Evolution Layer. The Evolution Layer contains three new workflows: the Situation Change workflow is responsible for monitoring semantic changes in the Active System and to propagate them into the DPS, in order to keep the preserved content understandable; the Setting Change workflow deals with changes in practices, formats and technology in the environment of the preservation (setting); finally, the System Change workflow is responsible for situa- tions, where one of the involved systems changes. The first two workflows are described in more detail below, whereas the last workflow is left to the revised version of the PoF Ref- erence Model which will be reported in deliverable D8.5 [ForgetIT, 2016]. In support of the aforementioned workflows, the Evolution Layer includes additional functionalities: Evolu- tion Monitoring, Context Evolution Management, Content Value Re-assessment and Context-aware Preservation Management. The Situation Change workflow consists of four steps (as depicted in Figure 8): (1) change monitoring, (2) change assessment (assessment of detected changes), (3) change notification (notification of involved components as well as the DPS on rele- vant changes) and (4) change propagation, which performs different types of actions depending on the observed change and the chosen change propagation strategy. For monitoring, assessing the changes and deciding about the consequences, in support to the Situation Change workflow, the functionalities Evolution Monitoring (mainly part of Active System), Context Evolution Management and Content Value Re-assessment have been introduced in the Evolution Layer: Figure 8: Situation Change Workflow in the Evolution Layer Evolution Monitoring The Evolution Monitoring functionality is required for the change monitoring step in the Situation Change workflow. This is mainly performed in the Active System (extension), because this is the main place, where evolution in the conceptual model of the application become visible. Such changes might, for ex- ample, be changes in the ontology (implicitly) underlying the organization of the information triggered e.g. by a major re-organization. Evolution Monitoring has to observe changes in the explicit representations of the conceptual model (such as taxonomies, information structures) in the Active System as well as more implicit signals of context evolution (e.g. newly upcoming topics, tags getting out of use, department sites no longer updated). Context Evolution Management The C...
Evolution Layer. A preservation framework per definition exists in a long-lived environment aimed to sur- vive at least decades. Clearly, most of the involved parts widely ranging from formats, technology and systems to semantics, and relevant real world situations (represented by the application) will not remain stable (i.e. unchanged) over such long period of times. This implies that adequately dealing with changes is a core property that is required from such a framework. The purpose of the Evolution Layer is to adequately deal with the upcoming changes, such that the preserved content remains accessible and understandable. Clearly this means different things for different types of changes. Other types of actions are, for example, required in case a media format gets out of use as compared to the situation that an organization is re-organized. The Evolution Layer, therefore, groups the changes considered in three classes, each handled by its own type of change workflow. Thus, the Evolution Layer contains three new workflows: the Situation Change workflow is responsible for monitoring semantic changes in the Active System and propagating them into the DPS, in order to keep the preserved content understandable; the Setting Change workflow deals with changes in practices, formats and technology in the environment of the preservation (setting); finally, the System Change workflow is responsible for situations, where one of the involved systems changes. In support of the aforementioned workflows, the Evolution Layer includes additional func- tionalities: Content Value Re-assessment, Evolution Monitoring, Context Evolution Management and Context-aware Preservation Management.
