Outline. XML vs. HTML and Well Formed vs. Valid. XML Overview. CSC309 Tutorial --XML 4. Edward Xia

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1 CSC309 Tutorial XML Edward Xia November 7, 2003 Outline XML Overview XML DOCTYPE Element Declarations Attribute List Declarations Entity Declarations CDATA Stylesheet PI XML Namespaces A Complete Example 1 CSC309 Tutorial --XML 2 XML Overview XML vs. HTML and Well Formed vs. Valid EXtensible Markup Language (XML) XML is a simplified version of SGML (Structured Generalized Markup Language) and designed for ease of implementation. XML fundamentally separates content from presentation; HTML specifies the presentation. HTML explicitly defines a set of legal tags as well as the grammar. XML is used to describe the content of the document. XML allows any tags or grammar to be used. All XML elements must have a closing tag. XML tags are case sensitive. All elements must be properly nested. All XML documents must have a root tag. Attribute values must always be quoted. W3C home page on XML XML 1.0 specification An XML document is well-formed if it follows basic syntax rules. Every tag must have an end tag. <elementone> </elementone> <elementtwo /> All tags are completely nested (tag order cannot be mixed). An XML document is valid if its structure matches a DTD. A valid XML document must be well-formed. A well-formed document may not be valid. CSC309 Tutorial --XML 3 CSC309 Tutorial --XML 4

2 XML Components XML Prolog Prolog Defines the xml version, entity definitions, and DOCTYPE Components of the document Elements and attributes CDATA (character data) Entities Processing instructions Comments (the same as html) CSC309 Tutorial --XML 5 XML files always start with a prolog <?xml version= 1.0 encoding= UTF-8 standalone= no?> The version of XML is required The encoding identifies character set (default UTF-8) The value standalone identifies if an external document is reference for DTD or entity definition The prolog can contain entities and DTD definitions Prolog example <?xml version= 1.0 encoding= UTF-8 standalone= yes?> <DOCTYPE authors [ <!ELEMENT authors (name)*> <!ELEMENT name (firstname, lastname)> <!ELEMENT firstname (#PCDATA)> <!ELEMENT lastname (#PCDATA)> CSC309 Tutorial --XML 6 XML DOCTYPE overview XML DOCTYPE Internal DTD Document Type Declarations Specifies the location of the DTD defining the syntax and structure of elements in the document Common forms: <!DOCTYPE root [DTD <!DOCTYPE root SYSTEM URL> <!DOCTYPE root PUBLIC FPI-identifier URL> The root identifies the starting element (root element) of the document. The DTD can be external to the XML document, referenced by a SYSTEM or PUBLIC URL. SYSTEM URL refers to a private DTD located on the local file system or HTTP server PUBLIC URL refers to a DTD intended for public use. CSC309 Tutorial --XML 7 (1) <!DOCTYPE root [DTD <?xml version="1.0" encoding="utf-8" standalone="yes"?> <!DOCTYPE person [ <!ELEMENT person (name)+> CSC309 Tutorial --XML 8

3 XML DOCTYPE External - SYSTEM (2) <!DOCTYPE root SYSTEM URL> <?xml version="1.0" encoding="utf-8" standalone="no"?> <!DOCTYPE person SYSTEM "person.dtd"> or using absolute URL <?xml version="1.0" encoding="utf-8"?>  <!ELEMENT person (name)+> <!DOCTYPE person SYSTEM " CSC309 Tutorial --XML 9 XML DOCTYPE External - PUBLIC (3) <!DOCTYPE root PUBLIC FPI-identifier URL> <?xml version="1.0" encoding="utf-8" standalone="no?> <!DOCTYPE person PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN " /xhtml1-transitional.dtd"> <html> <head>public dtd</head> <body> This is an example of public dtd. </body> </html> CSC309 Tutorial --XML 10 XML DOCTYPE External & Internal (4) <!DOCTYPE root SYSTEM URL [DTD] > <?xml version="1.0" encoding="utf-8" standalone="no?> <!DOCTYPE person SYSTEM "person.dtd [<!ATTLIST person sex (male female) male >] > Element Declarations <!ELEMENT name content> content: EMPTY, ANY, (#PCDATA), mixed, elements (1) EMPTY: The element is declared to be an empty one - no content allowed. <!ELEMENT empty_element EMPTY> e.g., <empty_element /> (2) ANY: The element can have any element or character data. <!ELEMENT any_element ANY> e.g., <any_element> This is a line of characters. <other_element>... </other_element> </any_element> CSC309 Tutorial --XML 11 CSC309 Tutorial --XML 12

4 Element Declarations (cont d) (3) (#PCDATA): The content can be only character data. e.g., <first> John </first> (4) mixed: The content may contain character data and/or child elements. <!ELEMENT mix_element (#PCDATA first last)*> e.g., <mix_element> My first name is and my last name is <last>smith </last> </mix_element> CSC309 Tutorial --XML 13 Element Declarations (cont d) (5) child elements: The content can only contain the child elements (no character data). The sequence, alternative, and cardinality can be expressed using parentheses, commas(,), pipes( ) and modifiers. <!ELEMENT a (x,y,z)>: element a must have an element x, followed by y, followed by z. <!ELEMENT b (x y z)>: element b must have an element x, or y, or z. <!ELEMENT c (((x,y)+ z)*)> modifier: * stands for zero or more. + stands for one or more.? stands for zero or one. CSC309 Tutorial --XML 14 Attribute List Declarations Define which attributes may be associated with a particular element. An attribute can have a name, a type, whether optional, required or fixed, and possibly a default. <!ATTLIST element_name attribute_name attribute_type default_declaration> attribute_type string type: CDATA Enumerated type: (value1 value2 value3) Tokenized type: ID, IDREF, IDREFS, NMTOKEN, NMITOKENS, ENTITY, ENTITIES default_declaration #REQUIRED, #IMPLIED, #FIXED, value Attribute List Declarations attribute_type String type: any unparsed data <!ATTLIST student sex CDATA #IMPLIED> Enumerated type: The type explicitly states the set of possible values an attribute may take. <!ATTLIST car color (red black blue white) #REQUIRED> ID: An ID type attribute must contain an value which is unique within the XML document. IDREF: An IDREF type attribute refers to the ID type attribute of an another element in the document. It is often used to create relationships between elements. CSC309 Tutorial --XML 15 CSC309 Tutorial --XML 16

5 Attribute List Declarations default_declaration #REQUIRED: Every element must have this attribute. <!ATTLIST person id ID #REQUIRED> #IMPLIED: The attribute is optional. <!ATTLIST person salary CDATA #IMPLIED> #FIXED: The attribute must always have this value. <!ATTLIST person language CDATA #FIXED "EN">  value: The attribute may or may not appear in the element. If not, using this value. <!ATTLIST person contract (true false) 'false'> Entity Declarations Internal General Entities <?xml version="1.0" encoding="utf-8" standalone="yes"?> <!DOCTYPE person [ <!ELEMENT person ((name)+, university)> <!ELEMENT university (#PCDATA)> <!ENTITY ut "university of toronto"> <university>&ut;</university> CSC309 Tutorial --XML 17 CSC309 Tutorial --XML 18 Entity Declarations External General Entities Entity Declarations Parameter Entities <?xml version="1.0" encoding="utf-8" standalone="no"?> <!DOCTYPE person [ <!ELEMENT person ((name)+, university)> <!ELEMENT university (#PCDATA)> <!ENTITY UfT SYSTEM "ut.xml"> &UfT; File: ut.xml <university>university of Toronto</university> CSC309 Tutorial --XML 19 Parameter Entities can only be used within the DTD. Declaration: <!ENTITY % name "replacement text"> Usage: %name; e.g., <!ENTITY % week_attr "Mon Tue Wed Thu Fri Sat Sun"> <!ELEMENT day EMPTY> <!ATTLIST day today %week_attr; "Mon"> <!ENTITY anyday %week_attr;> CSC309 Tutorial --XML 20

6 Entity Declarations Predefined Entities CDATA < produces the left angle bracket < > produces the right angle bracket > & produces the ampersand & ' produces a single quote character ' " produces a double quote character " Character data in a CDATA section is not processed by the XML parser. <![CDATA [ content ] e.g., <![CDATA[ if (this->getvalue() < 3 && value[1]!=3 ) cout << "error message" ] If we don't use CDATA, we have to write as following: if (this->getvalue() < 3 && value[1]!= 3) cout << "error message" CSC309 Tutorial --XML 21 CSC309 Tutorial --XML 22 Stylesheet PI XML Namespaces (1) Associate CSS (Cascading Style Sheets): <?xml version="1.0" encoding="utf-8 standalone="no"?> <?xml-stylesheet type="text/css" href="book.css"?> <!DOCTYPE bookdatabase SYSTEM "book.dtd"> <bookdatabase>... </bookdatabase> (2) Associate XSL (extensible Stylesheet Language) <?xml version="1.0" encoding="utf-8" standalone="no"?> <?xml-stylesheet type="text/xsl" href="book.xsl"?> <!DOCTYPE bookdatabase SYSTEM "book.dtd"> <bookdatabase>... </bookdatabase> Required to avoid name collisions when many are defining their own XML applications. An XML namespaces is a collection of names, identified by a URI reference, which are used in XML documents as element types and attributed names. A namespace is declared using a family of reserved attributes. Such an attribute s name must either be xmlns or have xmlns: as a prefix. xmlna sts a default namespace xmlns: is used to declare a namespace which will be used in the document. CSC309 Tutorial --XML 23 CSC309 Tutorial --XML 24

7 XML Namespaces (cont ) A Complete Example DTD Qualified Names Namespace prefix: local part The namespace prefix maps to namespace URI. <html: html xmlna:html= > <html:head> <html:title>title</html:title> </html:head> </html:html> A variable in that element and all nested elements. A default can be set for a tag and all its nested tags. <html xmlns= > <head> <title>title</html:title> </head> </html> <?xml version="1.0" encoding="utf-8"?>  <!ELEMENT bookdatabase (book+)> <!ENTITY % CH "(chapter, description)"> <!ELEMENT book (author+, image*, content+, newchapters*)> <!ATTLIST book bookid ID #REQUIRED> <!ELEMENT author (#PCDATA)> <!ELEMENT image (#PCDATA)> <!ELEMENT content %CH;> <!ELEMENT newchapters %CH;> <!ATTLIST newchapters added (true false) "false"> <!ELEMENT chapter (#PCDATA)> <!ATTLIST chapter number CDATA #REQUIRED> <!ELEMENT description (section*, summary?)> <!ELEMENT section (#PCDATA)> <!ELEMENT summary (#PCDATA)> <!ENTITY EH "Elliotte Rusty Harold"> <!ENTITY IF "Ian Foster"> <!ENTITY CK "Carl Kesselman"> CSC309 Tutorial --XML 25 CSC309 Tutorial --XML 26 A Complete Example XML A Complete Example XML (cont d) <?xml version="1.0" encoding="utf-8" standalone="no"?> <!DOCTYPE bookdatabase SYSTEM "book.dtd"> <bookdatabase> <book bookid="isbn-0-13-xxx"> <author>&eh;</author> <content> <chapter number="1">xml Structure, Syntax</chapter> <description> <section>xml Fundamentals</section> </description> </content> <content> <chapter number="2">document Type Definitions</chapter> <description> <section>element Declarations</section> <section>attributes Declarations</section> <summary>summary of the chapter 2</summary> </description> </content> </book> CSC309 Tutorial --XML 27 <book bookid="isbn xxx"> <author>&if;</author> <author>&ck;</author> <image>grid architecture</image> <content> <chapter number="1">grids in Context</chapter> <description /> </content> <newchapters> <chapter number="20">network structure</chapter> <description> <section>the Future( )</section> <summary>summary of the new chapter</summary> </description> </newchapters> </book> </bookdatabase> How to validate: java -cp /u/csc309h/lib/xerces.jar:/u/csc309h/lib/ Validator -v book.xml CSC309 Tutorial --XML 28

Outline. XML DOCTYPE External - SYSTEM. XML DOCTYPE Internal DTD &6&7XWRULDO ;0/ (GZDUG;LD

Outline. XML DOCTYPE External - SYSTEM. XML DOCTYPE Internal DTD &6&7XWRULDO ;0/ (GZDUG;LD &6&7XWRULDO ;0/ (GZDUG;LD Outline XML DOCTYPE Element Declarations Attribute List Declarations Entity Declarations CDATA Stylesheet PI A Complete Example -DQXDU\ 1 CSC309 Tutorial --XML 2 XML DOCTYPE Internal