1. SOAP-based Web Services
Web Technology
2II25
Dr. Katrien Verbert
Dr. ir. Natasha Stash
Dr. George Fletcher

2. Contents
• Big Web Services
• SOAP, WSDL and UDDI
• Comparison RESTful Web Services
• Next lecture
• JAX-WS: Building SOAP-based services in Java
• JAXB: SOAP and XML processing
• JAX-RS: Building RESTful services in Java

3. What Are Web Services?

4. Web Services, Web Applications and
APIs (Application Programming Interface)
• Web Applications == Web Services == Web APIs ?

5. Web Services, Web Applications and
APIs (Application Programming Interface)
• Web Applications are designed to be accessed by end
users through Web client software
• Web Services are intended to be used by other software
applications
• Web APIs ≈ Web Services

6. Example Mashup: Last on AM/FM
http://people.cs.kuleuven.be/~sten.govaerts/lastonamfm/
http://www.programmableweb.com/mashup/last-on-am-fm

7. Example web client application
http://ariadne.cs.kuleuven.be/alocom/alocom_plugin/alocom_plugin.swf

9. Disaggregation service

10. What Are Web Services?
• W3C definition:
• A software system designed to support interoperable
machine-to-machine interaction over a network...

11. Web Services Use
• Connect existing software
• Reusable application components

12. Terminology
• Major classes of Web Services:
• Big Web Services
• (L. Richardson and S. Ruby)
• RESTful (REST-compliant) Web Services
• Service-Oriented Architecture (SOA)
• The Competing Web Service Architectures:
• (L. Richardson and S. Ruby):
• RPC-Style Architectures (Remote Procedure Calls)
• RESTful, Resource-Oriented Architectures (ROA)
• REST-RPC Hybrid Architectures

13. Web Service Technologies
• Basic Web Services platform:
• XML+HTTP
• Related to Big Web Services:
• SOAP (Simple Object Access Protocol)
• WSDL (Web Services Description Language)
• UDDI (Universal Description, Discovery, and
Integration)

14. Roles and Operations in a
Service-Oriented Architecture (SOA)
Service
Broker
Find Publish
Service Service
Requester Provider
Bind

15. Goals of SOA
• separation of concerns
• loose coupling among interacting software applications
• reusability of services
• interoperability

16. The Standards, Components and Relationships for
Big Web Service Implementation
Service Broker
2) Find (UDDI registry)
Web Service
Service
Requester 3) Download
(Web WSDL
Service
client) 1) Publish
Web Service
4) Invoke Service
Web Service Provider (Web
Service)

17. What is SOAP
• SOAP used to stand for Simple Object Access Protocol
• SOAP is a communication protocol
• SOAP is designed to communicate via Internet
• SOAP is based on XML
• SOAP is simple and extensible
• SOAP is platform and language independent
• SOAP is a W3C standard

18. SOAP Message Structure
<?xml version='1.0' ?><env:Envelope
xmlns:env="
SOAP Envelope http://www.w3.org/2003/05/soap-envelope">
SOAP Header <env:Header>
...
header block </env:Header>
<env:Body>
SOAP Body ...
<env:Fault>
body block ...
</env:Fault>
</env:Body>
</env:Envelope>

19. SOAP Example: RPC-Style Request Message
<?xml version='1.0' ?> Request
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope">
<env:Body>
<ts:getPrice xmlns:ts="http://travelagency.example.org/wsdl/trips"
s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding">
<ts:departing>Amsterdam (Schiphol)</ts:departing>
<ts:arriving>Saint-Petersburg (Pulkovo)</ts:arriving>
<ts:departureDate>01-05-2010</ts:departureDate>
<ts:/getPrice>
</env:Body>
</env:Envelope>
<?xml version='1.0' ?><env:Envelope xmlns:env=" Response
http://www.w3.org/2003/05/soap-envelope">
<env:Body>
<ts:getPriceResponse xmlns:ts="http://travelagency.example.org/wsdl/trips"
s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding" >
<ts:price>180.00</ts:price>
</ts:getPriceResponse>
</env:Body>
</env:Envelope>

20. RPC-Style Architectures
• Envelopes exchange between Web Service and its
client
• Kinds of envelopes:
• HTTP
• SOAP

21. SOAP Example:
Conversational Message Exchanges
<?xml version='1.0' ?> Response
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope">
<env:Body>
...
<ts:arriving>
<ts:arrivingChoices>airport1 airport2 airport3</ts:arrivingChoices>
</ts:arriving>
...
</env:Body>
</env:Envelope>
<?xml version='1.0' ?><env:Envelope xmlns:env=" Request
http://www.w3.org/2003/05/soap-envelope"> <env:Body>
...
<ts:arriving>airport1</ts:arriving>
... </env:Body>
</env:Envelope>

22. Fault Scenarios
<?xml version='1.0' ?>
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"
xmlns:rpc='http://www.w3.org/2003/05/soap-rpc'>
<env:Body>
<env:Fault> x
<env:Code>
<env:Value>env:Sender</env:Value>
<env:Subcode>
<env:Value>rpc:BadArguments</env:Value>
</env:Subcode>
</env:Code>
<env:Reason>
<env:Text xml:lang="en-US">Processing error</env:Text>
</env:Reason>
</env:Fault>
</env:Body>
</env:Envelope>

23. SOAP HTTP Binding:
SOAP HTTP Post Usage
POST /pricesService/getPrice HTTP/1.1
Host: http://travelagency.example.org
Content-Type: application/soap+xml; charset=utf-8
Content-Length: nnn
<?xml version='1.0' ?>
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope">
<env:Body>
<ts:getPrice xmlns:ts="http://travelagency.example.org/wsdl/trips">
<ts:departing>Amsterdam (Schiphol)</ts:departing>
<ts:arriving>Saint-Petersburg (Pulkovo)</ts:arriving>
<ts:departureDate>21-04-2010</ts:departureDate>
<ts:/getPrice>
</env:Body>
</env:Envelope>

24. SOAP HTTP Binding:
SOAP Response
HTTP/1.1 200 OK
Content-Type: application/soap+xml; charset=utf-8
Content-Length: nnn
<?xml version='1.0' ?>
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope">
<env:Body>
<ts:getPriceResponse xmlns:ts="http://travelagency.example.org/wsdl/trips">
<ts:price>180.00</ts:price>
</ts:getPriceResponse>
</env:Body>
</env:Envelope>

25. What is WSDL
• WSDL stands for Web Services Description Language
• WSDL is used to describe and locate Web Services
• WSDL is based on XML
• WSDL is a W3C standard

26. WSDL
Describes three fundamental properties
• What a service does
• Operations (methods) provided by the service
• How a service is accessed
• Data format and protocol details
• Where a service is located
• Address (URL) details

27. WSDL Document Structure
WSDL Specification Main structure of WSDL document
abstract part
<definitions targerNamespace= ... >
types
<types>definition of types...</types>
messages
<message>definition of a message...</message>
operations
port types <portType>definition of a port</portType>
concrete part <binding>definition of a binding...</binding>
bindings
<service>
service <port>...</port>
</service>
port
</definitions>

28. WSDL Document Example:
Abstract Part
<message name="itineraryMsg">
<part name="departing" type="xs:string"/>
<part name="arriving" type="xs:string"/>
<part name="departureDate" type="xs:date"/>
</message>
<message name="itineraryRespMsg">
<part name="price" type="xs:string"/>
</message>
<portType name="pricesPT">
<operation name="getPrice">
<input message="itineraryMsg"/>
<output message="itineraryRespMsg"/>
</operation>
</portType>

29. Operation Types
Type Definition
One-way The operation can receive a message but will not return
a response
Request- The operation can receive a request and will return a
response response
Solicit-response The operation can send a request and will wait for a
response
Notification The operation can send a message but will not wait for
a response

30. Example: One-Way Operation
<message name="newPrices">
<part name="departing" type="xs:string"/>
<part name="arriving" type="xs:string"/>
<part name="departureDate" type="xs:date"/>
<part name="price" type="xs:string"/>
</message>
<portType name="pricesPT">
...
<operation name="setPrice">
<input message="newPrices"/>
</operation>
</portType >

31. WSDL Document Example:
Concrete Part
<service name="pricesService">
<port name="getPriceRPCPort" binding="ts:b1">
<soap:address
location="http://travelagency.example.org/pricesService">
</port>
</service>
xmlns:ts='http://travelagency.example.org/wsdl/trips'

32. WSDL Document Example:
Concrete Part
<binding name="b1" type="ts:getPriceRPCPort">
<soap:binding style="rpc"
transport="http://schemas.xmlsoap.org/soap/http" />
<operation name="ts:getPrice">
<input>
<soap:body use="encoded"
namespace="http://travelagency.example.org/wsdl/trips"
encodingStyle="http://schemas.xmlsoap.org/soap/encoding" />
</input>
<output>
<soap:body use="encoded"
namespace="http://travelagency.example.org/wsdl/trips"
encodingStyle="http://schemas.xmlsoap.org/soap/encoding" />
</output>
</operation>
...
</binding>
xmlns:soap='http://schemas.xmlsoap.org/wsdl/soap/'

33. What is UDDI
• UDDI stands for Universal Description, Discovery and Integration
• UDDI a standard for publishing and discovering Web services
• UDDI is a specification for a distributed registry of Web services
• UDDI is built upon standards such as HTTP, XML, XML Schema,
SOAP, WSDL
• UDDI can communicate via SOAP, CORBA, Java RMI Protocol
• UDDI uses WSDL to describe interfaces to Web Services

34. Ways to Use UDDI Registry
• White pages
– name, address, contact person, Web site
• Yellow pages
– types of business, locations, products, services,
categorizations
• Green pages
– technical information about business services, pointers to
WSDL descriptions of the services

35. UDDI Data Model:
UDDI Core Data Types
Example: http://www.tutorialspoint.com/uddi/uddi_data_model.htm

36. UDDI Data Model:
tModel example
<?xml version="1.0"?>
<tModel tModelKey="”>
<name>http://www.getquote.com/StockQuoteService-interface</name>
<description xml:lang="en">…</description>
<overviewDoc>
<description xml:lang="en”>WSDL Service Interface Document </description>
<overviewURL>
http://www.getquote.com/services/SQSinterface.wsdl#SingleSymbolBinding
</overviewURL>
</overviewDoc>
<categoryBag>
<keyedReference tModelKey="UUID:C1ACF26D-9672-4404-9D70-39B756E62AB4”
keyName="uddi-org:types" keyValue="wsdlSpec"/>
<keyedReference tModelKey="UUID:DB77450D-9FA8-45D4-A7BC-04411D14E384”
keyName="Stock market trading services”
keyValue="84121801"/>
</categoryBag>
</tModel>

37. UDDI: Programmatic Interfaces
• UDDI Inquiry Interface:
– find_business, find_service, find_tModel, find_binding,
find_relatedBusiness
– get_businessDetail, get_serviceDetail, get_bindingDetail,
get_tModelDetail
• UDDI Publisher Interface:
– save_business, save_service, save_binding, save_tModel
– delete_business, delete_service, delete_binding,
delete_tModel
– ...

38. Big Web Services Examples
• http://www.xmethods.com
• http://www.programmableweb.com/

39. Web services enable
1. data exchange between various applications and different platforms
2. to resolve interoperability issues
3. applications to function between two different operating systems server
4. all of the above

40. Coding and decoding, and transporting the data is
performed by
1. XML and UDDI respectively
2. XML and SOAP respectively
3. HTML and HTTP respectively
4. HTML and SOAP respectively

41. Which of the following is used to locate and
describe web services?
1. SOAP
2. Web page
3. WSDL
4. UDDI

42. Why SOAP is used as a protocol for accessing a
web service?
1. SOAP platform and language independent, allows to get around firewalls
2. SOAP is based on HTML
3. SOAP is designed to communicate through LAN
4. All of the above

43. Big Web Service Operations vs
RESTful Web Service URIs
Big WS operations RESTful WS URIs
getAllUsers() http://example.com/users/
"
getUserById() http://example.com/users/id/<user-id>
getUserByName(), addUser() http://example.com/users/name/<user-name>
removeUser(), updateUser()
03/28/11

44. Big Web Services versus REST
A SOAP service has a single endpoint
• that handles all the operations
• therefore it has to have an application-specific interface.
A RESTful service has a number of resources
• so the operations can be distributed onto the resources
• and mapped to a small uniform set of operations.
03/28/11

45. Comparison:
Big Web Services vs RESTful Web Services
• How the client conveys its intentions to the server?
Where method information is kept?
– Big Web Services: in HTTP header and entity body
– RESTful Web Services: in HTTP header
• How the client tells the server which part of the data set
to operate on? Where is scoping information kept?
– Big Web Services: in the entity body
– RESTful Web Services: in the URI path

46. Comparison:
Big Web Services vs RESTful Web Services
• Big Web Services pros:
– protocol transparency and independence
– existence of tools to hide the complexity
– security
• Big Web Services cons:
– rudimentary processing protocol
– complexity
– heavyweight architecture
– do not get the benefits of resource-oriented services
– opaqueness

47. Comparison:
Big Web Services vs RESTful Web Services
• Big Web Services are the preferred option for enterprise
application integration
• RESTful Web services are well suited for basic, ad hoc
integration scenarios over Web (Mashup)

48. Comparison:
Big Web Services vs RESTful Web Services
• RESTful Web Services pros:
– simplicity
– lightweight infrastructure
– addressability
– uniform interface
– scalability of stateless RESTful Web Service
– improved performance using JSON
• RESTful Web Services cons:
– bound to one protocol: HTTP
– only POST and GET can be used in XHTML form
– dealing with large input data - malformed URI
– security issues

49. Recommended reading
Cesare Pautasso,Olaf Zimmermann,Frank Leymann
(2008) RESTful Web Services vs. Big Web Services:
Making the Right Architectural Decision. Proc. of the
17th International World Wide Web Conference
(WWW2008), Bejing, China, April 2008.

50. k.verbert@tue.nl
n.v.stash@tue.nl
g.h.l.fletcher@tue.nl
03/28/11