Service Data Objects (SDO) is an open standard for enabling applications to handle data from different data sources in a uniform way, as data graphs. SDO data graphs are an important concept for mediation programmers. This topic describes how SDO data graphs are used to represent different types of message information in a standard way, giving a simple and powerful model for programming mediations.
Using SDO, your applications can uniformly access and manipulate data from diverse data sources including relational databases, XML data sources, Web services, and enterprise information systems.
For more information about SDO, see Introduction to Service Data Objects.
SDO data graphs are structured collections of data objects. In general, data graphs generated from messages have a tree structure. A mediation retrieves a data graph from a message, transforms the data graph, and reflects the updates to the data graph in the message.
In WebSphere Application Server, data access services connect mediations to data sources, allowing mediations to manipulate an abstract representation of the message, the SIMessage. The SIMessage API provides a method, getDataGraph(), that returns the SDO data graph containing the SIMessage content in a tree representation, or graph of data objects. Each data object represents one or more fields in the message, or it points to other objects.
When a data graph is requested from a message, the appropriate data access service is identified by a format property in the SIMessage. The format string controls which data access service is used to process the message, and can contain additional control information for that data access service. The data access service controls the structure of the message. For more information about the data access services available in WebSphere Application Server, see Mapping of SDO data graphs for Web services messages