The OAI-PMH protocol is for selectively retrieving metadata. It is based on the HTTP and XML technologies.

The dLibra system supports the newest version of the OAI-PMH protocol. The base URL of the OAI-PMH repository for digital libraries based on the dLibra system is: http://<biblioteka cyfrowa>/dlibra/oai-pmh-repository.xml, where <digital library> is the address of a particular digital library. The dLibra system can also function as a server which retrieves metadata from other OAI-PMH repositories and, on that basis, allows search in those resources. However, because the operations of retrieving and processing metadata from other repositories put a huge load on a server, digital libraries usually search for distributed resources with the use of the server of the Digital Library Federation (DLF).

The DLF portal communicates with various digital libraries in Poland through the OAI-PMH protocol, retrieves resource metadata, and, on that basis, makes various services (for example, search in the resources of all the digital libraries) available to users. For more information about the DLF portal, see http://fbc.pionier.net.pl.