Home > Articles > Software Development & Management

Web Services Part 3: What Are Web Services?

  • Print
  • + Share This
In the third part of his series, Alex Nghiem defines web services, provides a history of previous network technologies, and describes how web services can save valuable time and money.
Like this article? We recommend

In the first two articles, "Web Services Part I: Existing Problems" and "Web Services Part II: Current Technologies," we outlined some of the challenges that exist in the current business market and various attempts at addressing these challenges. Previous attempts to manage the inherent complexity in building distributed applications and web systems included object-oriented technology, component based development, and HTML. Each of these technologies, on their own, fell short of solving many of the aforementioned challenges. This article focuses on the definition of web services and provides the groundwork for future articles.

The concept of a web service is not a totally new idea: it is a refinement of many of the predecessor technologies. In fact, as we will see later, web services leverage (or at least integrate) much of the functionality provided by the previously mentioned technologies.

Loosely speaking, a web service is a piece of functionality (an object, a component, an application, a database call) that can be invoked over a network using a predefined syntax. The term web service is highly misleading because it has very little to with the World Wide Web, but unfortunately, the industry has adopted it.

Before continuing too much further, let us define the many ways which the term web services has been used in the industry:

  • Architecture—the term web services often specifies a group of technologies (SOAP, WSDL, UDDI, HTTP, and the like) on which applications can be built.

  • Predefined functionality that can be invoked in a distributed fashion—as mentioned earlier, a web service is callable across a network.

  • Market size—as usual, there have been quotes by various analyst groups about how this will be a multi-billion dollar market in the next 18 months.

More precisely, for our needs, we define a web service as:

  • A self describing piece of functionality that can be invoked over the Internet and can be combined to form higher level services.

  • A language and operating system independent architecture built on existing infrastructure and open standards (XML, HTTP, SOAP, and WSDL). The last two acronyms will be detailed in future articles.

NOTE

(Strictly speaking, web services can also invoke other protocols such as FTP (file transfer protocol) and SMTP (Simple Mail Transfer Protocol.)

Let us look at the terms in italics more closely:

  • Self-describing—the definition (the required parameters, the return values, and the like) of the web service is defined in a WSDL (web services definition language) document, and since WSDL is an XML grammar, the definitions for the document are embedded in the document (as opposed to being stored in an external file).

  • Can be combined—primitive web services can be combined to form more complex web services. This is analogous to building more complex objects or components out of simpler objects or components.

  • Architecture—using web services implies the existence of certain prerequisite technologies (the most fundamental being SOAP, defined further below).

  • Existing infrastructure—to leverage existing technologies, web services use the existing infrastructure (in most cases, the Internet) as its transport mechanism.

  • Open standards—a web service can be registered in a UDDI directory (UDDI is an XML grammar), its functionality is described in WSDL (an XML grammar, as described above), its result set is captured in a SOAP document (SOAP, an acronym for Simple Object Access Protocol, is also an XML grammar) and it is typically invoked via HTTP. These various technologies have been endorsed and adopted by many of the major technology vendors including Microsoft, IBM, Sun, BEA Systems, Oracle, Iona and many others. (In fact, Microsoft was a co-inventor of SOAP.) The technologies are also at various stages of standardization by the W3C standards committee, the same committee that defines many of the other Internet standards including HTML, XML, and the like.

NOTE

The term Simple Object Access Protocol is highly misleading because SOAP is not simple, nor is it object-oriented. Many developers now informally refer to SOAP as Service Oriented Architecture Protocol.

On the surface, the ability to invoke functionality across a network is nothing new (RPC, or remote procedure calls, have existed since the early days of Unix) and may seem fairly trivial. However, the adoption of web services has wide reaching implications. One of the biggest challenges of enterprise software development revolves around integrating two or more incompatible systems (either by intent or by accident). These incompatibilities usually arise because the systems were written in different languages (or different versions of the same language) and/or they use different middleware (for example, a CORBA object needs to communicate with a DCOM object), programming languages (say, Java and COBOL) or network protocols.

Traditional middleware solutions usually require that both the sender and the receiver need to be on the same platform and/or language. These factors tend to lead to high licensing costs (in the thousands and sometimes in the millions) and potential incompatibilities, which often lead to a lower adoption rate.

Web services, being based on open standards, alleviate the licensing costs (in many cases, the tools are free or built-in as part of low-cost development tools) and, being platform and language-independent, can solve many of the incompatibilities that exist with traditional middleware. As an example, rather than try to get a CORBA object to communicate to a DCOM object (not a trivial task because the two middleware have a totally different way of representing objects in their respective domains), the calling program can pass an XML document to the receiver and let the receiver populate the XML document with the result set. This sequence of steps is the core of SOAP, one of the prerequisites for a web services architecture. We will explore SOAP in greater detail in future articles.

Thus, rather than requiring one party to adopt a language (or middleware platform) of the other party, a web services architecture (or more specifically, the SOAP layer) allows both parties to keep the native platforms and communicate via XML, a more widely adopted standard than any existing proprietary middleware platform. This form of integration is considerably simpler and cheaper than traditional middleware. As a point of reference, Dollar-Rent-A-Car has implemented a solution that allows their customers to book flights with Southwest Airlines in two weeks. The implementation cost $40,000 using .Net (Microsoft's web services platform) while a competing option (presumably traditional middleware or an application server) would have cost $200,000.

The reduced integration costs allow a company to expand into new markets and more easily service existing customers. Most companies use business integration as a competitive advantage because it can lead to lower costs, better inventory visibility, and often revenue growth. To achieve any form of true business automation between two parties requires that the back end systems at the respective parties communicate directly with each other (as opposed to sending data that has to be manually reentered). Such a task has historically required a lengthy integration project (due to the challenges outlined above) and in many cases, expensive software and hardware on both ends. (In some extreme cases, the length of the project was longer than the duration of the relationship!) Consequently, many firms attempt business automation only with their largest clients or suppliers. However, if the integration costs were lower, then companies could now offer that same benefit to their smaller clients and suppliers as well. As an example of a smaller client that can benefit from business automation, consider a small firm that uses an Excel spreadsheet as a budgeting and forecasting tool. While working inside Excel, the user can write a macro to

  • Highlight the column with the budgetary values

  • Convert the highlighted fields to an XML document (using the built-in functionality of Excel)

  • Send an XML document (via the Internet) to his supplier

The receiving program on the supplier side can

  • Parse the XML document (that is, break it down to its simplest units)

  • Feed these simpler units directly into a quoting system

  • Generate a PO in the form of an XML document to be sent back to the client

The client can import the XML document into Excel and then compare it side-by-side with the budgetary values (or just display the document in a XML-aware browser, such as Internet Explorer). Note that both parties are integrated together but it is a much looser form of integration than what is normally present through traditional middleware (normally referred to as tight integration). As long as the two parties agree on the data format that needs to be exchanged, neither party needs to worry about platform or middleware compatibilities. In future articles, we will explore the various architectural patterns of web services along with real-world case studies.

The ubiquity of XML (and XML parsers) is one of the reasons why web services have such a high chance of succeeding in the market place.

NOTE

An XML parser is a program that is responsible for decomposing an XML document into meaningful data. The data is usually represented as a series of fields. Because XML defines a much stricter criteria for validness than HTML, an XML parser is considerably less complex (and hence, smaller in memory) than an HTML browser.

HTML (a platform independent lightweight markup language), combined with a browser (a universal reader and display mechanism) ushered in a new era of browsing of information (witness the explosion of web sites after the creation of the browser) because the technologies were simple, accessible and, for the most part, free or almost free. (Many have criticized the many shortcomings and lack of features of HTML, but HTML's rapid adoption as the primary Web programming language is because of its simplicity and low learning curve.)

XML promises to create even larger markets because it can be used for browsing (when combined with XLST) and for business automation, as shown in the simple example above. Additionally, it is being supported by all the major technology players (including IBM, Microsoft, Oracle, BEA, and the like) rather than created by a start-up, which then has to get market acceptance. Additionally, the adoption costs are very low (many of the tools are free) and the standards are being closely monitored and endorsed by third parties such as the W3C.

Note that web services are not the first industry attempt to solve the business-to-business automation problem. A much earlier effort at solving some of these challenges was EDI (electronic data interchange). EDI fell short of its vision because it was inflexible. As businesses evolve, they often need to add new data formats and fields, and trying to accomplish those tasks with EDI was extremely difficult. EDI's inflexibility often led to many implementations that deviated from the proposed standards (X12, EDIFACT, and so on), thus slowing down the adoption rate. Additionally, when EDI was invented, there was no global public network (that is, the Internet), and many firms had to invest in building (or paying for) proprietary networks.

NOTE

These networks are called Value Added Networks (VANs), and companies that offered these solutions include Harbinger (now part of Peregrine Systems), GE, IBM, and IBM. We will explore the counterpart to a VAN, a web service network, in a future article.

Thus, EDI is still very prevalent but only among the largest of companies (Wal-Mart, GM, and the like). We will explore EDI standards and how XML will co-exist with EDI in future articles.

The author would like to express his gratitude to the following people for their insights and help: Kevin Wittkopf, Randy Pilkenton, and Isaac Adams.

  • + Share This
  • 🔖 Save To Your Account

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.

Overview


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.

Surveys

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.

Newsletters

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.

Security


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

Children


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

Marketing


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.

Choice/Opt-out


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.

Links


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