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XML Technology
15th Meeting of the European Working Group on
Operational Workstations (EGOWS)
sdm AG software design management Carl-Wery-Str
. 42 81739 München phone [phone] www.sdm.de
Martin Lehmann, sdm AG Potsdam, June 14th
2004 Version 1.0
A Company of
2
ltspeech title"XML Technology"
subtitle"15th Meeting of the European
Working Group on Operational
Workstations (EGOWS)"
/gt
ltauthor name"Martin Lehmann"
company"sdm AG"/gt ltconference
location"Potsdam" dateJune 14th
2004"/gt ltversion no"1.0"/gt
sdm AG software design management Carl-Wery-Str
. 42 81739 München phone [phone] www.sdm.de
A Company of
3
Agenda
Agenda

• An Overview of XML

4
Documents consist of several Parts
An Overview of XML
Data Pure Information
Structure Relationship of Data
XML
Format / Layout Makes Structure visible
5
XML Basics
An Overview of XML

• Definition XML is a cross-platform, software
  and hardware independent tool for transmitting
  information
• XML describes data and its structure
• XML does not do anything
• XML is platform independent
• XML is (more or less) human readable
• XML is not designed for the minimization of
  storage size
• XML has been defined by World Wide Web Consortium
  W3CThe W3C forum develops interoperable
  technologies (specifications, guidelines,
  software, and tools) to lead the Web to its full
  potential.

6
XML is the eXtensible Markup Language
An Overview of XML

• XML stands for eXtensible Markup Language
• XML is a markup language (much like HTML but
  better)
• XML was designed to describe the structure of
  data.
• Advantages of Structuring Data
• Structured Data can be interpreted by machines
  much more effective (like for example in Search
  Engines)
• Data can be separated from the application much
  easier.

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XML vs. HTML Where is the difference ?
An Overview of XML

• XML is not a replacement for HTML.
• XML and HTML were designed with different goals
• XML describes what a document means
• HTML describes what a document looks like

• Therefore XML can be used to store, exchange,
  share any kind of data.
• XML Document Structure Definition

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History
An Overview of XML

• Vannevar Bush MEMEX

• Ted Nelson XANADU

• IBM GML (Goldfarb, Mosher, Lorie)

• ISO 8879 SGML

SGML as an importantpredecessor Standardized
GeneralizedMarkup Language

• World Wide Web

• W3 Consortium HTML

• W3 Consortium XML

• '45

• '60

• '69

• '86

• '89

• '91

• '98

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Agenda
Agenda

• XML Markup of Data

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The M in XML Markup of Data
XML Markup of Data

• Markup
• XML tags are not predefined (ie The X in XML).
  You must define your own tags.
• XML is therefore a Meta Language. Each structure
  definition defines a new XML language.
• Structure
• XML uses a Document Type Definition (DTD) or an
  XML Schema (XSD) to describe the data structure
• XML with a DTD or XML Schema is designed to be
  self-descriptive

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An XML Document is divided into three Parts
XML Markup of Data
Header

• Header Section

Prolog
DTDorXSD

• Section defining the underlying structure of the
  XML document
• Document Type Definition (.dtd)or XML Schema
  Definition (.xsd)

Structure
Data

• Data Section itself
• XML file (.xml)

Content
We will focuson Data first.
12
XML Data Description in Elements ...
XML Markup of Data

• Data is described with the markup of element tags
• ltelementgtlt/elementgt or ltelement/gt
• Example
• ltPersongtFriedrich der Großelt/Persongt
• Nesting of elements is possible. Elements
  therefore form a tree (have parents, childs etc.)
• Example
• ltPersongt
• ltfirstNamegtFriedrichlt/firstNamegtltlastNamegtder
  Großelt/lastNamegt
• lt/Persongt

Header
Prolog
DTDorXSD
Structure
Data
Content
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XML Data Description in Elements ... and
Attributes
XML Markup of Data
Header

• You can add an unlimited number of attributes to
  each element
• Example
• ltPerson profession"king" born"Jan
  24th 1712" died"Aug 17th 1786"/gt

Prolog
DTDorXSD
Structure
Data
Content
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XML Data Description in Elements ... and
Attributes
XML Markup of Data
Header

• Data can be stored in elements, attributes or
  both

Prolog
ltPerson firstName"Friedrich" lastName"der
Große" profession"king"/gt
DTDorXSD
Structure
ltPersongt ltfirstNamegtFriedrichlt/firstNamegtltlastNa
megtder Großelt/lastNamegtltprofessiongtkinglt/professi
ongt lt/Persongt
Data
Content
ltPerson profession"king"gt ltfirstNamegtFriedrichlt/
firstNamegtltlastNamegtder Großelt/lastNamegt lt/Person
gt
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Elements vs. Attributes
XML Markup of Data
Header

• Some of the problems using attributes
• Attributes cannot describe structures
• Attributes cannot contain multiple values
• Attributes are not easily expandable
• Attributes are more difficult to manipulate (by
  code)
• Attribute values are not easy to test against a
  DTD
• If you use attributes as data containers, you end
  up with documents that are difficult to read and
  maintain.
• Use elements to describe data.
• Use attributes only to provide information that
  is describing additional information.

Prolog
DTDorXSD
Structure
Data
Content
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XML Syntax Overview in brief
XML Markup of Data
Header

• A closing tag is always necessary
• XML tag names are case sensitive
• XML elements must be nested properly
• An XML document must have a root element
• White space is not truncated
• CR/LF is converted to LF
• XML comments are like in HTML lt!-- This is
  an annotation --gt

Prolog
DTDorXSD
Structure
Data
Content

• not like in HTML

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XML Markup Looking back to the XMLized Title
Slide
XML Markup of Data
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Agenda
Agenda

• XML Structure DTD and XML Schema

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XML Structure
XML Structure DTD and XML Schema
Header

• Structure
• XML uses a Document Type Definition (DTD) or an
  XML Schema (XSD) to describe the data structure
• XML with a DTD or XML Schema is designed to be
  self-descriptive
• An XML document with correct syntax is called
  well formed .
• XML validated against a DTD is called valid.
• A DTD is optional, ie not absolutely necessary
  but recommended to check the structure. If one
  knows what to do, the DTD can be omitted.

Prolog
DTDorXSD
Structure
Data
Content
By the way HTML does not even have to be
well-formed
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Document Type Definition DTD
XML Structure DTD and XML Schema
Header

• A DTD defines the underlying document structure.
• It names and qualifies all XML elements and their
  attributes.

Prolog
DTDorXSD
Structure
lt?xml version"1.0" encoding"UTF-8"?gt lt!ELEMENT
person (firstName, lastName)gtlt!ATTLIST person
profession CDATA REQUIREDgtlt!ELEMENT
firstName PCDATAgtlt!ELEMENT lastName PCDATAgt
Data
DTD
Content
ltPerson profession"king"gt ltfirstNamegtFriedrichlt/
firstNamegtltlastNamegtder Großelt/lastNamegt lt/Person
gt
XML
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Document Type Definition DTD
XML Structure DTD and XML Schema
Header

• All elements have to be named
• The structure has to be defined with regular
  expressions to define the nesting of elements
• Element defining child elements in a
  sequencelt!ELEMENT Person (firstName , lastName)gt
• Element defining child elements but optional
  lt!ELEMENT Person (firstName?, lastName)gt
• Element defining a series child elements
  lt!ELEMENT Person (firstName, lastName)gt means
  0 or more means at least 1
• Element defining a choice lt!ELEMENT Person
  (firstName lastName)gt
• EMPTY elementlt!ELEMENT firstName EMPTYgt

Prolog
DTDorXSD
Structure
Data
Content
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XML Schema Better than a DTD
XML Structure DTD and XML Schema
Header

• DTD is pretty old and has several disadvantages.
  XML Schema (XSD) has been defined to overcome DTD
  limitations.
• A XSD uses XML syntax, ie only one language is
  used. Any application which can work with XML can
  work with XSD, too.
• XSD has support for data types and data content
  limitation. This allows
• permissible document content
• to validate the correctness of data
• to define restrictions on data and data patterns
• easier conversion

Prolog
DTDorXSD
Structure
Data
Content
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XML Schema
XML Structure DTD and XML Schema

• Predefined Data Types
• Type hierarchy consists of base and derived types
• Own data types can be defined as
• Restrictions of existing types
• List of existing types
• Union (of the value ranges) of existing types
• Aspects can be defined for each data type (like
  setting min and max, defining a pattern,
  enumerations etc.)

Header
Prolog

• String
• Various Numerical Types
• Time- and Date

• Boolean
• Binary (hex- or Base64-coded)

DTDorXSD
Structure
Data
Content
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XML Header Information
XML Structure DTD and XML Schema

• XML Version information required
• lt?xml version"1.0"?gt
• More attributes optional
• standalone
• encoding
• Example
• lt?xml version"1.0" encoding"ISO-8859-1"
  standalone"no"?gt

Header
Prolog
DTDorXSD
Structure
Data
Content
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Putting it all together ...
XML Structure DTD and XML Schema
Header

lt?xml version"1.0" encoding"UTF-8"?gt
Structure as DTDElements, Attributes
andEntities (Shortcuts)
lt!DOCTYPE employee lt!ENTITY auml "228"gt
lt!ELEMENT employee (name, phone)gt lt!ELEMENT
name (PCDATA)gt lt!ELEMENT phone EMPTYgt
lt!ATTLIST phone country (DCHDKCDNunknown) "D"
predial CDATA IMPLIED
number CDATA REQUIREDgt gt
Data
ltemployeegt ltnamegtErich Kuchikaumlschtlilt/namegt
ltphone predial"123" number"4567"/gt ltphone
country"CH" predial"041" nummer"987654"/gt lt/em
ployeegt
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Agenda
Agenda

• XML Usage in Applications

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Using XML in Applications
XML Usage in Applications

• XML can be used to ...
• ... transfer data between applications (used as
  self-describing data)
• ... store data
• Steps when using the data of a XML document
• The data has to be read and interpreted
• The data has to be transformed to other
  formats(like to Java Objects, Database Content,
  Web-Pages etc.)

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DOM and SAX
XML Usage in Applications

• Two Standard Programming APIs are defined DOM
  and SAX
• DOM Object Model for XML Document
• Defined by W3C
• The structure of the XML Document is defined in a
  tree structure.
• Creation of documents, navigation through the
  structure and the modification of elements is
  easy - as based on the document tree.
• SAX Event-based Callback interface
• Defined by XML-DEV community (SAX 1.0 since Mai
  1998)
• Open Source but de facto standard
• Events are generated whenever the parser reads a
  special type of element or other content

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DOM Example
XML Usage in Applications
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SAX Example
XML Usage in Applications

• Interface ContentHandler defines events
• Opening a Document
• Opening an Element
• Closing an Element
• CDATA Sections
• ...
• MyContentHandler has to implement the Callback
  Functions

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SAX Example
XML Usage in Applications

• 12 endDocument()

1 startDocument()
SAX Parser Method Calls
2 startElement("company", attribs)
3 startElement("employee", attribs)
4 startElement("name", attribs)
5 characters(char, start, length)means
Dilbert
6 endElement("name")
7 startElement("phone", attribs)
8 characters(char, start,
length)means 1234
9 endElement("phone")
10 endElement("employee")
11 endElement("company")
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DOM vs. SAX
XML Usage in Applications

• DOM
• Easy navigation in the document
• Modification and creation of documents is
  possible
• Parsing process is quite transparent
• Lots of resources needed
• Should be used, if the whole document needs to be
  read anyway

• SAX
• Faster
• Less ressources needed
• API is easy
• Lower-level-access
• Should be used, if only special parts of the
  documents have to be read (fast)

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Agenda
Agenda

• Example NinJo Configuration using XML

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Automatic Data Binding
Example NinJo Configuration using XML

• Disadvantage of DOM and SAX Application
  programmers should not know about the parsing
  process, it should be kept transparent
• Idea Automatic Data Binding
• The structure (DTD or XSD) of the document is
  normally known in advance. One can use this
  structure to generate other representations out
  of it, like for example sourcecode for Java
  classes
• The transformation from XML to Java can then be
  done automatically, the programmer does not need
  to care about parsing.
• The standard Java API JAXB provides this data
  binding idea.

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Automatic Data Binding
Example NinJo Configuration using XML
XML Structure
Java Structure
XML Content
Java Content
36
NinJo Configuration Framework
Example NinJo Configuration using XML

• NinJo Configuration Framework cares for
  (un-)marshalling automatically, ie Data Binding
  technology is used in the background.
• In here, configuration files can be read from and
  written to a local directory tree. Extension of a
  Configuration Server currently in work.
• Therefore NinJo has developed a own XML language
  (NML NinJo Modeling Language) to define the
  structure and to simplify the automatic mapping.
  
• The structure is defined in a so-called XBD file
• The content is defined in a XML file
• The XBD structure defines the configuration
  structure
• Configuration contents
• Configuration references (links to or reusage of
  other modules)

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NML NinJo Modeling Language
Example NinJo Configuration using XML
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NinJo Configuration Framework ConfigDesigner
Example NinJo Configuration using XML
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NinJo Configuration Framework Config Context
Example NinJo Configuration using XML

• Each NinJo module has its own Configuration
  Context (ie its own location where its config
  files are stored).
• The Configuration context is stored in a
  hierarchy Global, site specific and user
  specific configurations can be stored and
  retrieved.

SystemContext
SiteContext
UserContext
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Example NinJo ColorTable Configuration
(Temperature)
Example NinJo Configuration using XML
lt?xml version"1.0" encoding"UTF-8"?gt ltcolorTable
Cfg defGreen"204" unit"C/10"gt ltunitClass
configName"temperature"/gt ltcolors blue"200"
green"0" red"200" value"-350.0"/gt ltcolors
blue"255" green"150" red"255"
value"-300.0"/gt ltcolors blue"255" green"150"
red"0" value"-200.0"/gt ltcolors blue"255"
green"255" red"255" value"-100.0"/gt ltcolors
blue"255" green"255" red"0"
value"0.0"/gt ltcolors blue"200" green"200"
red"0" value"50.0"/gt ltcolors blue"50"
green"200" red"50" value"100.0"/gt ltcolors
blue"50" green"255" red"50"
value"150.0"/gt ltcolors blue"0" green"240"
red"255" value"200.0"/gt ltcolors blue"50"
green"150" red"255" value"250.0"/gt ltcolors
blue"0" green"0" red"255"
value"300.0"/gt ltcolors blue"0" green"0"
red"200" value"350.0"/gt lt/colorTableCfggt
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Agenda
Agenda

• An Overview of Advanced XML Technologies

42
Advanced XML Techniques
An Overview of Advanced XML Technologies
Namespacesavoid name conflicts
XSL is used for applying Style Sheets
XHTML and XForms are replacements for or
extensions to HTML
SOAP is the basic protocol for WebServices

43
XSL, XSLT and XSL-FO
An Overview of Advanced XML Technologies

• XSL eXtensible Style Language
• The W3C started to develop XSL because there was
  a need for an XML based Style Sheet Language.
• Style Sheets describe how documents are presented
  on screens, in print or published somewhere else
• XSL consists of three parts
• XSLT is a language for transforming XML documents
• XPath is needed as a underlying language for
  defining parts of an XML document
• XSL-FO is a language for formatting XML documents

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What can be done with XSL ?
An Overview of Advanced XML Technologies

• Think of XSL as set of languages that can
• transform one XML language into another,
• filter and sort XML data,
• define parts of an XML document,
• format XML data based on the data value (like for
  example displaying negative numbers in red)
• output XML data to different media (like screens,
  paper, or voice).

45
What can be done with XSL ?
An Overview of Advanced XML Technologies
46
XSLT used for Transformations
An Overview of Advanced XML Technologies

• XSLT is a language for transforming XML documents
  into other XML documents (hence the name).
• Often, this is used to transform XML to a type of
  document that is recognized by a browser, like
  HTML. Normally XSLT does this by transforming
  each XML element into an HTML element.
• XSLT can test and make decisions about which
  elements to display, like ...
• ... adding new elements to the output,
• ... removing elements,
• ... rearranging or sorting elements.
• A common way to describe the transformation
  process is to say that XSLT transforms an XML
  source tree into an XML result tree.

47
XPath
An Overview of Advanced XML Technologies

• XPath is the basic adressing language XSL is
  working on.
• It defines a node tree (quite similar to DOM).
  The nodes are ordered (depending on their
  apperance in the document).
• One can navigate through the tree. Some
  relationships shown below(not all , 11 are
  defined in total).

parent
ancestor
childs
descendants
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An Example for XSL Publish a CD Catalog on the
Web
An Overview of Advanced XML Technologies
Output is HTML pagewith the CD Catalog
4
3
Apply XSL to XML
2
XSL Document
CD CatalogXML Document
1
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An Example for XSL - Step 1 XML Document
An Overview of Advanced XML Technologies
lt?xml version"1.0" encoding"ISO-8859-1"?gt lt?xml-
stylesheet type"text/xsl" href"cdcatalog.xsl"?gt
ltcataloggt ltcdgt lttitlegtThe Joshua
Treelt/titlegt ltartistgtU2lt/artistgt
ltcountrygtIrelandlt/countrygt ltcompanygtIsland
Recordslt/companygt ltpricegt16.99lt/pricegt
ltyeargt1995lt/yeargt lt/cdgt ... lt/cataloggt
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An Example for XSL - Step 2 XSL Stylesheet
An Overview of Advanced XML Technologies
lt?xml version"1.0" encoding"ISO-8859-1"?gt
ltxslstylesheet version"1.0" ...gt
ltxsltemplate match"/"gt lthtmlgt ltbodygt
lth2gtMy CD Collectionlt/h2gt lttable
border"1"gt lttr bgcolor"9acd32"gt
ltth align"left"gtTitlelt/thgt ltth
align"left"gtArtistlt/thgt lt/trgt
ltxslfor-each select"catalog/cd"gt lttrgt
lttdgtltxslvalue-of select"title"/gtlt/tdgt
lttdgtltxslvalue-of select"artist"/gtlt/tdgt
lt/trgt lt/xslfor-eachgt lt/tablegt
lt/bodygtlt/htmlgt lt/xsltemplategt lt/xslstylesheetgt
HTML (blue) writtento output as shown
XSL Transformations
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An Example for XSL Step 3/4 Apply XSL to XML,
Browser Output
An Overview of Advanced XML Technologies
52
Advanced XML Techniques
An Overview of Advanced XML Technologies
Namespacesavoid name conflicts
XSL is used for applying stylesheets
?
XHTML and XForms are replacements or extensions
to HTML
SOAP is the basic protocol for WebServices

53
Namespaces
An Overview of Advanced XML Technologies

• Since element names in XML are not fixed, very
  often a name conflict will occur when two
  different documents use the same names describing
  two different types of elements.
• This problem is solved with unique prefixes.

Table uses theHTML4 namespace
ltftable xmlnsf"http//www.ikea.com/furniture"gt
ltfnamegtAfrican Coffee Tablelt/fnamegt
ltfwidthgt80lt/fwidthgtltflengthgt120lt/flengthgt lt/f
tablegt
lthtable xmlnsh"http//www.w3.org/TR/html4/"gt
lthtrgt lthtdgtAppleslt/htdgt
lthtdgtBananaslt/htdgtlt/htrgt lt/htablegt
Table uses afurniture namespace
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Advanced XML Techniques
An Overview of Advanced XML Technologies
Namespacesavoid name conflicts
XSL is used for applying stylesheets
?
?
XHTML and XForms are replacements or extensions
to HTML
SOAP is the basic protocol for WebServices

55
XHTML eXtensible HyperText Markup Language
An Overview of Advanced XML Technologies

• XHTML is HTML defined in XML.
• Why XHTML?
• Web has reached a point where many pages contain
  "bad" HTML.
• HTML Code might work fine if you view it in a
  browser, even if it does not follow the HTML
  rules.
• XHTML is almost identical to HTML 4.01. It is
  aimed to replace HTML, but it is stricter and
  cleaner.
• XHTML elements must be properly nested
• XHTML documents must be well-formed
• Tag names must be in lowercase
• All XHTML elements must be closed

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XForms
An Overview of Advanced XML Technologies

• XForms are the next generation of HTML forms
• XForms are richer and more flexible than HTML
  forms
• They are platform and device independent
• It is designed to handle interactive transactions
• Data and logic is separated from presentation
• XForms contain features like calculations and
  validations of forms (less scripting is required)
• XForms forms can be routed to multiple users and
  locations

57
Advanced XML Techniques
An Overview of Advanced XML Technologies
Namespacesavoid name conflicts
XSL is used for applying stylesheets
?
?
XHTML and XForms are replacements or extensions
to HTML
SOAP is the basic protocol for WebServices

?
58
SOAP Simple Object Access Protocol
An Overview of Advanced XML Technologies

• SOAP will be developed as a W3C standard
• SOAP is a protocol for accessing Web Services
• SOAP is a simple communication protocol to let
  applications exchange information via Internet
  protocol
• SOAP is platform and language independent
• SOAP is based on XML
• SOAP is simple and extensible

59
SOAP
An Overview of Advanced XML Technologies

• SOAP messages are ordinary XML documents

lt?xml version"1.0"?gt ltsoapEnvelope
xmlnssoap"... " ltsoapHeadergt ...
lt/soapHeadergt ltsoapBodygt ...
ltsoapFaultgt ... lt/soapFaultgtlt/soapBod
ygt lt/soapEnvelopegt
60
Usage of SOAP in Web Services
An Overview of Advanced XML Technologies

• SOAP is the protocol for Web Services.
• Web Services are loosely coupled software
  components based on standard Internet
  technologies (a current hype, not a very new
  idea).
• Two of the key problems solved by Web Services
  (over earlier distributed systems such as CORBA,
  DCOM, RPC ...) are
• Interoperability Usage of a standardized format
  for distributed messaging.
• Firewall traversal Usage of non-standard ports
  is a problem for collaboration across
  corporations. But most of the firewalls allow
  access through port 80 (for HTTP).

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Usage of SOAP in Web Services
An Overview of Advanced XML Technologies

• SOAP communication can be based on several
  underlying protocols HTTP, FTP, TCP, SMTP, POP3,
  MQSeries, ...
• Architecture Registry knows about Providers.
  Consumers asks for Providers and calls Provider
  then.

62
Usage of SOAP in Web Services
An Overview of Advanced XML Technologies

• Each application can be a combination of
  Providers, Consumers or Registries.

63
Agenda
Agenda

• Literature

64
Literature
Literature
http//www.w3.org/TR/REC-xml http//www.xml.org ht
tp//www.xmlsoftware.com http//www.w3.org/DOM/ h
ttp//sax.sourceforge.net/ http//www.w3.org/Style
/XSL/ http//www.w3.org/TR/xpath http//www.w3.or
g/TR/soap/ http//java.sun.com/xml/jaxb/
http//www.irb.hr/cern/WWW/publications/sgmlen/s
gmlen.html http//www.xmlfiles.com/xml/ http//w
ww.w3schools.com/default.asp http//java.sun.com/
xml/tutorial_intro.html

• XML
• XML Software
• DOM
• SAX
• XSL
• XPath
• SOAP
• Data Binding
• SGML
• Tutorials

65
Any Questions (about the Content -) ?
Literature