Introduction
Installing/Configuring
Introduction
PHP Manual

## The Structure of a Service Data Object

A Service Data Object instance is made up of a tree of data objects. The tree is defined by containment relationships between the data objects. For example, a Company data object might consist of a number of Department data objects and therefore the Company would have a containment relationship to the Departments.

An SDO may also have non-containment references between data objects in the tree. For example, one Employee data object might reference another Employee to identify a career mentor.

As well as data objects referencing each other, they can also have primitive properties. For example, the Company data object might have a property called "name" of type string, for holding the name of the company (for example, "Acme").

Each of these properties of a data object - containment relationships, non-containment references, or primitive properties - may be many-valued or single-valued. In the above examples, Departments is many-valued and the Company name is single-valued.

In PHP, each SDO data object is represented as a PHP object. The properties of the data object can be accessed using either object syntax or associative array syntax. We'll see some examples of this later.

Introduction
Installing/Configuring
Introduction
PHP Manual