The free DDI Registry lets you register permanent Agency IDs, which is used in defining full identification of your DDI objects and is a critical part of a DDI URN (a unique identification for your DDI object). Using this permanent identifier in your DDI instances allows you to specify the authoritative source of your data and metadata. The registry is connected with the global DNS system, allowing DDI URNs to be resolved using standard tools.
On the DDI Registry, you may:
- Register your Agency ID. The agency name should be in the form [country code] dot [name]. For example:
- Search for existing Agency IDs or browse a list of all registered Agency IDs.
- Manage your collection using sub-agencies. For example, DDI has the DDI Agency ID of int.ddi and also has the sub-agency int.ddi.cv, which allows them to handle resolution of DDI Controlled Vocabularies with separate rules from other managed objects.
- Designate the administrative and technical contacts for your DDI Agency ID.
Additionally, the DDI Registry lets you:
Provide information for the resolution of your DDI URNs
You may post your DDI objects at a web addressable location, organized according to specific identifier parts, making your DDI content available to others without hosting a resolution service on your local system (e.g.,
To set up various means of resolving your DDI URNs:
- Log in and open the list of Agency IDs that you manage from the top bar. This will bring up a list of Agency IDs with a manage/edit option.
- Click on Manage to bring up a listing of Agency and Sub Agency assignments under the selected Agency ID. Click on Edit to edit available service designations on the Assignment Page.
- Add HTTP Resolver for a website, ddi item (single identified item), or a ddi set (the identified item and the related items).
- Define the HTTP path using a template consisting of the parts of a DDI URN (agency, identifier, version, or full URN).
- Double click for default resolution type options (see examples in the below "DDI Agency Registry Upgrades" presentation).
- website – an HTML page providing information or HTML representation of the object such as a controlled vocabulary.
- ddiitem – a single identified item such as a concept, variable, study unit, etc.
- ddiset – a set of data including the identified item and the related items.
Designate your DNS SRV service records for resolution
You may direct URN queries to your DNS SRV Service point. Use this option to record the host name and port for your services. Most other DNS records only specify a server or an IP address, but SRV records include a port at that IP address as well.
Set up a local resolution service
You may install and set up your own agency or subagency registry and local resolution service. Information under the Developer menu provides links to the open source software and instructions.
For more details about the features available in the DDI Agency ID Registry, please watch the 2021 European DDI User Conference (EDDI) presentation, "DDI Agency Registry Upgrades," by Dan Smith.
The source code for the registry and several related tools is also available under an open source license. The DDI Registry is maintained by the DDI Alliance.