Generic library for accessioning any object type. It provides the core interfaces to generate hash-based and monotonically increasing accessions, which must be extended by each application to support a particular object type.
A set of objects must be passed to the accessioning service layer. This service will generate a summary with the relevant fields of the object, and then a hash value will be calculated based on it. This hash will be used as a key to check if the object has been previously accessioned; if it already exists in the system, the existing accession will be returned for that object, otherwise a new accession will be generated and stored in the database. Finally, the user will receive a mapping between accessions/objects.
The following sections describe the components involved in the process, starting from the top layer the user interacts with, to the lowest layer where the data is stored.
Via the BasicAccessionGeneratorRestController class, the library offers a basic implementation of the REST andpoints to generate accessions and query the existing ones. This implementation also allows to use the validation of the rest message against a DTO that represents your model.
This layer acts as intermediary between user interfaces and the lower layers that generate and store the accessions. An accessioning service requires the following:
- Summary function
- Hash function
- Accession generator service
- Database service layer
A summary function is a Java lambda or Function implementation from your object model to a string. It is meant to generate the minimum text string that uniquely identifies your object model.
The hash function is a Java lambda or Function implementation from the summary string to your preferred hash representation (which could also be a string). This hash value will be used as unique key for your object. The library already contains a SHA1 implementation.
Service layer that generates accessions. It receives a mapping (hash, model) and generates an accession for each pair, resulting in a triplet (accession, hash, model). The generated accession will depend on the specific implementation. The library currently includes a timestamp based, hash based and monotonic accession implementations.
This service layer handles the database persistence of the triplet (accession, hash, model) and the related queries offered through the accessioning service. The library currently includes a basic implementation that supports the use of Spring Data repositories and entities.