Whenever a new technology comes along, the whole technical community reaches to grasp the details as well as the implications. If this technology represents a “sea change” in the way that computers are programmed, the need to comprehend becomes a matter of technical survival.
Web services represents a sea change. There have been other drastic changes in the computing environment in the past few decades. Here are a few of them:
Stored programs replaced punch cards and paper tape.
Online systems largely replaced batch systems.
Graphical user interfaces replaced green screens.
Networked computers replaced standalone computing.
Internet-based systems replaced LAN-based systems.
In a year or two we will add the following:
Web services–based systems replaced simple Internet-based and LAN-based systems.
One of the characteristics of a sea change is that it negatively impacts the employment prospects of everyone who gets left behind. After online CICS became popular, batch COBOL programmers had trouble finding work. DOS programmers went looking after Windows was introduced. Client-server programmers found the going tough after Internet-based systems became widespread.
This book was written to help you make the transition from the computer systems of the past. If you are a CORBA or DCOM programmer, you will likely find that Web services–based systems are trying to solve the same problems you have solved, but in a nonproprietary way.
If you are a GUI programmer, you will find that the data sources for your applications will start coming from SOAP messages. For you JSP programmers, you will soon find that you can send a lot more information over the Internet than just HTML and JavaScript code.
This book is broad. A quick perusal of the table of contents will tell you that this book contains a lot of subject matter; therefore, the number of pages available for each topic is limited. As a result, each hour’s emphasis is to provide the information to jump start you in each topic.
The subject matter was chosen by answering the question, “What does a programmer or manager need to know about each topic to understand Web Services?” The answer is: this book.
This book is organized into five parts:
Each of them plays a key role helping you understand Web Services.
Before we get into too much detail, it is critical that we create a foundation of basic understanding.
Hour 1, “Understanding Web Services,” gives you a high-level understanding of what Web services are.
Hour 2, “Advantages of Web Services,” provides an explanation of why Web services are better than alternative technologies.
Hour 3, “Disadvantages and Pitfalls of Web Services,” helps you understand when Web services are not appropriate.
Hour 4, “Comparing Web Services to Other Technologies,” shows you how Web services are different from CORBA, RMI, DCOM, and so on.
Hour 5, “Typical Web Services Designs,” shows you some of the ways the Web services are being used. This will help you understand the range of problems that Web services are designed to solve.
The details of the standards that Web services are based on are provided in this section.
Hour 6, “The Web Services Architecture,” talks about how the different standards that Web services is built on interact with each other to provide a complete solution.
Hour 7, “Understanding XML,” provides you with an overview of XML, the metalanguage that all of the Web services standards are built with.
Hour 8, “Understanding How Web Services Communicate,” shows you the different ways that a client can communicate with a Web service.
Hour 9, “Exchanging Messages with SOAP,” provides an explanation of how the SOAP language is used to make method calls against a Web service.
Hour 10, “Describing a Web Service with the Web Services Description Language (WSDL),” teaches you how to create an XML document that exactly describes both the logical and physical details needed to communicate with a Web service.
Hour 11, “Advertising a Web Service,” teaches you how to use the Universal Description, Discovery, and Integration (UDDI) protocol to publish the existence and capabilities of your Web service.
Hour 12, “Sending Attachments with Web Services,” provides an overview of how non-textual data such as images and computer programs can be sent efficiently using Web services.
Many different products have been written to help you create Web services. This part looks at each of the major products available and gives you an overview of each, along with some simple examples of how to use them.
Hour 13, “Creating Web Services with Apache Axis,” introduces you to Axis, the open-source toolkit that is maintained by Apache.
Hour 14, “Creating Web Services with Java,” shows you how to use option Java packages from Sun Microsystems to create Web services.
Hour 15, “Creating Web Services with .NET,” introduces you to Microsoft’s Web services offering.
Hour 16, “Creating .NET Web Service Clients,” teaches you how to use .NET to create rich clients for accessing Web services.
Hour 17, “Creating Web Services with BEA WebLogic Workshop,” shows you how create Web services using this dedicated toolkit from BEA Systems.
Hour 18, “Creating Web Services with IBM WebSphere,” shows you how to use this software development suite to create Web services.
Hour 19, “Creating Web Services with Other Toolkits,” introduces you to some of the alternative toolkits that have been written.
Hour 20, “Comparing the Different Web Services Tools,” analyzes the different products covered in this part of the book. It covers documentation, cost, learning curves, and a host of other considerations.
Java is a great platform for dealing with media. This section introduces you to the stars of the Java Media packages.
Hour 21, “Web Services Interoperability,” teaches you about the interoperability challenges that remain and the efforts underway to solve them.
Hour 22, “Web Services Security,” shows you the different approaches and proposals that are being considered for improving the security of Web services transactions.
Hour 23, “Web Services in the Real World,” shows you some of the ways that Web services are being used today by pioneering companies.
Hour 24, “The Future of Web Services,” tells you about the direction in which Web services standards are heading. It provides an overview of some of the more interesting proposals being considered.
Appendix A shows you how to install Apache Tomcat and Apache Axis.
Appendix B shows you how to install the Java Web Services Developer Pack.
Appendix C shows you how to install and configure other Web services toolkits that were covered in Hour 19.
Certain conventions have been followed in this book to help you digest all the material. For example, at the beginning of each hour, you’ll find a list of the major topics that will be covered in that particular hour. You will also find that icons are used throughout this book. These icons either are accompanied by additional information on a subject or supply you with shortcuts or optional ways to perform a task. These icons are as follows:
New terms are introduced using the New Term icon. The new term appears in italic.
The following typographic conventions are used in this book:
Code lines, commands, statements, variables, and any text you type or see onscreen appears in a
monospacetypeface.Italics highlight technical terms when they’re being defined.
The
icon is used before a line of code that is really a continuation of the preceding line. Sometimes a line of code is too long to fit as a single line on the page. If you see before a line of code, remember that it’s part of the line immediately above it.
At the end of each hour, you will find both a Summary section and a Q&A section. The Summary section provides a brief encapsulation of the core information covered in the hour. The Q&A section provides a series of questions and answers that help cement important facts and concepts covered in the hour.
For updates to this book and to download the source code and examples presented in this book, visit http://www.samspublishing.com. From the home page, type this book’s ISBN (0672325152) in to the Search window (without hyphens), and click on Search to access information about the book as well as a direct link to the source code.