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The Danish newspaper digitisation project (http://en.statsbiblioteket.dk/national-library-division/newspaper-digitisation/newspaper-digitization) is an in-production example of Minimal Effort Ingest using Autonomous Preservation Tools. In this project we receive scanned newspaper pages in batches of about 25,000 pages along with MIX (https://www.loc.gov/standards/mix/), MODS (https://www.loc.gov/standards/mods/) and ALTO (https://www.loc.gov/standards/alto/) metadata. We receive two batches a day and a total of about 30 million newspaper pages throughout the duration of the project. All ingest, validation and enrichment preservation actions are performed with the Autonomous Components.
Each new batch of scanned newspaper pages must be ingested in our repository system, undergo a large number of quality checks and have access copies generated.
In keeping with the Minimal Effort Ingest model, we first ingest the batch of pages, and then perform the quality checks. Metadata is stored in DOMS, our Fedora Commons (http://fedorarepository.org/) 3.x based repository, whereas the data files are stored in our Bit-Repository (http://bitrepository.org/). We use Solr (http://lucene.apache.org/solr/) to index the content of DOMS for our discovery platforms.
We store an additional object in DOMS, the batch object, which represents the batch of scanned pages, rather than any single page. In this object, we store PREMIS (http://www.loc.gov/standards/premis/)(Events detailing which actions and transformations have been performed on the batch. This information is also indexed by Solr.
We implemented the Autonomous Preservation Tool model in what we call Autonomous Components. Each component corresponds to a single action, such as "Ingest batch into repository" or "Schema-validate all XML files in batch".
All autonomous components are Linux executables and have the following characteristics:
- Can query Solr for batch objects having specific combinations of PREMIS Events.
- Registers a component-specific PREMIS Event on the batch object after execution.
The current location of a batch in the workflow is determined by the set of PREMIS events present on the batch object - in other words which components have processed the batch so far. Each component knows which PREMIS events must be present or absent on a given batch for it to be ready to be processed by the component.
We have created Tree Iterators as a framework for autonomous components to handle batches in a storage-agnostic way. Tree iterators allow you to iterate through complex directory structures, whether in the repository or on disk, in a uniform way. With this framework, the autonomous components are able to work identically on batches not yet ingested, and batches inside the repository. This gives us great flexibility when testing, and allows us to easily re\-arrange which components should be run before ingest, and which should be run after.
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