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- Herausgeber: Packt Publishing
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
In Detail
Service Oriented Architecture provides a way for applications to work together over the Internet. Usually, SOA applications are exposed through web services.
Web services have been around for a while, but complex adoption processes and poor standardization hampered their use at first. However, with the adoption of new, simpler protocols such as REST, and major companies supporting SOA, the time is now right to adopt these standards.
This book will show you how to build SOA, web services-based applications using Java. You will find out when SOA is the best choice for your application, how to design a sound architecture, and then implement your design using Java.
The book covers the important web services protocols: XML-over-HTTP, REST, and SOAP. You will learn how to develop web services at all levels of complexity and for all kinds of business situations.
This book shows how to use SOA and web services to build powerful applications in Java. It teaches the concepts and the implementation with best-practice real-world examples. You will learn to design a sound architecture for successful implementation of any business solution, the different types of architecture, and various tenets of SOA. The book explains the fundamentals and the advantages of using the Service Oriented Architecture in designing your business solution.
Approach
This book is an overview of how to implement SOA using Java with the help of real-world examples. It briefly introduces the theory behind SOA and all the case studies are described from scratch.
Who this book is for
This book is for Java programmers or architects who are interested in implementing SOA concepts in their applications. Readers should be familiar with Java Enterprise concepts.
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Seitenzahl: 198
Veröffentlichungsjahr: 2008
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Table of Contents
Service Oriented Architecture with Java
Binildas A. Christudas
Malhar Barai
Vincenzo Caselli
Service Oriented Architecture with Java
Copyright © 2008 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the authors, Packt Publishing, nor its dealers or distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.
First published: June 2008
Production Reference: 1180608
Published by Packt Publishing Ltd.
32 Lincoln Road
Olton
Birmingham, B27 6PA, UK.
ISBN 978-1-847193-21-6
www.packtpub.com
Cover Image by Nik Lawrence (<[email protected]>)
Credits
Authors
Binildas CA
Malhar Barai
Vincenzo Caselli
Reviewer
Shyam Sankar S
Acquisition Editor
Bansari Barot
Technical Editor
Dhiraj Chandiramani
Editorial Team Leader
Akshara Aware
Project Manager
Abhijeet Deobhakta
Project Coordinator
Abhijeet Deobhakta
Indexer
Monica Ajmera
Proofreader
Petula Wright
Production Coordinator
Shantanu Zagade
Cover Work
Shantanu Zagade
About the Authors
Malhar Barai is a senior systems analyst with Satyam Computer Services Ltd., one of India's leading IT services organizations. He has more than seven years of experience in the industry working for leading organizations across India.
Malhar has interest in service-oriented technologies and application integration tools. He has worked on EAI toolset of webMethods and Cast Iron, Java technologies.
You can catch him on various forums that deal with SOA and some of the webMethods forums, or you can read about him on his blog http://malharbarai.blogspot.com
He gets spurred by the daily challenges at work, finding solutions to the problems, and trying his hand at improving processes and solutions.
I would like to acknowledge and dedicate this book to my parents for being sources of inspiration and for guiding me on the right path when it mattered the most. To Jalpa, my lovely wife for, being a constant support and carving out a wonderful life for us. My ex-manager Ajay Mulkalwar for his guidance and encouragement, and the most important person — my soul, my sweet daughter Preisha whose lovely smile makes my time wonderful...
Vincenzo Caselli graduated with a degree in electrical engineering in 1991 from the University of Bologna. He has worked as an independent consultant and a Java trainer for several Italian software houses since 1996. He began working as a developer in Delphi and other visual IDE's with AS/400-based companies. Soon he shifted his focus on Java and began to propose Swing client/server multi-layered solutions to his customers. He also worked in the web development area with several frameworks (Struts, Hibernate, Spring, JSF, and GWT) in different fields (banking, manufacturing, healthcare, e-learning). Recently, he collaborated with IBM in projects based on Eclipse RCP and SOA. He is interested in consultancy and training activities aimed to improve the productivity and quality of the software development process by using open-source products.
I would like to thank my wife Silvia and my daughter Linda for being patient while I worked on this book. I also want to thank my friend Luca Masini for his precious technical advice and help.
Binildas C. A. provides Technical Architecture consultancy for IT solutions. He has more than 13 years of IT experience, mostly in Microsoft and Sun technologies. Distributed Computing and Service Oriented Integration are his mainstream skills, with extensive hands-on experience in Java and C#.NET programming. Binil holds a Bachelor of Technology degree in mechanical engineering from the College of Engineering, Trivandrum (www.cet.ac.in) and an MBA in systems management from Institute of Management, Kerala (www.imk.ac.in). A well-known and a highly sought-after thought leader, Binil has designed and built many highly scalable middle-tier and integration solutions for several top-notch clients including Fortune 500 companies. He has been previously employed by multiple IT consulting firms including IBS Software Services (www.ibsplc.com) and Tata Consultancy Services (www.tcs.com), and he currently works for Infosys Technologies (www.infosys.com) as a Principal Architect where he heads the J2EE Architects group servicing Communications Service Provider clients.
Binil is a Sun Certified Programmer (SCJP), Developer (SCJD), Business Component Developer (SCBCD) and Enterprise Architect (SCEA), Microsoft Certified Professional (MCP), and Open Group (TOGAF8) Certified Enterprise Architecture Practitioner. He is also a Licensed Zapthink Architect (LZA) in SOA. Besides Technical Architecture, Binil also practices Enterprise Architecture.
When not in software, Binil spends time with wife Sowmya and daughter Ann in 'God's Own Country', Kerala (www. en.wikipedia.org/wiki/Kerala). Binil is a long distance runner and is a national medalist in power lifting. You may contact Binil at <[email protected]> or <[email protected]>.
About the Reviewer
Shyam Sankar S is currently working as a Technical Architect with Allianz Cornhill Information Services, Trivandrum. He has around 11 years of experience in the IT industry and has worked in companies like IBS, Verizon, and Infosys. He has been working on Java technologies since 1999 and has been the lead architect for many JEE systems. Shyam, an Industrial Engineer from the University of Kerala, is also a Sun Certified Enterprise Architect and a Sun Certified Java Developer.
Preface
Service Oriented Architecture is mainly a mindset, an enterprise strategy whose natural implementation is represented by web services. SOA is not a single product or single reference architecture to be followed, but SOA is all about best practices, reference architectures, processes, toolsets, and frameworks, along with many other things which will help you and your organization to increase the responsiveness and agility of your enterprise architecture. Standards and frameworks play a greater role in enabling easy and widespread industry adoption of SOA.
This book will help you learn the importance of designing a sound architecture for successful implementation of any business solution, different types of C/S architecture, and various tenets of SOA, explaining the fundamentals and explaining the advantage of using the Service Oriented Architecture in designing of the business solution. From a basic XML-over-HTTP approach to the REST and SOAP protocols, we get into the details of how web services can be implemented with various degrees of complexity and flexibility using JAVA.
This book will explain the concepts of business layer that is 'The SOA core'. You will also learn when SOA will define as an asset to your project with the help of practical examples.
In the early years when the WS-approach began to emerge it suffered from difficulties due to many factors, for instance, complex adoption process and poor standardization. Now, with little effort times are mature for using this technology and also getting great advantages, both immediate and as an investment for our future works. The book concludes with the focus on explanation of these assets.
What This Book Covers
In Chapter 1 we will discuss the role of Architecture for successful implementation of any business solution followed by brief discussion on different types of client-server architecture and SOA.
In Chapter 2 we will examine the relationship between the SOA methodology and the web service implementation basics. We will also discuss how XML can be used as the common language to decouple the communication between web service implementations and their consumer clients.
In Chapter 3 we will introduce major web service implementations available specifically in the Java and J2EE world, WS using JAX-WS 2.0, WS using Apache Axis, WS using Spring, and WS using XFire.
In Chapter 4 we shall see few emerging standards like SDO and SCA, addressing from data integration to service and component integration.
In Chapter 5 we will look into a couple of case studies where one of the solutions is based on principles of Enterprise Application Integration and in the second one we shall build our solution based on SOA fundamentals.
In Chapter 6 we will explore in detail the advantages that the SOA approach can lead to. Basically a concluding chapter discussing what we can and what we have achieved with SOA approach.
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Chapter 1. The Mantra of SOA
Today, we are living in a world, where 'the age of information technology' is erasing the boundaries of cities, states, and countries. This age is all about M and A's and key to the success of such partnerships would depend on how well current independent resources of each of these entities is re-used. But the biggest challenge would be aligning these independent solutions into components that can be re-used across the enterprise.
The answer lies in "architecting" a design that would take care of inter-enterprise communication in a scalable form. But before getting into that, let's first try to understand the term 'architecture' in the broader sense. This is one of the most under-valued but the most important building block for any solution.
Architecture
"Architecture" is a Holy Grail for any design solution. It shows the major components of the software solution and serves as a blueprint for the entire design. It is like a core to the design of complex software solution.
It can be defined as a representation group(s) of relationship between various components of a complex software solution. The solution is decomposed into smaller, self-describing components and represented as structural relationships to provide a high-level overview of the entire system. The system is divided into runtime elements, which in itself could have architecture as well.
Shown here is a typical architecture for a database driven, web-based solution. It provides us with a high-level overview of the entire system. The consumer only has a view of the 'presentation layer' and other layers are tightly encapsulated. Each layer would have its own characteristics as well as its own architecture.
Architecture can be compounded as a logical set of decisions to describe the life of the project. These decisions will have a cascading affect on the selection and integration of components such as the selection of software, hardware, and behavior of the system. A good architecture will also take care of the future needs of the project.
But then, why is architecture so important? Without proper architecture in place, it would be difficult to achieve the following:
Moving on from architecture, we will now dive into different architecture paradigms.
Application Architecture
At the most granular level in a system, you will always find sets of applications running to achieve some business goals. These applications are developed using different kinds of blueprints that we refer to as architecture. They provide an abstract view of the entire application, or let us say a high-level overview of the system.
Application architecture can be considered as a representation of the structure of components and the interaction between them in the system. They provide a framework within which the business objectives are represented.
The previous figure shows a typical architecture of a web-based application. The business requirements are converted into a high-level design where the:
Each organization will have multiple application architectures, which would cater to the need of different business goals. These applications could be web based, or even the custom client server applications.
Client-Server Architecture
The client-server architecture also known as two-tier architecture separates the client from the server. Client is the system requesting a service from the provider (in our case, server). The client will always initiate the request, which the server processes and responds to. The client could send the request to one or more than one server at a time.
Using this architecture, you can divide the responsibilities of the requester from the provider. Earlier, as seen in monolithic systems, objectives were divided into smaller pieces, and then tightly coupled into an application. Due to this, it was difficult to process multiple clients. But, with the client-server architecture in place, business process is done within the provider. This enables multiple clients to be plugged in at the same time.
Large organizations usually have more than one application to support their business goals. These are well supported by mainframes. Mainframes act as the core business-processing unit with capacity to handle large chunks of data transactions. Other computers in the organizations access the mainframe to achieve the business goals. So in a way, the mainframes act as a server, and cater to different clients across the organization. With the advent of monolithic computing, where applications were tied to the data sources, the client-server architecture had become a welcome sign for the industry.
The main advantage of the client-server architecture is that it is scalable. With minimal performance impact, either the client or the server could be added.
Client-server architecture can be divided further into 1, 2, 3....n-tier architecture. We will glance through each of these. The architecture is made up of three basic layers — the presentation layer, the business layer, and the database or services layer.
Presentation layer is the one with which the client will interact. The consumer shall either move through a click-based solution, or will input data into the front-end to initiate the business process.
This layer could either be a thin or a fat client.
Business layer will enumerate the consumer action(s) and process the information supplied by the 'presentation layer' to accomplish a business goal with a set of business rules.
Data layer stores the data and logic that would be used to successfully achieve business goals.
1-Tier Application
The single tier application would have the three layers, that is, the presentation, the business, and the data layer tightly coupled which runs out of a single processing unit. The application is designed in a way that the interaction between the layers is interwoven.
Within the tenets of client-server architecture, the single tier application can share the data layer in a multi-user environment and achieve the client-server capabilities. The limitations of 1-tier application in client-server architecture are as follows:
2-Tier Application
Within the 2-tier application, the presentation and the business layer combine on the client side, while the data layer acts as the server. This enables the business logic to be separated from the data services.
The 2-tier application would generally consist of a 'fat' client and a 'thin' server - 'fat' client because it will embed the presentation as well as the business logic of the application, and a 'thin' server, as it will only cater to the data needs of the client.
Another flavor of the 2-tier application can be a 'thin' client and a 'fat' server. This would have the presentation logic served in the 'client'. The business logic and data logic reside on the 'server'.
