DOI Foundation Services: Registration Agencies and Resolution

Registration Agencies provide services to people or organisations that need to identify and track things, allocating DOI prefixes, registering DOI names and providing a metadata schema associated with each DOI record. Because each RA represents a distinct industry or community, most have developed services that build on basic DOI registration. RAs sign an agreement that grants rights, sets out the obligations of the RA and the DOI Foundation, clarifies intellectual property rights and details change, termination and continuity procedures. Each RA nominates a DOI Foundation Board Director, and all agree to take on the responsibilities of another agency if it ceases to be an RA, so that DOIs persist.

• Allocation of DOI prefixes
• Registration of DOI names
• Metadata schema for each DOI record
• Community-specific added services such as reference linking and metadata lookup
• Commitment to continuity if another RA withdraws

To obtain a DOI name, an organisation uses a service offered by a DOI Registration Agency; membership of the DOI Foundation is not required in order to work with an RA. The cost of registering new DOI names depends on the services purchased, and each RA is free to offer its own business model. Existing DOI names are free to resolve and, according to the Foundation, always will be. Any organisation able to represent a defined community of interest may apply to the DOI Foundation to become an agency, with applications considered by the Board.

• Registration via an RA of the applicant's choice
• No DOI Foundation membership required to work with an RA
• Pricing set independently by each RA
• Resolution of existing DOI names free of charge

The DOI system proxy server resolves DOI names structured for use in URL syntax, so that the DOI name 10.123/456 is resolved from the address https://doi.org/10.123/456. The proxy is a web server that queries the Handle System for the DOI name, takes the URL in the handle record and issues an HTTP redirect to the user's browser. It also understands handle values of type 10320/loc, which describe multiple redirection endpoints, and displays a "DOI Name Not Found" page when a name cannot be found. The service is accessible over IPv6, supports DNSSEC and responds to both HTTPS, which is preferred, and HTTP requests.

• Preferred resolution address https://doi.org
• Earlier, no longer preferred address dx.doi.org
• Proxy server query parameters and REST API
• Support for multiple resolution and additional handle data
• IPv6 access and DNSSEC support

The doi.org resolver uses Cloudflare as a provider of authoritative DNS service and as a content distribution network. Requests are routed to a nearby Cloudflare edge node, which then contacts a geographically close doi.org backend server, improving response times and allowing queries to be redirected if the closest server is unreachable. In rare cases Cloudflare may present a CAPTCHA challenge, which the Foundation states affects fewer than one in a million requests to doi.org. Cloudflare may also store a cookie that holds no personally identifiable information but can distinguish users sharing an IP address.

• Authoritative DNS and CDN provided by Cloudflare
• Globally distributed doi.org backend servers
• Failover redirection between backend servers
• Cloudflare cookie deposited when resolving DOI names

ISBN-A, described as "the actionable ISBN", is a service powered by DOI in which an existing ISBN is expressed in the DOI system as a DOI name derived from that ISBN. It can only be registered for a 13-digit ISBN; legacy 10-digit ISBNs must first be converted, usually by adding the GS1 prefix 978 and recalculating the check digit. An ISBN-A identifies the same referent as the ISBN, but ISBN-As do not exist automatically for every ISBN and are only assigned by DOI Registration Agencies authorised to do so. The approach was agreed between the ISBN International agency and the International DOI Foundation, and lets publishers keep the ISBN as principal identifier while gaining network actionability.

• Derived from an existing 13-digit ISBN
• Assigned only by authorised DOI Registration Agencies
• Identifies the same referent as the source ISBN
• An ISBN alone cannot be resolved in the DOI system

shortDOI provides shortened links to DOI names, addressed in the Foundation's Frequently Asked Questions alongside questions on registration, membership and standardisation. The factsheet on key facts for the DOI system records that over 30 million shortDOI links to DOI names are in use. The FAQs are supported by the DOI Handbook and a glossary of terms, and enquiries can be sent to info@doi.org.

• Shortened links to DOI names
• Over 30 million shortDOI links in use
• Further detail in the DOI Handbook and FAQs