Łukasz Sokołowski: /* Entity References ⌘ */

2017-05-29T12:45:58Z

Entity References ⌘

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{{Cat|Web Services Basics For Non-programmers|04}}

<slideshow style="nobleprog" headingmark="⌘" incmark="…" scaled="true" font="Trebuchet MS" >
;title: Web Services Basics For Non-programmers
;author: Pete George (NobleProg Ltd)
</slideshow>

=Day One Schedule ⌘=
# Introductions
# Service-Oriented Architecture
# Web Services Overview
# XML
# SOAP
=XML ⌘=
Learning Objectives
* To appreciate the advantages and disadvantages of using XML for Web services
* To understand the basic structure of an XML message
* To be aware of Xpath, XSD and XSLT
=XML Messaging ⌘=
[[File:XML 1.png|600px]]

=XML eXtensible Markup Language ⌘=
*W3C Recommendation 1998
*Most common method for data exchange
=eXtensible Markup Language ⌘=
[[File:XML 2.png|600px]]

=eXtensible Markup Language ⌘=
*Markup language, like HTML
[[File:XML 3.png|600px]]

=Why XML and Web Services? ⌘=
* Data not presentation
* Interoperability
* Resilience
* Easily readable
=Why XML and Web Services? ⌘=
*Data not presentation
[[File:XML 5.png|400px]]

=Why XML and Web Services? ⌘=
*Interoperability
-Easy to agree XML format for data exchange

-High availability of XML parsers

-No need for low-level code to read/write data

[[File:XML 4.png|600px]]

=Why XML and Web Services? ⌘=
XML is more resilient
[[File:XML 6.png|600px]]

=Why XML and Web Services? ⌘=
*Easily readable
[[File:XML 7.png|600px]]

=Easily Readable? ⌘=
[[File:XML 10.png|400px]]

=Elements and Attributes ⌘=
*Elements, e.g.
<Users> some users </User>

*Attributes, e.g.
<user name=“Pete”> User1 </user>
or
<user name=“Pete”/>
=Elements and Attributes ⌘=
[[File:XML 8.png|600px]]

=Root Element ⌘=
*Well-formed XML has one element at root

<rootElement>
<anotherElement anAttribute=“some data”>
</anotherElement>
</rootElement>

=Root Element ⌘=
[[File:XML 9.png|600px]]

=XML Prolog ⌘=
*XML Prolog

<?xml version=“1.0”?>

-Optional, but usually declared

-May contain other information, e.g.
<?xml version=“1.0” encoding=“UTF-8”?>

=XML Prolog ⌘=
[[File:XML 02.png|600px]]

=Namespaces ⌘=
*Group XML elements together

*Declare namespace
xmlns=<URI>

-E.g.
xmlns:PETE=http://pa-uk.net/etc
<PETE:users >
=Namespaces ⌘=
*<big>URI = Uniform Resource Identifier</big>
-String that points to something
*Can be:
-<big>URL = Uniform Resource Locator</big>

-Specifies location of a resource

-[scheme]://[Domain]:[Port]/[Path]?[Querystring]#[FragmentId]

-<big>URN = Uniform Resource Name</big>

-Uniquely identifies something

-urn:[namespace identifier]:[namespace specific string]

=Namespaces ⌘=
[[File:XML 03.png|600px]]

=Comments ⌘=
*Comments can also be included
< !--This is a comment-- >
=Entity References ⌘=
*Illegal characters can be used by inserting entity references
<syntaxhighlight lang="html">
& = &

< = <

> = >

“ = "

‘ = '
</syntaxhighlight>

=XPath ⌘=
*XML Path Language
*Query language used to target specific elements or attributes
*Works like file system paths:
<users>
<user name=“Pete” />
</users>

XPath = /Users/user

=XPath ⌘=
[[File:XML 11.png|600px]]

=XML Document Definition ⌘=
*Describe structure of XML document
*Used to test XML document is valid
*Used to author XML document in editor

*Document Type Definition (DTD)
-Widespread but on decline

-Not in XML format
=XML Schema (XSD) ⌘=
*Defines rules XML document must conform to be considered 'valid’

*Advantages over DTD:
-In XML format

-Namespace aware

-Data type aware
*defines elements/attributes containing values such as integers

=XSLT ⌘=
*Extensible Stylesheet Language Transformations
*Transforms XML file into new XML file in new style
*Can transform XML into other forms, e.g. XHTML
=XML Disadvantages ⌘=
[[File:XML 12.png|800px]]

=Quiz – No Prizes! No Pressure! ⌘=
[[File:XML 14.png|600px]]

XML - Revision history

Łukasz Sokołowski: /* Entity References ⌘ */