XML: A Brief Glimpse

XML: A Brief Glimpse

Although Chapter 2, “The Fundamentals of XML,” lays the foundation work for XML, in order to have a good discussion about what XML can do for you and how it differs from past efforts, it does make sense to give you a brief glimpse of what XML is. XML stands for Extensible Markup Language, a series of three words that mean a whole lot. The basic idea is that with XML, you can encode information in a text document that not only has data in it but also has information that describes what the information means— and in a structured manner that humans can read. This may sound abstract or extremely simple, depending on your viewpoint, but it is the truly basic core of the language. XML is simply a text document that allows users to store data in a structured manner that also encodes information, or “metadata,” as to what that data means.

For a more detailed introduction to XML, you should read Chapter 2. The remainder of this book details extensions to this basic concept to power robust applications and make XML work in a real-world context.

With this explanation in mind, we can now address the bigger questions: Why does XML matter? Why will it solve our data-representation problems? Why is it different from other formats that have attempted to solve the same problems? Why will it make a differ-ence in the way we run our businesses, day-to-day tasks, and lives?

The Time Is Right

Before we talk about what XML is and how it began, it makes sense to talk about why the revolution in structured data is happening now. As you’ll learn later in this section, although XML has many compelling features, as a technology, it offers little that others have not attempted with differing degrees of success. So, the question that begs to be asked is, “how is XML different?”

As a partial answer to this question, timing is everything. There are many reasons why XML may not have worked as a technology or movement even a decade ago. Some of these reasons are technology based, whereas others deal more with the sociological rami-fications of how technology is used and adopted.

The simplest of reasons why XML is becoming popular is that our machines are only now capable of the processing requirements of this data format. It simply would have been extremely difficult, if not impossible, to support the processing, data storage, and bandwidth requirements for the exchange of XML documents 20 years ago. We started approaching the ability to process this information in an effective manner only a decade ago. Simply put, processing power, data storage, and bandwidth is becoming incredibly cheap these days. Processing XML now is not as big a challenge as it would have been in 1980.

The driving force for the use of a technology like XML is the desire to exchange infor-mation in an open, nonproprietary manner. The terms open systems and open software imply that a particular application or data format can be created by Corporation A’s tools and processed by Corporation B, C, or D’s tools or by open-source applications and tools. Open systems can be created and processed in any combination of different tools and applications by different or competing tool vendors. For vendors of software applica-tions who open their data formats and programming layers, this means their software can be replaced more easily. Obviously, this primarily represents an advantage to the con-sumers, who have increased choices in how they choose to have their problems addressed. But this is also an advantage for the software vendors in that they can develop open interfaces that keep their software applications always current and open for modifi-cation. In the past few years, the movement to open-source systems and platforms has been tremendous. In part, this has been a reaction to the dominance of the industry by particular software corporations, and in part this is due to the general demand for sys-tems that can interoperate with each other. Ten years ago, this cry for openness was hardly a whisper. It simply would have been impossible to demand open, nonproprietary systems in 1990 when most desktop computers ran DOS and back-office servers ran either Novell or Unix. However, the environment today is ripe for the use of open, nonproprietary data formats.

Of course, the development of the Internet itself is a reason why XML could not have existed in any widespread manner a decade or more ago. Although the Internet was developed in the late 1960s, widespread commercial use of the vast worldwide network was not possible until the early 1990s. Without the Internet, it would be costly, ineffi-cient, and difficult to exchange data in a format such as XML. In fact, the Electronic Data Interchange (EDI) format thrived mainly because it provided both a means for rep-resenting data as well as a method for transporting it from place to place. With the wide-spread use of the Internet, however, technologies such XML could be used in a more extensive manner than formats requiring the use of a closed, proprietary network.

Furthermore, we have had experience now with many technologies that have worked to varying degrees of success. Our experience with EDI has given us an understanding of what it takes to perform electronic transactions. Usage of the Standard Generalized Markup Language (SGML) and the widely popular Hypertext Markup Language (HTML) has given us experience in what it takes to create, manage, and maintain struc-tured data stores. The development and use of various object-oriented and distributed application technologies such as Microsoft’s Component Object Model (COM) and the Common Object Request Broker Architecture (CORBA) have given us the required know-how of when and how to apply distributed processing techniques and methodolo-gies. All that XML has given us is another means for expressing this experience. Without that experience, there is no doubt that XML would simply be another step in the path towards a more perfect data-representation technology. Although XML may not be that final step, it surely is a product of all the experience, mistakes, and wisdom learned from our previous attempts to exchange information in an open manner.

The advent of HTML has brought a new kind of developer to the forefront. These “developers” are not programmers, EDI data wranglers, or publishing industry workers but rather the hordes of individuals who create and manage content on a daily basis. The Web has taught them that they, too, can be part of the information revolution—and now they will be part of the XML revolution. These are the very same developers who would be capable of implementing XML in all its different forms. After all, how can the revolu-tion be fought without any soldiers?

So, not only does XML solve some of the key problems facing data interchange, but its technology comes at a time when we can deal with its existence. In technology, timing is everything.