Pal gov.tutorial3.session1.soa

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

Tutorial III:
Process Integration and Service Oriented Architectures

Session 1
Introduction to SOA

Prepared By

Mohammed Aldasht

Reviewed by
Prof. Marco Ronchetti and Prof. Paolo Bouquet, Trento University, Italy
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 1: Introduction to SOA

Session ILOs
After completing this module students will be able to:
1. Demonstrate knowledge of the fundamentals of
middleware
2. Explain the concept of service oriented architecture
3. Describe some characteristics of web services and
applications based on SOA

Session Outlines

 Introduction
 SOA concepts and terms.
 SOA key principles and basic role.
 Middleware
 Web services
 Palestinian e-Government Architecture
 Summary

What is SOA?

• SOA: an architectural style based on loosely coupled interacting
software components that provide services [3].
• A service is a piece of functionality provided by a service
provider and delivers final results to the service consumer.
• SOA based application packages functionality as a suite of
interoperable services to be used within multiple systems from
several business domains [5].
• The core concept of SOA is loose coupling of software services.
– Means organizing different services to minimize their interdependencies
• This is much more adaptable than expensive and tightly coupled
technologies, like CORBA and DCOM

SOA key terms

• A service: is a repeatable business task; e.g. renew
driving license or register a student.
• Service oriented: a way of integrating a business
as a linked services and the outcomes that they
bring.
• Service oriented architecture: an IT architectural
style that supports service orientation [6].
• A composition application: a set of related and
integrated services that support a business process
built on an SOA.

Key principles of SOA

• Some key principles are [7]:
1. With loose coupling, a service logic can change with
minimal impact on other services within the same SOA.
2. Service contract: descriptions and other documents
describing how a service can be accessed.
3. Abstraction of underlying logic means that services
interact with each other only via their public interfaces,
hiding the service implementation details.
4. Autonomy means that services control only the logic they
encapsulate
5. Interoperability.

SOA: Basic Role

• SOA decouples interfaces from applications.
• The number and complexity of interfaces is
reduced.
• Business applications and their interfaces become
reusable.
• Interfaces tightly coupled with point to point
connections

SOA: Basic Role

Application Application Application Service Service Service

Interface Interface Interface

Interface Interface Interface
Application Application Application

Service Service Service

= Interface
Source, IBM education assistant:
http://publib.boulder.ibm.com/infocenter/ieduasst

Introduction to Middleware

• A layer of software that lies between the
application code and the run-time infrastructure [1].
– Connects software components or people and their
applications
– Provide interoperability in support of the move to
coherent distributed architectures
– Allows data contained in one database to be accessed
through another.
– Fits enterprise application integration and data
integration software.

Middleware-based distributed system

General structure of a distributed system as middleware, source [2]

Middleware protocols and interfaces

1.23

In an open middleware-based distributed system, the protocols used by each
middleware layer should be the same, as well as the interfaces they offer to
applications, source [2]

Communication models in Middleware

• 3 widely used communication models [2]:
1. RPC: a client calls procedures running on remote systems,
can be asynchronous or synchronous.
2. Message Oriented Middleware (MOM)
3. Data streaming: communication in which timing plays a
crucial role “Audio and video”.
• Generally, there are two ways to communicate:
– Enterprise messaging system: message passing in
standard formats, using XML, SOAP or web services.
– Enterprise Service Bus: some type of integration
middleware that supports both MOM and Web services.

What is a web service?

• Have an application!
• Want to convert your application into a web application?
• Web services is the answer!
• Web application then, can publish its function to the rest of the
world!
• Web Services are published, found, and used through the Web
• XML is the basis for Web services

SOA and Web services

• The term Web service describes a standardized way of
integrating Web-based applications [4];
– This can be done using the XML, SOAP, WSDL and UDDI open
standards over an Internet protocol backbone.
– SOAP (Simple Object Access Protocol)
– UDDI (Universal Description, Discovery and Integration)
– WSDL (Web Services Description Language)
• Web service is an implementation of service oriented
architecture

Service Service Request Service
Provider Consumer
Software Service Response Software Implementation Web Service

SOA and Web services, cont.

• SOAP, WSDL and UDDI support the interaction
between the WS requester and the WS provider
• Provider can publish a WSDL description of its Web
service, and the requester accesses the description
using a UDDI
• Requester can request the execution of the provider's
service by sending a SOAP message to it
• WS standards add a layer of abstraction which is
open to integrate with new and existing
environments.

Basic Web services architecture

Directory

Service Description

SOAP SOAP

WSDL

Service Service Request (XML format) Service
Provider Consumer
Software Service Response (XML format) Software

Requests and responses are
Based on the specification defined in
service description using WSDL

Web services architecture consists of specifications, source [4].

Web Services Technology

• XML: enabling the definition, transmission, validation, and
interpretation of data between applications and between
organizations.
• SOAP: lightweight XML-based (W3C standard) messaging
protocol used to encode the information in Web service request
and response messages before sending them over the Internet.
– SOAP is platform independent
– SOAP is language independent
– SOAP allows you to get around firewalls

Web Services Technology, cont.

• WSDL: an XML-based language (W3C standard)
– Used to locate and describe a Web service’s capabilities as
collections of communication endpoints capable of exchanging
messages.
• UDDI: a Web-based distributed directory
– UDDI enables businesses to list themselves on the Internet and
discover each other.
– UDDI is a directory for storing information about web services
– UDDI is a directory of web service interfaces described by WSDL
– UDDI communicates via SOAP

Why using Web services?

• Reusable application-components
– Application-components like language translation, currency conversion,
etc... can be reused.
– A widely used approach to simplify software reuse is the component-
based software engineering.
• Connect existing software
– Interoperability problem is solved!
– Existing applications are developed in different technologies like:
ms.net, PHP, Java, etc…
– With Web services different applications and different platforms can
exchange data (interoperate).

Web Service example:

• A simple ASP.NET Web Service that converts the temperature
from Fahrenheit to Celsius, and vice versa.
• Go to the following link:
http://www.w3schools.com/webservices/ws_example.asp
• To use the Web Service Example, Go to the following link:
http://www.w3schools.com/webservices/ws_use.asp

• Now we can Implement our first web service example using MS
Visual Studio 2010!

• Start new web site,
• Select from visual C# with .NET Framework 3.5, the
template called ASP.NET Web Service.
• Put the name you want! (name your service)

• Edit the C# code “service.cs”; to add the WebMethod,
which will achieve the required function:
[WebMethod]
public int GetMyAgeInDays(int day, int month, int year){
DateTime dt = new DateTime(year, month, day);
int days = DateTime.Now.Subtract(dt).Days;
return days;
}

• Save, build the Web site, and from the solution explorer,
right click the “page”.asmx and select as a default page.
• Run the website! Press “Crtl + F5”
• You will get the output in the next slide!

Pal gov.tutorial3.session1.soa

Internet Based Computing

Cloud
Intelligent web with
SOC-Based web 2.0
Dynamic Computing web 2.0 & web 3.0
UDDI, WSDL, SOAP
composition

WWW Semantic-Based web 3.0
Static URI, HTML, HTTP RDF, RDFS, OWL

Syntax Semantics

Designing for service-oriented integration, source[4], with minor adjustment

The Palestinian e-Government Architecture

• The Palestinian e-Government architecture has been
developed in cooperation with the Estonian
government [8].
– The architecture connects all ministries together through a
government service bus, called “x-road Palestine”.
– The service bus, with the other components, represents
standard service oriented architecture with an emphasis on
the provision of secure services.
– Not yet implemented, but there is a general consensus about
it among most governmental bodies

The Palestinian e-Government Architecture

Source, [8]

Summary

In this session we have introduced SOA where the concept of
service oriented architecture has been explained, then the
fundamentals of middleware were discussed.
Finally, we have described the most important characteristics of
applications (web services) based on SOA.

References

1. Extracted from http://en.wikipedia.org/wiki/Middleware
2. Andrew S. Tanenbaum and Maarten van Steen Distributed Systems: Principles
and Paradigms, 2nd Edition, Publisher: Pearson Education Inc., Copyrights: 2007
3. E.Newcomer and G.Lomow, Understanding SOA with Web Services, Addison
Wesley Professional, ISBN: 0-321-18086-0, 2004.
4. Effective Performance Management for Service-Oriented Applications, WHITE
PAPER, Copyright © 2009 Precise Software Solutions, Inc.
5. Extracted from: http://en.wikipedia.org/wiki/Service-oriented_architecture
6. Extracted from IBM education assistant:
http://publib.boulder.ibm.com/infocenter/ieduasst, 9/2011.
7. Yuli Vasiliev , SOA and WS-BPEL, Copyright © 2007 Packt Publishing
8. Ministry of Telecommunication and Information Technology: e-Government
Program, Palestine X-Road: Palestinian e-Government Architecture. Ramallah,
Palestine. January 2011.

Pal gov.tutorial3.session1.soa

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