It took me a while to understand/figure out some things about how DOIs work in ways related to my applications, both for assignment and using DOIs out there in the world. I wrote the following in a thread on the Code4Lib listserv, seems worth sharing here too, so it’s googlable and such: The overall DOI environment is a bit confusing to understand exactly what the options and trade-offs are and what’s going on.
So there are various DOI top-level registrars that can register DOIs. (I don’t know if “registrar” is actually the name DOI uses for em, it’s what I’m calling them. Any readers who can supply the correct terminology as used by DOI?).
For scholarly publications, CrossRef is the one that’s typically used. But to register a DOI through CrossRef, a “publisher” needs to have a relationship/membership with CrossRef, which has some non-trivial expenses and obligations (such as being _required_ by CrossRef to look up DOIs for any works cited in the published work, and include those in the published work). And I’m not entirely sure what tools CrossRef gives you for managing your DOIs.
I am not sure how an individual dude who wants a few DOIs would best go about getting them through CrossRef, might be worth asking CrossRef is there is any feasible way to do this.
Any DOI registration through any registrar will get DOI forwarding resolution. That is, for instance, http request to http://dx.doi.org/something gets redirected to your destination URL. Any DOI through any registrar gets this.
When you register a DOI through CrossRef, you also get a ‘metadata lookup’ service, where a person or machine armed with a DOI can look up article metadata such as author, title, journal, etc., from a CrossRef service. This is not part of the central DOI architecture, but something through CrossRef. Some library-sector software (such as SFX) is set up to do these metadata lookups from CrossRef on any DOI — if the DOI wasn’t registered through CrossRef, they won’t get any info back.
Now, in addition to CrossRef, there are some other registrars. One I know about is DateCite. And as Keven mentions, the EZID service is a pretty slick front-end that allows you to register and maintain DateCite DOIs. While DataCite was set up for assigning DOIs to data sets, as far as I know nothing in any policies (of DOI foundation, DataCite, or EZID) prevents you from using DateCite DOIs in general or EZID-managed DataCite DOIs in particular for any kind of information resource you want, including scholarly articles, or whatever.
EZID may still be free at the moment in it’s testing phase, but eventually, I am told by EZID, that there WILL be a cost charged. However, I think the cost model, tools provided, and obligatory requirements (none) of EZID/DataCitecompared to CrossRef may be more amenable/feasible for a small project. (The EZID service is not limited to DOIs, it also supports several other types of global unique identifiers, which I am largely even less familiar with). EZID is sort of an intermediary between you and DateCite; I don’t know if there any similar value-added intermediaries with CrossRef, I believe it’s typical for publishers to deal with CrossRef directly without an intermediary.
So EZID sounds good for a small project: However, using EZID/DataCite you won’t get the CrossRef metadata lookup that some library-sector applications (like SFX) use.
DataCite is, I hear, planning on adding their own metadata lookup service. But the library applications will still only be using the CrossRef one unless they are updated, and the DataCite one may use an entirely different data schema/vocabulary than CrossRef — this metadata lookup thing is not something actually standardized for DOI in general, in terms of either API or response schema. Or discovering a metadata lookup service to use for a given DOI. (I tend to think DOI probably ought to work on some standardization and auto-discovery here, personally, I don’t know if they are. )