Pal gov.tutorial3.session7

‫أكاديمية الحكومة اإللكترونية الفلسطينية‬
The Palestinian eGovernment Academy
www.egovacademy.ps

Tutorial III:
Process Integration and Service Oriented Architectures

Session 8
WSDL

Prepared By

Mohammed Aldasht

PalGov © 2011 1

About

This tutorial is part of the PalGov project, funded by the TEMPUS IV program of the
Commission of the European Communities, grant agreement 511159-TEMPUS-1-
2010-1-PS-TEMPUS-JPHES. The project website: www.egovacademy.ps
Project Consortium:
Birzeit University, Palestine
University of Trento, Italy
(Coordinator )

Palestine Polytechnic University, Palestine Vrije Universiteit Brussel, Belgium

Palestine Technical University, Palestine
Université de Savoie, France

Ministry of Telecom and IT, Palestine
University of Namur, Belgium
Ministry of Interior, Palestine
TrueTrust, UK
Ministry of Local Government, Palestine

Coordinator:
Dr. Mustafa Jarrar
Birzeit University, P.O.Box 14- Birzeit, Palestine
Telfax:+972 2 2982935 mjarrar@birzeit.eduPalGov © 2011
2

© Copyright Notes
Everyone is encouraged to use this material, or part of it, but should properly
cite the project (logo and website), and the author of that part.

No part of this tutorial may be reproduced or modified in any form or by any
means, without prior written permission from the project, who have the full
copyrights on the material.

Attribution-NonCommercial-ShareAlike
CC-BY-NC-SA

This license lets others remix, tweak, and build upon your work non-
commercially, as long as they credit you and license their new creations
under the identical terms.

PalGov © 2011 3

Tutorial Map

Intended Learning Objectives
A: Knowledge and Understanding
Title T Name
3a1: Demonstrate knowledge of the fundamentals of middleware.
3a2: Describe the concept behind web service protocols.
Session0: Syllabus and overview 0 Aldasht
3a3: Explain the concept of service oriented architecture. Sesson1: Introduction to SOA 2 Aldasht
3a4: Explain the concept of enterprise service bus. Session2: XML namespaces & XML schema 2 Aldasht
3a5: Understanding WSDL service interfaces in UDDI. Session 3: Xpath & Xquery 4 Romi
B: Intellectual Skills Session4: REST web services 3 M. Melhem
3b1: Design, develop, and deploy applications based on Service Session5: Lab2: Practice on REST 3 M. Melhem
Oriented Architecture (SOA). Session 6: SOAP 2 Aldasht
3b2: use Business Process Execution Language (BPEL). Session 7: WSDL 3 Aldasht
3b3: using WSDL to describe web services.
Session8: Lab 3: WSDL practice 3 Aldasht
C: Professional and Practical Skills Session9: ESB 4 Aldasht
3c1: setup, Invoke, and deploy web services using integrated
Session10: Lab4: Practice on ESB 4 Aldasht
development environment.
Session11: integration patterns 4 M. Melhem
3c2: construct and use REST and SOAP messages for web
services communication. Session12: Lab5: integration patterns 4 M. Melhem
D: General and Transferable Skills Session13: BPEL 3 Aldasht
d1: Working with team. Session14: Lab6: Practice on BPEL 3 Aldasht
d2: Presenting and defending ideas. Session15: UDDI 2 Aldasht
d3: Use of creativity and innovation in problem solving.
d4: Develop communication skills and logical reasoning abilities.

Session 8: WSDL
Session ILOs
After completing this session students will be able to use
WSDL to describe web services.

Session Outlines

 Introduction
 WSDL building blocks
 Structure of a WSDL document
 The SOAP binding

Overview

• A consumer first examines the WSDL description before
requesting a service.

Web Services Application Code

WSDL API SOAP API

WSDL SOAP

XML / XML namespace / XML Schema

Source, [3]

Introduction I

• Web Services Description Language (WSDL): is an XML-
based language that provides a model for describing Web
services [2].
• WSDL is often used in combination with SOAP and an XML
Schema to provide Web services over the Internet.
– A client program connecting to a Web service can read the WSDL file
to determine what operations are available on the server.
– Any special datatypes used are embedded in the WSDL file in the form
of XML Schema.
– The client can then use SOAP to actually call one of the operations
listed in the WSDL file using XML or HTTP.

Introduction II

• Web service refers to the piece of code implementing
the XML interface to a resource
• This enables consumer with XML support to integrate
with Web service applications
• XML Schema
– Allows developers to describe the structure of XML
messages
– But, can't describe the additional details involved in
communication with a Web service

Introduction III

• A message exchange is referred Messages
to as an operation.
• Operations are what consumers
care about most since they're
the focal points of interaction. Service

• Consumers must be aware of
the groupings of related
operations into interfaces, since
Resource
it impacts the way they write
their code service [1]
Communicating with a web service ,
Source, [1]

Introduction IV

• Consumers must be aware of
Messages
these groupings since it Operation
impacts the way they write
their code. Input Output

• Consumers must also know
what communication Service
protocol to use for sending
messages to the service [1].
– Also, specific mechanics Resource
involved in using the given
protocol such as the use of
Operations (message exchange),
commands, headers, and Source, [1]
error codes

Introduction V

• A binding influences the way abstract messages are
encoded on the wire by specifying the style of
service.
– Document vs. RPC
– The encoding mechanism, literal vs. encoded.
• A service can support multiple bindings for a given
interface.
• Each binding should be accessible at a unique address
identified by a URI, also referred to as a Web service
endpoint [1].

Introduction VI: Interfaces and Bindings

Interfaces and Bindings,
Source, [1]

WSDL building Blocks

• WSDL separates a service into two parts [3]:
– Abstract interfaces: unfolds the operations supported by the
web service, the operation parameters and abstract data
types.
• Independently from, any concrete network address, communication
protocol or data structure.
– Concrete implementation: binds the abstract interface
description to a concrete network address, to a protocol and
to a concrete data structure.
• A web service consumer can bind to such an implementation and
invoke a service.

WSDL building Blocks

• A WSDL document is an XML instance composed of
elements.
• Elements are declared in a WSDL schema definition
with target namespace:
http://schemas.xmlsoap.org/wsdl/.
• See next slide for:
– An initial WSDL interface description for the
getPhoneNumber service, Source, [3].

getPhoneNumber service
<definitions name = “phoneNumberService”
targetNamespace = “http://companyx.com/ns/phoneNumber/wsdl”
xmlns:tns=“http://companyx.com/ns/phoneNumber/wsdl”
xmlns:SOAP-EXT=“http://schemas.xmlsoap.org/wsdl/soap/”
xmlns=“http://schemas.smlsoap.org/wsdl/”> Abstract
<types> data type
<schema definitions
targetNamespace=“http://companyx.com/ns/phoneNumber/wsdl”
xmlns=“http://www.w3.org/2001/XMLSchema”>
<complexType name=“NameInType”>
<sequence>
<element name=“first-name” type=“xsd:string”/>
<element name=“last-name” type=“xsd:string”/> Data that is
</sequence> returned
</complexType>
</schema>
</types>
<message name=“GetPhoneNumberIn”>
<part name=“name” type=“tns:NameInType”/>
</message > Port type containing
<message name=“GetPhoneNumberOut”> one operation
<part name=“return” type=“xsd:string”/>
</message >
<portType name=”PhoneNumberPortType”> An operation with
<operation name=“getPhoneNumber”> input and output
<input message=“tns:GetPhoneNumberIn”/>
<output message=“tns:GetPhoneNumberOut”/>
message
</operation>
</portType>

Summary of elements collectively describing a
web service interface

• portType: a named collection of operations
• operation: abstractly describes a service call.
– May contain input message, output message and optionally several
fault message.
• message: an abstract description of the data that is sent.
– Messages consist of logical units called parts.

Summary of elements collectively describing a
web service interface

• part: is associated with a data type.
• type: provides a container for data type definitions.
– WSDL 1.1 refer to XML schema data types, but doesn’t prohibit the
use of other type systems.
• See next slide for:
– A WSDL implementation description for the getPhoneNumber
service, Source, [3].

<binding name=“PhoneNumberSoapBinding” type=“tns:PhoneNumberPortType”>
<SOAP-EXT:binding style=“rpc”
Use SOAP
transport=“http://schemas.xmlsoap.org/soap/http”/> RPC style
<operation name=“getPhoneNumber”>
<SOAP-EXT:operation soapAction=“”/>
<input> Bind an abstract operation to this
concrete implementation …
<SOAP-EXT:body use=“encoded”/>
</input>
… and map
<output> the abstract
<SOAP-EXT:body use=“encoded”/> input and
</output> output
</operation> Service name messages
</binding> to these
concrete
<service name=“PhoneNumberService”>
messages
<port name=“PhoneNumberPort” binding=“tns:PhoneNumberSoapBinding”>
<SOAP-EXT:address
location=“http://www.companyx.com/servlet/rpcrouter”/>
</port>
</service>
</definitions> Network address of service

Summary of elements describing a web service
implementation

• binding: provides concrete protocol and data format
specifications for a particular port type.
• port: describes the network address of a service.
– In combination with a binding it provides info about concrete service
endpoint.

Summary of elements describing a web service
implementation

• service: a collection of related ports.
– May share the same port type, but employ different bindings or
network addresses.
– May be concrete service endpoint implementations of several port
types.

WSDL service interface and service
implementation description

port binding

service binding type portType

port binding
Associated with
Containment Relationship
Relationship

Source, [3]

WSDL related name spaces

• Although the use of other type systems is not forbidden, WSDL
uses XML schema definitions and XML schema instance
attributes from representing abstract data types:
– Namespace prefix xsd refers to URI
http://www.w3.org/2001/XMLSchema.
– Namespace prefix xsi refers to URI
http://www.w3.org/2001/XMLSchema-
instance

WSDL related name spaces, cont.

• Additional namespaces with WSDL 1.1 specification:
– Namespace prefix wsdl refers to URI
http://schemas.xmlsoap.org/wsdl
– Namespace prefix SOAP-EXT refers to URI
http://schemas.xmlsoap.org/wsdl/soap

WSDL document containment structure

• Three important containment structure elements: (see next slide)
– definitions: a container for all WSDL elements.
– portType.
– binding: each binding related to a distinct port type maps a concrete
protocol implementation to this port type.


• Message provides a data types container for operations via its
ports.
• Individual data types may appear multiple times in several
messages.
• A specific input message may be identical, and reusable for
several applications.
• Bindings might be reusable, also.


Source, [3]

Service interface-related elements of WSDL
document

• definitions element: may have name, targetNamespace
and xmlns.
• types element: a container for all data type definitions that
belong to the messages.
• message element: represents operation parameters for one
interaction between a client and a service. e.g:
– Input parameters for a SOAP RPC are described as a message.
– Another message presents the return and output parameters for this call.
• part element: contained in message element; may carry name
attribute, element attribute and type attribute.

Definitions elements

• wsdl namespace prefix is defined by default.
• Identical namespaces assigned to the
targetNamespace attribute and the tns
namespace prefix.
• The target namespace of local WSDL definitions
together with the tns namespace prefix helps a
processor to locate these local definitions when they
are referred to.

Definitions example

<definitions name=“phoneNumberService”
targetNamespace=“http://companyx.com/ns/phoneNumber/wsdl”
xmlns:tns=“http://companyx.com/ns/phoneNumber/wsdl”
xmlns:SOAP-EXT=“http://schemas.xmlsoap.org/wsdl/soap/”
xmlns:”http://schemas.smlsoap.org/wsdl”>
<documentation>
WSDL document describing a phone number service
</documentation>
<!–- The WSDL specification goes here. -->
...
</definitions>

Types element

• The types element is a container for all abstract data
type definitions that belong to messages.
• Message parts link types to messages.
• WSDL prefers the use of XML schema for the type
definitions
• In the following example all elements are based on
the XML schema built-in string type.

Types Example

<types>
<schema

targetNamespace=“http://companyx.com/ns/phoneNu
mber/wsdl”
xmlns=“http://www.w3.org/2001/XMLSchema”>
<element name=“FirstNameIN”
type=“xsd:string”/>
<element name=“LastNameIN”
<element name=“PhoneNumber”
<element name=“NoNameFound”
</schema>
</types>

Message and part elements

• As mentioned earlier, a message represents operation parameters
for one interaction between a client and a service.
• See next slide for an example of three messages, each holding
one part, respectively:

Message and part example

<part name=“name” element=“tns:NameIn”/>
</message>
<message name=“GetPhoneNumberOut”>
<part name=“return” element=“tns:PhoneNumber”>
</message>
<message name=“NoNameFoundOut”>
<part name=“failure” element=“tns:NoNameFound”/>
</message>

Message and part example, cont.

• The element attribute refers to the element declarations in the
types container.
• Alternatively, we can have defined the data type of each part
via the type attribute.

<part name=“name” type=“tns:NameInType”/>
</message>
<message name=“GetPhoneNumberOut”>
<part name=“return” type=“xsd:string”>
</message>
<message name=“NoNameFoundOut”>
<part name=“failure” type=“xsd:string”/>
</message>

Mapping of a WSDL part to a SOAP RPC
style message

• See the message in the next slide.
• Dotted arrows illustrate how a part name of the WSDL
document describing the phone number service is mapped to a
procedure call parameter accessor in a SOAP RPC style
message body to invoke this service.

WSDL part to a SOAP RPC style message

WSDL Document:

<part name=“name” type=“tns:NameIn”/>
</message>

SOAP Message Body (RPC Style):
<SOAP-ENV:Body>
<getPhoneNumber ...>
<name>
<first-name xsi:type=“xsd:string”>Ahmad M.</first-name>
<last-name xsi:type=“xsd:string”>Ahmad</last-name>
</name>
</getPhoneNumber>
</SOAP-ENV:Body>

Source, [3]

Mapping of a WSDL part to a SOAP
document style message

• Here, parts point to the XML instance contained in the SOAP
message body.
• No additional wrapper.
• The element representing the XML instance goes directly into
the SOAP message body element.
• See next slide!

WSDL part to a SOAP document style message

WSDL Document:

<part name=“name” element=“tns:NameIn”/>
</message>

SOAP Message Body (Document Style):
<SOAP-ENV:Body>
<NameIn>
<first-name xsi:type=“xsd:string”>Ahmad M.</first-
name>
<last-name xsi:type=“xsd:string”>Ahmad</last-name>
</NameIn>
</SOAP-ENV:Body>

Source, [3]

The operation element

• 4 operation types:
– One-way: has only an input element specifying the operation
message.
– Request-response: contains one input, one output and optionally,
one or more fault elements.
– Solicit-response: contains one input, one output and optionally, one
or more fault elements.
– Notification: contains only an output element specifying the operation
message.

operation element

Source, [3]

Mapping of a WSDL operation to a SOAP
RPC style message

• An operation element may hold two attributes:
– name: it is mandatory and specifies the operation name
– parameterOrder: carries a space-separated list of message parts.
• May be used for request-response and solicit-response operations with an
RPC binding to save the function call signature.

WSDL operation to a SOAP RPC style message

WSDL Document:

<portType name=“PhoneNumberPortType”>
<input message=“tns:GetPhoneNumberIn”/>
<output message=“tns:PhoneNumberOut”/>
</operation>
</portType>

SOAP Message Body (RPC Style):
<SOAP-ENV:Body>
<getPhoneNumber ...>
...
</getPhoneNumber>
</SOAP-ENV:Body>

Source, [3]

Binding-related elements of a WSDL
document

• binding element almost matches the structure of portType
element.
• binding must map the abstract portType description to a
concrete implementation, carries two attributes:
– name: is mandatory, and specifies the name of the binding
– type: is mandatory, and refers to the port type that it binds.

binding example, Source, [3]

<binding name=“PhoneNumberSoapBinding”
type=tns:PhoneNumberPortType”>
<!–- SOAP binding extensibility element -->
<SOAP-EXT:binding style=“rpc”>
transport=“http://schemas.xmlsoap.org.soap/http”/>
<!–- SOAP operation extensibility element -->
<input>
</input>
<output>
</output>
</operation>
</binding>

The binding element

• binding type attribute together with the name attribute
uniquely identifies a binding.
• Since various bindings may refer to the same port type.

binding element details

Source, [3]

The SOAP binding

• Binding to SOAP 1.1, means that we must fill these containers
with SOAP 1.1 extensibility elements.
• Providing a distinct WSDL binding requires the definition of
extensibility elements for the binding, the operation and
the port elements.
• In our examples, the namespace prefix for SOAP binding is
SOAP-EXT.
• The table contains WSDL-defined binding elements and
contained SOAP extensibility element.

WSDL-defined binding elements and contained
SOAP extensibility element

Source, [3]

SOAP extensibility elements

• SOAP binding extensibility element: has two attributes:
– transport: indicates the transport protocol for the SOAP message.
– style: can have value rpc or document.
• SOAP operation extensibility element: provides operation
scope info, has two attributes:
– style: may overwrite binding-wide sittings for individual operations.
– soapAction: specifies the value of the soapAction HTTP header for
the operation.

SOAP extensibility elements

• SOAP body extensibility element: defines the mapping of
abstract message parts into the SOAP message body:
– parts: contains the set of abstract message parts in message body.
– use: can take value literal or encoded.
– encodingStyle: if encoded, this defined the encoding rules.
– namespace: holds the namespace of the operation name.

SOAP RPC style binding using Section 5 encoded
message parts

• getPhoneNumber operation, or procedure call, is identified
using namespace attribute.

<operation name=“getPhoneNumber”
<input>
<SOAP-EXT:body use=“encoded”
encodingStyle=“http://schemas.xmlsoap.org/soap/encoding”
namespace=“http://companyx.com/ns/employees”/>
</input>
<output>
<SOAP-EXT:body use=“encoded”
encodingStyle=“http://schemas.xmlsoap.org/soap/encoding”
namespace=“http://companyx.com/ns/employees”/>
</output>
</operation>

SOAP address extensibility element for SOAP
over HTTP, example

• This extensibility element specifies the network address of the
SOAP-accessible service.
• It is a member of the WSDL port element.
• It contains one attribute:
– location: defines the network address for the binding.

<service name=“PhoneNumberService”>
<port name=“PhoneNumberPort” binding=“tns:PhoneNumberSoapBinding”>
<SOAP-EXT:address
location=“http://www.companyx.com/servlet/rpcrouter”/>
</port>
</service>

Practices 1

• Create a web application to consume a web service called
(GlobalWeather) available on the web:
http://www.webservicex.net/globalweather.asmx
• Use the WSDL file of the web service available on:
http://www.webservicex.net/globalweather.asmx
• Create new ASP.Net web site
• In the design add a button and a text box.
• To the solution name add a web reference (Use the link of the WSDL file above)
• Go to the design, double click on the button. Add: using (the referenced webservice name).
Button Click code:
protected void Button1_Click(object sender, EventArgs e)
{
GlobalWeather G = new GlobalWeather();
string cities = G.GetCitiesByCountry(TxtCountry.Text.ToString());
Response.Write(cities);
}

Practice 2: Self Hosting Service

• Create a service library (any service), name your solution (SelfHostingService)
• Add a new console application project to the solution, (MyserviceHost)
– Here, add references, to your service library and to .Net System.ServiceModel
– Add inside the main class ,the following code:
ServiceHost host = new ServiceHost(typeof(MyService));
host.Open(); //read service configurations from .config file and build
the runtime to support all endpoints defined in the configuration
Console.WriteLine("MyService is up and running ...");
Console.ReadLine();
host.Close();
– Build your solution
– Add an item (application configuration file) for the project and edit it using WCF editor:
• Create new service (browse for your the service library), then next. Use http binding , next: use basic WS
interoperability, nex: address: use relative address (e.g. name it basic) and finish.
• Create another service endpoint, the same, but use advanced WS interoperability, and use relative address (ws)
• Click Host in the configuration and create new base address (http://localhost:8080/MyService)
• Create another service endpoint, use tcp binding, use address (http://localhost:8080/MyService)
• Create another service endpoint, use Named pipes binding, use address (net.pipe://localhost/MyService)
• To enable metadata in your service; click advanced, then service behaviour, and new service behaviour, and add the
service meta data element, then select the element from the tree and set httpGetEnabeled to true
• Click the service name in the top, and Apply the new behaviour to the behaviour configuration
• Save the configuration and exit.

Practice 2: Self Hosting Service

• Right-click your host project and set as startup project.
• Press Crtl+F5 to start.
• Open internet explorer and in the address (localhost:8080/MyService)

Summary

During this session we have introduced the use of WSDL to
describe web services; Thus, the following subjects have
been described:
1. WSDL building blocks
2. Structure of a WSDL document
3. The SOAP binding
In the next session we will cover the enterprise service bus
“ESB”

References

1. Aaron Skonnard, Understanding WSDL, Microsoft Digital Network,
“http://msdn.microsoft.com/en-us/library/ms995800.aspx”, March 2003
2. Extracted from: http://en.wikipedia.org/wiki/WSDL
3. Olaf Zimmermann, Mark Tomlinson, Stefan Peuser, “Perspectives on Web services-
Applying SOAP, WSDL and UDDI to real-world projects, 2nd edition, Springer, 2005

Pal gov.tutorial3.session7

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