Controlled Migration in Digital Archives Thomas Triebsees University of the Federal Armed Forces Munich Department of Computer Science

Thomas Triebsees, Department of Computer Science 2 What is the challenge? The burden of long term preservation new file formats new storage media new computer technologies Technologies change And the digital objects?

Thomas Triebsees, Department of Computer Science 3 What is the challenge? The digital objects must be accessible, viewable and understandable for future generations But can have various dependenciesare only interpretable in a context can have very complex structures

Thomas Triebsees, Department of Computer Science 4 What is the challenge? And when it is up to migration? Crucial points about migration The tools are many The dependencies are many and can induce migration obligations The objects are many Automation Formal model allowing to qualify infor- mation and object dependencies Full content hardly preservable

Thomas Triebsees, Department of Computer Science 5 What is the challenge? And when it is up to migration? How do we manage it? The information model (1) Hierarchical structure of ‘‘information” through type system with inheritance ArticleRec Identifiable Obj ID Image NewspaperLocatorArticle NewsDescrArtDescr NewsRec

Thomas Triebsees, Department of Computer Science 6 What is the challenge? And when it is up to migration? How do we manage it? The information model (2) Type description fully formal > Article(id:ID, h: String, c:String, refs:List):Article { } + { > True, > result=id } + getHeadline():String { > True, > result=headline } + getContent():String{ > True, > result=content } + getPicRefs():List{ > True, > result=refs } + toString():String{ > True, > result=id.concat(headline.concat(content)) } - id : ID - - content : String - refs : List { Valid XML file according to Article.dtd } Article getID():ID headline : String > id.isValid(), > self.id=id and self.headline=headline and self.content=c and self.refs=refs Formal inheritance mechanism Automatic dependency generation

Thomas Triebsees, Department of Computer Science 7 What is the challenge? And when it is up to migration? How do we manage it? The information model (3) Dependencies described fully formal Identifiable Obj ID Image NewspaperNewsRecLocatorArticleRecArticle NewsDescrArtDescr *** * * * ) describes6) describes 7)describes8)describes 1) references 3) references 2) 4) 9) 1..* * 10) references

Thomas Triebsees, Department of Computer Science 8 What is the challenge? And when it is up to migration? How do we manage it? Transformations Described fully formalBlack box view, i.e. only characterized by  source type  target type  type of preserved contents What about other migration obligations? Set(Image)NewspaperNewsDescr LocatorNewsRec δ δ2δ2 But: describes 11 11

Thomas Triebsees, Department of Computer Science 9 What is the challenge? And when it is up to migration? How do we manage it? What has still to be done? Future Research Choice of best transformation functions according to defined user preferences Further automation according to type definitions Automatic derivation of migration algorithm respec- ting object dependencies...

Thomas Triebsees, Department of Computer Science 10 What is the challenge? And when it is up to migration? How do we manage it? What has still to be done? Questions? Questions Thank you for your patience ! Thomas Triebsees University of the Federal Armed Forces Munich Department of Computer Science