Presenting Data with the XML DSO
By Michael Floyd
In the early '90s, one very popular feature of the so-called rapid application development (RAD) tools was the data-bound control. These "data-aware" controls were popular because they possessed internal logic to retrieve, display, modify, and write database records. Thus, it was easy for the PowerBuilder developer, or Visual Basic or Borland Delphi programmer to create a table that paged through and presented database records.
Many of these early controls have long since been standardized into what Microsoft calls Data Source Objects, or DSOs. Generally speaking, DSOs are ActiveX controls that let you establish a connection between the control and a data source. Once the connection is established, the DSO lets you populate forms, fields, tables, edit controls, and similar objects with data. In most cases, DSOs have the ability to update themselves dynamically. Therefore, users have the experience of a live data connection.
As part of its increasing support for XML, Microsoft introduced the XML DSO in Internet Explorer 4. The XML DSO lets you bind markup from an XML document with HTML presentation elements. The markup can come from an external data source, or it can be contained in an XML data island. The cool thing about these DSOs is that since they maintain live connections to the data source, your Web pages can update themselves as new XML data streams arrive.
This month, I'll examine the XML DSO and show how you can quickly grab XML text and present it in a browser.
