Transcript What does web services

Web Services
Course Introduction
Week1
Eva Rose, Ph.D.
Who am I?
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Became interested in programming in H.S.
Masters thesis on Java and the Java Virtual
Machine.
Ph.D. thesis on the Java bytecode verifier.
Studied web services at IBM T.J.Watson
research center.
Teach web services and advanced
programming language theory to graduate
students and juniors.
Attached to Center for Collaborative and OnDemand Computing (CCODC).
Syllabus
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also available from http://eva.rose.name
contact and course announcements
course objective, approach, and assessment
class participation and attendance
course overview
Introduction to Web services.
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What is a web service?
SOA and distributed information systems
Web service architecture
Go and explore....
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go to the w3c.org website, or
go to the oasis.org website.
What does web services
“solve”?
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Evolved around the problem of application
integration in distributed systems.
Removes the need for tightly coupled
components,
resulting in monolithic, inflexible applications.
Hides technical details about the service
behind the service Interface
When does SOA and web
services apply?
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part of the solution exists in multiple
networks.
solution components are built and run by
different organizations.
the components which needs to be
integrated have heterogenious platforms
(OS, application server, programming
language).
the business process could be automated
without human interaction.
dynamic and flexible business environmet.
Example of an XML document
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Viewing Listing 2.1: purchase order
iinformation in a browser.
The XML document prolog
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The processing instruction “?xml” identifies a
document as an XML document.
All XML documents begins with:
<?xml version=”1.0” encoding=”UTF-8” ?>
Comments in XML
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cannot be nested.
<--! this will not be processed as XML -->
XML syntax rules
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Elements
Attributes
Character data
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organized as a tree.
one root element
child, parent, sibling,
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XML Element syntax
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Element start and end tags: <po> ... </po>
Empty element: <po />
Non-empty:
<po>
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</po>
Element content
(ie, text, XML)
XML Attribute Syntax
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name-value pair
lives within an element (start) tag.
name = “ value”
Character data (reserved)
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encoding, whitespace, entities.
Character
Escape sequences
<
>
&
'
“
&lt;
&gt;
&amp;
&apos;
&quot;
Exercise: Escape characters
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Go to eclipse on your lab machine.
Use the text editor to enter the XML
document on p.43.
Open the XML document in your browser.
What do you see?
The CDATA construct
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Allows any sequence of characters.
<![ CDATA{
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]]>
Exercise: CDATA
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Go to the previous file (corresponding to the
XML document on p. 43). Use the CDATA
construct instead of all the escape
characters.
See you next week.
Lecture (please read in advance): p.44-91.