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A good discussion of the Fedora digital object model (for Fedora 2 and prior versions) exists in a recent paper (draft) published in the International Journal of Digital Libraries. While some details of this paper have been made obsolete by the CMA (e.g. Disseminators), the core principles of the model are still part of the CMA. The Fedora digital object model is defined in XML schema language (see The Fedora Object XML - FOXML). For more information, also see the Introduction to FOXML in the Fedora System Documentation.
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The Service Deployment object is a special type of control object that describes how a specific repository will deliver the Service Operations described in a SDef for a class of Data objects described in a CModel. The SDep is note executable code but instead it contains information that tells the Fedora repository how and where to execute the function that the SDep represents. In the CMA, the SDep acts as a deployment object only for the specific repository in which it is ingested; each repository is free to provide functionality in a different way. For example, one Fedora repository may choose to use a Servlet and another may use a SOAP Web service to perform the same function. As another example, individual repository implementations may need to provide the functionality at different end points. Or perhaps, a specific installation may use a dynamic end point resolution mechanism to permit failover to different service providers.
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