Description Service

Description Service

identify, validate and extract

Description Service performs format identification, validation and characterization on a given file. The result is expressed in PREMIS schema containing a PREMIS object for the identification and characterization result, a PREMIS event describing the validation status with applicable anomaly, and a PREMIS agent identifying the software agent that generates PREMIS output, in this case, the description service.


Description Service uses DROID for format identification and JHOVE for format validation and characterization. Based on the identification result, the Format Description Service launches applicable JHOVE validators to perform format validation and characterization. The JHOVE characterization and validation results are then transformed into PREMIS along with applicable standard metadata schema.

Characterization Result

General file metadata such as format information, file size, checksum, creator, create date, inhibitors are extracted and expressed in PREMIS schema. The Description Service currently exports the following standard format-specific metadata schema,

Validation Result

Description service utilize PREMIS event objects to record validation result. General validation result is recorded the eventDetail, for example, this following line indicates that the file is both well-formed and valid according to the file format specification.

<eventDetail>Well-Formed and valid</eventDetail>

If there is any anomaly detected during format validation, it will be recorded in the eventOutcomeDetailExtension section.


<anomaly>Improperly formed date</anomaly>