms”

• CSS controls the formatting properties of elements, their so-called “decorations”
• XSL actually “transforms” an XML tree into a new tree, one expressed in HTML
• XSL allows “extensive reordering, generated text, and calculations-all without modification to the XML source” (Microsoft Development Network (MSDN) Library)
• Some additional features provided by XSL include:
  • Generated text labels for data items
  • More sophisticated layout using HTML tables
  • Multiple use of the data items, for example, in the page title as well as in a header line, etc.
  • Access to information stored in attribute values
  • Reordering of items
  • Dynamic display behaviors not easily possible through CSS

Creating a Stylesheet

• An XSL stylesheet “is_a” XML file, so its first line must contain the XML Processing Instruction

<?xml version='1.0'?> 

• The root element of an XSL stylesheet is xsl:stylesheet, therefore opening and closing tags for this element must appear before and after all other elements, respectively

<?xml version='1.0'?> 
<xsl:stylesheet ... > 
   ... 
</xsl:stylesheet> 

• Standard comments delimited by <!-- and --> may appear outside the root element opening and closing tags

• The xsl:stylesheet tag requires an attribute specifying the namespace for all XSL elements and attributes

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

• Note that the URL for the XSL namespace is a W3C location (www.w3.org), not a Microsoft URN
  • Two parts of the XSL specification have been W3C Recommendations for quite some time, so they are now standard throughout the industry
    • XPATH, the XML Path Language
    • XSLT, the XSL Transformations Specification
  • XSL, the Extensible Stylesheet Language, became a Recommendation on October 15, 2001

xsl:stylesheet Element

• Syntax

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

• Attributes
  • xmlns:xsl -- The styles sheet namespace. For the processor shipped with Microsoft Internet Explorer 5, the value should be set to "http://www.w3.org/1999/XSL/Transform".
  • version -- The version of XSLT that the style sheet requires. Value should be set to "1.0".
• Important Documentation Note
  • The elements discussed in this module are not found in the W3C Working Draft on the Extensible Stylesheet Language
  • Rather, they are found in the W3C XSL Transformations (XSLT) Recommendation, found at http://www.w3.org/TR/xslt11
  • Thus, the constructs discussed here are a subset of official W3C “Recommendations” (recognized standards)

Defining a Template

• Templates are sections of XSL code to be executed when the node context matches that of the match attribute

<xsl:template match="node-context">
   ...
</xsl:template>

• The node context is expressed as an XSL pattern, which is one type of XPath expression
• The XSL pattern is also referred to as a node-set-expression in the W3C documentation

• The initial processing context is the root node, which is represented by the pattern "/"

<xsl:template match="/"> 

• This template is the first one applied when the XML document associated with the XSL stylesheet is displayed
• It is sometimes referred to as the “root template” because it “defines the structure of the overall output document” [MSDN]
• One can think of this template as equivalent to the main function in C, C++, or Java

xsl:template Element

• Syntax

<xsl:template match="node-context">
   ...
</xsl:template>

• Attributes
  • match - Context for which the template should be executed, expressed as an XSL pattern. This attribute can be used to change the context of the source document and provides a convenient way to navigate down into the document tree. The default matches all nodes.

Sample XSL Patterns (adapted from MSDN)

• title
  • Matches title elements
• section/title
  • Matches title elements that are children of section elements
• section//title
  • Matches title elements contained within section elements (title elements that have a section ancestor)
• section/title[@short-name]
  • Matches title elements that are children of section elements, and that have a short-name attribute
• appendix//section[@type='reference']/title
  • Matches title elements that are children of section elements, where the section must also have a type attribute with the value reference, and have an appendix ancestor
• appendix[.//section[@type='reference']/title]
  • Matches appendix elements that contain section descendants, which in turn have both a type attribute with the value reference and a title child

XSL Pattern Operators and Special Characters (adapted from MSDN)

Operator	Use
/	Child operator — selects immediate children of the left-side collection. At the start of a pattern, this operator indicates that children should be selected from the root node
//	Recursive descent — searches for a specified element at any depth. At the start of a pattern, this operator indicates recursive descent from the root
.	Indicates the current context
*	Wildcard — selects all elements regardless of name
@	Attribute — prefix for an attribute name
@*	Attribute wildcard — selects all attributes regardless of name
:	Namespace separator — separates the namespace prefix from the element or attribute name
[ ]	Applies a filter pattern
Extended XSL Pattern methods in the XQL Proposal:
!	Applies the method following the ! to the reference node preceding the !
( )	Groups operations to set precedence explicitly
[ ]	Subscript operator. Used for indexing within a collection

File Systems vs. XSL Patterns (adapted from MSDN)

File Systems (URLs)	XSL Patterns
Hierarchy comprised of directories and files in a file system	Hierarchy comprised of elements and other nodes in an XML document
Files at each level have unique names-URLs always identify a single file	Element names at each level might not be unique-XSL patterns identify a set of all the matching elements
URLs are evaluated relative to a particular directory-called the “current directory”	XSL patterns are evaluated relative to a particular node-called the “context” for the query


xsl:value-of Element

• Syntax

  <xsl:value-of select="pattern">
   ...
</xsl:value-of>

• Attributes
  • select - XSL pattern to be matched against the current context. The default value is “.”, which inserts the value of the current node
    • See the below for a comparison of select patterns vs. match patterns
• <xsl:value-of select="pattern">

Example:  XSL Patterns - XML File

 1  <?xml version="1.0" ?>
 2  <?xml-stylesheet type="text/xsl" href="HomeOwners04a.xsl"?>
 3  <!--
 4    File: HomeOwners04.xml
 5    (c) 2000 by Hands On Technology Transfer, Inc.
 6  -->
 7  <HomeOwners>
 8    <Resident>
 9      <LastName>Armstrong</LastName>
10      <FirstName>George</FirstName>
11      <UnitNumber>49</UnitNumber>
12      <HouseNumber>31</HouseNumber>
13      <StreetName>St. Andrews Way</StreetName>
14      <ClosingDate>
15        <Month>5</Month>
16        <Day>13</Day>
17        <Year>1999</Year>
18      </ClosingDate>
19    </Resident>
20    <Resident>
21      <LastName>Beaudoin</LastName>
22      <FirstName>Carole</FirstName>
23      <UnitNumber>11</UnitNumber>
24      <HouseNumber>21</HouseNumber>
25      <StreetName>Augusta Way</StreetName>
26      <ClosingDate>
27        <Month>8</Month>
28        <Day>12</Day>
29        <Year>1998</Year>
30      </ClosingDate>
31    </Resident>
32    <Resident>
33      ...
34    </Resident>
35    ... additional Resident elements ...
36  </HomeOwners>

Example:  XSL Patterns - XSL File

37  <?xml version="1.0" ?>
38  <!--
39    File: HomeOwners04a.xsl
40    (c) 2000 by Hands On Technology Transfer, Inc.
41  -->
42  <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
43    <xsl:template match="/">
44      <html>
45      <body>
46        <p>
47          <i>Name:&#160;</i>
48          <b><xsl:value-of
49                select="HomeOwners/Resident/LastName"/>,
50             <xsl:value-of
51                select="HomeOwners/Resident/FirstName"/></b><br/>
52
53          <i>Unit Number:&#160;</i>
54          <b><xsl:value-of
55                select="HomeOwners/Resident/UnitNumber"/></b><br/>
56
57          <i>Address:&#160;</i>
58          <b><xsl:value-of
59                select="HomeOwners/Resident/HouseNumber"/>
60             <xsl:value-of
61                select="HomeOwners/Resident/StreetName"/></b><br/>
62
63          <i>Closing Date:&#160;</i>
64          <b><xsl:value-of
65                select="HomeOwners/Resident/ClosingDate/Month"/> /
66             <xsl:value-of
67                select="HomeOwners/Resident/ClosingDate/Day"/> /
68             <xsl:value-of
69                select="HomeOwners/Resident/ClosingDate/Year"/>
70        </p>
71      </body>
72      </html>
73    </xsl:template>
74  </xsl:stylesheet>

Example:  XSL Patterns - Discussion

• The root template in the XSL file begins at line 43
• Note that the HTML code can be written in either upper or lowercase, but it must be well-formed
  • Thus we cannot use a <br> tag without a </br> tag
  • It is easiest to just use a <br/> tag as in lines 51, 55, and 61
• The   entity for a non-breaking space is not recognized (it generates a parsing error), but it can be entered using   as in lines 47, 53, 57, and 63
• Note that we have supplied the full XSL path to each desired node
  • We’ll make this more sophisticated later
• Note that the data for only the first Resident is displayed
• Note that the xsl:value-of tag translates to a string containing the node’s contents
  • In some cases we have output just one node’s contents per screen line, and in others we have output multiple nodes’ contents
• Note how various output elements - HTML tags, XSL tags, and regular text - are mixed throughout the file

Applying Templates, Sorting, Conditionals, and Filtering

Processing Multiple Records

• Note that XSL Example 1 displayed only the first record from the XML file
• One way to display multiple records is to apply a template to all nodes that match a specified criterion

 1  <?xml version="1.0" ?>
 2  <!--
 3    File: HomeOwners04b.xsl
 4    (c) 2000 by Hands On Technology Transfer, Inc.
 5  -->
 6  <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
 7
 8    <xsl:template match="/">
 9      <html>
10      <body>
11        <xsl:apply-templates select="HomeOwners/Resident"/>
12      </body>
13      </html>
14    </xsl:template>
15
16    <xsl:template match="Resident">
17        <p>
18          <i>Name:&#160;</i>
19          <b><xsl:value-of select="LastName"/>,
20             <xsl:value-of select="FirstName"/></b><br/>
21
22          <i>Unit Number:&#160;</i>
23          <b><xsl:value-of select="UnitNumber"/></b><br/>
24
25          <i>Address:&#160;</i>
26          <b><xsl:value-of select="HouseNumber"/>
27             <xsl:value-of select="StreetName"/></b><br/>
28
29          <i>Closing Date:&#160;</i>
30          <b><xsl:value-of select="ClosingDate/Month"/> /
31             <xsl:value-of select="ClosingDate/Day"/> /
32             <xsl:value-of select="ClosingDate/Year"/></b>
33        </p>
34    </xsl:template>
35  </xsl:stylesheet>

• The root template at lines 8-14 is applied as soon as the document is opened
• The root template applies any templates that match HomeOwners/Resident
• The template that matches HomeOwners/Resident is at lines 16-34
• Note that the node context for this template is HomeOwners/Resident, so this part of the XPath is eliminated from the xsl:value-of tags select attribute at lines 19-20, 23, 26-27, and 30-32

xsl:apply-templates Element

• Syntax

  <xsl:apply-templates
   select="pattern"
   order-by="sort-criteria-list">
</xsl:apply-templates>

• Attributes
  • select - Context for which the template should be executed. The default value node() indicates selection of the children of current node, of all node types except attributes.
  • order-by (obsolete! see below!) - Sort criteria in a semicolon-separated list. When the first sort results in two equal items, the second sort criterion is checked, and so on. The first non-white-space character in each sort criterion indicates whether the sort is ascending (optional +) or descending (-). The sort criterion is expressed as an XSL pattern, relative to the pattern described in the select attribute.

order-by Attribute

• The order-by attribute became obsolete with the W3C December 1999 XSL Working Draft, which defines the xsl:sort element instead
• The latest release of Microsoft’s MSXML parser supports the xsl:sort element, but the version shipped with Internet Explorer 5 only supports the order-by attribute
• The new xsl:sort element has the following syntax

  <xsl:sort
  select = string-expression
  lang = { nmtoken }
  data-type = { "text" | "number" | name }
  order = { "ascending" | "descending" }
  case-order = { "upper-first" | "lower-first" } />

  • The data-type name may be a qualified name (like those in elements, optionally containing a namespace prefix), but not a namespace name alone.
• To use xsl:sort, one must use the latest namespace

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

• The version attribute is required

• Note that when using the order-by attribute, sorting is always alphabetic
  • Thus “15” comes before “2”
  • This is one of the problems solved by the xsl:sort element’s data-type attribute
• The figure shows the effect of changing lines 8-11 above to:

 1  <xsl:template match="/">
 2    <xsl:apply-templates select="HomeOwners/Resident"
 3      order-by="+UnitNumber">
 4        <!--
 5          <xsl:sort select="UnitNumber"
 6                    data-type="number"
 7                    order="ascending"/>
 8        -->
 9    </xsl:apply-templates>
10  </xsl:template>

• Note the increased expressiveness of the xsl:sort element over the order-by attribute, but it is commented out here because we are using order-by instead
• The screen capture below has been scrolled down to show the alphabetic nature of sorting with the order-by attribute
  • Note that Unit Number 4 (Field, Jerry) sorts to a position after Unit Number 39 (Sullivan, Daniel)

Simple Conditionals

• Suppose we wanted to print closing dates in Month Day, Year (MMMM D, YYYY) format rather than M / D / YYYY format as they are in previous examples
• One way to do this is to use xsl:if elements
• The figure shows the effect of changing lines 27-30 above to:

 1  <i>Closing Date:&#160;</i>
 2  <b><xsl:if test="ClosingDate/Month[.='2']">February </xsl:if>
 3     <xsl:if test="ClosingDate/Month[.='3']">March </xsl:if>
 4     <xsl:if test="ClosingDate/Month[.='4']">April </xsl:if>
 5     <xsl:value-of select="ClosingDate/Day"/>,
 6     <xsl:value-of select="ClosingDate/Year"/></b>

• The value of the test attribute is an XSL pattern
• The part of the XSL pattern within square brackets is a filter
• The test in line 2 above is true when “the current context contains a ClosingDate element with a Month child element whose value is 2”
• Note that . in the filter refers to the current node context, which is set by the ClosingDate/Month pattern that precedes it
• This test can also be written:

  test="ClosingDate/Month[textnode()='2']"

More on XSL Patterns and Filters

• XSL patterns were introduced previously, as were XSL pattern operators and special characters
• The XQL (eXtensible Query Language) proposal contains many additional operators and functions to support complex queries into the database
• An XSL pattern defines a node context which returns a collection of all elements in that context
• A filter applies a constraint to that collection using a filter pattern
  • Only elements in the collection for which the constraint is true are returned
• A filter is analogous to an SQL WHERE clause

Examples

• Find all books that contain at least one excerpt element

  book[excerpt]

• Find all authors of books where the book contains at least one excerpt, and the author has at least one degree

  book[excerpt]/author[degree]

• Find all books that have authors with at least one degree

  book[author/degree]

• Find all books that have an excerpt and a title

  book[excerpt][title]

XSL Filter Information Methods

Method	Use
date	Casts values to date format.
end	Returns true for the last element in a collection.
index	Returns the index number of the node within the parent.
nodeName	Returns the tag name of the node, including the namespace prefix.
nodeType	Returns a number to indicate the type of the node.
number	Casts values to number format.
text	Returns the content of the node.
value	Returns a typed version of the value of the node.

Examples

• Find the last book

  book[position()=last()]

• Find the last author for each book

  book/author[position()=last()]

• Find the last author from the entire set of authors of books

  (book/author)[position()=last()]

• Find the first three books (0, 1, 2)

  book[index() <= 2]

• Find all authors whose "from" attribute is not equal to "Harvard":

  degree[@from != "Harvard"]

XSL Filter Operators

Microsoft		W3C	Use
Oper.	Alt.
Logical Operators
$and$	and	and	logical AND
$or$	or	or	logical OR
$not$	not()	not()	logical NOT
Comparison Operators
$eq$	=	=	equal
$ieq$	none	nyi *	case-insensitive equality
$ne$	!=	!=	not equal
$ine$	none	nyi	case-insensitive inequality
$lt$	<	&lt;	less than
$igt$	none	nyi	case-insensitive greater than
$gt$	>	>	greater than
$ilt$	none	nyi	case-insensitive less than
$le$	<=	&lt;=	less than or equal to
$ile$	none	nyi	case-insensitive less than or equal to
$ge$	>=	>=	greater than or equal to
$ige$	none	nyi	case-insensitive greater than or equal to
Set Operators
$all$	none	use set functions	returns true if filter-specified conditions are met by all occurrences of the pattern
$any$	none	use set functions	returns true if filter-specified conditions are met by any occurrences of the pattern

* nyi = not yet implemented (after Ceponkus and Hoodbhoy, 2000, pp. 397-399)

xsl:if Element

• Syntax

  <xsl:if test="pattern"></xsl:if>

• Attributes
  • test - Condition in the source data to test. If the select pattern in this attribute identifies at least one node in the current source document, the contents of xsl:if are placed in the output.
• Example
  • Microsoft-specific:  Insert HR elements before the first item element in a set and after the last item element in the set. The context() method refers to the set of item elements selected by the xsl:apply-templates that caused this template to be invoked.

    1 <xsl:template match="item">
    2   <xsl:if test="context()[position()=1]"><HR/></xsl:if>
    3   <xsl:apply-templates />
    4   <xsl:if test="context()[position()=last()]"><HR/></xsl:if>
    5 </xsl:template>

Multiple Conditionals

• Multiple conditionals are similar to switch statements in C and C++ and select case statements in Visual Basic
• The basic syntax is:

 1 <xsl:choose>
 2   <xsl:when test="pattern"> output </xsl:when>
 3     ...
 4   as many additional xsl:when elements as desired
 5     ...
 6   <xsl:otherwise> output </xsl:otherwise>  ¬ optional
 7 </xsl:choose>

• The test pattern is the same as that in the xsl:if element

• Note the presence of an optional xsl:otherwise element
  • Developers often use xsl:choose elements just so that they can specify an xsl:otherwise element, because there is no “else” clause for an xsl:if element
• Note that dates in January are followed by dates in October, because these are sorted alphabetically by month number. Likewise, January 5 follows January 29.

Example:  Transforming Month Numbers

 1 <?xml version="1.0" ?>
 2 <!--
 3   File: HomeOwners04e.xsl
 4   (c) 2000 by Hands On Technology Transfer, Inc.
 5 -->
 6 <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
 7
 8   <xsl:template match="/">
 9     <html>
10      <body>
11        <h3>Note that closing dates in January are followed by dates
12        in October, November, and December because these are sorted
13        alphabetically by month number.  Thus, the months are output
14        in the following order: 1, 10, 11, 12, 2, 3, ...  In
15        addition, the days are output in alphabetical order, so
16        January 5 follows January 29.</h3>
17
18        <xsl:apply-templates select="HomeOwners/Resident"
19          order-by="+ClosingDate/Year; +ClosingDate/Month;
20                    +ClosingDate/Day"/>
21            <!-- new syntax in W3C Working Draft and May 2000 MXSML Parser
22              <xsl:sort select="ClosingDate/Year"
23                        data-type="number" order="ascending"/>
24              <xsl:sort select="ClosingDate/Month"
25                        data-type="number" order="ascending"/>
26              <xsl:sort select="ClosingDate/Day"
27                        data-type="number" order="ascending"/>
28            -->
29      </body>
30      </html>
31    </xsl:template>   code continues on next page
32    <xsl:template match="Resident">
33        <p>
34          <i>Name:&#160;</i>
35          <b><xsl:value-of select="LastName"/>,
36             <xsl:value-of select="FirstName"/></b><br/>
37
38          <i>Unit Number:&#160;</i>
39          <b><xsl:value-of select="UnitNumber"/></b><br/>
40
41          <i>Address:&#160;</i>
42          <b><xsl:value-of select="HouseNumber"/>
43             <xsl:value-of select="StreetName"/></b><br/>
44
45          <xsl:apply-templates select="ClosingDate"/>
46        </p>
47    </xsl:template>
48
49    <xsl:template match="ClosingDate">
50      <i>Closing Date:&#160;</i><b>
51      <xsl:choose>
52         <xsl:when test="Month[.='1']">January </xsl:when>
53         <xsl:when test="Month[.='2']">February </xsl:when>
54         <xsl:when test="Month[.='3']">March </xsl:when>
55         <xsl:when test="Month[.='4']">April </xsl:when>
56         <xsl:when test="Month[.='5']">May </xsl:when>
57         <xsl:when test="Month[.='6']">June </xsl:when>
58         <xsl:when test="Month[.='7']">July </xsl:when>
59         <xsl:when test="Month[.='8']">August </xsl:when>
60         <xsl:when test="Month[.='9']">September </xsl:when>
61         <xsl:when test="Month[.='10']">October </xsl:when>
62         <xsl:when test="Month[.='11']">November </xsl:when>
63         <xsl:when test="Month[.='12']">December </xsl:when>
64         <xsl:otherwise>Bad Month Number </xsl:otherwise>
65       </xsl:choose>
66       <xsl:value-of select="Day"/>,
67       <xsl:value-of select="Year"/></b>
68    </xsl:template>
69
70  </xsl:stylesheet>

• Here we have chosen to put the main HTML code (<html> <body>...</body></html>) in the XSL root element
• This allows us to provide explanatory text (in the <h3> element) that will appear only once in the output
• The xsl:apply-templates element at line 19 applies the template on the next page
• To use the W3C version, don't forget to change the namespace above and eliminate the schema reference in the XML file
• Note that the node context is changed to the current node’s ClosingDate child by the xsl:apply-templates element at line 47, so that reference is eliminated from the test and select attributes in the applied template at lines 51-70

xsl:choose and xsl:otherwise Elements

• Syntax

  <xsl:choose>
   ...
</xsl:choose>

• Syntax

  <xsl:otherwise>
   ...
</xsl:otherwise>

xsl:when Element

• Syntax

  <xsl:when test="pattern">
   ...
</xsl:when>

• Attributes
  • test - XSL pattern to be tested against the current context. The default value is “.”, which indicates evaluation of the current node and thus is always true.
• Notes
  • Only one xsl:when element (or the xsl:otherwise element) is executed within a single xsl:choose element
  • If the patterns in two xsl:when elements are both true, only the first one is executed
  • C/C++ programmers may think of each xsl:when tag as containing an implicit break statement

Looping

• It is important to keep in mind that XSL patterns and filters typically return collections of nodes
• For example, the following record contains two collections, Authors and RecSubjCategories, each with three subelements

 1  <Book>
 2    <Title>Professional Site Server 3.0</Title>
 3    <Authors>
 4      <Author>Rob Howard</Author>
 5      <Author>Craig McQueen</Author>
 6      <Author>Marco Tabini</Author>
 7    </Authors>
 8    <Publisher>Wrox Press, Ltd.</Publisher>
 9    <PubDate>July 1999</PubDate>
10    <Pages>1058</Pages>
11    <ISBN>1-861002-69-6</ISBN>
12    <RecSubjCategories>
13      <Category>Internet</Category>
14      <Category>Web Server</Category>
15      <Category>Site Server</Category>
16    </RecSubjCategories>
17  </Book>

• It is often desirable to apply a template to each item in a collection
  • Repeating a process is also known as iteration
• This can be done using the xsl:for-each element

xsl:for-each Element

• Syntax

  <xsl:for-each
   select="pattern"
   order-by="sort-criteria-list">
</xsl:for-each>

• Attributes
  • select - XSL pattern query evaluated the current context to determine the set of nodes to iterate over. The default value node() indicates selection of all children of current node.
  • order-by (obsolete! see previous notes!) - Sort criteria in a semicolon-separated list.

Example:   XSL Iteration - XML File

 1 <?xml version="1.0" encoding="utf-8" standalone="yes"?>
 2 <?xml-stylesheet type="text/xsl" href="RowWiseJMH.xsl" ?>
 3 <!--
 4   File: CatalogJMH.xml
 5   The Wrox Press Book Catalog Application
 6   adapted from Martin et al., 2000, pp. 356-357, by Jesse Heines, May 2000
 7 -->
 8 <Catalog>
 9   <Book>
10       <Title>Professional Java XML</Title>
11       <Authors>
12          <Author>Alexander Nakhimovsky</Author>
13          <Author>Tom Myers</Author>
14       </Authors>
15       <Publisher>Wrox Press, Ltd.</Publisher>
16       <PubDate>August 1999</PubDate>
17       <Pages>600</Pages>
18       <ISBN>1-861002-85-8</ISBN>
19       <RecSubjCategories>
20          <Category>Java</Category>
21          <Category>Programming</Category>
22          <Category>XML</Category>
23       </RecSubjCategories>
24       <Price>$49.99</Price>
25    </Book>
26    <Book>
27       <Title>Professional ASP 3.0</Title>
28       <Authors>
29          <Author>Brian Francis</Author>
30          <Author>Alex Homer</Author>
31          <Author>David Sussman</Author>
32       </Authors>
33       <Publisher>Wrox Press, Ltd.</Publisher>
34       <PubDate>October 1999</PubDate>
35       <Pages>1278</Pages>
36       <ISBN>1-861002-61-0</ISBN>
37       <RecSubjCategories>
38          <Category>Internet</Category>
39          <Category>Web Publishing</Category>
40          <Category>ASP</Category>
41       </RecSubjCategories>
42       <Price>$59.99</Price>
43    </Book>
44       ... additional Book elements ...
45  </Catalog>

Example:   XSL Iteration - XSL File

46  <?xml version="1.0"?>
47  <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
48  <!--
49    File: RowWiseJMH.xml
50    The Wrox Press Book Catalog Application
51    adapted from Martin et al., 2000, pp. 357-358 by Jesse Heines, May 2000
52    see p. 380 for important note on use of the WD-xsl namespace
53  -->
54    <xsl:template match="/">
55      <HTML>
56      <BODY>
57        <xsl:apply-templates select="Catalog"/>
58      </BODY>
59      </HTML>
60    </xsl:template>
61
62    <xsl:template match="Catalog">
63      <xsl:for-each select="Book/Authors[Author='Alex Homer']">
64      <!-- node context is now an Authors node within a Book element -->
65        <P>
66        Book/Title: <B>
67          <xsl:value-of select="../Title"/></B><BR/>
68        Book/Authors (collection): <B>
69          <xsl:value-of select="."/></B><BR/>
70        First Author (<code>Author[position()=1]</code>): <B>
71          <xsl:value-of select="Author[position()=1]"/></B><BR/>
72        Last Author (<code>Author[position()=last()]</code>): <B>
73          <xsl:value-of select="Author[position()=last()]"/></B><BR/>
74        First Author with Name that starts with "A" (<code>Author[starts-with(.,'A')]</code>): <B>
75          <xsl:value-of select="Author[starts-with(.,'A')]"/></B><BR/>
76        First Author with Name that starts with "A" or "B"<br />
77        &#160;&#160;&#160;(<code>Author[substring(.,1,1)='A' or substring(.,1,1)='B']</code>): <B>
78          <xsl:value-of select="Author[substring(.,1,1)='A' or substring(.,1,1)='B']"/></B><BR/>
79        First Author with Name that starts with "A" or "B"<br />
80        &#160;&#160;&#160;(alternative solution, <code>Author[contains('AB', substring(.,1,1))]</code>): <B>
81          <xsl:value-of select="Author[contains('AB', substring(.,1,1))]"/></B><BR/>
82        First Author with Name that starts with a letter greater than "C"<br />
83        &#160;&#160;&#160;(<code>Author[contains('DEFGHIJKLMNOPQRSTUVWXYZ', substring(.,1,1))]</code>): <B>
84          <xsl:value-of select="Author[contains('DEFGHIJKLMNOPQRSTUVWXYZ', substring(.,1,1))]"/></B><BR/>
85        </P>
86      </xsl:for-each>
87    </xsl:template>
88
89  </xsl:stylesheet>

Example:  XSL Iteration - Result (handout p. 6-45)

• Note that Author elements contain both first and last names (see page 6-43), thus the Book/Authors collections shown contain 0, 3, and 3 elements, respectively
• The patterns at lines 81 and 84 return only the first matching element; to get all matching elements, use:

1 All Authors with Name that starts with a letter greater than "C"<br />
2   <xsl:for-each select="Author[contains('DEFGHIJKLMNOPQRSTUVWXYZ', substring(.,1,1))]">
3     <xsl:value-of select="."/>
4   </xsl:for-each></b><BR/>

XSL Element Summary  (after Ceponkus & Hoodbhoy, 1999, p. 372)

Element	Use
Elements discussed in this tutorial
xsl:stylesheet	Begins definition of a stylesheet - the root node that encompasses the set of templates applied to an XML source tree to generate an output tree
xsl:template	Defines a series of transformations or formatting procedures that are applied when the node context matches a particular pattern
xsl:value-of	Inserts the string value of the specified node into the output stream
xsl:apply-templates	Invokes other templates based on their match attributes
xsl:if	Provides simple if/then conditional processing
xsl:choose	Provides multiple conditional processing with the xsl:when and xsl:otherwise elements
xsl:when	Defines one conditional case within the body of an xsl:choose element
xsl:otherwise	Defines the default action to be taken if all xsl:when conditions within an xsl:choose element are false
xsl:for-each	Defines a loop that is applied to all nodes which match its select attribute
Additional XSL elements
xsl:comment	Inserts a comment into the output
xsl:pi	Inserts a processing instruction into the output
xsl:element	Inserts an XML element with a specified name into the output
xsl:attribute	Creates an attribute with a specified name and appends that attribute and its value to its parent element
xsl:copy	Copies the contents of all subelements to the output

Why use Java on the server rather than JavaScript on the client?

• fully reliable operating environment
• much more strongly-typed language
• much more powerful language
• access to capabilities not available in JavaScript

A first program

<html>
<body>
  <% for ( int k=0 ; k < 5 ; k++ )
     { 
  %>
       k is now <%= k %><br>
  <% } %>
  <p><% out.println( getServletName() ) ; %></p>
</body>
</html>

Output

k is now 0
k is now 1
k is now 2
k is now 3
k is now 4

jsp

• JSP code is placed withing <% ... %> delimiters
  • note the integration of Java and HTML code

Equivalent, alternative code that produces the same output

<html>
<body>
  <% 
     for ( int k=0 ; k < 5 ; k++ )
     {
       out.println( "k is now " + k + "<br/>" ) ;
     }
     out.println( "<p>" + getServletName() + "<p>" ) ; 
  %>
</body>
</html>

• this version is mostly Java
• some might find it easier to follow

Characteristics of both versions

• this code is completely processed on the server before the page is sent to the client
• the client sees only the results of the JSP plus any static HTML
• the entire file is actually translated into a Java Servlet and then compiled and run on the server
• the language is real Java (as opposed to JavaScript), so variable k must be declared
• out.println is analogous to JavaScript’s document.writeln
  • out is referred to as the response object, which is the stream to which responses are to be sent
  • the response object is virtually always a stream to the client (browser or other net application)
  • println is a method member of object out
• getServletName() is one of many functions available to get and set information shared between Web pages 

JSP Syntax Basics

You’re writing real Java code

• any standard Java text will do for help
• code is case-sensitive
• all variables must be declared
• user-defined objects can be used
• object methods (functions) can be used
• as in JavaScript, a String is an object, not an array of characters
• most basic C/C++ constructs will work, but arrays require some different handling

Comments

• comments delimited by <!-- ... --> will be output to the client
• comments delimited by <%-- ... --%> will not be output to the client

Defining Functions

• place within <%! ... %>

Expressions

• easily display the value of any variable be placing it within <%= variable name or single function call %>
• this is a shortcut for out.print( variable name or single function call ) %>

We’ll see lots of examples in the remainder of the tutorial

JSP Syntax Summary

Source:  http://javaboutique.internet.com/tutorials/JSP/part11/page02.html

Captured by JMH on March 03, 2003 at 02:23 PM

<%= expression %>

<% code %>

<%! code %>

<%-- comment --%>

 1  <?xml version="1.0" ?>
 2  
 3  <!--
 4    starter.xsl
 5    Jesse M. Heines, UMass Lowell Computer Science, heines@cs.uml.edu
 6    for ITiCSE XML and XSL Tutorial, Thessaloniki, Greece
 7    Copyright (c) 2003 by Jesse M. Heines.  All rights reserved, but may be freely 
 8      copied or extracted from for educational purposes with credit to the author.
 9    updated by JMH on June 18, 2003 at 02:21 PM
10  -->
11  
12  <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
13  
14  
15  <!-- main template -->
16  
17  <xsl:template match="/">
18    <html>
19      <body>
20        <!--
21          change the select attribute below to the XPath to your second level elements
22        -->
23        <xsl:apply-templates select="root/secondlevel" />
24      </body>
25    </html>
26  </xsl:template>
27  
28  
29  <xsl:template match="secondlevel">
30    <!--
31      add processing statements here
32    -->
33  </xsl:template>
34  
35  
36  </xsl:stylesheet>

tutorialRoster.xml

  9  <?xml version="1.0" ?>
 10  
 11  <!--
 12    tutorialRoster.xml
 13    Jesse M. Heines, UMass Lowell Computer Science, heines@cs.uml.edu
 14    for ITiCSE XML and XSL Tutorial, Thessaloniki, Greece
 15    Copyright (c) 2003 by Jesse M. Heines.  All rights reserved, but may be freely 
 16      copied or extracted from for educational purposes with credit to the author.
 17    updated by JMH on June 18, 2003 at 02:21 PM
 18  -->
 19  
 20  <?xml-stylesheet type="text/xsl" href="tutorialRoster.xsl" ?>
 21  
 22  <tutorialRoster>
 23    <particulars>
 24      <title>Using XML and XSL with JavaServer Pages</title>
 25      <date>2003-06-29</date>
 26      <location>Thessaloniki, Greece</location>
 27      <organization>ACM SIG CSE</organization>
 28      <conference>ITiCSE</conference>
 29    </particulars>
 30    <presenter>
 31      <name last="Heines" first="Jesse" />
 32      <institution name="University of Massachusetts Lowell" />
 33      <emailaddress>heines@cs.uml.edu</emailaddress>
 34    </presenter>
 35    <participant>
 36      <name last="Adams" first="Elizabeth" />
 37      <institution name="James Madison University" />
 38      <emailaddress>adamses@jmu.edu</emailaddress>
 39    </participant>
 40    <participant>
 41      <name last="Eyfrosynh" first="Grousouzakou" />
 42      <institution name="1o Esperino Tee Peristeriou" />
 43      <emailaddress>efigr@dolnet.gr</emailaddress>
 44    </participant>
 45    <participant>
 46      <name last="Haddow" first="John" />
 47      <institution name="Bell College" />
 48      <emailaddress>j.haddow@bell.ac.uk</emailaddress>
 49    </participant>
 50    <participant>
 51      <name last="Meyerowitz" first="Jane" />
 52      <institution name="University of Natal" />
 53      <emailaddress>meyerowi@nu.ac.za</emailaddress>
 54    </participant>
 55    <participant>
 56      <name last="Or-Bach" first="Rachel" />
 57      <institution name="Emek Yezreel College" />
 58      <emailaddress>orbach@yvc.ac.il</emailaddress>
 59    </participant>
 60    <participant>
 61      <name last="Pothering" first="George" />
 62      <institution name="College of Charleston" />
 63      <emailaddress>pother@cs.cofc.edu</emailaddress>
 64    </participant>
 65    <participant>
 66      <name last="Psarri" first="Dimitra" />
 67      <institution name="1st Lykeio Agias Varvaras" />
 68      <emailaddress>mail@1lyk-ag-varvar.att.sch.gr</emailaddress>
 69    </participant>
 70    <participant>
 71      <name last="Stalvey" first="RoxAnn" />
 72      <institution name="College of Charleston" />
 73      <emailaddress>stalveyr@cs.cofc.edu</emailaddress>
 74    </participant>
 75    <participant>
 76      <name last="Walker" first="Henry" />
 77      <institution name="Grinnell College" />
 78      <emailaddress>walker@grinnell.edu</emailaddress>
 79    </participant>
 80  </tutorialRoster>

Display this file -- right-click this link and select “Save Target As...” from the popup menu to download this code

To download file the linked file tutorialRoster.xsl (see below), right-click HERE and select “Save Target As...” from the popup menu

tutorialRoster.xsl

 88  <?xml version="1.0" ?>
 89  
 90  <!--
 91    tutorialRoster.xsl
 92    Jesse M. Heines, UMass Lowell Computer Science, heines@cs.uml.edu
 93    for ITiCSE XML and XSL Tutorial, Thessaloniki, Greece
 94    Copyright (c) 2003 by Jesse M. Heines.  All rights reserved, but may be freely 
 95      copied or extracted from for educational purposes with credit to the author.
 96    updated by JMH on June 18, 2003 at 02:21 PM
 97  -->
 98  
 99  <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
100  
101  
102  <!-- main template -->
103  
104  <xsl:template match="/">
105    <html>
106      <body>
107        <h1><xsl:value-of select="tutorialRoster/particulars/title" /></h1>
108        <table>
109          <xsl:apply-templates select="tutorialRoster/participant" />
110        </table>
111      </body>
112    </html>
113  </xsl:template>
114  
115  
116  <!-- template executed once for each participant -->
117  
118  <xsl:template match="participant">
119    <tr>
120      <td><xsl:value-of select="name/@last" />, <xsl:value-of select="name/@first" /></td>
121      <td>&#160;&#160;&#160;&#160;&#160;</td>
122      <td><xsl:value-of select="institution/@name" /></td>
123      <td>&#160;&#160;&#160;&#160;&#160;</td>
124      <td><a href="mailto:{emailaddress}"><xsl:value-of select="emailaddress" /></a></td>
125    </tr>
126  </xsl:template>
127  
128  
129  </xsl:stylesheet>

To download this file, right-click HERE and select “Save Target As...” from the popup menu

 1  <html>
 2  <!--
 3    minimum.jsp - code to apply an XSL file to an XML file on the server side
 4      adapted from xalan-j_2_3_1\samples\SimpleTransform\SimpleTransform.java
 5      download Xalan-Java from http://xml.apache.org/xalan-j free of charge
 6    Jesse M. Heines, UMass Lowell Computer Science, heines@cs.uml.edu
 7    Copyright (c) 2003 by Jesse M. Heines.  All rights reserved, but may be freely 
 8      copied or extracted from for educational purposes with credit to the author.
 9    updated by JMH on June 18, 2003 at 05:01 PM
10  -->
11  
12  <%@ page import="java.io.*" %>                    <!-- for StringWriter                    -->
13  <%@ page import="javax.xml.transform.*" %>        <!-- for Transformer, TransformerFactory -->
14                                                    <!--    and TransformerException         -->
15  <%@ page import="javax.xml.transform.stream.*" %> <!-- for StreamSource and StreamResult   -->
16    
17  <head>
18  <%!
19    /** Apply an XSL file to an XML file and return the results as a String.
20     *  @param  strXMLfile  String containing full URL to the XML file 
21     *  @param  strXSLfile  String containing full URL to the XSL file 
22     *  @return String containing the output of the transformation
23     */
24    String ApplyXSL( String strXMLfile, String strXSLfile )
25    {
26      // StringWriter is a child of java.io.Writer and can therefore be 
27      // used as an argument to a StreamResult constructor, which is 
28      // required by Transformer.transform().
29      StringWriter swResult = new StringWriter() ;
30    
31      try {
32        // Use the static TransformerFactory.newInstance() method to instantiate
33        // a TransformerFactory. The javax.xml.transform.TransformerFactory
34        // system property setting determines the actual class to instantiate --
35        // org.apache.xalan.transformer.TransformerImpl.
36  
37        TransformerFactory tFactory = TransformerFactory.newInstance();
38    
39        // Use the TransformerFactory to instantiate a Transformer that will work
40        // with the stylesheet you specify. This method call also processes the 
41        // stylesheet into a compiled Templates object.
42  
43        Transformer transformer = 
44            tFactory.newTransformer( new StreamSource( strXSLfile ) ) ;
45    
46        // Use the Transformer to apply the associated Templates object to an XML 
47        // document (foo.xml) and write the output to a file (foo.out).
48  
49        transformer.transform( new StreamSource( strXMLfile ),
50                               new StreamResult( swResult ) ) ;
51  
52        // Return the result.
53        return swResult.toString() ;
54  
55      } catch ( TransformerConfigurationException tfce ) {
56        return tfce.toString() ;
57  
58      } catch ( TransformerException tfe ) {
59        return tfe.toString() ;
60      }
61    }
62  %>
63  </head>
64  
65  <body>
66  <%
67    // This code assumes that the XML and XSL files reside in the same directory
68    // as this JSP.  Those file names are hard-code here, but they could be passed
69    // as parameters from an HTML form or via some other such technique.
70    String strXMLfilename = "tutorialRoster.xml" ;  // replace with your XML file name
71    String strXSLfilename = "tutorialRoster.xsl" ;  // replace with your XSL file name
72    
73    // We need to construct a full URL to the XML and XSL files, including the
74    // "http://" protocol specification, server name, and server port number (if 
75    // it's not the default of 80).  The following code accomplishes this.
76    String strFullPath = "http://" + request.getServerName() ;
77    if ( request.getServerPort() != 80 ) 
78      strFullPath += ":" + request.getServerPort() ;
79  
80    // We then add the full path to this JSP and finally strip off this JSP's file 
81    // name and extension that follow the last forward slash (/).
82    strFullPath += request.getRequestURI() ;
83    strFullPath = strFullPath.substring( 0, strFullPath.lastIndexOf( "/" ) + 1 ) ;
84  
85    // We append the XML and XSL file names to the full path to pass them to our
86    // ApplyXSL method, which applies the XSL file to the XML file and returns the 
87    // result as a string.  Printing that String shows the result in the browser.
88    out.println( ApplyXSL( strFullPath + strXMLfilename,
89                           strFullPath + strXSLfilename ) ) ;
90  %>
91  </body>
92  </html>

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  1  <html>
  2  <!--
  3    onthefly.jsp - JSP code to apply an XSL document stored in a String to an XML file
  4      adapted from xalan-j_2_3_1\samples\SimpleTransform\SimpleTransform.java
  5      download Xalan-Java from http://xml.apache.org/xalan-j free of charge
  6    Jesse M. Heines, UMass Lowell Computer Science, heines@cs.uml.edu
  7    Copyright (c) 2003 by Jesse M. Heines.  All rights reserved, but may be freely
  8      copied or extracted from for educational purposes with credit to the author.
  9    updated by JMH on June 18, 2003 at 09:23 PM
 10  -->
 11  
 12  <%@ page import="java.io.*" %>                    <!-- for StringWriter                    -->
 13  <%@ page import="javax.xml.transform.*" %>        <!-- for Transformer, TransformerFactory -->
 14                                                    <!--    and TransformerException         -->
 15  <%@ page import="javax.xml.transform.stream.*" %> <!-- for StreamSource and StreamResult   -->
 16  
 17  <head>
 18  <%!
 19    /** Apply an XSL String to an XML file and return the results as a String.
 20     *  @param  strXMLfile    String containing full URL to the XML file
 21     *  @param  strXSLstring  String XSL to be applied
 22     *  @return String containing the output of the transformation
 23     */
 24    String ApplyXSLstring( String strXMLfile, String strXSLstring )
 25    {
 26      return ApplyXSLstring( strXMLfile, strXSLstring, null ) ;
 27    }
 28  
 29  
 30    /** Apply an XSL String to an XML file and return the results as a String.
 31     *  @param  strXMLfile    String containing full URL to the XML file
 32     *  @param  strXSLstring  String XSL to be applied
 33     *  @param  arrParams     2D array of parameter name and value Strings
 34     *  @return String containing the output of the transformation
 35     */
 36    String ApplyXSLstring( String strXMLfile, String strXSLstring, String[][] arrParams )
 37    {
 38      StringWriter swResult = new StringWriter() ;
 39  
 40      try {
 41        // Use the static TransformerFactory.newInstance() method to instantiate
 42        // a TransformerFactory.
 43        TransformerFactory tFactory = TransformerFactory.newInstance();
 44  
 45        // Use the TransformerFactory to instantiate a Transformer that will work
 46        // with the stylesheet you specify.
 47        Transformer transformer =
 48            tFactory.newTransformer( new StreamSource( new StringReader( strXSLstring ) ) ) ;
 49  
 50        // Set parameters to pass to the top level of the XSL file
 51        if ( arrParams != null )
 52          for ( int k = 0 ; k < arrParams.length ; k++ )
 53            transformer.setParameter( arrParams[k][0], arrParams[k][1] ) ;
 54  
 55        // Use the Transformer to apply the associated Templates object to an XML
 56        // document (foo.xml) and write the output to a file (foo.out).
 57        transformer.transform( new StreamSource( strXMLfile ), 
 58                               new StreamResult( swResult ) ) ;
 59  
 60        // Return the result
 61        return swResult.toString() ;
 62  
 63      } catch ( TransformerConfigurationException tfce ) {
 64        return tfce.toString() ;
 65  
 66      } catch ( TransformerException tfe ) {
 67        return tfe.toString() ;
 68      }
 69    }
 70  %>
 71  </head>
 72  
 73  <body>
 74  <%
 75    // show date and time from server side to verify that page has loaded
 76    out.println( "<p><i>Server Side Time Stamp:</i>  " +
 77                 ( new java.util.Date() ) + "</p>" ) ;
 78  
 79    // This code assumes that the XML and XSL files reside in the same directory
 80    // as this JSP.  Those file names are hard-code here, but they could be passed
 81    // as parameters from an HTML form or via some other such technique.
 82    String strXMLfilename = "tutorialRoster.xml" ;  // replace with your XML file name
 83  
 84    // We need to construct a full URL to the XML and XSL files, including the
 85    // "http://" protocol specification, server name, and server port number (if
 86    // it's not the default of 80).  The following code accomplishes this.
 87    String strFullPath = "http://" + request.getServerName() ;
 88    if ( request.getServerPort() != 80 )
 89      strFullPath += ":" + request.getServerPort() ;
 90  
 91    // We then add the full path to this JSP and finally strip off this JSP's file
 92    // name and extension that follow the last forward slash (/).
 93    strFullPath += request.getRequestURI() ;
 94    strFullPath = strFullPath.substring( 0, strFullPath.lastIndexOf( "/" ) + 1 ) ;
 95  
 96    // construct the XSL file as a string
 97    // note that single quotes can be used to quote attributes inside the double quotes
 98    //    that delimit the Java String constants
 99    String strXSLstring =
100        "<?xml version='1.0' ?>" +
101        "<xsl:stylesheet version='1.0' xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>" +
102        "  <xsl:template match='/'>" +
103        // replace the next statement with one appropriate to your own XML file
104        "    <xsl:value-of select='tutorialRoster/particulars/location' />" +
105        "  </xsl:template>" +
106        "</xsl:stylesheet>" ;
107  
108    // We append the XML file name to the full path to pass it to our ApplyXSLstring
109    // method, which applies the XSL String to the XML file and returns the result as 
110    // a String.  Printing that String shows the result in the browser.
111    out.println( "<p><i>XSL Result:</i>  " +
112                 ApplyXSLstring( strFullPath + strXMLfilename, strXSLstring ) ) ;
113  %>
114  </body>
115  </html>

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xsl_query.jsp

Replace the lines in bold red type with ones appropriate to your own XML file

  9  <html>
 10  <!--
 11    XSL Query Starter Code for Final 91.513 Assignment
 12    Jesse M. Heines, UMass Lowell Computer Science, heines@cs.uml.edu
 13    updated by JMH on June 20, 2003 at 09:56 AM
 14  -->
 15  <head>
 16    <title>XSL Query Starter Code</title>
 17    
 18  <%!
 19    /** name of XML file to process on the server */
 20    String strXMLFileName ;
 21    
 22    /** full path to the XML file to process on the server */
 23    String strRealXMLFilePath ;
 24  %>
 25    
 26    <%-- include XSL functions defined in an external file --%>
 27    <%@ include file="xsl_functions.jsp" %>
 28  </head>
 29  
 30  <body>
 31  <%
 32    // set main variables here so that they are reinitialized in each independent run
 33    strXMLFileName = "tutorialRoster.xml" ;  // replace with your XML file name
 34    strRealXMLFilePath = getRealPath( application, request ) + strXMLFileName ;
 35    
 36    // extract a single piece of data from the XML file
 37    String strTutorialTitle =     // replace with an XPath appropriate to your XML file
 38        getElementContentFromXML( strRealXMLFilePath, 
 39                                  "tutorialRoster/particulars/title" ) ;
 40    
 41    // extract another single piece of data from the XML file
 42    String strTutorialLocation =  // replace with an XPath appropriate to your XML file
 43        getElementContentFromXML( strRealXMLFilePath, 
 44                                  "tutorialRoster/particulars/location" ) ;
 45    
 46    // extract multiple pieces of data from the XML file
 47    String strXPath = "//participant/name/@last[starts-with( . , 'P' )]" ;  // replace
 48    String[] arrStudents = 
 49        getMultipleElementContentFromXML( strRealXMLFilePath, strXPath ) ;
 50  %>
 51    
 52    <h2>  <!-- copy document title to page header -->
 53      <script type="text/javascript"><!--
 54        document.writeln( document.title ) ;
 55      --></script>
 56    </h2>
 57  
 58    <!-- show time stamps to verify reloading -->
 59    <%
 60      // show date and time from server side to verify that page has loaded
 61      out.println( "<p><i>Server Side Time Stamp:</i>  " + ( new java.util.Date() ) + "<br/>" ) ;
 62    %>
 63    <script type="text/javascript"><!--
 64      // show date and time from client side to verify that page has loaded
 65      document.writeln( "<i>Client Side Time Stamp:</i>  " + new Date() + "</p>" ) ;
 66    --></script>
 67    
 68    <!-- show the full path to the XML file -->
 69    <p>The full path to the XML file on the server is:<br/>
 70       <b><%= strRealXMLFilePath %></b></p>
 71    
 72    <!-- show single data items extracted from the XML file -->
 73    <p>The XML file indicates that the title and location of this tutorial are:<br/>
 74       <b><%= strTutorialTitle %><br/>
 75       <%= strTutorialLocation %></b></p>
 76  
 77    <!-- show multiple data items extracted from the XML file -->
 78    <p>Querying the course roster with the XPath:</p>
 79    <blockquote>
 80      <code><b><%= strXPath %></b></code>
 81    </blockquote>
 82    <p>returns:<br/>
 83      <ol>
 84        <%
 85          for ( int k = 0 ; k < arrStudents.length ; k++ )
 86            out.println( "<li>" + arrStudents[ k ] + "</li>" ) ;
 87        %>
 88      </ol>
 89    </p>
 90  
 91    <p><a href="xsl_query_jsp-listing.htm">View Source</a></p>
 92    
 93    <p>XML File Listing:</p>
 94    
 95    <%= getXMLListing( strRealXMLFilePath ) %>
 96  
 97  </body>
 98  </html>

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To download file the included file xsl_functions.jsp (see below), right-click HERE and select “Save Target As...” from the popup menu

xsl_functions.jsp

106  <%--
107    XSL Helper Functions for Applying XSL Strings to XML Files
108    Jesse M. Heines, UMass Lowell Computer Science, heines@cs.uml.edu
109    updated by JMH on June 18, 2003 at 09:12 PM
110  --%>
111  
112  <%@ page import="java.io.*" %>                      <%-- for StringWriter and File    --%>
113  <%@ page import="java.util.*" %>                    <%-- for StringTokenizer          --%>
114  <%@ page import="javax.xml.transform.*" %>          <%-- for Transformer classes      --%>
115  <%@ page import="javax.xml.transform.stream.*" %>   <%-- for some XSL transformations --%>
116  <%@ page import="org.apache.xml.serialize.*" %>     <%-- for OutputFormat             --%>
117  <%@ page import="org.w3c.dom.*" %>                  <%-- for Document                 --%>
118  <%@ page import="org.apache.xerces.parsers.*" %>    <%-- for DOMParser and SAXParser  --%>
119  <%@ page import="java.awt.*, javax.swing.*" %>      <%-- for debugging windows        --%>
120  
121  <%!
122    /** This function can be used for debugging to display messages in a simple dialog box.
123     *  Note that it only works on a Windows-based server, not a Unix-based one.
124     *  @param  str  string to display
125     */
126    public void show( String str )
127    {
128      JOptionPane.showMessageDialog( null, str,
129          "Debugging Information", JOptionPane.INFORMATION_MESSAGE ) ;
130    }
131  
132    
133    /** This function returns the real path to the directory containing currently running JSP.
134     *  @param  application  the standard application object
135     *  @param  request      the standard request object
136     *  @return String containing the real path in the current OS's format with a "/" appended
137     */
138    public String getRealPath(
139        ServletContext application,   // the standard application object
140        HttpServletRequest request    // the standard request object
141      )
142    {
143      // use request and application objects to get the real path on the server
144      String strRealPath = request.getServletPath() ;
145      strRealPath = strRealPath.substring( 0, strRealPath.lastIndexOf( "/" ) ) ;
146      strRealPath = application.getRealPath( strRealPath ) ;
147  
148      // append the approprate slash for the server's operating system
149      strRealPath += System.getProperty( "file.separator" ) ;
150      
151      // return the result
152      return strRealPath ;
153    }
154  
155  
156    /** Apply an XPath String to an XML file and return the results as a String.
157     *  @param  strXMLfile    String containing full URL to the XML file 
158     *  @param  strXSLstring  String XSL to be applied
159     *  @return String containing the output of the transformation
160     */
161    String ApplyXSLstring( String strXMLfile, String strXSLstring )
162    {
163      return ApplyXSLstring( strXMLfile, strXSLstring, null ) ;
164    }
165  
166  
167    /** Apply an XSL String to an XML file and return the results as a String.
168     *  @param  strXMLfile    String containing full URL to the XML file 
169     *  @param  strXSLstring  String XSL to be applied
170     *  @param  arrParams     2D array of parameter name and value Strings
171     *  @return String containing the output of the transformation
172     */
173    String ApplyXSLstring( String strXMLfile, String strXSLstring, String[][] arrParams )
174    {
175      StringWriter swResult = new StringWriter() ;
176      
177      try {
178        // Use the static TransformerFactory.newInstance() method to get a reference to 
179        // a TransformerFactory
180        TransformerFactory tFactory = TransformerFactory.newInstance();
181    
182        // Use the TransformerFactory to instantiate a Transformer that will work
183        // with the stylesheet you specify
184        Transformer transformer = 
185            tFactory.newTransformer( new StreamSource( new StringReader( strXSLstring ) ) ) ;
186    
187        // Set parameters to pass to the top level of the XSL file
188        if ( arrParams != null )
189          for ( int k = 0 ; k < arrParams.length ; k++ )
190            transformer.setParameter( arrParams[k][0], arrParams[k][1] ) ;
191  
192        // Use the Transformer to apply the associated XSL file to an XML document and write 
193        // the output to an output stream
194        transformer.transform( new StreamSource( strXMLfile ),
195                               new StreamResult( swResult ) ) ;
196  
197        // Return the result
198        return swResult.toString() ;
199  
200      } catch ( TransformerConfigurationException tfce ) {
201        return tfce.toString() ;
202  
203      } catch ( TransformerException tfe ) {
204        return tfe.toString() ;
205      }
206    }
207  
208  
209    /** Extract element content from a specified XML file given an XPath.
210     *  @param  strXMLFile  name of XML file from which to extract data
211     *  @param  strXPath    XPath to data to extract
212     *  @return String element content
213     */
214    String getElementContentFromXML( String strXMLFile, String strXPath )
215    {
216      // convert single quotes to double quotes to allow both to be in XPath filters
217      strXPath = strXPath.replaceAll( "'", "\"" ) ;
218      
219      // query result to be returned to calling function
220      String strResult = ApplyXSLstring( strXMLFile, 
221          "<?xml version='1.0' ?>" +
222          "<xsl:stylesheet version='1.0' " +
223          "         xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>" +
224          "  <xsl:template match='/'>" +
225          "    <xsl:value-of select='" + strXPath + "' />" +
226          "  </xsl:template>" +
227          "</xsl:stylesheet>" ) ;
228  
229      // remove initial directive (ending with ">") and remove leading and trailing white space
230      strResult = strResult.substring( strResult.indexOf( ">" ) + 1 ).trim() ;
231      
232      return strResult ;  // return final result
233    }
234  
235  
236    /** Extract content from multiple elements from an XML file given an XPath.
237     *  @param  strXMLFile    name of XML file from which to extract data
238     *  @param  strXPath      XPath to data to extract
239     *  @return String array containing multiple element content
240     */
241    String[] getMultipleElementContentFromXML( String strXMLFile, String strXPath )
242    {
243      // convert single quotes to double quotes to allow both to be in XPath filters
244      strXPath = strXPath.replaceAll( "'", "\"" ) ;
245      
246      // string to delimit multiple results for subsequent tokenizing
247      String strDelimiter = "|" ;
248  
249      // query result to be returned to calling function
250      String strResult = ApplyXSLstring( strXMLFile, 
251          "<?xml version='1.0' ?>\n" +
252          "<xsl:stylesheet version='1.0' xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>\n" +
253          "  <xsl:template match='/'>\n" +
254          "    <xsl:apply-templates select='" + strXPath + "' />\n" +
255          "  </xsl:template>\n" +
256          "  <xsl:template match='" + strXPath + "'>\n" +
257          "    " + strDelimiter + "<xsl:value-of select='.' />" + 
258          "  </xsl:template>\n" +
259          "</xsl:stylesheet>\n" ) ;
260          
261      // remove initial directive (ending with ">") and remove leading and trailing white space
262      strResult = strResult.substring( strResult.indexOf( ">" ) + 1 ).trim() ;
263      
264      // break result into tokens with which to populate array to be returned
265      StringTokenizer st = new StringTokenizer( strResult, strDelimiter ) ;
266  
267      // populate array to be returned with the results found
268      String[] strArrayResult = new String[ st.countTokens() ] ;
269      for ( int k = 0 ; st.hasMoreTokens() ; k++ )
270        strArrayResult[ k ] = st.nextToken().trim() ;
271        
272      return strArrayResult ;  // return final result
273    }
274  
275  
276    /** Return a String containing an XML file in serialized form.
277     *  @param  strXMLFile    name of XML file from which to extract data
278     *  @return String the XML file in serialized form
279     */
280    String getXMLListing( String strXMLFile )
281    {
282      // open XML file
283      Document doc = null ;                     // the XML document in the specified file
284      File fileXML = new File( strXMLFile ) ;   // the File object for the XML file to open
285      if ( ! fileXML.exists() )
286        return "File " + strXMLFile + " does not exist." ;
287      else
288      {
289        // instantiate the XML parser
290        DOMParser parser = new DOMParser() ;
291    
292        try {      // inherited from class XMLParser
293          parser.parse( strXMLFile ) ;
294        } catch ( IOException e ) {
295            return "<p>XML File Load Error:  " + e.toString() + "</p>" ;
296        } catch ( org.xml.sax.SAXException e ) {
297            return "<p>XML File Parsing Error:  " + e.toString() + "</p>" ;
298        } catch ( Exception e ) {
299            return "<p>Undetermined Error:  " + e.toString() + "</p>" ;
300        }
301        
302        doc = parser.getDocument() ;
303      }
304  
305      // make a serializable version of the XML Document object
306      // reference:  www-106.ibm.com/developerworks/xml/library/x-injava2/?dwzone=xml
307      OutputFormat of = new OutputFormat( doc ) ;
308      of.setIndenting( true ) ;
309      of.setIndent( 2 ) ;
310      of.setPreserveSpace( true ) ;
311      StringWriter sw = new StringWriter() ;
312        // use a StringWriter instead of serializing directly to the 
313        // ObjectOutputStream because serializing directly yields a 
314        // java.io.OptionalDataException when reading the data with 
315        // ObjectInputStream.readObject()
316      XMLSerializer xmlser = new XMLSerializer( sw, of ) ;
317      try {
318        xmlser.serialize( doc ) ;
319      } catch ( IOException ioe ) {
320         return "<p>IOException in getXMLListing:<br/>   " + ioe.toString() ;
321      }
322      
323      // format the string for HTML output
324      String strDoc = sw.toString().replaceAll( "&", "&amp;" ) ;
325      return "<pre>\n" + strDoc.replaceAll( "<", "&lt;" ) + "\n</pre>" ;
326    }
327  %>

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