| MetaLookupInterface | It is a common problem to couple binary data with their metadata. |
| MetaLookupConstant | Simply adds same fixed set of metadata properties to every file. |
| MetaLookupException | Exception thrown when a resource metadata were not found in the external source. |
| MetaLookupFile | Implements metadata lookup by searching in a given metadata locations for a file with an original file name with a given extension appended. |
| MetaLookupGraph | Searches for file metadata inside an RDF graph. |