Abstract. Digital libraries are increasingly relying on distributed services to support increasingly complex tasks such as retrieval or preservation. While there is a growing body of services for migrating digital objects into safer formats to ensure their long-term accessability, the quality of these services is often unknown. Moreover, emulation as the major alternative preservation strategy is often neglected due to the complex setup procedures that are necessary for testing emulation. However, thorough evaluation of the complete set of potential strategies in a quantified and repeatable way is considered of vital importance for trustworthy decision making in digital preservation planning. This paper presents a preservation action monitoring infrastructure that combines provider-side service instrumentation and quality measurement of migration web services with remote access to emulation. Tools are monitored during execution, and both their runtime characteristics and the quality of their results are measured transparently. We present the architecture of the presented framework and discuss results from experiments on migration and emulation services.

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Many digital preservation scenarios are based on the migration strategy, which itself is heavily tool-dependent. For popular, well-defined and often open file formats – e.g., digital images, such as PNG, GIF, JPEG – a wide range of tools exist. Migration workflows become more difficult with proprietary formats, as used by the several text processing applications becoming available in the last two decades. If a certain file format can not be rendered with actual software, emulation of the original environment remains a valid option. For instance, with the original Lotus AmiPro or Word Perfect, it is not a problem to save an object of this type in ASCII text or Rich Text Format. In specific environments, it is even possible to send the file to a virtual printer, thereby producing a PDF as a migration output. Such manual migration tasks typically involve human interaction, which may be feasible for a small number of objects, but not for larger batches of files.We propose a novel approach using a software-operated VNC abstraction layer in order to replace humans with machine interaction. Emulators or virtualization tools equipped with a VNC interface are very well suited for this approach. But screen, keyboard and mouse interaction is just part of the setup. Furthermore, digital objects need to be transferred into the original environment in order to be extracted after processing. Nevertheless, the complexity of the new generation of migration services is quickly rising; a preservation workflow is now comprised not only of the migration tool itself, but of a complete software and virtual hardware stack with recorded workflows linked to every supported migration scenario. Thus the requirements of OAIS management must include proper software archiving, emulator selection, system image and recording handling. The concept of view-paths could help either to automatically determine the proper pre-configured virtual environment or to set up system images for certain migration workflows. View-paths may rise in demand, as the generation of PDF output files from Word Perfect input could be cached as pre-fabricated emulator system images. The current groundwork provides several possible optimizations, such as using the automation features of the original environments.

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