Mariela Hristova's Assignment 6


Describe the issues involved with various preservation strategies for digital objects.


Both in the readings and in the classroom discussions, two main techniques for the preservation of digital objects have stood out for me: emulation and migration.

Emulation focuses on the software. That is, it deals with recreating a system's functionality in a backward-compatible manner, creating new systems that emulate specific out-dated software. As one might imagine, the variations and ownership of software and of operating systems can make such a process extremely difficult. At the same time, the potential for doing this effectively is great because the technique allows for some centralization of resources. The emulation can be provided as a service by a company specializing in it and can be delivered in a virtual manner. One of the limitations, however, is the necessity for continuous service because this technique does not convert files to modern formats, but just keeps them accessible by having the technology to read them.

By contrast, migration focuses on the file and its format. The technique deals with converting every file to an up-to-date format. An immediate limitation that comes to mind is the quick pace of change in technology, which will undoubtedly dictate incessant migration to keep up with new formats and software. Another limitation comes from the potential for loss in the conversion. The obvious benefit is that the actual documents are accessible and ready for use. Also, the gap between the out-dated and the new format is never too large or at least not as large as emulation can encourage.

Neither of those two techniques offers an ultimate solution to current concerns about preservation of digital objects. Perhaps a combination of the two approaches can be devised. As Alexa McCray and Marie Gallagher (2001) exemplify, preserving an original format and accessing it through emulation only to generate a working copy for display into an up-to-date format can be one direction for developing digital preservation. This approach would allow the emulation of just one (ideally) piece of software, while having the best of migration for your users' benefit as well.



McCray, Alexa T., & Gallagher, Marie E. (2001). Principles for Digital Library Development. Communications of the ACM 44 (5): 49-54.