Extended Information Model Sample Clauses

Extended Information Model. Middleware Perspective‌ In the previous section we have described the PoF Middleware from the point of view of the User. Here we describe the point of view of the Middleware. The Middleware has to manage the mapping between the Information Model as seen by the user (or organization) and the Information Model of the underlying preservation system (or systems). Figure 13 shows the Extended information model, which reflects the perspective of the Middleware. The elements (classes) coming from the User Perspective have been high- lighted (yellow background color) and can be considered as core elements of the model. This model introduces a number of concepts that are relevant for the preservation sys- tem, extending the user experience and adding the needed elements for managing and supporting the digital preservation. The Middleware Perspective in Figure 13 introduces the so called Detachment Elements [Borghoff et al., 2006] that are the low level elements such as File and Bitstream (chil- dren of Component, aggregated by Item) as well as the detailed metadata information represented by Descriptors (that are all children of Information Object). These De- tachments have been designed in order to be compliant to the most widely adopted preservation metadata standards, as described in Section 6. A core aspect of the Middleware perspective is shown at the right corner of the figure, the ID Mappinfg Table. Since the preservation entities as they are seen by the active system are not mapped 1:1 to the DPS, it is necessary that the Middleware manages a mapping between the Preservation Entities and the Archival Resources in the respective repositories. For maximal flexibility an ID mapping is used for this puprpose. The class Preservation Entity Identifier, which is a type of Reference, is the identifier of a pre- served entity. This can be identifiers of different kinds. Therfore, there are at least three children, the CMIS ID is the identifier used for the resource in the Active System, PoF ID is an identifier used for internal purposes and Repository ID is the ID of the Resource in the Archive. All these IDs are related to each other by the ID Mapping Table that can be considered as their aggregator (represented by the black diamond in the diagram). This mapping table is also use to link archival resource to Situations. A class specifically useful for the Middleware and not for the User, is the Archival Re- source, a parent class of Preservation Entity. Actually the...