Xml

An overview of XML & SOAP Ch.Vishwa Mohan Project Manager KREST Embedded Technologies

Agenda What is XML ? Where XML using ? What is DTD ? XML Schema Language XML Query Languages RSS Web Services SOAP & WSDL

XML Related Technologies XML DTD XML Schema XPath XQuery XSLT XLink & XPointer CSS XAML SOAP & WSDL RSS All types of XML Specifications you can find at XML organization. www.xml.org WS-* specifications you can find at OASIS Web Site. www.oasis-open.org

Microsoft .NET Experiences & Solutions Tools Software for Connecting Information, People, Systems and Devices XML Web Services across the Entire Microsoft Platform Servers Clients Services

What is XML ? XML is self describing Open standard Any kind of data Unicode Character set Clear syntax & Textual representation of data Unambiguous structure A language for creating markup languages Platform Independent Portable Data Resembles HTML or SGML Tags, Attributes & Values DTD’s

What is XML ? XML is a markup language for document containing structured information. XML is a markup specification language With which you can design ways of describing information (text or data), usually for storage, transmission or processing by a program. A markup language is a mechanism to identify structures in a document. XML is, roughly speaking, a restricted form of SGML. XML is more then a markup language. It is a meta language A language used to define other languages . XML is fully Unicode complaint. XML is extensible, platform independent and supports internationalization and localization.

Different Types of XML Documents An XML document to be considered to be correct. It must meet two requirements: Well-formed Valid A well-formed document must confirm to the following rules: An XML Document may contain XML declarations, PI’s, encoding and other information may exists. Only one root element in specified XML document. Elements those are not empty must specify start & end tags. Empty elements can mark with the empty element tag. Attributes must be enclosed in a single or double quotes. Tags may be nested but must not overlap. Elements names are case sensitive. Document must used specified encoding (UTF-8). A valid document has data that confirms to a set of content rules. These rules describes the correct data values and document organizational structure.

What is Self Describing? ST*323*712990413 V1*7039610*NEW ZEALAND QUEEN*D*104N*SCAC***L LS*0100 R4*D*D*JAX*JACKSONVILLE FL**** V9*EAD**920819**JACKSONVILLE FL***A26 R4*D*D*ORF*NORFOLK, VA**NORFOLK INTL TERMIN** V9*EAD**920817**NORFOLK, VA***A26 R4*L*K*MEB*MELBOURNE, AUST**** V9*EDD**920712**MELBOURNE, AUST***A40 R4*L*K*SYD*SYDNEY, AUST**** V9*EDD**920715**SYDNEY, AUST***A40 R4*L*K*WLG*WELLINGTON, NEW ZEALAND**** V9*EDD**920721**WELLINGTON, NEW ZEA***A40 LE*0100 SE*25*712990413 This is not self describing data!

XML is Self Describing <?xml version=“1.0”?> <Data> <Item ID=“112”> <Name> Rod </Name> <Price> 12.00 </Price> <Units> 1 </Units> </Item> <Item ID=“114”> <Name>Reel</Name> <Price>15.00</Price> <Units>1</Units> </Item> <Item ID=“120”> <Name>Bait</Name> <Price>24.00</Price> <Units>3</Units> </Item> </Data> Here data is self explanatory In XML documents make structure explicit through markup: Bad way to represent: <Transaction>Withdrawal 2003 12 15 200.00 </Transaction> Better way : <Transaction type="withdrawal"> <Date>2003-12-15</Date> <Amount>200.00</Amount> </Transaction>

What is XML is Not ? A replacement for HTML A Programming Language A Network Transport Protocol A Database

XML vs HTML HTML is a markup language for presentation and XML is a language for creating markup language that describes the structured data. XML HTML Describes the structured data HTML describes layout. Allows you to define your own tags Has a fixed tag set Case sensitive Case insensitive All tags must be closed Not required. All attribute values must be in single or double quote mark. Different heading. First line of XML document is with <?xml ?>

The need for XML The real XML’s power come from the fact that it can be used regardless of the platform, language or data store of system using. It is desirable to transport data around networks (including the internet). XML is the format of choice for marking up that data. SGML was too complex, HTML not robust enough.

A Simple XML File <?xml version="1.0" encoding="utf-8“ ?> <books xmlns="http://www.MyStore.com/books"> <book publisher="IDG books" on-loan="Sanjay"> <title>XML Bible</title> <author>Elliotte Rusty Harold</author> </book> <book publisher="Prentice Hall" on-loan="Sander" > <title>Definitive XML Schema</title> <author>Priscilla Walmsley</author> </book> <book publisher="APress"> <title>A Programmer's Introduction to C#</title> <author>Eric Gunnerson</author> </book> </books> Optional Specifies version , character set and encoding .

XML Syntax Rules Tags are case sensitive Each document must have a root. Closing tags are required Values must be enclosed in quotation marks Elements must be properly nested Entities must be declared

An XML Example We will define a employee structure as follow: An employee is required to specify either male or female . An employee has a name consists of A first name A last name An (optional) nick name An employee has a qualification. An employee has a designation.

XML Document Example <?xml version="1.0" encoding="utf-8“ ?> <!DOCTYPE employees SYSTEM "C:\employee.dtd"> <employees xmlns="http://www.krestembedded.com/empinfo"> <employee gender=“male"> <name> <first>Vishwa</first> <last> Mohan</last> <nick>C.V</nick> </name> <qualification>M.E </qualification> <designation>Project Manager</designation> </employee > <employee gender=“female"> <name> <first>Subba</first> <last>Laxmi</last> </name> <qualification>B.Tech</qualification> <designation>Project Associate</designation> </employee > </employees>

XML Document Example <?xml version="1.0" encoding="utf-8“ ?> The document begins with a processing instruction: While it is not required, its presence explicitly identifies the document as an XML document and its version. XML documents are composed of markup and content. There are six kinds of markup that can occur in an XML document: elements ( and attributes) entity references comments processing instructions marked sections document type declarations

Elements vs Attributes Elements are the most common form of markup. Delimited by angle brackets, most elements identify the nature of the content they surround. <title> An introduction to C# Programming </title> Some elements may be empty ( i.e., no content ). Attributes are name-value pairs that occur inside start-tags after the element name. <book publisher ="Prentice Hall" > </book> In XML, all attribute values must be either single or double quoted.

Attributes Advantages & Disadvantages Attributes Disadvantages: Can’t contain multiple values Not very expandable Can’t describe structures More difficult to manipulate Hard to test against DTD. Attribute Advantages: Great for internal info not needed by the user <messages> <Note ID ="100">New Batch on .NET starts today </Note> <Note ID ="101">New Batch on Java starts today </Note> </messages>

Entity References Some of the characters are reserved for markup language ( Eg: ‘ < ‘, ‘ > ’, ..,). These characters have alternative name to represent them ( i.e., lt, gt, etc.,). In XML, entities are used to represent these special characters. To use an entity, you simply reference it by name. Entity references begin with the ampersand and ends with a semicolon . <book>  < book>  < book > Entities are also used to refer to often repeated or varying text and to include the content of external files. Every entity must have a unique name. You can also define your own entities. A special form of entity reference, called a character reference can be used to insert arbitrary Unicode characters into your document. It can be represented as ℞  ℞  Represents Rx symbol

Entity References The XML Specification provides 5 predefined internal entities: < produces the left angle bracket, < > produces the right angle bracket, > & produces the ampersand, & ' produces a single quote character (an apostrophe), ' " produces a double quote character, " In addition to above entities there are other types of entities: External entities Parameter Entities

Comments Comments begin with  . Comments can contain any data except the literal string “ -- ”. You can place comments anywhere between markup. Comments are not part of the textual content of an XML document. An XML processor is not required to pass them along to an application.

Processing Instructions Processing instructions (PIs) as an alternative means of passing information to a particular application that may read the document. ( Always appear before the root element) Like comments, they are not textually part of the XML document but the XML processor is required to pass them to an application. Processing instructions have the form: <?name pidata?> Processing Instruction is just markup, but not element. In the processing instructions section, you can script code, SQL statements etc.., PI names beginning with xml are reserved for XML standardization. <?xml version="1.0" encoding="utf-8“ ?> <?xml-stylesheet href=”person.css” type=”text/css”?>

Marked Sections In a document, a CDATA section instructs the parser to ignore most markup characters. This CDATA section starts with <![CDATA[ and ends the section with ]]> . <![CDATA[ *p = &q; b = (i <= 3); ]]> All character data is passed directly to the application, without interpretation. Elements, entity references, comments, & processing instructions are all unrecognized and the characters that comprise them are passed literally to the application. The only string that cannot occur in a CDATA section is ]]>.

Document Type Declarations (DTD) Generally, declaration ( DTD, or Schema ) allows a document to communicate meta information to parser about its contents. Meta-information includes the allowed sequence and nesting of tags, attribute values and their types and defaults, the names of external files that may be referenced and whether or not they contain XML. There are four kinds of declarations in XML: Elements Attributes Entities PCDATA & CDATA Element Type declaration identify the name of elements and the nature of their content. < !ELEMENT books (title, author+, price?)> DTD’s can be specified externally or you can embed internally.

Declaring Elements in a DTD General form of declaring element is : <!ELEMENT Element-Name Element-Rule> Creating an element which can contain both plain text & tags. <!ELEMENT Element-Name ANY > Create an element which contain plain text but not other tags: <!ELEMENT Element-Name ( #PCDATA )> To Create an empty element <!ELEMENT Element-Name EMPTY > Create an element with children which must present in the order listed. <!ELEMENT Element-Name ( child1, child2 )> Create an element with options ( Any one of them can appear, but not both). <!ELEMENT Element-Name ( child1 | child2 )>

Declaring Elements in a DTD Some more element declarations are shown below: Create an element with child which must appear 0 or 1 times. <!ELEMENT Element-Name ( child ) ? > Create an element with a child which must appear 1 or more times. <!ELEMENT Element-Name ( child ) + > Create an element with a child which may appear 0 or more times <!ELEMENT Element-Name ( child ) * > Declaring Attributes in a DTD as follows: <!ATTLIST target-element attr-name type default > The type specifies what type of data that attribute contains. Legal types are : CDATA The default specifies whether the item is required or not. Possible values for default are: #REQUIRED, #IMPLIED

The “employee” DTD <?xml version="1.0" encoding="UTF-8"?> <!ELEMENT employees ((employee+))> <!ATTLIST employees xmlns CDATA #FIXED "http://www.krestembedded.com/empinfo"> <!ELEMENT employee ((name, qualification, designation))> <!ATTLIST employee gender (male | female) #REQUIRED> <!ELEMENT name ((first, last, nick?))> <!ELEMENT first (#PCDATA)> <!ELEMENT last (#PCDATA)> <!ELEMENT nick (#PCDATA)> <!ELEMENT qualification (#PCDATA)> <!ELEMENT designation (#PCDATA)>

DTD’s are Limited The problem with DTD’s are: DTDs express only relationships and data typing intended by ISO 8879 DTD’s do not easily express data types or conceptual relationships such as those found in RDBMS. DTDs are specifications in a syntax unique to SGML and SGML tools DTD’s works well for textual data. DTD’s use old SGML style definitions. DTD’s are not written in XML.

XML Schema An XML Schema is a description of a type of XML document. The schema is typically expressed as constraints on the structure and content of document. An XML schema provides a superset of the capabilities found in DTD. A schema used to defines the elements It also defines structural information about the XML doc. It also defines the sequence in which child elements can appear and the no of child elements. It can define whether an element is empty or can include text as well as default values for attributes. XML Data Schema provides one standard schema language for both text and relational data. XML Schema uses XML syntax.

Schema vs DTD XML Schema definition language (XSD) has become the mainstream language for describing XML documents. XML schema an improvement over DTDs that allows the author to specify data types, default value, maximum and minimum values , enumerations and other types. The Schema and DTD both provide a method for specifying the structure of an XML element, whereas the both allow for element definitions, only schemas allow you to specify the type information. XML Schema supports reusable types and allow you to create new types using inheritance. XML Schema allows you to group elements to control the recurrence of elements and attributes.

XML Schema Definition Language (XSD) The Schema definition must have a root xsd:schema element. There are a variety of elements that may be nested within xsd:schema including, but not limited to: xsd:element xsd:attribute xsd:complextType These are approximately 44 ( int, string, long, etc., ) simple data types defined in the XSD. Also possible to define custom simple types. XML Schema provides Enhanced ability to validate data. ( Element structure, Attribute values, Element content, etc., ). Default values for elements. Uniqueness as well as Key constraints. Pattern matching.

Schema Representation Within XSD file, you can derive complex types from the existing complex types also. <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:tns="http://example.org/person"> <xsd:complexType name=" Person "> <xsd:sequence> <xsd:element name="name" type="xsd:string"/> <xsd:element name="age" type="xsd:byte " minOccurs="0"/> <xsd:element name="phone" type="xsd:string“ minOccurs="1“ maxOccurs="5"/> </xsd:sequence> <xsd:attribute name="id" type="xsd:string "/> </xsd:complexType> <xsd:element name=“employee" type="tns:Person"/> </xsd:schema>

Pattern Definition in Schema Within your schema if you want to specify any element should present within specified pattern you can use <xsd:pattern …> . Suppose if you want to the phone element should be present in xxx-xxx-xxxx format then you can define as follow: <xsd:simpleType name=" Phone "> < xsd:restriction base="xsd:string"> <xsd:pattern value=" \d{3}-\d{3}-\d{4} "/> < /xsd:restriction > </xsd:simpleType> XML Schema defines a set of type characteristics, or facets, which can be used to restrict certain aspects of the base type. There are total 12 facets ( Eg: minInclusive, maxInclusive ). Each facet makes it possible to restrict the value space of the base type in a different way.

Schema for Employees <?xml version="1.0" encoding="utf-8"?> <xs:schema targetNamespace="http://www.krestembedded.com/empinfo" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="employees"> <xs:complexType> <xs:sequence> <xs:element maxOccurs="100" name="employee"> <xs:complexType> <xs:sequence> <xs:element name="name"> <xs:complexType> <xs:sequence> <xs:element name="first" type="xs:string" /> <xs:element name="last" type="xs:string" /> <xs:element minOccurs="0" name="nicK" type="xs:string" />

Schema for Employees </xs:sequence> </xs:complexType> </xs:element> <xs:element name="qualification" type="xs:string" /> <xs:element name="designation" type="xs:string" /> </xs:sequence> <xs:attribute name="gender" type="xs:string" use="required" /> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:schema>

Parsing XML Two popular types of XML processing exists: DOM ( Document Object Model ) SAX ( Simple API for XML ) The key differences between these two processing's are: DOM loads the entire document into in-memory data structure. ( In case of SAX it doesn’t required ). SAX is a simple and straightforward, event based API for parsing XML documents. In case of SAX iterates over the XML document one piece at a time in a forward-only and read-only fashion. SAX allows the developers to take advantage of event-driven XML parsing. Both SAX and DOM provide the client application access to XML processing instructions. The DOM is intended to be OS and language neutral.

DOM The DOM is W3C defined standard for accessing documents like XML & HTML. DOM is platform and language neutral. The DOM is separated into 3 different parts: Core DOM XML DOM HTML DOM The DOM defines the objects and properties of all document elements and the methods ( interfaces ) to access them. The XML DOM is a standard object model for XML and a standard programming interface for XML. ( W3C Standard ). With XML DOM interfaces you can get, change, add or delete XML elements. According to DOM everything in XML document is a node.

DOM According to DOM everything in XML document is a node. The entire document is a document node . Every XML element is an element node . The text in the XML elements are text nodes . Every attribute is an attribute node . Comments are comment nodes . A common error in DOM processing is to expect an element node to contain text, however the text of an element node is stored in a text node. <year>2005</year> , The element node <year>, holds a text node with the value " 2005 ". So the "2005" is not the value of the <year> element !. Most browsers have a build-in XML parser. An XML parser reads XML and converts into an XML DOM object that can be accessed by JavaScript.

SAX SAX stands for Simple API for XML . SAX provides a mechanism for reading data from an XML document. ( Alternative to DOM ). SAX is a callback implementation. It provides event driven API. The SAX events includes: XML Text nodes XML Element nodes XML Processing Instructions XML Comments. Events are fired when each of these XML features are encountered, and again when the end of them is encountered. XML attributes are provided as part of the data passed to element events. The quantity of the memory by SAX parser is much smaller then DOM parser. Because of the event-driven nature of SAX, processing documents can often be faster than DOM-style parsers. SAX also have some draw backs. Certain validation requires full document to be loaded.

Classes in .NET The following are important classes defined in .NET to work with XML documents: XmlReader & XmlWriter ( abstract classes ) XmlTextReader & XmlTextWriter XmlValidatingReader XmlNodeReader XmlDocument XPathDocument XslTransform XmlSchema XPathNavigator XmlCsvReader

XML Query Languages At present XML has the following three types of Query languages: XPath XQuery XSLT XML support for Microsoft SQL server are: In MS SQL Server 2000 with the FOR XML and OPENXML T-SQL keywords. In MS SQL Server 2005 introduced xml data type that supports XSD schema validation and XQuery based operations and XML indexing . In 2005, FOR XML feature was enhanced. In 2008 enhancements includes, Improved Schema validation, Enhancement to XQuery support, Enhancements in XML Data Manipulation Language ( DML ).

XML Query Languages From SQL Server 2005 supports XML as a data type . So it allows you to combine T-SQL Queries and XQuery expressions to search within XML data. An XML data type can be used as a variable, a parameter or a return value from a UDF. With Office 2003, Word & Excel documents as XML. Example of combining T-SQL query and XQuery: Now T-SQL statement with XQuery is: SELECT [id], [Number], [info]. query (‘ Exam/Course ’) As Course FROM [Exams] XQuery is allowed to query data. Microsoft extends this XQuery has named XML DML ( Data Modification Language ) to manipulate data. The following keywords of XML DML are: insert, delete & replace value of. ID (int) Number (NCHAR(10)) Info(XML) 1 123456 XML Data 2

XPath XPath is a language for addressing parts of an XML document. The most basic construct in XPath is the expression . Using XPath expressions, developers can easily identify nodes in an XML document. The following are XPath expressions: match=“/” the root element Select=“/author/surname” select the surname element which is child of the author element. Select=“@date” select the elements with the attribute “date” Select=“./fname” select fname children of the current node.

XPath XPath 2.0 supports 19 primitive data types plus some more derived data types . Within XPath expressions you can use comparison operators such as ( =, <, > and <= , etc., ). In addition XPath 2.0 also supports some string processing functionalities such as upper-case, starts-with , concat , etc., XPath also supports for expression as well as if expression. An XPath expression can contain location paths, function calls, variable references, unions of sets, comparisons, mathematical operations, and so on.

XPath Example Form the Employees XML document check whether is an employee element exists whose first name is ‘vishwa’. /employees/employee/name/first='Vishwa‘ // return boolean Similarly to find the nick name for an employee whose first name is ‘Vishwa’ /employees/employee/name[first='Vishwa']/nick To find the gender for an employee whose designation is ‘Project Associate’. /employees/employee[designation='Project Associate']/@gender

XPath Example Let us assume the XML document to represent cars as follow: <?xml version='1.0'?> <cars xmlns='urn:schemas-develop-com:cars'> <car make='BMW'> <model>323i</model> <year>2000</year> <price>26,990</price> </car> </cars> The following expression returns the car model /cars/car/model // returns ‘323i’ The following expressions yields Boolean value starts-with(model, '32') // returns true car/price < 27,000 // returns false The following expression concatenation the make and model concat(car/make, car/model)

XSLT XSLT strands for Extensible Stylesheet Language Transformation XSLT can be used to transform XML to XML ( One format to another format ) XML to Non XML ( Eg: HTML, Text, Pdf, etc., ) XML to FO ( XML to Formatting Objects ) XSLT uses the XPath language for identifying the appropriate data in the source tree. <xsl:template match = XPath Expression > <xsl:apply-templates select = XPath Expression > XPath also provides range of functions that assist XSLT. Within the .NET Framework there is an XML Transform Control to convert XML document contents into different format. <asp:Xml ID=“ x " runat="server" DocumentSource =" My .xml“ TransformSource =" MyTrans .xslt“ />

XSLT The XSLT document is an XML document so starts of XML PI. The root element that declares the document to be an XSL style sheet is <xsl:stylesheet> or <xsl:transform> . With the help of <?xml-stylesheet?> PI, you can reference stylesheet for your XML document. An XSL style sheet consists of one or more set of rules that are called templates . A template contains rules to apply when a specified node is matched. The <xsl:template> element is used to build templates. The match attribute is used to associate a template with an XML element. The value for the match attribute is an XPath expression .

XSLT Functions The below are some of the XSLT built-in commands. These functions ranged from string processing, date processing and loop operators etc., <xsl:template match =“myElement” /> <xsl:value-of select =“myElement” /> <xsl:for-each select =“myElement” > … </xsl:for-each> <xsl:sort /> <xsl:if test=“cost > 20.00”> …. </xsl:if> <xsl:choose > and <xsl:when >

XSLT Example The below is an XML document and its transformation file. <?xml version="1.0" encoding="UTF-8"?> <menuitem xmlns:xsi= http://www.w3.org/2001/XMLSchema-instance > < item>Hamburger</item> <item>French Fries</item> <item>Milk Shake</item> <cost>4.99</cost> </menuitem> XSLT file for the above XML document is: <?xml version="1.0" encoding="UTF-8" ?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns="http://www.w3.org/1999/xhtml"> <xsl:template match="/item"> <xsl:apply-templates /> </xsl:template> <xsl:template match="item"> <xsl:value-of select="." /> <br /> </xsl:template> <xsl:template match="cost" /> </xsl:stylesheet>

XQuery XQuery is based on existing XPath query language. The XQuery language is to XML as the SQL language is to relational databases. XQuery provides a distributed query mechanism across data sources that are exposed as XML and is set to become a universal query language for data integration. So you can use XML Query over SQL Server database. The following are the benefits of XQuery are: A greater expressiveness with an ability to perform complex query operations ( Eg: joins, ordering, sorting, etc., ). A human-friendly, non-XML syntax. Strong typing at both runtime and compile time. A rich set of functions and operators to operate on the XML schema types.

XQuery XQuery is a powerful and convenient language designed for processing XML data. XQuery not only used on files in XML format, but also other data including databases whose structure nested, named trees with attributes is similar to XML. The primitive data types in XQuery are same as XML Schema. Some of the data types used in XQuery are: Numbers & Boolean Strings of Characters Types to represent dates, times and duration. A few XML Related types In addition to primitive types also supports derived types. The derived types are just variations or restrictions of other types. The following are other data types to represent XML values: Element, attributes, namespace, text, comment, PI, & document(root) nodes. These types are very similar to corresponding DOM classes. Such as Node, Element, and so on.

XQuery Functions Various XQuery functions creates or returns nodes. Take note the function parameters and function results can be primitive values, nodes or sequences of either. document() : Returns the root node of specified XML file. count() : Returns the number of values in the sequence. children() : Returns the sequence of child nodes. sortby() : To sort a sequence. max() : The biggest element in the given element. contains() : Is given element contains specified word or etc.,

XQuery User Defined Functions In addition to predefined functions, in XQuery you can also define your own utility function. Below function returns all the descendent nodes of argument: define function descendant-or-self ($x) { $x, for $y in children ($x) return descendant-or-self ($y) } By invoking the above function for the given node as below: descendant-or-self(<a>X<b>Y</b></a>) Evaluates to the sequence: <a>X<b>Y</b></a>; "X"; <b>Y</b>; "Y"

XQuery Expressions XQuery borrows path expressions from XPath . XQuery can be viewed as generalization of XPath . All XPath expressions are also XQuery expressions. The following XQuery expression retrieves the <chapter> sub elements from the <book> main element from books.xml file. let $book := document("books.xml")/book return $book/chapter The below code retrieves the titles from each chapter from the books.xml file. <html> { let $book := document("mybook.xml")/book for $ch in $book/chapter return <h2>{$ch/title)</h2> }</html>

XQuery Expressions The below is a SQL query and the corresponding XQuery: The below query is a join of two tables named Customers & Orders. select customers.name from customers, orders where customers.cust_id=orders.cust_id and orders.part_id="xx" For the above SQL query expression corresponding XQuery is: for $c in customers for $o in orders where $c.cust_id=$o.cust_id and $o.part_id="xx“ return $c.name The below is another example of XQuery: for $seller in document("users.xml") return for $item in document("items.xml")//item_tuple return if $seller/userid = $item/offered_by then if $seller/name = "Tom Jones" then $item else () else ()

XQuery Expressions Take note, in XQuery every thing is an expression which evaluates to a value. An XQuery program or script is just an expression together with some other optional functions and other definitions. So 3+4 is a valid XQuery expression. //Evaluates 7 The below is a query expression which evaluates a string. if (3 < 4) then "yes!" else "no!" In XQuery you can define local variables with ‘let’ statement. let $x := 5 let $y := 6 return 10*$x+$y //Evaluates 56 The primitive data types in XQuery is same as XML Schema adsfasf

XQuery Expressions XQuery supports the following different types of expressions: Path expressions : ( Based on syntax of XPath ) /doc/chapter[5]/section[2] Element constructors : Consists of start and end tags, enclosing an optional list of expressions. <emp empid = {$id}> {$name} {$job} </emp> FLWOR expressions : ( For and Let expressions ) FOR $b IN document(“myBooks.xml")//book WHERE $b/publisher = "Morgan Kaufmann" AND $b/year = "1998" RETURN $b/title Expressions involving operators and functions Conditional expressions (If, then else, etc.) Quantified expressions List constructors Expressions that test or modify data types.

XQuery Operators & Functions The following are different types of operator Infix and prefix operators Parenthesized expressions Arithmetic and logical operators Sequence operators UNION, INTERSECT and EXCEPT Functions can be defined in XQuery The function will find the maximum depth of the xml document. DEFINE FUNCTION depth($e AS ELEMENT) AS xsd:integer { IF empty($e/*) THEN 1 ELSE max(FOR $c in $e/* RETURN depth($c)) + 1 } depth(document("partlist.xml"))

XQuery Conditional Expression IF THEN ELSE construct Make a list of holdings. For journals, include the editor, and for all other holdings, include the author. FOR $h IN //holding RETURN <holding> {$h/title, IF $h/@type = "Journal" THEN $h/editor ELSE $h/author } </holding>

XQuery Quantified Expressions Existential and Universal quantifiers Find titles of books in which both sailing and windsurfing are mentioned in the same paragraph. FOR $b IN //book WHERE SOME $para IN $b contains($para, "sailing") AND contains($para, "windsurfing") RETURN $b/title Find titles of books in which sailing is mentioned in every paragraph. FOR $b IN //book WHERE EVERY $p IN $b //Para SATISFIES contains($p, "sailing") RETURN $b/title

XQuery Sequence-related Operators A sequence may be constructed by enclosing zero or more expressions separated by commas. For example: ($x, $y, $z) denotes a sequence containing three members represented by variables The >> (precedes) and << (follows) Boolean. functions () denotes an empty sequence.

XQuery Operators on Data Types INSTANCE OF returns True if its first operand is an instance of the type named in its second operand. CAST is used to convert a value from one data type to another. TREAT AS causes the query processor to treat an expression as though its data type were a subtype of its static type. VALIDATE executes XML Schema validation.

XQuery Functions You can also create new node objects directly in the program. By using an element constructor expression <p>See <a href="index.html"><i>here</i></a> for info.</p> You can use {curly braces} to embed XQuery expression inside element constructors. let $i := 2 return let $r := <em>Value </em> return <p>{$r} of 10*{$i} is {10*$i}.</p> it creates following node <p><em>Value </em> of 10*2 is 20.</p> The below evaluates the children’s of sequences: children( <p>This is <em>very</em> cool.</p> ) evaluates to "This is ", <em>very</em>, " cool.“

XQuery Sequences XQuery expressions actually evaluates to sequences of simple values. The comma operator can be used to concatenate two values or sequences. ( Eg: 3,4,5 ). The simple values can be atomic values or node values. The following is an example of sequences: let $a := 3,4 let $b := ($a, $a) let $c := 99 let $d := () return ( count ($a), count($b), count($c), count($d)) Evaluates to (2, 4, 1, 0) Iterating over sequences: for $x in (1 to 3) return ($x,10+$x)

XML Linking Languages (XLink, XPointer)

XML Linking Language The XML Linking Language is called Xlink . In HTML <A> provides linking and URL’s is the pointing mechanism. ( In XML we can still use <A> links). XML Links have two options. Actuate specifies when the link occurs. USER: Here user clicks on link to activate. AUTO: Here the link is automatically activated when displays. In addition SHOW option in XML Links. It specifies what will “show” when link is actuated. NEW: means a new window appears REPLACE: a new window replaces the existing EMBED: the link will be embedded, becoming part of it Eg: <IMG> links are ACTUATE =AUTO and SHOW =EMBED

XPointers X Pointers enable us to more precisely point to data within a Web resource. doc: document which contains the reference from: beginning section to be linked to: end of section to be linked

XML Style Sheet Specification (CSS, XSLT, XSLT-FO)

XML Style Sheet Languages HTML is simple markup tags that Web browsers use to format text on a screen. The basic HTML tags are simple. The HTML tag set identifies the basic document structure. It doesn’t specify much about styles. In 1996, CSS was emerged as a separate stylesheet for formatting HTML. At present CSS was used to style XML as well. In addition to CSS XSL ( Extensible Stylesheet Language ) was specially developed to specify styles for XML.

Splitting Content from Style So HTML page contains document structure, contents and Styles. Now you can split the content and styles. HTML + Style Sheet Style sheets can be exchanged with users across authoring, browsing, and viewing tools. The first Web Style language is CSS. A CSS style sheet can be directly placed into an HTML 4.0 document. It is within <STYLE> in <HEAD> or it can be placed in a separate file. Style/Content Coding Content Coding Style Coding

Simple Style Sheet Example The below is a sample CSS example: <STYLE type="text/css"> H1 {color: blue; font-size: 18pt; font-style: italic; font-weight: bold;} H2, H3, H4 {font-size: 12pt; font-style: normal; font-weight: bold;} H2 {color: black} H3 {color: aqua} H4 {color: fuchsia} </STYLE> CSS uses a linear model to directly apply formatting to the source HTML or XML. CSS Selectors are used to match styles to tags/attributes. Only a single “flow area” is recognized for CSS styling. CSS can be used along with XSL for rendering XML or XHTML. The CSS2 style sheet is made up of number of rules. Each rule can be declaration. The declaration can be simple or complex.

Selectors The patterns which are used to apply styles in CSS are called selectors . A selector may simply be an element name Selectors also may be rich contextual patterns Case-sensitivity of document language element names in selectors depends on the document language. HTML is not case sensitive XML is case sensitive Different kinds of selectors: * Matches any element (universal selector) E Matches any type E element. E F Matches any E element that is a descendant of an F element. E > F Matches any F element that is a child of an element E (child selector)

CSS for XML The below is an XML document with stylesheet PI. <?xml version=“1.0”?> <?xml:stylesheet type="text/css" href=”MyStyles.css"?> <Presentation> <Title> XML and Related Technologies </Title> <Date> 14 th of Dec 2009 </Date> <Speaker>Ch.Vishwa Mohan</Speaker> </Presentation> The below is style sheet for above document. <STYLE type="text/css"> Title {color: blue; font-size: 14pt; font-style: italic; font-weight: bold;} Date {color: red; font-size: 12pt; font-style: normal; } Speaker {color: black; font-size: 12pt; font-style: normal; } </STYLE>

XSL XSL stands for Extensible Style Sheet Language . XSL was designed to specify styles for XML. Unlike CSS XSL is in XML syntax. XSL has a 2-part processing model Transform / Format . XSL also allows for multiple flow areas and support for online and print formatting. XSLT ( XSL Transformation Language ) was the first module of XSL.

XSLT with Templates <?xml version=“1.0”?> <xsl:transform xmlns:xsl= “http://www.w3.org/1999/ XSL/ Transform” xsl:version=“1.0”> <xsl:template match=“/”> <xsl:text> <html><head><title>Article Summary</title></head> <body><h1>Article Summary by Author</h1></xsl:text> <xsl:apply-templates> <xsl:text></body></html></xsl:text> </xsl:template/> <xsl:template match=“author”> <xsl:text><p><b>Author: </b></xsl:text> <xsl:apply-templates select=”/author/surname”/> <xsl:text>, </xsl:text> <xsl:apply-templates select=:”/author/fname”/></p> </template>

From Objects to Services Polymorphism Encapsulation Subclassing Message-based Schema+Contract+Policy Broad Interop Location Transparent Tight Coupling Runtime Metadata Object-Oriented Service-Oriented Component-Oriented 1980s 2000s 1990s

What is SOA ? Service Oriented Architecture ( SOA ) is an approach to loosely coupled, protocol independent, standards-based distributed computing where software resources available on the network are considered as Services. SOA represents business functions as shared, reusable services. SOA is not a product but an architectural paradigm . The software component in a SOA are services based on standard protocol. In SOA share schema and contract not class/database. Service orientation provides the benefits of loosely coupled , message-oriented programming. Two critical characteristics are realized for SOA development are: Services are truly independent. Services can be managed.

Four Tenets of Service Orientation SERVICE ORIENTATION Compatibility Based On Policy Share Schema & Contract, Not Class Services Are Autonomous Boundaries Are Explicit

What is a Service ? Services are reusable units providing business functionality that are .., Clearly defined using standard policies, practice and framework. Clearly described (usually with XML) Autonomous Abstraction of the underlying business logic and functionality. Here functionality exposed via structured messaging scheme. Not XML Centric, Not HTTP centric. JSON, XML, SOAP, .., over TCP, HTTP, Named Pipes, MSMQ .., Messages sent and received. Moves from client server model to a sender/receiver model. Versioning independency.

Web Services The Web Service technology is simulated (inspired) by SOA. Take note Web Services and Services are not identical. In Web Services, XML used as “ wire format ” of RPC that is SOAP. With Web Services following specifications are used: SOAP : XML based messaging protocol UDDI: Yellow Pages for Web Services WSDL: Web Service Description Language XML Web Services use SOAP as the primary transport and serialization protocol.

SOAP SOAP is a XML based protocol for invoking Remote Procedure Calls, specially for Web Applications. SOAP is a specification that defines the XML format for messages. SOAP uses the following transports HTTP, MSMQ, TCP/IP, SMTP, etc.,. Basically SOAP doesn’t care what the transport is. It can be used combination of all the above transports. The most compelling feature of SOAP is that it has been implemented on many different hardware and software platforms.

SOAP Message <?xml version="1.0" encoding="UTF-8" ?> < env:Envelope xmlns:env= " http://www.w3.org/2002/12/soap-envelope "> < env:Header > <n:alertcontrol xmlns:n="http://example.org/alert"> <n:priority>1</n:priority> <n:expires>2012-12-12T00:00:00</n:expires> </n:alertcontrol> < /env:Header > < env:Body > <m:alert xmlns:m="http://example.org/alert"> <m:msg>World is going to destroy ! </m:msg> </m:alert> < /env:Body > < /env:Envelope >

SOAP SOAP is a light weigh protocol for the exchange of information in a decentralized, distributed environment. It is an XML based protocol consists of three parts: An Envelope Optional Header Mandatory Body A SOAP message must not contain DTD. Similarly SOAP message must not contain processing instructions. SOAP versioning is based on XML namespaces: SOAP 1.1 is identified by the http://schema.xmlsoap.org/soap/evelope namespace. SOAP 1.2 is identified by the http://www.w3.org/2002/12/soap-envelop namespace.

Schema for SOAP Envelop The below schema states every SOAP envelope consists of optional header and mandatory body. <schema targetNamespace='urn:schemas-xmlsoap-org:soap.v1'> <element name='Envelope'> <type> <element name='Header' type='Header' minOccurs ='0' /> <element name='Body' type='Body' minOccurs ='1' /> </type> </element> </schema>

SOAP Faults Exceptions thrown by an Web Services are sent back to the client in the form of SOAP Fault . A SOAP Fault is a <Fault> XML element within the SOAP message. In ASP.NET these faults are converted to SoapException . The SOAP Fault element is used to carry error and/or status information within a SOAP message. The SOAP Fault element defines the following sub elements: FaultCode FaultString FaultActor Detail Node Role

What is RSS RSS ( Really Simple Syndication ) is a family of web feed formats used to publish frequently updated works such as blog entries, news, headlines, audio and video in standardized format. An RSS document ( called as “feed”, ‘web feed” or “channel” ) includes full or summarized text, plus metadata such as publishing dates and authorship. RSS feeds can be read by an RSS reader/feed reader , or aggregator , which can be web based, desktop based or mobile devices based. The feeds are stored in XML format. RSS formats are specified using XML , a generic specification for the creation of data formats. Users can subscribe the feed by entering RSS URI, or by clicking on RSS icon in a web browser.

Simple RSS Example <rss version="0.91"> <channel> <title>XML.com</title> <link>http://www.xml.com/</link> <description>XML.com features services for XML community</description> <language>en-us</language> <item> <title>Normalizing XML, Part 2</title> <link>http://www.xml.com/pub/a/2002/12/04/normalizing.html</link> <description> Relation normalization techniques to XML schema data modeling </description> </item> <item> <title>The .NET Schema Object Model</title> <link>http://www.xml.com/pub/a/2002/12/04/som.html</link> <description>Describes in detail the use of the .NET Schema Object Model </description> </item> </channel> </rss>

Thank You ! You can reach me at : [email_address] 9490995632

Xml

More Related Content

What's hot

Viewers also liked

Similar to Xml

More from Vishwa Mohan

Xml

Editor's Notes