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Version: 2.0

OAIS starter

Purpose​

This starter is a REGARDS representation of an information package described by the OAIS recommandation of the CCSDS.

Configuration​

Add starter dependency to your POM (version depends on the REGARDS BOM)

<dependency>
  <groupId>fr.cnes.regards.framework</groupId>
  <artifactId>oais-starter</artifactId>
</dependency>

Business dependency :

<dependency>
  <groupId>fr.cnes.regards.framework</groupId>
  <artifactId>oais-regards</artifactId>
</dependency>

Dependency :

Autoconfiguration​

Starter autoconfigures Gson to (de)serialize base objects. At the moment, only Gson can do this properly.

How to​

How to use the starter​

You can extend AbstractInformationPackage to make your own information package. AbstractInformationPackage is compliant with GeoJSON format by extending AbstractFeature. As consequences, information packages contain a geometry attribute, an id attribute and a property attribute, the former being of type InformationPackageProperties.

How to build information packages​

Information packages can be built thanks to extensions of abstract builder IPBuilder. IPBuilder allows to set the properties of the information package.

InformationPackageProperties can be built thanks to InformationPackagePropertiesBuilder which gives access to ContentInformationBuilder and PDIBuilder that has to be used to build ContentInformation and PreservationDescriptionInformation. With a specific action to actually add ContentInformation to your InformationPackageProperties: once a ContentInformation has been prepared, you have to use InformationPackagePropertiesBuilder.addContentInformation method to actually build and add a ContentInformation to your InformationPackageProperties. In addition to ContentInformationBuilder and PDIBuilder, InformationPackagePropertiesBuilder allows you to add descriptive informations.

Structure​

Information packages​

Information packages into REGARDS follow GeoJSON structure, it has an id, a geometry and properties. Those properties has a specific structure: it is InformationPackageProperties.

It also has an extension ipType which represents the type of your information package (Collection, Dataset, Data, ...)

Information package properties​

InformationPackageProperties contains many sections:

  • contentInformations: set of content informations (data references)
  • pdi: preservation and description information (minimal information to understand content informations for a long time)
  • descriptiveInformation (optional) : set of description information to ease data discovery and retrieval
  • miscInformation (optional) : miscellanous information

Content informations​

Content informations by their structure allow to give some informations on the files associated to an information package.

Each ContentInformation contains 2 sections:

  • OAISDataObject: file reference
  • RepresentationInformation: object describing how to handle, understand, etc. this data object.

OAISDataObject​

OAISDataObject contains minimal metadata to handle a file :

  • regardsDataType : the data type in term of REGARDS concept :

    • RAWDATA : the main data (at least one ContentInformation qualified as RAWDATA is required in one AIP)
    • QUICKLOOK_SD, QUICKLOOK_MD, QUICKLOOK_HD : optional RAWDATA quicklook with definition level (small, medium or high definition)
    • DOCUMENT : optional document related to the RAWDATA
    • THUMBNAIL : optional RAWDATA thumbnail
    • DESCRIPTION : optional description

AIP data type is also available for internal use in archival storage. Indeed, archival storage stores all referenced files described in all available ContentInformation of the AIP plus itself.

  • reference : reference flag allows to just store reference to external data file, not store the physical file.
  • urls : list of file URLs pointing to the same file
  • filename : the filename
  • algorithm : used to compute the checksum for data integrity control
  • checksum : data checksum
  • fileSize : optional file size

RepresentationInformation​

RepresentationInformation contains metadata related to OAISDataObject:

  • semantic : optional semantic description,
  • syntax : required syntax with a least the data file MIME type plus eventually the MIME type name and description
  • environmentDescription : optional software and hardware environment to handle data file

Preservation and description informations​

Unlike ContentInformation, preservation and description informations provides informations to an entire information package and not only the files associated to an information package.

PreservationDescriptionInformation contains 5 sections:

  • contextInformation: contains the tags and any key/value couple. (optional)
  • referenceInformation: contains key/value couple which key should be a system identifier and its value should be the said identifier into this system.
  • provenanceInformation: see new section.
  • fixityInformation: it is empty for now and still there to be compliant with the OAIS recommandations.
  • accessRightInformation: it contains the access level (public, secure, ...), an optional licence and an optional public release date.

Provenance informations​

Provenance informations have an unorthodox structure, it contains informations on the life of your information package: the history.

In addition to the history, ProvenanceInformation contains optional informations (related to spatial domain semantic, probably not useful for other domain):

  • facility
  • instrument
  • filter
  • detector
  • proposal

and a field "additional" that allows to add any key/value couple on additional provenance information that are not already there.

Descriptive informations​

Informations (key/value pairs) which are publish, they do not have technical meaning, they are business related.