I am a software developer at GBV which is Germany's largest library union network and I create or maintain several APIs to access the catalogs of our libraries, for instance SRU and Z39.50 for search and unAPI to get single records in several formats (Dublin Core, MARC, METS/MODS, etc.). One API is DAIA, which can be used to retrieve the actual availability of documents and holdings. Some documents are availabe for loan, some are not available at the moment but later, some can only be viewed locally, some are open access etc. I found that there is some overlap between DAIA and OPDS, so it would be good to align development. Here are some example:
Query the availability of documents identified by ISBN 978-3-8274-2804-2 in the library identified by ISIL DE-960:
This particular eBook is licensed by the library, so it is not Open Access but can be viewed locally in the library.
Query the availability of documents identified by ISBN 3-518-10012-2 in the library identified by ISIL DE-27:
The result contains two distinct editions, one with a single copy and the other with seven copies, each with different usage conditions.
You can get the DAIA response in XML, JSON, and RDF (or even RDF graphs):
I could add a OSDP response format or a wrapper from DAIA to OSDP, but only for single document records. Would there be any use for this? Are there other libraries using OPDS to look how they have implemented it? In particular DAIA defines a set of services, what you can do with a holding, similar to Acquisition links:
= The item is accessible outside of the institution (by lending or online access) for a limited time.
= The item is accessible within the institution (in their rooms, in their intranet etc.).
= The item is accessible freely without any restrictions by the institution (Open Access or free copies).
= The item is accessible mediated by another institution.
= The item is accessible for an unspecified purpose by an unspecified way.
I'd say that (expressed in RDF):
There is no equivalent for "buy", so I'd just reuse <http://opds-spec.org/acquisition/buy
> instead of creating my own DAIA service type. I am not sure about "sample" and "subscribe". Currently I do not express the former as special type of acquisition, because you can also borrow, buy, view etc. parts of a document. "sample" is orthogonal to the other acquisition types, isn't it?
You may also think about reusing the "presentation" service type from DAIA - there seems to be no way to express in OPDS that you need to visit the library to actually make use of a document.
Alignment with ODSP would surely be important, wouldn't it?