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The XML Usage Spectrum

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Uncover the key concepts of XML and the spectrum of its uses. You will see how the MOM (Machine-Oriented Messaging) and POP (People-Oriented Publishing) store can be successful on the Web.
This chapter is from the book

Introductory Discussion

  • Real-world concepts

  • Documents vs. data

  • Machine-oriented messaging (MOM)

  • People-oriented publishing (POP)

Like the Jets and the Sharks, the factions never mixed.1

On the one hand there were the document-heads armed with word processors and formatters. On the other, the data-heads from the relational database world. It's time for a truce – no, an alliance. XML finally makes clear an internal truth: documents and data are the same thing. To be precise, documents are the interchangeable form of data!

3.1 Is XML for documents or for data?

What is a document?

The dictionary says:

"Something written, inscribed, engraved, etc., which provides evidence or information or serves as a record".

Documents come in all shapes and sizes and media, as you can see in Figure 3-1. Here are some you may have encountered:

Figure 01Figure 3-1 Documents come in all shapes and sizes.


  • Long documents: books, manuals, product specifications

  • Broadsides: catalog sheets, posters, notices

  • Forms: registration, application, etc.

  • Letters: email, memos

  • Records: "Acme Co., Part# 732, reverse widget, $32.50, 5323 in stock"

  • Messages: "job complete", "update accepted"

An e-commerce transaction, such as a purchase, might involve several of these. A buyer could start by sending several documents to a vendor:

  • Covering note: a letter

  • Purchase order: a form

  • Attached product specification: a long document

The vendor might respond with several more documents:

  • Formal acknowledgment: a message

  • Thank you note: a letter

  • Invoice: a form

The beauty of XML is that the same software can process all of this diversity. Whatever you can do with one kind of document you can do with all the others. The only time you need additional tools is when you want to do different kinds of things – not when you want to work with different kinds of documents.

And there are lots of things that you can do.

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