MetaFetcher

How the Meta Fetcher works

The Meta Fetcher is located in the backend and is responsible for collecting meta data about works and their authors. These are for example the subtitle and the thumbnail for a piece of work or the death dates and nationalities of the authors.

For fetching all this information, requests are sent to the DDB API („Deutsche Digitale Bibliothek“) and to the DNB API („Deutsche Nationalbibliothek“). The results are returned as XML or JSON files and are then interpreted by the Meta Fetcher. The needed data is extracted from the data fields in the files and are then assigned to the according variables within the program. After that, it is forwarded to the classes which calculate the public domain status.

In precise, the following requests are made by the Meta Fetcher (for a successful request to the DDB API a valid API key is needed for authentication):

API	Method	Format	Data Fields
DNB		XML	author's name, date of birth, place of birth, date of death and nationality
DDB	/search	JSON	item id
DDB	/entities	JSON	institution
DDB	/items//aip	XML	title, subtitle, thumbnail, published year, authors