Transcript pps
Slide 1
ICE0534 – Web-based Software Development
ICE1338 – Programming for WWW
- Summer 2005 -
Lecture #10
In-Young Ko
iko .AT. icu.ac.kr
Information and Communications University (ICU)
Slide 2
Announcements
Reading Questions #5 (for the Ph.D.
lecture) is due by Tuesday August 2nd
Summer 2005
Submit the homework to Mr. Byungsang Kim
(bskim .AT. icu.ac.kr)
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
2
Slide 3
Last Lecture
Internationalization
Technology Reviews
P3P [u11: Youngjin Ro]
XML Signature [u12: Yoonjung choi]
Technology Surveys
Web security [g16: Jonggul Park]
Grid Computing [g17.1: Youngjoo Han]
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
3
Slide 4
This Lecture
Web Services
Technology Reviews
Web Services Architecture
SOAP (Simple Object Access Protocol)
WSDL (Web Services Description Language)
UDDI (Universal Description, Discovery and Integration)
SOAP [u13: Jongwook Lee]
WSDL [u14: Hyunho Park]
Technology Surveys
Summer 2005
UDDI [g19: Jongha Jung]
SOA (Service-oriented Architecture) [g20: Changsup Keum]
Web-services Platforms [g21: Youngkyu Park]
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
4
Slide 5
Difficulties in Using Web Wrappers
http://websearch.naver.com/search.naver?where=w
ebkr&query=www&xc=&qt=df&f=all&r=&st=s&fd=1&
start=101&display=10&domain=&dftf=&qf=1&qvt=0
Summer 2005
ICE 0534/ICE1338 – WWW
Need to analyze
how to generate a
URL
Need to parse Web
pages to obtain
result data
Need to modify the
wrapper when the
result page format
is changed
© In-Young Ko, Information and Communications University
5
Slide 6
What would be better?
Access the Web site as if we call functions:
e.g., result = Naver.webSearch(“ICU”);
String[] titles = result.getTitles();
String[] urls = result.getURLs();
APIs are independent from the changes on the
layout of the result pages
Use standard protocols such as HTTP to
directly access the Web site from a program
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
6
Slide 7
Solution: Web Services
xmethods.com
Allow users to test Web
Services via a Webbased interface
Provides a list of
publicly available
Web Services
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
7
Slide 8
Web Services
Web services provide a standard means of interoperating
between different software applications, running on a variety of
platforms and/or frameworks [W3C]
External Users
Web Services Platform
WSDL, SOAP, UDDI
Services
External Software System
Software Components
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
8
Slide 9
Service-oriented Architectures (SOA)
SOA is a form of distributed systems architecture
that is composed of loosely coupled services,
which interact with each other by exchanging
messages
Service Request
Message
Service
Provider
Service
Consumer
Service Response
Message
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
9
Slide 10
SOA Properties
Logical view: The service is an abstracted, logical view of actual
programs, databases, business processes, etc., defined in terms of
what it does
Message orientation: The service is formally defined in terms of
the messages exchanged between provider agents and requester
agents, and not the properties of the agents
Description orientation: A service is described by machineprocessable meta data
Granularity: Services tend to use a small number of operations
with relatively large and complex messages
Network orientation: Services tend to be oriented toward use over
a network
Platform neutral: Messages are sent in a platform-neutral,
standardized format delivered through the interfaces (in XML)
http://www.w3.org/TR/ws-arch/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
10
Slide 11
Benefits of Using Web Services
Inheriting the benefits of service-oriented
software development
Enable outsourcing services
Adaptability, Scalability, Maintainability
Abstraction, Loose coupling, Asynchrony, Agility
Standard-based solution
Ubiquitous services via the Web
Clean division between production and
delivery of service
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
11
Slide 12
Main Elements in Web Services
http://www.w3.org/TR/ws-arch/
An agent is a program acting on behalf of person or
organization; implements a Web service
A provider entity is the person or organization that
provides an appropriate agent to implement a service
A requester entity is a person or organization that
wishes to make use of a provider entity's Web service
A Web Services description is a machine-processable
specification of the Web service's interface, written in
WSDL
The semantics of a Web service is the shared
expectation about the behavior of the service (the
"contract" between the requester and the provider)
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
12
Slide 13
Engaging a Web Service
http://www.w3.org/TR/ws-arch/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
13
Slide 14
RPC (Remote Procedure Call)
A method by which a client can invoke a procedure on a
remote server as if it were running on the client
Sun popularized RPCs in the 1980s for its Unix systems
1. A client process, known as a client stub, converts a
request from a local application into a common data
format
2. The request is then transported across a network to a
server stub
3. The server stub translates the request into a form the
server process can understand
4. Once the server process processes the request, the
procedure is reversed
http://www.nwfusion.com/details/783.html
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
14
Slide 15
RPC Model
Marshalling
Client Process
Server Process
Client
Routines
Server
Routines
(1)
(6)
(10)
(7)
(9)
(8)
Network
Routines
Summer 2005
ICE 0534/ICE1338 – WWW
Unmarshalling
Server
Stub
Client
Stub
(2)
(5)
(4)
Network
Routines
(3)
© In-Young Ko, Information and Communications University
15
Slide 16
RPC Examples
SunPRC
Java RMI (Remote Method Invocation)
Use of the XDR (External Data Representation)
standard for describing message formats
Use of Java interfaces for describing message
formats
Use of the Java object serialization for data
transmission
Web Services
Summer 2005
Use an XML-based mechanism (SOAP) for
describing message formats
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
16
Slide 17
Web Services and RPC
Web Services use an XML-based RPC
mechanism (called SOAP)
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
17
Slide 18
Web Services Standards
WSDL (Web Services Description Language)
DAML-S (DARPA Agent Markup Language for
Services)
Language for Describing Semantic Web Services
SOAP (Simple Object Access Protocol)
Language for Describing Functionality and I/O Data
of Web Services
Envelop for sending messages
UDDI (Universal Description Discovery and
Integration)
Summer 2005
Directory service for Web Services
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
18
Slide 19
Web Services Architecture
SOAP Message
(Service Request in WSDL)
Service Consumer
Service Provider
4
5
SOAP Message
(Service Response)
1 SOAP Message
SOAP Message
(Queries)
2
3
SOAP Message
(Query Response in
WSDL)
(Service Description in
WSDL)
Directory Service
(UDDI)
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
19
Slide 20
SOAP
Provides a standard, extensible, composable
framework for packaging and exchanging XML
messages
Service Oriented Architecture Protocol:
Represents the information needed to invoke a service
or reflect the results of a service invocation
Contains the information specified in the service
interface definition
Simple Object Access Protocol:
Summer 2005
Represents a method invocation on a remote object
Represents the serialization of in the argument list of
that method that must be moved from the local
environment to the remote environment http://www.w3.org/TR/ws-arch/
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
20
Slide 21
SOAP Elements
A required Envelope element that identifies the
XML document as a SOAP message
An optional Header element that contains
header information
A required Body element that contains call and
response information
An optional Fault element that provides
information about errors that occurred while
processing the message
http://www.w3schools.com/soap/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
21
Slide 22
Skeleton SOAP Message
soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
...
...
...
http://www.w3schools.com/soap/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
22
Slide 23
SOAP Example – Service Request
X1lNZ…………………+Y9j
0
10
true
false
lang_ko
A SOAP message for
latin1
accessing the Google
latin1
Web Service
http://www.google.com/apis/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
23
Slide 24
Web Service Request via HTTP
C:\>telnet api.google.com 80
POST /search/beta2 HTTP/1.0
Host: api.google.com
Accept: text/*
Content-type: text/xml
SOAPAction: urn:GoogleSearchAction
Content-length: 408
X1lN… .. .. ..
Y9j 0 10>true false latin1 oap:Envelope>
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
24
Slide 25
SOAP Example – Service Response
Result header
xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/1999/XMLSchema">
false
10
false
…
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
25
Slide 26
SOAP Example – Service Response
Web page
http://www.yahoo.com/
listing
32k
Top/Computers/Internet/Searching/Directories/Yahoo
Yahoo!
... Business… Media Newspapers, TV...
The first large scale directory of the
Internet...
Yahoo!
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
26
Slide 27
WSDL
Web Services Description Language
An XML-based language for describing Web services
Submitted as a W3C Note by Ariba, IBM and Microsoft
for the W3C XML Activity in March 2001
Defines the message formats, datatypes, transport
protocols, and transport serialization formats that should
be used between the requester agent and the provider
agent
Represents an agreement governing the mechanics of
interacting with that service
http://www.w3.org/TR/ws-arch/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
27
Slide 28
WSDL Description Levels
Abstract-level Descriptions: describe a Web service in
terms of the messages it sends and receives
An operation associates a message exchange pattern with one
or more messages
A message exchange pattern identifies the sequence and
cardinality of messages sent and/or received as well as who they
are logically sent to and/or received from
An interface groups together operations without any
commitment to transport or wire format
Concrete-level Descriptions:
A binding specifies transport and wire format details for one or
more interfaces
An endpoint associates a network address with a binding
A service groups together endpoints that implement a common
interface
http://www.w3.org/TR/wsdl20/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
28
Slide 29
WSDL Document Structure
Main Elements:
The operations performed by the web
service
The messages used by the web service
The data types used by the web service
The communication protocols used by the
web service
Skeleton WSDL Document:
definition of types........
definition of a message....
definition of a port.......
definition of a binding....
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
29
Slide 30
WSDL Example
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
30
Slide 31
WSDL Example (cont.)
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
31
Slide 32
Google WSDL
http://api.google.com/GoogleSearch.wsdl
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
32
Slide 33
Web Services Examples
WS Index: http://www.wsindex.org/Web_Services/index.html
XMethods (List of publicly available Web
Services): http://www.xmethods.com/
Summer 2005
Google search
Amazon.com
InstantMessageAlert
SendEmail
Global Weather
StockQuote
Air Fare Quote Search
BabelFish
…
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
33
Slide 34
The Problem with Web Services
How can I discover business partners
with compatible web service solutions?
How do let other business know about my
exposed web services?
Web services are great, after you find out
about them, but the discovery process is
difficult
http://sern.ucalgary.ca/courses/CPSC/547/W2002/slides/uddi-wsdl.ppt
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
34
Slide 35
UDDI
Universal Description, Discovery and Integration
UDDI creates a standard interoperable platform that
enables humans and applications to quickly, easily, and
dynamically find and use Web services over the Internet
UDDI allows operational registries to be maintained for
different purposes in different contexts
UDDI is a cross-industry effort (UDDI.org) driven by major
platform and software providers, as well as marketplace
operators and e-business leaders
http://www.uddi.org/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
35
Slide 36
UDDI Data
Entities: data structures that expressed in XML, and are
persistently stored by UDDI nodes
Entity Types:
Summer 2005
businessEntity: Describes a business or other organization that
typically provides Web services
businessService: Describes a collection of related Web services
offered by an organization
bindingTemplate: Describes the technical information necessary
to use a particular Web service
tModel: Describes a “technical model” such as a Web service
type, a protocol, or a category system
publisherAssertion: Describes, the relationship that the
businessEntity has with another businessEntity
subscription: Describes a standing request to keep track of
changes to the entities described by the subscription http://www.uddi.org/
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
36
Slide 37
UDDI Example – Data Type Structure
authorizedName="0100002CAL"
operator="www-3.ibm.com/services/uddi">
BooksToGo
The source for all professional books
Ramesh Mandava
(877)1111111
Taken from http://developer.java.sun.com/developer/technicalArticles/WebServices/WSPack/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
37
Slide 38
Access UDDI via API’s
SOAP and XML Schema are the basis
UDDI Registry
Node
User
UDDI
SOAP Request
HTTP
Server
UDDI
SOAP Response
SOAP
Processor
UDDI
Registry Service
Create, View,
Update, and Delete
registrations
B2B Directory
Implementationneutral
© Copyright 2000 By Ariba, Inc., International Business Machines
Corporation and Microsoft Corporation. All Rights Reserved.
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
38
Slide 39
Web Services Stack
http://www-306.ibm.com/software/solutions/webservices/pdf/WSCA.pdf
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
39
Slide 40
Web Services Platforms
Provides facilities to support Web Servicesrelated activities
Service Description
Service Implementation
Service Publishing, Discovery and Binding
Service Invocation and Execution
Examples
Microsoft .NET
IBM’s WebSphere
Sun’s J2EE (Java 2 Platform, Enterprise Ed.)
http://www.webservicesarchitect.com/content/articles/hanson01.asp
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
40
Slide 41
Web Services References
W3C Web Services page: http://www.w3.org/2002/ws/
Web Services Architecture: http://www.w3.org/TR/wsarch/
Web Services Conceptual Architecture: http://www306.ibm.com/software/solutions/webservices/pdf/WSCA.pdf
Web Services Description Language (WSDL):
http://www.w3.org/TR/wsdl20/
WSDL Tutorial: http://www.w3schools.com/wsdl/default.asp
SOAP Tutorial: http://www.w3schools.com/soap/default.asp
SOAP Primer: http://www.w3.org/TR/soap12-part0/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
41
Slide 42
Web Services References (cont.)
UDDI Technical White Paper:
http://www.uddi.org/pubs/Iru_UDDI_Technical_White_Paper.pdf
UDDI Spec Technical Committee Specification:
http://uddi.org/pubs/uddi-v3.0.1-20031014.htm
The Java Web Services Tutorial:
http://java.sun.com/webservices/docs/1.0/tutorial/
Microsoft .NET - http://www.microsoft.com/net/
IBM’s WebSphere http://www.ibm.com/software/info1/websphere/index.jsp
Sun’s J2EE (Java 2 Platform, Enterprise
Edition) - http://java.sun.com/j2ee/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
42
Slide 43
Programming Homework #5
Due by Tuesday August 9th
Choose one of the Web Services (listed in Xmethods.com,
except Google) that accepts at least two inputs
Analyze the WSDL description of the Web Service and
identify how to access the Web Service
Develop a Web Service client program that
Accepts user’s inputs via a user interface (textual or graphical)
Generates a SOAP query based on the inputs
Connects to the Web Service and sends the SOAP query
Receives and parses the result SOAP-document
Displays the parsed results (in a textual or graphical user interface)
Extra Credit: Make a client program that accesses more
than one Web Services sequentially so that an output of a
Web Service is used by another Web Service as an input
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
43
ICE0534 – Web-based Software Development
ICE1338 – Programming for WWW
- Summer 2005 -
Lecture #10
In-Young Ko
iko .AT. icu.ac.kr
Information and Communications University (ICU)
Slide 2
Announcements
Reading Questions #5 (for the Ph.D.
lecture) is due by Tuesday August 2nd
Summer 2005
Submit the homework to Mr. Byungsang Kim
(bskim .AT. icu.ac.kr)
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
2
Slide 3
Last Lecture
Internationalization
Technology Reviews
P3P [u11: Youngjin Ro]
XML Signature [u12: Yoonjung choi]
Technology Surveys
Web security [g16: Jonggul Park]
Grid Computing [g17.1: Youngjoo Han]
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
3
Slide 4
This Lecture
Web Services
Technology Reviews
Web Services Architecture
SOAP (Simple Object Access Protocol)
WSDL (Web Services Description Language)
UDDI (Universal Description, Discovery and Integration)
SOAP [u13: Jongwook Lee]
WSDL [u14: Hyunho Park]
Technology Surveys
Summer 2005
UDDI [g19: Jongha Jung]
SOA (Service-oriented Architecture) [g20: Changsup Keum]
Web-services Platforms [g21: Youngkyu Park]
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
4
Slide 5
Difficulties in Using Web Wrappers
http://websearch.naver.com/search.naver?where=w
ebkr&query=www&xc=&qt=df&f=all&r=&st=s&fd=1&
start=101&display=10&domain=&dftf=&qf=1&qvt=0
Summer 2005
ICE 0534/ICE1338 – WWW
Need to analyze
how to generate a
URL
Need to parse Web
pages to obtain
result data
Need to modify the
wrapper when the
result page format
is changed
© In-Young Ko, Information and Communications University
5
Slide 6
What would be better?
Access the Web site as if we call functions:
e.g., result = Naver.webSearch(“ICU”);
String[] titles = result.getTitles();
String[] urls = result.getURLs();
APIs are independent from the changes on the
layout of the result pages
Use standard protocols such as HTTP to
directly access the Web site from a program
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
6
Slide 7
Solution: Web Services
xmethods.com
Allow users to test Web
Services via a Webbased interface
Provides a list of
publicly available
Web Services
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
7
Slide 8
Web Services
Web services provide a standard means of interoperating
between different software applications, running on a variety of
platforms and/or frameworks [W3C]
External Users
Web Services Platform
WSDL, SOAP, UDDI
Services
External Software System
Software Components
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
8
Slide 9
Service-oriented Architectures (SOA)
SOA is a form of distributed systems architecture
that is composed of loosely coupled services,
which interact with each other by exchanging
messages
Service Request
Message
Service
Provider
Service
Consumer
Service Response
Message
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
9
Slide 10
SOA Properties
Logical view: The service is an abstracted, logical view of actual
programs, databases, business processes, etc., defined in terms of
what it does
Message orientation: The service is formally defined in terms of
the messages exchanged between provider agents and requester
agents, and not the properties of the agents
Description orientation: A service is described by machineprocessable meta data
Granularity: Services tend to use a small number of operations
with relatively large and complex messages
Network orientation: Services tend to be oriented toward use over
a network
Platform neutral: Messages are sent in a platform-neutral,
standardized format delivered through the interfaces (in XML)
http://www.w3.org/TR/ws-arch/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
10
Slide 11
Benefits of Using Web Services
Inheriting the benefits of service-oriented
software development
Enable outsourcing services
Adaptability, Scalability, Maintainability
Abstraction, Loose coupling, Asynchrony, Agility
Standard-based solution
Ubiquitous services via the Web
Clean division between production and
delivery of service
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
11
Slide 12
Main Elements in Web Services
http://www.w3.org/TR/ws-arch/
An agent is a program acting on behalf of person or
organization; implements a Web service
A provider entity is the person or organization that
provides an appropriate agent to implement a service
A requester entity is a person or organization that
wishes to make use of a provider entity's Web service
A Web Services description is a machine-processable
specification of the Web service's interface, written in
WSDL
The semantics of a Web service is the shared
expectation about the behavior of the service (the
"contract" between the requester and the provider)
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
12
Slide 13
Engaging a Web Service
http://www.w3.org/TR/ws-arch/
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
13
Slide 14
RPC (Remote Procedure Call)
A method by which a client can invoke a procedure on a
remote server as if it were running on the client
Sun popularized RPCs in the 1980s for its Unix systems
1. A client process, known as a client stub, converts a
request from a local application into a common data
format
2. The request is then transported across a network to a
server stub
3. The server stub translates the request into a form the
server process can understand
4. Once the server process processes the request, the
procedure is reversed
http://www.nwfusion.com/details/783.html
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
14
Slide 15
RPC Model
Marshalling
Client Process
Server Process
Client
Routines
Server
Routines
(1)
(6)
(10)
(7)
(9)
(8)
Network
Routines
Summer 2005
ICE 0534/ICE1338 – WWW
Unmarshalling
Server
Stub
Client
Stub
(2)
(5)
(4)
Network
Routines
(3)
© In-Young Ko, Information and Communications University
15
Slide 16
RPC Examples
SunPRC
Java RMI (Remote Method Invocation)
Use of the XDR (External Data Representation)
standard for describing message formats
Use of Java interfaces for describing message
formats
Use of the Java object serialization for data
transmission
Web Services
Summer 2005
Use an XML-based mechanism (SOAP) for
describing message formats
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
16
Slide 17
Web Services and RPC
Web Services use an XML-based RPC
mechanism (called SOAP)
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
17
Slide 18
Web Services Standards
WSDL (Web Services Description Language)
DAML-S (DARPA Agent Markup Language for
Services)
Language for Describing Semantic Web Services
SOAP (Simple Object Access Protocol)
Language for Describing Functionality and I/O Data
of Web Services
Envelop for sending messages
UDDI (Universal Description Discovery and
Integration)
Summer 2005
Directory service for Web Services
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
18
Slide 19
Web Services Architecture
SOAP Message
(Service Request in WSDL)
Service Consumer
Service Provider
4
5
SOAP Message
(Service Response)
1 SOAP Message
SOAP Message
(Queries)
2
3
SOAP Message
(Query Response in
WSDL)
(Service Description in
WSDL)
Directory Service
(UDDI)
Summer 2005
ICE 0534/ICE1338 – WWW
© In-Young Ko, Information and Communications University
19
Slide 20
SOAP
Provides a standard, extensible, composable
framework for packaging and exchanging XML
messages
Service Oriented Architecture Protocol:
Represents the information needed to invoke a service
or reflect the results of a service invocation
Contains the information specified in the service
interface definition
Simple Object Access Protocol:
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Represents a method invocation on a remote object
Represents the serialization of in the argument list of
that method that must be moved from the local
environment to the remote environment http://www.w3.org/TR/ws-arch/
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SOAP Elements
A required Envelope element that identifies the
XML document as a SOAP message
An optional Header element that contains
header information
A required Body element that contains call and
response information
An optional Fault element that provides
information about errors that occurred while
processing the message
http://www.w3schools.com/soap/
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Skeleton SOAP Message
soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
...
...
...
http://www.w3schools.com/soap/
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SOAP Example – Service Request
www
A SOAP message for
accessing the Google
Web Service
http://www.google.com/apis/
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Web Service Request via HTTP
C:\>telnet api.google.com 80
POST /search/beta2 HTTP/1.0
Host: api.google.com
Accept: text/*
Content-type: text/xml
SOAPAction: urn:GoogleSearchAction
Content-length: 408
Y9j
www
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SOAP Example – Service Response
Result header
xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/1999/XMLSchema">
…
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SOAP Example – Service Response
Web page
listing
Top/Computers/Internet/Searching/Directories/Yahoo
Internet...
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WSDL
Web Services Description Language
An XML-based language for describing Web services
Submitted as a W3C Note by Ariba, IBM and Microsoft
for the W3C XML Activity in March 2001
Defines the message formats, datatypes, transport
protocols, and transport serialization formats that should
be used between the requester agent and the provider
agent
Represents an agreement governing the mechanics of
interacting with that service
http://www.w3.org/TR/ws-arch/
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WSDL Description Levels
Abstract-level Descriptions: describe a Web service in
terms of the messages it sends and receives
An operation associates a message exchange pattern with one
or more messages
A message exchange pattern identifies the sequence and
cardinality of messages sent and/or received as well as who they
are logically sent to and/or received from
An interface groups together operations without any
commitment to transport or wire format
Concrete-level Descriptions:
A binding specifies transport and wire format details for one or
more interfaces
An endpoint associates a network address with a binding
A service groups together endpoints that implement a common
interface
http://www.w3.org/TR/wsdl20/
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WSDL Document Structure
Main Elements:
service
web service
Skeleton WSDL Document:
definition of types........
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WSDL Example
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WSDL Example (cont.)
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Google WSDL
http://api.google.com/GoogleSearch.wsdl
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Web Services Examples
WS Index: http://www.wsindex.org/Web_Services/index.html
XMethods (List of publicly available Web
Services): http://www.xmethods.com/
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Google search
Amazon.com
InstantMessageAlert
SendEmail
Global Weather
StockQuote
Air Fare Quote Search
BabelFish
…
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Slide 34
The Problem with Web Services
How can I discover business partners
with compatible web service solutions?
How do let other business know about my
exposed web services?
Web services are great, after you find out
about them, but the discovery process is
difficult
http://sern.ucalgary.ca/courses/CPSC/547/W2002/slides/uddi-wsdl.ppt
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UDDI
Universal Description, Discovery and Integration
UDDI creates a standard interoperable platform that
enables humans and applications to quickly, easily, and
dynamically find and use Web services over the Internet
UDDI allows operational registries to be maintained for
different purposes in different contexts
UDDI is a cross-industry effort (UDDI.org) driven by major
platform and software providers, as well as marketplace
operators and e-business leaders
http://www.uddi.org/
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UDDI Data
Entities: data structures that expressed in XML, and are
persistently stored by UDDI nodes
Entity Types:
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businessEntity: Describes a business or other organization that
typically provides Web services
businessService: Describes a collection of related Web services
offered by an organization
bindingTemplate: Describes the technical information necessary
to use a particular Web service
tModel: Describes a “technical model” such as a Web service
type, a protocol, or a category system
publisherAssertion: Describes, the relationship that the
businessEntity has with another businessEntity
subscription: Describes a standing request to keep track of
changes to the entities described by the subscription http://www.uddi.org/
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UDDI Example – Data Type Structure
authorizedName="0100002CAL"
operator="www-3.ibm.com/services/uddi">
The source for all professional books
Taken from http://developer.java.sun.com/developer/technicalArticles/WebServices/WSPack/
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Access UDDI via API’s
SOAP and XML Schema are the basis
UDDI Registry
Node
User
UDDI
SOAP Request
HTTP
Server
UDDI
SOAP Response
SOAP
Processor
UDDI
Registry Service
Create, View,
Update, and Delete
registrations
B2B Directory
Implementationneutral
© Copyright 2000 By Ariba, Inc., International Business Machines
Corporation and Microsoft Corporation. All Rights Reserved.
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Slide 39
Web Services Stack
http://www-306.ibm.com/software/solutions/webservices/pdf/WSCA.pdf
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Slide 40
Web Services Platforms
Provides facilities to support Web Servicesrelated activities
Service Description
Service Implementation
Service Publishing, Discovery and Binding
Service Invocation and Execution
Examples
Microsoft .NET
IBM’s WebSphere
Sun’s J2EE (Java 2 Platform, Enterprise Ed.)
http://www.webservicesarchitect.com/content/articles/hanson01.asp
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Web Services References
W3C Web Services page: http://www.w3.org/2002/ws/
Web Services Architecture: http://www.w3.org/TR/wsarch/
Web Services Conceptual Architecture: http://www306.ibm.com/software/solutions/webservices/pdf/WSCA.pdf
Web Services Description Language (WSDL):
http://www.w3.org/TR/wsdl20/
WSDL Tutorial: http://www.w3schools.com/wsdl/default.asp
SOAP Tutorial: http://www.w3schools.com/soap/default.asp
SOAP Primer: http://www.w3.org/TR/soap12-part0/
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Web Services References (cont.)
UDDI Technical White Paper:
http://www.uddi.org/pubs/Iru_UDDI_Technical_White_Paper.pdf
UDDI Spec Technical Committee Specification:
http://uddi.org/pubs/uddi-v3.0.1-20031014.htm
The Java Web Services Tutorial:
http://java.sun.com/webservices/docs/1.0/tutorial/
Microsoft .NET - http://www.microsoft.com/net/
IBM’s WebSphere http://www.ibm.com/software/info1/websphere/index.jsp
Sun’s J2EE (Java 2 Platform, Enterprise
Edition) - http://java.sun.com/j2ee/
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Programming Homework #5
Due by Tuesday August 9th
Choose one of the Web Services (listed in Xmethods.com,
except Google) that accepts at least two inputs
Analyze the WSDL description of the Web Service and
identify how to access the Web Service
Develop a Web Service client program that
Accepts user’s inputs via a user interface (textual or graphical)
Generates a SOAP query based on the inputs
Connects to the Web Service and sends the SOAP query
Receives and parses the result SOAP-document
Displays the parsed results (in a textual or graphical user interface)
Extra Credit: Make a client program that accesses more
than one Web Services sequentially so that an output of a
Web Service is used by another Web Service as an input
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