Service Data Objects (SDOs) allow PHP to work with data from different sources (like a database query, an XML file, and a spreadsheet) using one interface.
Each different kind of data source requires a Data Access Service (DAS) to provide access to the data it holds. Here are some key features of "SDO with PHP":
· Service Data Objects (refered to as SDOs) - the data that the PHP programmer manipulates in a PHP script
· Data Access Service (refered to as DAS) - provides the means for reading and writing data from/to a data resource
· Type Model - describes the types of SDOs and primitives that may validly appear in the SDO tree, this is created using an API or by reading in an XSD (in the case of the XML DAS)
· Change Summary - a record of how the data has been changed during script execution, for example, if I have an SDO representation of a shopping cart and I change the quantity ordered for a particular item from 1 to 2 then the change summary will record that the original value was 1 and the new value is 2. This is used by the DAS to write the data back to the data resource.