In addition to the simple string identifiers described in Section 4.6, “Identifiers and Equality”, every ContentObject on the Content Management Server has a UUID since version 2004.1. UUIDs are stable and universally unique identifiers as defined in RFC 4122 and are represented as java.lang.UUID. They are not meant as replacement of simple string IDs, and should not be used where a simple ID is sufficient. UUIDs make sense in certain scenarios where uniqueness across multiple repositories is important, or when content objects may be transferred to another repository and should keep their identity. For details see: Section 3.13.2.17, “Serverimport/Serverexport” in Content Server Manual.

Similar to string IDs, the API provides a getUuid() method in class ContentObject to retrieve a UUID, and methods to look up a Content or Version for a given UUID. A Content with a given UUID can be retrieved from the ContentRepository with method getContent(UUID). A Version with a given UUID can be retrieved from its containing Content with method getVersion(UUID). It is important to note, that a UUID does not encode information about the location of the ContentObject. By itself, it cannot be used to identify the repository or even the containing Content of a Version.

Note, that as of version 2004.1, UUIDs are only available on the Content Management Server. If a connection is made to a live server, or to a server of a previous release, then all methods that would return a UUID will return null instead.