8. The computer-readable medium of claim 5 , wherein the first and second data objects are XML documents, and wherein each fragment includes one or more XML elements stored as an independent XML document by the CMS.
5. A computer-readable storage medium containing a program which, when executed, performs an operation for managing data objects in a content management system (CMS), the operation comprising: accessing a first data object managed by the CMS, wherein the first data object includes a collection of one or more data object fragments, wherein a first fragment of the one or more data object fragments is referenced by a second data object stored in the CMS, and wherein the first data object and the second data object are composed according to respective schemas; receiving a modified version of the first data object to store in the CMS wherein the modified version of the first data object includes a modified version of the first fragment; fragmenting the modified version first data object into the one or more data object fragments; validating the modified version of the first fragment against the schema associated with the second data object; and upon determining that the modified version of the first fragment fails to validate against the schema associated with the second data object, performing a corrective action specified by the CMS, wherein the corrective action comprises generating an unmodified version of the first fragment, and further comprises one of: (i) incorporating the content from the modified version of the first fragment into the first data object, associating the unmodified version of the first fragment with the second data object, and discarding the modified version of the first fragment; and (ii) incorporating the content from the unmodified version of the first fragment into the second data object, associating the modified version of the first fragment with the first data object, and discarding the unmodified version of the first fragment.