Challenges for the Evaluation of Emulation

Emulation is one of the main strategies for preserving digital objects. With different emulation environments to choose from when preserving a collection of digital objects it is necessary to choose the emulator that is able to render the significant properties of an object best. But also on the development side it is necessary to run automated tests for new versions of emulators. In this work we present some of the main challenges for automated testing of emulators with specific digital objects. To compare different original and emulated environments it is necessary to document the environment used to render an object. Changes in this ’view-path’ comprising all secondary digital objects needed to perform the emulation can lead to changes in behavior or appearance. For interactive and dynamic objects it is necessary to determine the external events influencing an object, e.g. user input and changes in synchronized timing can lead to different results when executing a digital object. Significant properties of descriptive forms, i.e. the physical manifestations of an object, are compared when using migration as a strategy by comparing the original and the migrated form. With emulation the descriptive form of the object remains unchanged, so properties of a rendered version of the object have to be compared to determine if the preservation was successful. Emulation environments have to be extended to allow for the extraction of significant properties of digital objects. These properties can vary over different points in the rendering process.