If I am hosting a hierarchical CMDI metadata collection, do I need to offer all records over OAI-PMH or only the root nodes?

[twagoo]

Short answer: as indicated in the OAI-PMH protocol, you need to offer all records. There is no automatic harvesting of any of the CMDI child nodes.

Long answer: in the case of our toy example hierarchy, you would need to provide the following files over OAI-PMH:

• http://www.clarin.eu/cmd/example/collection/collection_root.cmdi
• http://www.clarin.eu/cmd/example/collection/collection_olac.cmdi
• http://www.clarin.eu/cmd/example/collection/collection_lrt_inventory.cmdi
• http://www.clarin.eu/cmd/example/collection/lrt/lrt-1001.cmdi
• http://www.clarin.eu/cmd/example/collection/lrt/lrt-1002.cmdi
• http://www.clarin.eu/cmd/example/collection/lrt/lrt-1003.cmdi
• http://www.clarin.eu/cmd/example/collection/lrt/lrt-1004.cmdi
• http://www.clarin.eu/cmd/example/collection/olac/oai_childes_psy_cmu_edu_Biling_DeHouwer.cmdi
• http://www.clarin.eu/cmd/example/collection/olac/oai_childes_psy_cmu_edu_Biling_Deuchar.cmdi
• http://www.clarin.eu/cmd/example/collection/olac/oai_childes_psy_cmu_edu_Biling_FerFuLice.cmdi
• http://www.clarin.eu/cmd/example/collection/olac/oai_childes_psy_cmu_edu_Biling_Genesee.cmdi

Providing collection_root.cmdi (or even collection_olac.cmdi and collection_lrt_inventory.cmdi) is not enough, as all OAI harvesters are protocol-agnostic and thus do not know about CMDI’s hierarchy building! CMDI-consuming applications, such as the VLO, also need the physical files locally.