eXcelon and Databases

Many XML systems generate their documents from traditional databases. Yet, the content management system outlined in this article uses XML as its native database format. This is becoming less of a rarity in major projects due to the emergence of new products. Just as relational databases have matured over the last decade, we're starting to see software that's explicitly developed to manipulate XML in ways similar to ordinary database systems. XML systems such as eXcelon have parallel functionality to that of relational database management systems. With the purchase of eXcelon's B2B Portal server, the developer receives a suite of tools:

The Studio's Standard Project feature lets you define elements, attributes, and relationships between elements. This feature is similar to the design tool functionality built into Microsoft Access and CAI's Erwin. The tool saves a schema in document content description (DCD) format. You can also use eXcelon Studio to create an XML document in an XMLStore based on this schema.

eXcelon also includes tools to manipulate documents, such as insert, delete, and update queries. After you store a document in eXcelon, you can also add indices to improve query performance.

Although there are several methods of executing eXcelon queries, we chose to interface with eXcelon using a COM object. The Studio automatically creates this COM object in response to a Generate Wizard command. This provides great flexibility. One statement creates a query that specifies an XML document, applies a style sheet, and specifies the type of operation. You can also optionally cause eXcelon to validate the document against a DTD.