XSL extensible Style Language" DOCUMENTS MULTIMEDIA! Transforming documents using! XSLT" XSLT processor" XSLT stylesheet"

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1 DOCUMENTS MULTIMEDIA! Transforming documents using! XSLT" XSL extensible Style Language"!" A family of languages for defining document transformation and presentation" XSL XSLT XSL-FO Christine Vanoirbeek" EPFL IC CGC" Bâtiment BC (Station 14)" 1015 LAUSANNE" xpath christine.vanoirbeek@epfl.ch" Documents Multimedia - Restitution de documents (XSLT) ! (2)! XSLT processor"!" XSLT allows to specify transformations from XML documents into other documents (any target formats)" XSLT stylesheet"!" XSLT is an XML application"!" Use of a namespace"!" Global structure of an XSLT file" source XML processeur XSLT règles XSLT Résultat (XML, HTML, ) <?xml version="1.0" encoding="utf-8"?> <xsl:styleheet version="1.0" xmlns:xsl=" <xsl:template match="...">... <xsl:template/>... </xsl:stylesheet/> Documents Multimedia - Restitution de documents (XSLT) ! (3)! Documents Multimedia - Restitution de documents (XSLT) ! (4)!

2 Output format <xsl:output>" Introductory example: schema "!" The element <xsl:output method="format"> specifies the target output format"!" Possible values for format are"!" xml (default value)!" html for HTML; in this case, some tags may be corrected!!" text for any textual format! ProductId Language Currency Documents Multimedia - Restitution de documents (XSLT) ! (5)! Documents Multimedia - Restitution de documents (XSLT) ! (6)! Introductory example: document instance" <?xml version="1.0" encoding="utf-8"?> Introductory example: tree representation" Root (/) <Catalog> <Product ProductId="R1"> <Book Language="FR"> <Price Currency="CHF">79</Price> <Title>XML - le langage et ses applications </Title> <Authors> <Author> <FirstName>Alain</FirstName> <LastName>Michard</LastName> </Author> </Authors> <Publisher>Eyrolles</Publisher> <Year>1999</Year> </Book> <Product ProductId="R1"> Comment P. I. Element <! edited <?xml-style (Catalog) Element Element (Product) (Product) Attribute Element (ProductId) (Book) Attribute Element (Language) (Price) Documents Multimedia - Restitution de documents (XSLT) ! (7)! Documents Multimedia - Restitution de documents (XSLT) ! (8)!

Types of nodes" Example: a first stylesheet"!" XSLT distinguishes between 7 types of nodes:"!" The root!!" The elements!!" The attributes!!" The text nodes!!" The comments <!--...-->!

3 Types of nodes" Example: a first stylesheet"!" XSLT distinguishes between 7 types of nodes:"!" The root!!" The elements!!" The attributes!!" The text nodes!!" The comments <! >!!" The processing instructions <?...?>!" The namespaces definitions! <xsl:stylesheet version="1.0" xmlns:xsl=" XSL/Transform"> <xsl:template match="/"> </xsl:stylesheet> Documents Multimedia - Restitution de documents (XSLT) ! (9)! Documents Multimedia - Restitution de documents (XSLT) ! (10)! XSLT processor: processing model"!" Tree traversal"!" Processing = «#generation of data from the XML source#» through application of rules"!" Rules are specified via the templates!!" Default rule! Rules <xsl:template>"!" The element <xsl:template...> specifies a transformation rule."!" The attribute match=" " specifies the nodes the rule applies"!" For instance, "/" means the root of the document!!" xsl:template content specifies the output data to be generated"!" text (potentially structured)! " " Documents Multimedia - Restitution de documents (XSLT) ! (11)! Documents Multimedia - Restitution de documents (XSLT) ! (12)!

4 Example 2: catalog-flow.xsl! <xsl:stylesheet version="1.0" xmlns:xsl=" XSL/Transform"> <xsl:apply-templates/> Example 2: comments"!" Inside a rule, the instruction! <xsl:apply-templates...>! generates the application of rules in a recursive way"!" Applied on the elements!!" Default behaviour"!" Copy of the content! </xsl:stylesheet> Documents Multimedia - Restitution de documents (XSLT) ! (13)! Documents Multimedia - Restitution de documents (XSLT) ! (14)! Example 3: catalog-better-flow.xsl! Example 3: comments"!" Use of several rules" <xsl:template match="/"> <UL> <xsl:apply-templates/> </UL> <xsl:template match ="Product"> <LI> <xsl:apply-templates/> </LI>!" The match attribute specifies the nodes concerned by the rule"!" Examples: «#/#» (root) et «#Product#» (the Product element)!!" Use of ypath!!" All the rules are candidate rules" Documents Multimedia - Restitution de documents (XSLT) ! (15)! Documents Multimedia - Restitution de documents (XSLT) ! (16)!

5 Example 4: only-titles.xsl! <xsl:template match="/"> <UL> <xsl:apply-templates select=".//product/*/title"/> </UL> Example 4: comments"!" The select attribute, associated to the applytemplates element specifies the nodes to be processed"!" Example: «#.//Product/*/Title»!!" The path is specified accordingly to the context node" <xsl:template match ="Product/*/Title"> <LI> <xsl:value-of select="."/> </LI> Documents Multimedia - Restitution de documents (XSLT) ! (17)! Documents Multimedia - Restitution de documents (XSLT) ! (18)! Example 4: comments"!" The value-of instruction generates the text content of an element or an attribute, specified by select (XPath expresion)!" "." current element!!" "elt" child element!!" "@attr" attribute!!" Important remark:"!" Only the first occurrence is copied!! Example 5: simple-table.xsl! <xsl:template match="/"> <TABLE border="1"> <TR> <TH>Année</TH> <TH>Auteurs ou Editeurs</TH> <TH>Titre</TH> </TR> <xsl:apply-templates select=".//product"/> </TABLE> <TR> <TD><xsl:apply-templates select=".//year"/></td> <TD><xsl:apply-templates select=".//author.//editor"/></td> <TD><xsl:apply-templates select=".//title"/></td> </TR> <xsl:template match="author Editor Title Year"> <xsl:value-of select="."/><br/> Documents Multimedia - Restitution de documents (XSLT) ! (19)! Documents Multimedia - Restitution de documents (XSLT) ! (20)!

6 Example 5: comments "!" apply-templates instructions modify the default tree traversal performed by the XSLT processor "!" The attribute value of the «#match#» attribute of the last rule is an expression that uses the OR construct «# #»"!" Author Editor Title Year!!" This means that the same rule applies to each mentionned element name! Example 6: titles-and-language.xsl! <UL> <xsl:apply-templates select="product"/> </UL> <xsl:template match ="Product"> <LI> <xsl:value-of select="./*/title"/> <xsl:text> ( </xsl:text> <xsl:value-of select="./*/@language"/> <xsl:text> ) </xsl:text> </LI> Documents Multimedia - Restitution de documents (XSLT) ! (21)! Documents Multimedia - Restitution de documents (XSLT) ! (22)! Example 6: comments"!" The element <xsl:text> allows to generate text"!" Its content is the text value!!" Unlike text which is directly inserte, text generated by <xsl:text> "!" Keeps spaces!!" Does not interpret entities (such as &) in the output!!" The attribute disable-output-escaping="yes" allows to interpret entities in the output" Summary"!" An XSLT specification is a set of rules (<xsl:template> )"!" The match attribute indicates nodes for which the rule applies!!" The content of the element <xsl:template> specifies what must be generated in the output file; the elements that belong to the XSLT namespace are interpreted as instructions of the language, the others are simply copied.!!" The instruction <xsl:apply-templates> applies rules over the list of nodes specified using its select attribute"!" The instruction <xsl:value-of> allows to generate in the output file the content of a node from the input file"!" The instruction <xsl:text> allows to generate text in the output file, in a controled manner" Documents Multimedia - Restitution de documents (XSLT) ! (23)! Documents Multimedia - Restitution de documents (XSLT) ! (24)!

7 Example 6: sorted-catalog.xsl! <xsl:apply-templates select="./product"> <xsl:sort order="ascending" select="./*/title"/> </xsl:apply-templates> <P> <xsl:value-of select="./*/title"/> <xsl:text> - </xsl:text> <xsl:value-of select="./*/price"/> <xsl:text> </xsl:text> <xsl:value-of select="./*/price/@currency"/> </P> Example 6: comments"!" The element <xsl:sort>, that may occur in" <xsl:apply-templates> <xsl:for-each> " allows to sort elements"!" The attribute select="xpath" determines the elements that are going to be sorted!!" By default the sort follows the ascending alphabet order!!" The attribute order="descending" allows to reverse the sorting order!!" The attribute data-types="number" allows to modify the type of the considered data (default value is text)! Documents Multimedia - Restitution de documents (XSLT) ! (25)! Documents Multimedia - Restitution de documents (XSLT) ! (26)! Example 7: use-of-mode.xsl! <xsl:apply-templates mode ="toc" select=".//title"/> <H1>Details</H1> <xsl:apply-templates select="./product"/> <P> <xsl:apply-templates select="./*/title"/> <xsl:apply-templates select="./*/price"/> </P> <xsl:template match="price"> <I><xsl:value-of select="."/></i> Example 7: comments"!" If several distinct rules must be applied to the same source element in different contexts, we can use the mode attribute!" example: presentation of titles in the table of contents and in the detailed content!!" A rule <xsl:template... mode="name"> will only be applied in the context defined by! <xsl:apply-template... mode="name"> " <xsl:template match="price"> <xsl:template match="title" mode="toc"> <P><B><xsl:value-of select="."/></b></p> Documents Multimedia - Restitution de documents (XSLT) ! (27)! Documents Multimedia - Restitution de documents (XSLT) ! (28)!

8 Example 8: use-of-each.xsl! Example 8: comments"!" For performing iterations we can use <xsl:for-each> " <xsl:apply-templates select="./product"/> <P> <xsl:for-each select=".//author.//editor"> <I><xsl:value-of select="."/></i><br/> </xsl:for-each> <xsl:value-of select="./*/title"/> </P>!" The attribute select="xpath" determines the set of nodes to be processed"!" The same result can be achieved using <xsl:applytemplate>!!! Documents Multimedia - Restitution de documents (XSLT) ! (29)! Documents Multimedia - Restitution de documents (XSLT) ! (30)! Example 9: use-of-if.xsl! <UL> <xsl:apply-templates/> </UL> <P> <xsl:value-of select="./*/title"/> <xsl:if test="./*/@language='en'"> <B>(en anglais)</b> </xsl:if> </P> Example 9: comments"!" The element <xsl:if test="expr"> allows to generate output in a conditional manner"!" The evaluation of the (boolean) expression expr determines whether the output is generated or not!!" The element <xsl:choose> contains the elements:"!" <xsl:when test="expr">!!" <xsl:otherwise>! this allows to express conditional processing for several cases! Documents Multimedia - Restitution de documents (XSLT) ! (31)! Documents Multimedia - Restitution de documents (XSLT) ! (32)!

Today$s Outline - Pierre Geneves! Recall: basic principle of the XSLT execution model"!" More on XSLT"!" Rapid recall of the execution model!!" Some advanced techniques!

9 Today$s Outline - Pierre Geneves! Recall: basic principle of the XSLT execution model"!" More on XSLT"!" Rapid recall of the execution model!!" Some advanced techniques!!" A specific insight on the XSLT sublanguage used for selecting nodes from an XML document: XPath"!" Questions?" Documents Multimedia - Restitution de documents (XSLT) ! (33)! Documents Multimedia - Restitution de documents (XSLT) ! (34)! Example 10: generate-structured-doc.xsl! <STYLE TYPE="text/css"> p.ouvrage { margin: 2em; color: blue; font-size: 120%; } </STYLE > <BODY BGCOLOR="#FFFFCC"> <xsl:apply-templates select="./product"/> <xsl:element name="p"> <xsl:attribute name="class">ouvrage</xsl:attribute> <xsl:value-of select="./*/title"/> </xsl:element> Example 10: comments"!" The element <xsl:element> allows to generate an output element"!" The attribute name sets its name!!" This construct is useful for creating elements dynamically (for instance if the output element name depends on a source attribute)! <xsl:template match="..."> <xsl:element name="{@attr}">  </xsl:element> <xsl:template/>!" The element <xsl:attribute> allows to generate an attribute associated with the current element in the output "!" the attribute name sets its name!!" The content defines its value! Documents Multimedia - Restitution de documents (XSLT) ! (35)! Documents Multimedia - Restitution de documents (XSLT) ! (36)!

10 Example 11: use-of-copy.xsl! Example 11: comments"!" The element <xsl:copy> copies the current element" <xsl:element name="customizedcatalog"> <xsl:apply-templates = 'EN']"/> </xsl:element>!" The content of <xsl:copy> behaves like a rule (template)!!" The element <xsl:copy-of select="xpath"> allows to copy the specified sub-elements" <xsl:template match="book"> <xsl:copy-of select="."/> Documents Multimedia - Restitution de documents (XSLT) ! (37)! Documents Multimedia - Restitution de documents (XSLT) ! (38)! The Identity Transformation"!" The following stylesheet defines the identity transformation" <?xml version="1.0"?> <xsl:stylesheet version="1.0 xmlns:xsl=" <xsl:template match="@* node()"> <xsl:copy> <xsl:apply-templates select="@* node()"/> </xsl:copy> Generating Processing Instructions and Comments"!" Processing Instructions: the element <xsl:processing-instruction> allows to generate an XML instruction"!" The name attribute specifies the name of the instruction!!" The content of the element defines the other parameters!!" Comments: the element <xsl:comment> allows to generate an XML comment"!" The content of the element defines the content of the comment! </xsl:stylesheet> Documents Multimedia - Restitution de documents (XSLT) ! (39)! Documents Multimedia - Restitution de documents (XSLT) ! (40)!

11 XPath"!" A W3C recommendation"!" A path language for expressing node selection in an XML document"!" XPath is used in XSLT for specifying the value of the following attributes:" 1."match in <xsl:template> $" the template rule applies to nodes that match the XPath expression 2."select in <xsl:apply-templates>, <xsl:value-of>, <xsl:for-each>, <xsl:copy-of>, <xsl:sort> $" the evaluation of an XPath expression selects a set of nodes (elements or attributes) Sample Expressions for the match Attribute (1)"!" / : denotes the root of the document"!". : the current node (for which the rule applies)"!" e : an element <e>!" * : any element"!" f/e : an element <e> which is child of <f>!" f//e : an element <e> descendant of : an attribute a!" x y : either x or y!" e[s]: an element e which has a child s!" e[n] (where n is a number): the n-th element <e> Documents Multimedia - Restitution de documents (XSLT) ! (41)! Documents Multimedia - Restitution de documents (XSLT) ! (42)! Sample Expressions for the match Attribute (2)"!" e[f='v']: an element e whose child element f has value v"!" e[@a='v']: an element e whose attribute a has value v"!" id('v'): the (unique) element whose attribute ID="v"!" text(): a text pseudo-element"!" comment(): a comment"!" processing-instruction(): an instruction "!" processing-instruction("name") a specific instruction name"!" node(): a node (other than root or attribute)" XPath Expressions in select Attributes (1)"!!" From the context node, the expression returns a set of nodes"!" e : all elements <e> which are children of the current context node!!" XPath defines 13 axes for navigation:"!" self!!" child!!" descendant!!" descendant-or-self!!" parent!!" ancestor!!" ancestor-or-self!!" preceding-sibling!!" following-sibling!!" preceding!!" following!!" attribute!!" namespace!!" One may indicate the axis along which! we want to move:! axis::e!" When omitted, default axis is child" Documents Multimedia - Restitution de documents (XSLT) ! (43)! Documents Multimedia - Restitution de documents (XSLT) ! (44)!

12 XPath Expressions in select Attributes (2)"!" Example XPath Expressions in select Attributes (3)"!" Navigation steps can be composed, e.g.: company division department section member department section member member department section an ancestor a parent a preceding-sibling self a child a descendant a following-sibling!" At each step, nodes can be filtered, e.g child::e[child::f] Documents Multimedia - Restitution de documents (XSLT) ! (45)! Documents Multimedia - Restitution de documents (XSLT) ! (46)! Abbreviated Syntax"!" The following expressions are abbreviations"!" elt is equivalent to is equivalent to attribute::attr!!". is equivalent to self::node()!!".. is equivalent to parent::node()!!" // is equivalent to % /descendant-or-self::node()/! Other Expressions"!" XPath also allows the following operators"!" =,!=, <(<), <=(<=), >, >=!!" +, -, *, div, mod!!" and functions such as the following: (the list is nonexhaustive)"!" position(), last()!" round(e), floor(e), ceiling(), sum(e,...)!!" not(expr)!!" count(node-set)!" name(node-set), local-name(node-set)!" string-length(str), contains(sub,substr), substring(str,start,length) Documents Multimedia - Restitution de documents (XSLT) ! (47)! Documents Multimedia - Restitution de documents (XSLT) ! (48)!

13 Example 12: xpath-ancestor.xsl! <xsl:template match="/"> <TR> <TD><xsl:apply-templates select=".//year"/></td> <TD><xsl:apply-templates select=".//author.//editor"/></td> <TD><xsl:apply-templates select=".//title"/></td> </TR> <xsl:template match="author Editor Year"> <xsl:value-of select="."/><br/> <xsl:template match="title"> <xsl:value-of select="."/> <xsl:text> [ </xsl:text> <xsl:value-of select="ancestor::product/@productid"/> <xsl:text> ] </xsl:text> <BR/> Example 12: comments"!" This transformation is very similar to the one of Example 5 whose goal is to generate a table of 3 columns which respectively contain:"!" The publication year!!" The names of authors or editors!!" The title of the book!!" The difference is that here the product number is indicated, between brackets, just next to the book title"!" This information is accessed using the ancestor axis in an XPath expression! Documents Multimedia - Restitution de documents (XSLT) ! (49)! Documents Multimedia - Restitution de documents (XSLT) ! (50)! Think a moment "!" Recall XSLT execution model"!" Recall select attributes"!" Can you tell why the following example is not part of the archive?" <xsl:template match="book"> <p> <xsl:apply-templates select="."/> </p>! Example 13: xpath-last-function.xsl! <LI> <xsl:apply-templates select=".//author.//editor"/>: <xsl:value-of select="./*/title"/>. </LI> <xsl:template match="author Editor"> <xsl:value-of select="."/> <xsl:text>, </xsl:text> <xsl:template match="author [position()=last()] Editor [position()=last()]"> <xsl:value-of select="."/> Documents Multimedia - Restitution de documents (XSLT) ! (51)! Documents Multimedia - Restitution de documents (XSLT) ! (52)!

14 Example 13: comments"!" This example illustrates the use of the functions that allow to distinguish the processing of author elements and editor elements, according to their position."!" Remark: note the priorities for template instanciation:"!" Author [position()=last()] Editor [position()=last()]! Priorities for Template Rules"!" It may happens that a node of the source document matches multiple template rules"!" In this case, the most specific rule applies"!" Formally, the computation of priorities for electing the «#most specific#» rule is described in the XSLT specification" Documents Multimedia - Restitution de documents (XSLT) ! (53)! Documents Multimedia - Restitution de documents (XSLT) ! (54)! Definition of constants"!" The element <xsl:variable name="ident"> allows to define a constant"!" The content of the element defines the constant value!!" Such a variable can then be used"!" As element content % <xsl:value-of select="$ident"/>!!" As attribute value attr="{$ident}" Named Templates"!" A rule <xsl:template> can be named using the attribute name="rule" "!" Such a rule can be then explicitly invoked from another rule (like a procedure call) using the instruction! <xsl:call-template name="rule">!" Variables may be declared globally (in <xsl:stylesheet>) or locally (in <xsl:template>)" Documents Multimedia - Restitution de documents (XSLT) ! (55)! Documents Multimedia - Restitution de documents (XSLT) ! (56)!

15 Templates with parameters"!" It is possible to pass parameters to a rule"!" In the declaration of the rule, one must define <xsl:param name="ident">!" When the rule is invoked (in <xsl:template>) we use <xsl:withparam name="ident">!" In the rule, the parameter can be accessed using $ident Documents Multimedia - Restitution de documents (XSLT) ! (57)! Example 14: template-with-param.xsl! <xsl:element name="html"> <xsl:element name="body"> <xsl:attribute name="bgcolor">#ffffcc</xsl:attribute> <xsl:call-template name ="list"> <xsl:with-param name="thetitle">liste des livres</xsl:with-param> <xsl:with-param name="theelements" select="./product[book]"/> </xsl:call-template> <xsl:call-template name ="list"> <xsl:with-param name="thetitle">liste des actes de conferences </xsl:with-param> <xsl:with-param name="theelements" select="./product[proceedings]"/> </xsl:call-template> </xsl:element> </xsl:element> <xsl:template name="list"> <xsl:param name="thetitle"/> <xsl:param name="theelements"/> <xsl:element name="h2"> <xsl:value-of select="$thetitle"/> </xsl:element> <xsl:apply-templates select="$theelements"/> <P><xsl:value-of select="./*/title"/></p> Documents Multimedia - Restitution de documents (XSLT) ! (58)! Example 14: comments"!" This example illustrates the use of templates with parameters" Importing rules"!" The element <xsl:import href="url"> allows to import the rules from an external stylesheet"!" 2 parameters are passed (title and elements)!!" Remark: note the similarity w.r.t a «#classical#» approach for calling a procedure («#declarative#» vs «#procedural#» paradigms)!!" Such importations must occur at the beginning of <xsl:stylesheet>!" The element <xsl:include href="url"> allows to insert external rules inside a stylesheet" Documents Multimedia - Restitution de documents (XSLT) ! (59)! Documents Multimedia - Restitution de documents (XSLT) ! (60)!

16 Conclusion"!" Positive Aspects"!" XSLT is a very powerful declarative language!!" It allows to rapidly define simple/complex XML structure transformations!!" The language is functional (no side-effects)!!" XSLT processors exist and work very well!!" XSLT has contributed to the success and wide adoption of XML!!" Negative Aspects"!" The XSLT specification is quite long and complex (97 pages in english)!!" The language is hybrid (declarative and procedural)!!" There is currently no tool for helping the design, verification or maintenance of complex stylesheets!!" The language does not provide any static guarantee that the result of an XSLT stylesheet will be valid w.r.t a given output XML schema/dtd! $" the bad news: you have to be careful when developing as you are responsible $" the good news: you can earn a Ph.D. by designing such a tool " XSLT tools"!" There are many XSLT processors, commercial or opensource"!" For instance: Xalan ( An XSLT processor uses an XML parser"!" For instance Xerces ( With Xalan, the command for running a transformation looks like: java org.apache.xalan.xslt.process -in myfile.xml -xsl mytrans.xsl -out myres!" The «#XML Spy#»# editor includes an XSLT processor" Documents Multimedia - Restitution de documents (XSLT) ! (61)! Documents Multimedia - Restitution de documents (XSLT) ! (62)!

XSLT: How Do We Use It?

XSLT: How Do We Use It? Nancy Hallberg Nikki Massaro Kauffman 1 XSLT: Agenda Introduction & Terminology XSLT Walkthrough Client-Side XSLT/XHTML Server-Side XSLT/XHTML More Creative Server-Side XSLT 2 XSLT: