Home > Articles > Web Services

Understanding Web Services

Know the difference between UDDI and ebXML? What about WSDL and JAXR? Wade through these technologies and discover the basics of Web services, the future of this revolution, and where to start when building a Web service.
This chapter is from the book

In this chapter

  • What Is a Web Service?
  • Crystal Ball Readings
  • The ABCs of Web Services
  • How to Use a Web Service

The first revolution with the Internet was all about delivering information to people. We are now in the second revolution, which focuses on delivering information to systems. XML is the tool that makes this new revolution a reality, and Web services are the methods with which businesses will drive system-to-system communication.

This chapter will introduce the Web services concept and teach the basic facts behind both Web services and the various APIs that power it. The goal of the chapter is to introduce most of the major initiatives, standards, APIs, and toolsets that make up Web services. This will help reduce the confusion that arises when too many letters are strung together in meaningless names, a problem that plagues Web services. We will walk you through expanding the development environment that was set up in Chapter 1, "Integrating JSP and Data," to use Web services. Finally, the chapter will show some basic coding examples to get your feet wet with the Web services concept.

What Is a Web Service?

Let's start with the simplest definition. In the purest sense, a Web service is a product in the form of a reusable function built by one company that is exposed on the Internet for another company to use.

You can already find Web services on the Internet. A simple example is the automated site search service provided by Atomz. For a demonstration, use the search engine at http://www.jspinsider.com the search request happens at the JSP Insider site, but the actual search occurs at another site hosting the search service. The Web service concept is growing and an exciting new model of business is evolving. What we now have is a situation where the Web service concept is exploding into new territory and expanding in its capabilities. The basic high-level goal of Web services is to further distributed computing (where application logic is separated into logical pieces and runs across many machines). The practical reason to build a Web service is to permit businesses to provide small, reusable, and self-describing computing methods to each other. A Web service by itself is just a piece of code that can be called by other applications or remote processes; however, if a programmer in the near future could pull together enough Web services, he or she could stitch together most of the features needed to support an entire Web application. The practical goal of a Web service is to permit a business to concentrate only on its core business needs and call up prepackaged "Web services" to complement the core business.

At the time of this writing, Web services are new enough that all of this is still not a reality. However, networks such as Microsoft's .NET Passport are being built on this Web services concept. As the Web services networks are built, we have the chance to watch as they are cobbled together into realistic systems. In many respects, this situation is very similar to when the Internet first began to open up to the commercial world in the 1990s.

The definition given at the beginning of this section applies to a Web service in the broadest sense of the term. The fact is that, at the beginning of 2002, there really wasn't a standard definition of a proper Web service. Every expert would give you a slightly different answer. For this book, a Web service is a remote Internet service that is capable of sending and receiving data over an HTTP network within a well-defined XML package. The difference between a Web site and a Web service is the use of XML to finely define and control the data being sent to and from a Web service. This brings up an interesting point: Unlike XML, which has the W3C to control and define XML, currently no single organization exists to define the nature of a Web service. Instead, a Web service is defined by the collection of tools and specifications a programmer uses to build it. What makes it all work is that nearly everyone is using the same set of standard specifications. Over time, this confusion will be resolved, and some large organization such as the United Nations (see the section titled "ebXML" later in this chapter) or W3C will take control of the larger Web services definition.

It is important to note that in this general discussion of Web services we are discussing both the creation of a Web service and the use of one. The creation of a Web service includes writing, exposing, and registering it for all authorized users to see and use. The use of a Web service includes finding and interfacing with the Web service in a stable, predictable manner.

At this point, it would be appropriate to define the terms client and server. A server is a computer or device that manages resources. According to this definition, a Web service server is any machine or device that responds to requests. This server manages resources by controlling the output of information through Web service responses. A client is any application that relies on a server to perform some operations. In this case, the Web service requestor is the client, as it is relying on the Web service server for information through responses.

Key features of creating and using Web services are listed here:

  • They are accessible using standard Internet protocols such as HTTP or SMTP.

  • They are distributed, which means that a Web service will usually reside on a different server than the applications that use the service.

  • They can be centralized to a single source. This means that you can code once and access many times from many projects. In other words, Web services allow increased code reuse.

  • A single Web service isn't a full application, but rather a standalone function that can be called by many different applications.

  • A Web service can be self-describing. This enables businesses and applications to find and use Web services through automated processes and Internet registries (an electronic yellow pages to let other programs find the service).

All of these features add up to make a Web service a reusable component that can broadcast its functionality across an Internet network.

The advantages of creating and using a Web service come from the distributed nature of the overall system. They include the following:

  • Logic can be broken into smaller reusable pieces of code.

  • The code can be used by many different applications. For example, a Web service written in ASP.NET can be accessed by a JSP page.

  • The code can be registered so that many different organizations can use a single Web service. As a result, the builder of a Web service doesn't need to communicate with every customer.

  • Web services can describe themselves to the world through special registries.

  • Standard protocols, APIs (standard code), and tools (coding development packages) are evolving to allow programmers to build and access Web services. In the future, these tools will allow for the automatic creation of a Web service. This will open the creation of Web services to developers of all skill levels, as they won't need to know the underlying mechanics.

The disadvantages of Web services include the following:

  • You will need to create another software tier to utilize Web services. This new layer means that you must give careful consideration to application and service architecture in systems that utilize a Web service.

  • Accessing Web services over the Internet causes both security and speed concerns for an application designer. However, you can increase the security of a Web service at the expense of speed.

  • Automated tools such as Microsoft's Visual Studio .NET or Sun's Forte that support Web services are currently young and few. This means that in order to successfully build a Web service, you must clearly understand an entire set of protocols and APIs.

  • Web services are new within the programming community. Solid and proven design patterns still need to be established for them. As a result, very few practical online resources exist to help a struggling programmer learn how to successfully implement a Web service.

As is often the case in the computer industry, it takes several iterations to get things right. In the case of Web services, this is especially true, as Web services are truly another iteration of older ideas. Their design aids in the reduction of development time and promotes code reuse.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020