Administrivia

1
Administrivia

• Quiz on Tuesday
• Focus on lectures 1 through 4
• General notions about .NET
• C features
• C in hw1
• XNA
• Discussions
• Short answers, T/F, Multiple choice
• Closed book
• 20 to 30 minutes max
• Any questions?

2
Goal

• We may or may not need to use XML this semester,
  but learning it is important, so here you go!!!
• XML
• What it is and how to use it
• Some parts again stolen from
• Mark Sapossnek, CS Dept, Metropolitan College,
  Boston University, CS 594 (in MSDNAA Curriculum
  Repository)

3
XML Overview

• Extensible Markup Language (XML)
• Derived from Standard Generalized Markup Language
  (SGML)
• HTML is also derived from SGML
• Plain-text, Unicode-based meta-language
• A language for defining markup languages using
  markup tags (words surrounded by lt and gt)
• Generic
• Not programming language specific
• Not operating system specific
• Not software vendor specific

4
XML Overview - 2

• XML provides
• Manipulating data
• Structuring data
• Transforming data
• Querying data
• Originally for documents, now for any structured
  data
• Lingua franca of information interchange

5
More on XML

• Extensible
• Unlike HTML which has a fixed vocabulary, XML can
  be used to define app dependent vocabularies
• Additive changes to XML documents allow old code
  to still function
• Text-based
• Allows using standard tools to edit if the need
  arises
• Platform independence
• Interoperability is a natural consequence
• Strict rules
• Syntax
• Structure
• Case sensitive
• Separates presentation from content
• Permits reuse of content information

6
Syntax and Structure

• Prolog contains processing instructions
• Encoding specification (Unicode by default)
• Namespace declaration
• Schema declaration
• Elements
• Each element has a beginning and ending tag
• ltTAG_NAMEgt...lt/TAG_NAMEgt
• Elements can be empty (ltTAG_NAME /gt)
• Attributes
• Describes an element e.g. data type, data range,
  etc.
• Can only appear on beginning tag

7
Syntax and Structure - 2

• lt?xml version1.0 ?gt
• lt?xml-stylesheet type"text/xsl"
  hreftemplate.xsl"?gt
• ltROOTgt
• ltELEMENT1gtltSUBELEMENT1 /gtltSUBELEMENT2
  /gtlt/ELEMENT1gt
• ltELEMENT2gt lt/ELEMENT2gt
• ltELEMENT3 typestringgt lt/ELEMENT3gt
• ltELEMENT4 typeinteger value9.3gt
  lt/ELEMENT4gt
• lt/ROOTgt

Elements with Attributes
Elements
Prologue (processing instructions)
8
Well-Formed XML Rules

• There must be one, and only one, root element
• Sub-elements must be properly nested
• A tag must end with the tag in which it was
  started
• Attributes are optional
• Defined by an optional schema
• Attribute values must be enclosed in or
• Processing instructions are optional
• XML is case-sensitive
• lttaggt and ltTAGgt are not the same type of element

9
Well-Formed XML? - 1

• No, CHILD2 and CHILD3 do not nest propertly

ltxml? Version1.0 ?gt ltPARENTgt ltCHILD1gtThis is
element 1lt/CHILD1gt ltCHILD2gtltCHILD3gtNumber
3lt/CHILD2gtlt/CHILD3gt lt/PARENTgt
10
Well-Formed XML? - 2

• No, there are two root elements

ltxml? Version1.0 ?gt ltPARENTgt ltCHILD1gtThis is
element 1lt/CHILD1gt lt/PARENTgt ltPARENTgt ltCHILD1gtThi
s is another element 1lt/CHILD1gt lt/PARENTgt
11
Well-Formed XML? - 3

• Yes

lt?xml Version1.0 ?gt ltPARENTgt ltCHILD1gtThis is
element 1lt/CHILD1gt ltCHILD2/gt ltCHILD3gtlt/CHILD3gt lt
/PARENTgt
12
Namespaces Overview

• Part of XMLs extensibility
• Allow authors to differentiate between tags of
  the same name (using a prefix)
• Frees author to focus on the data and decide how
  to best describe it
• Allows multiple XML documents from multiple
  authors to be merged
• Essentially same concept as namespace in C, C,
  
• Identified by a URI (Uniform Resource Identifier)
• When a URI is used, it does NOT have to represent
  a live server
• Understand what that means? Must be a unique
  string!!

13
Sample

• lt?xml version"1.0" encoding"iso-8859-1" ?gt
• lt?xml-stylesheet href"orders.xsl"?gt
• ltorder id"ord123456"gt
• ltcustomer id"cust0921"gt
• ltfirst-namegtDarelt/first-namegt
• ltlast-namegtObasanjolt/last-namegt
• ltaddressgt
• ltstreetgtOne Microsoft Waylt/streetgt
• ltcitygtRedmondlt/citygt
• ltstategtWAlt/stategt
• ltzipgt98052lt/zipgt
• lt/addressgt
• lt/customergt
• ltitemsgt
• ltcompact-discgt
• ltpricegt16.95lt/pricegt
• ltartistgtNellylt/artistgt
• lttitlegtNellyvillelt/titlegt

14
Sample continued
Namespace

• lt!-- Always go the extra mile for the customer
  --gt
• ltspecial-instructions xmlnshtml"http//www.w3.
  org/1999/xhtml/"gt
• lthtmlpgtIf customer is not available at the
• address then attempt leave package at one
  of
• the following locations listed in order of
• which should be attempted first
• lthtmlolgt
• lthtmlligtNext Doorlt/htmlligt
• lthtmlligtFront Desklt/htmlligt
• lthtmlligtOn Doorsteplt/htmlligt
• lt/htmlolgt
• lthtmlbgtNotelt/htmlbgt Remember to leave a
  note
• detailing where to pick up the package.
• lt/htmlpgt
• lt/special-instructionsgt
• lt/ordergt

Namespace reference
15
XML Schema

• Defines the structure of the XML data
• ltxsschema xmlnsxs"http//www.w3.org/2001/XMLSch
  ema"gt
• ltxselement name"items"gt
• ltxscomplexTypegt
• ltxssequencegt
• ltxselement ref"compact-disc"
  minOccurs"0" maxOccurs"unbounded" /gt
• lt/xssequencegt
• lt/xscomplexTypegt
• lt/xselementgt
• ltxselement name"compact-disc"gt
• ltxscomplexTypegt
• ltxssequencegt
• ltxselement name"price" type"xsdecimal"
  /gt
• ltxselement name"artist" type"xsstring"
  /gt

16
Writing an XML Document

• System.Xml.XmlTextWriter
• One constructor takes a file name
• XmlTextWriter w new XmlTextWriter(foo.xml)
• Another takes a stream (which is useful for
  creating a string)
• using System.IO using System.Xml
• StringWriter sw new StringWriter()
• XmlTextWriter w new XmlTextWriter(sw)
• WriteStartElement (and WriteEndElement)
• WriteAttributeString
• w.WriteStartElement(order)
• w.WriteAttributeString(id, 33343)
• embed other write calls
• w.WriteEndElement()

17
Access to an XML Document

• Tree view
• Memory resident, tree of nodes
• Document Object Model (DOM)
• XmlDocument class
• Cursor view
• Not required to be in memory
• Cursor moves over document allowing examination
  of the contents
• XPathNavigator class
• Streaming API
• Manipulate as a stream for transformational and
  other processing
• Push-based model SAX pushes events to
  handlers
• Pull-based model forward-only cursor over data
  (XmlReader class)

18
Reading XML

• XmlTextReader
• Again from a stream or file
• Check out NodeType to determine what you have
• XmlNodeType.Element, .Text, .Attribute

System.IO.StringReader sr new
System.IO.StringReader("ltcompute op'
arg1'32' arg2'44'/gt") System.Xml.XmlTextReader
tr new System.Xml.XmlTextReader(sr) tr.Whitespa
ceHandling WhitespaceHandling.None tr.Read() C
onsole.WriteLine("Ele 01", tr.Name,
tr.Value) // Ele compute tr.MoveToAttribute("ar
g1") int arg1 Convert.ToInt32(tr.Value) Consol
e.WriteLine("Attr 01", tr.Name, tr.Value)
// Attr arg132 tr.MoveToAttribute("arg2") int
arg2 Convert.ToInt32(tr.Value) Console.WriteLin
e("Attr 01", tr.Name, tr.Value) // Attr
arg244 tr.MoveToAttribute("op") string op
tr.Value Console.WriteLine("Attr 01",
tr.Name, tr.Value) // Attr op
19
Other Tools

• XML Query
• Ability to find out information about the
  contents of an XML document
• XPath and XQuery
• XML Transformation
• Take XML documents and munge them into new
  documents
• XSLT is the prime contender for XML
  transformation
• XHTML
• XML version of HTML (eliminates some of the odd
  features of HTML)
• Such as the ltpgt tag without closing tag
• Most browsers accept XHTML just fine

20
XSLT Sample

• ltxslstylesheet xmlnsxsl"http//www.w3.org/1999/
  XSL/Transform" version"1.0" xmlns"http//www.w3.
  org/1999/xhtml"gt
• ltxsloutput method"xml" indent"yes"
• doctype-system"http//www.w3.org/TR/xhtml1/DT
  D/xhtml1-transitional.dtd"
• doctype-public"-//W3C//DTD XHTML 1.0
  Transitional//EN" /gt
• ltxsltemplate match"/"gt
• lthtml lang"en" xmllang"en"gt
• ltheadgt
• lttitlegtOrder Information -
  ord123456lt/titlegt
• lt/headgt
• ltbodygt
• lttable border"1"gt
• lttrgtltthgtArtistlt/thgtltthgtTitlelt/thgtltthgtPrice
  lt/thgtlt/trgt
• ltxslfor-each select"items/compact-disc"gt
  
• lttrgt
• lttdgtltxslvalue-of xmlns""
  select"artist" /gtlt/tdgt
• lttdgtltxslvalue-of xmlns"" select"title"
  /gtlt/tdgt
• lttdgtltxslvalue-of xmlns"" select"price"
  /gtlt/tdgt
• lt/trgt
• lt/xslfor-eachgt

21
Produces This XHTML

• lt!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
  Transitional//EN" "http//www.w3.org/TR/xhtml1/DTD
  /xhtml1-transitional.dtd"gt
• lthtml lang"en" xmllang"en" xmlns"http//www.w3
  .org/1999/xhtml"gt
• ltheadgt
• lttitlegtOrder Information - ord123456lt/titlegt
• lt/headgt
• ltbodygt
• lttable border"1"gt
• lttrgt
• ltthgtArtistlt/thgt
• ltthgtTitlelt/thgt
• ltthgtPricelt/thgt
• lt/trgt
• lttrgt
• lttdgtNellylt/tdgt
• lttdgtNellyvillelt/tdgt
• lttdgt16.95lt/tdgt
• lt/trgt
• lttrgt
• lttdgtBaby Dlt/tdgt

And this table
22
Serialization

• Allows you to create a class and turn its
  contents into XML using XMLSerializer
• Public class bar public int mumble
• XMLSerializer foo new XMLSerializer(typeof(bar))
  
• StringWriter swF new StringWriter()
• foo.Serialize(swF, b) // b is an instance of
  class bar
• Console.WriteLine(swF.ToString())
• // produces
• lt?xml version"1.0" encoding"utf-16"?gt
• ltbargt
• ltmumblegt123lt/mumblegt
• lt/bargt

23
DeSerialization

• Deserializer member function of XMLSerializer
  allows you to take an XML and turn it back into
  an object
• StringReader srF new StringReader(swF.ToString()
  )
• bar b2 (bar)foo.Deserialize(srF)
• Console.WriteLine(bar.mumble)
• Can control XML generation with attributes
• THIS IS COOL!!!

24
XML Summary

• XML is THE thing for sending data around
• Text-based
• Structured
• Standardized
• Many tools and standards for manipulation
• Easy to program with .NET Framework