Under XML Schema, a user notates element names, orders of occurrence, and number of occurrences. We know that in the RDB world, a schema is defined when designing tables to stipulate category (column) data types and data sizes, set the primary key, associate tables with other tables, etc. Y having to verify the content of each individual document.Ī "Schema" is what is required to allow the acceptance (or creation) of XML documents with a standardized element name and hierarchy structure. In this case, every purchase order would have to be processed by hand, and the entire system could never be automated.īut what would happen if all XML documents sent had the same element names and hierarchical structure? With standard element names and structures, a system could be created to handle all incoming XML documents, and order processing could be automated, without Mr. Y would have to open each XML document in an editor, confirm whether all of the required information was present, and then process the purchase order.
Having received XML documents with different element names and hierarchical structures, Mr. Y uses the three XML documents above, or your XML document, for order processing. As long as the information required for a purchase order is included, likely any XML document you could create would be a valid XML document for the purpose.īut what would change if you approached the task from Mr. Any of the three examples above can be considered to be proper XML documents. Y at Company X can take on a number of different XML document patterns. C has created elements having a hierarchical structure.Įven a simple request to create an XML document to serve as a purchase order to be sent to Mr. B has opted for rather abbreviated element names, and Ms. A has created very semantic element names. Y at Company X, what kind of XML document would you create? The following are three XML document examples, created by three different individuals. In this volume, we will be looking both at writing XML documents simply according to XML syntax (well-formed XML documents), as well as writing XML documents to be used as business-to-business data, or in other words, a data format to be shared between and among different companies.įor example, if requested to create an XML document to serve as a purchase order to be sent to Mr. Virtually any data can be created using XML format, since XML allows a user to freely define element names and hierarchical structure.
Now, we see XML used for personal data such as journals, household finances, and other applications. Order processing, invoices, estimates, travel expense reports, meeting minutes, accounting forms, manuals, and other data used on a daily basis at work are only the tip of the iceberg. XML documents are used for many different purposes today. Index The Need for XML Document Schema Types of XML Document Schema DTD Schema Definition Validating the XML Document Entity Declaration Review Questions The Need for XML Document Schema
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