The document describes a Linked Data registry that provides infrastructure for organizations to collaboratively manage identifiers and reference data. The registry allows for creation and registration of identifiers, management of shared namespaces, and discovery of published datasets. It provides functions for identifier and list management, acts as a repository for managed and referenced identifiers, and enables namespace management and federation. The registry information model is based on ISO and OASIS standards and supports versioning, status tracking, and federation/delegation. Examples provided illustrate how the registry could be used to manage code lists, local authority identifiers, and support dataset registration.

1. UKGovLD Registry
A register. Image by http://www.flickr.com/photos/tekniskamuseet/

2. UKGovLD Registry
Outline
• Background and motivation
• Details
– information model
– core functionality
– advanced topics
– status
• Applying it
• Discussion and next steps

3. UKGovLD Registry
Motivation
Support coordinated publication of reference
information as Linked Data
We want people to use URIs to identify things
– codes and code lists
– ontologies, thesauri and concepts
– units of measure
– organizations
– spatial objects
– licenses
– coordinate reference systems
– ...

4. UKGovLD Registry
but it’s not trivial ...
Each organization use its own namespace?
– need infrastructure and expertise to serve the data
– fragmented namespace
– where do consumers get the complete authoritative list?
Shared namespace?
– how to allocate new identifiers in that shared space?
– how to collaboratively maintain identifiers and lists?
– how to scale?
Either way:
– how to manage the life-cycle of introducing and
deprecating terms?

5. UKGovLD Registry
Linked Data Registry
Infrastructure to enable organizations to create
and manage identifiers and authoritative lists
– allocation and registration of approved codes,
vocabularies and reference URIs
– management of shared namespaces, including
clash-free allocation and delegation
– registration of published datasets supporting
discovery and cross-reference

6. UKGovLD Registry
Three functions
• identifier & list management
– create, update, reserve, lifecycle, versioning ...
• repository
– managed identifiers (information served from registry) as well
as referenced identifiers
• namespace management
– delegate a list or part of namespace to others
– federate to other repositories
=> very general platform
– can register anything you can give a URI and RDF description
– use only the aspects you need for a given situation
– “registry does X” does not mean it answers every X-shaped need
you might have

7. UKGovLD Registry
Conceptual architecture
router
renderer
request
processor
user
credentials
roles and
bindings
auth
registry
core
logic
Registry
RDF store
text index
style and
templates
external
UI
admin
UI
log
audit
trail
storeAPI
nginx
proxy
conf
API

8. UKGovLD Registry
Running examples
• Code list of colours
– simple, neutral
• UK Local authorities
– centrally created identifiers v. local creation?
– local control and maintenance?
– offloading management

9. UKGovLD Registry
Outline
• Background and motivation
• Details
– information model
– core functionality
– advanced topics
– status
• Applying it
• Discussion and next steps

10. UKGovLD Registry
Information model
• hierarchy of Registers
• things in registers are Register Items – metadata
• thing described by a RegisterItem called an entity
/
/reg1 /def /system
/def/colours /def/weather-types
/def/colours/_red /def/colours/_green
(describes /def/colours/red) (describes /def/colours/green)
Naming convention:
metadata item has “_”

11. UKGovLD Registry
Information model
complicated by:
– item v. entity
– versioning
reg:Register entity
reg:register
reg:definition
reg:entity
reg:RegisterItem reg:EntityReferencereg:RegisterItem reg:EntityReference

12. UKGovLD Registry
Information model
• default linked data view of Register is simplified
• configurable
– alternative membership property or inverse property
– so can make a register look like a skos:Collection,
skos:ConceptScheme, owl:Ontology ...
– also acts as a LDP container
• but can request full view (?_view=withMetadata)
reg:Register entity
reg:register
reg:definition
reg:entity
reg:RegisterItem reg:EntityReferencereg:RegisterItem reg:EntityReference
induced membership
relation default is
rdfs:member
container view
full view

13. UKGovLD Registry
Full information model
• Derives from ISO 19135
Geographic information - procedures for item registration
• Also considered OASIS ebRIM
– not so suited to flexible RDF model
– RegRep API did provide API checklist
• Container model compatible with Linked Data
Platform (1st draft!)
• Versioning model based on approached used
in Environment Agency linked data

14. UKGovLD Registry
reg:Register
rdfs:label [1..*]
dct:description [1..*]
reg:owner [1] (foaf:Agent)
reg:manager [1] (foaf:Agent)
dct:license [0..*]
reg:containedItemClass [0..*]
reg:operatingLanguage [0..*]
reg:governancePolicy [0..*] (rdfs:Resource)
reg:validationQuery [0..*]
dct:modified [0..1] (inferred)
void:uriLookupEndpoint [0..*]
void:uriSpace [0..1]
void:exampleResource [0..*]
void:openSearchDescription [0..*]
reg:subregister
reg:RegisterItem
rdfs:label [1..*]
dct:description [0..*]
dct:dateSubmitted [1] (automatic)
dct:dateAccepted [0..1]
dct:modified [0..1] (inferred)
reg:itemClass [1..*]
reg:submitter [1] (foaf:Agent)
dct:license [0..*]
reg:status [1..*]
reg:category [0..*] (skos:Concept)
reg:notation [0..1]
reg:alias [0..*]
reg:hasView [0..*]
reg:representationOf [0..*]
reg:register
reg:predecessor
version:Version
owl:versionInfo [1]
time:Inteval
version:interval
dct:replaces
dct:replacedBy
version:VersionedThing
version:currentVersion
reg:Status
reg:statusNotAccepted
reg:statusSubmitted
reg:statusInvalid
reg:statusAccepted
reg:statusValid
reg:statusExperimental
reg:statusStable
reg:statusDeprecated
reg:statusSuperseded
reg:statusRetired
dct:isVersionOf
reg:status
reg:EntityReference
reg:entity [1]
reg:sourceGraph [0..1]
reg:definition
Void:Dataset
ldp:Container
ldp:membershipPredicate
reg:inverseMembershipPredicate
Full information model

15. UKGovLD Registry
Status lifecycle

16. UKGovLD Registry
Status lifecycle
• controls visibility
– not accepted => doesn’t appear (register view, validation)
• guidance to consumers
– experimental/stable => no effect on behaviour
• workflow is external
– registry provides machinery to
• store status
• control who is authorized to change the status
• some validation of submissions
• list submissions in a given state
– how/whether submissions are scrutinized, how decision is
made up to the register manager

17. UKGovLD Registry
Outline
• Background and motivation
• Details
– information model
– core functionality
– advanced topics
– status
• Applying it
• Discussion and next steps

18. UKGovLD Registry
Functions: basic access
• read (GET)
– entity, item (its metadata), specific versions
– register (metadata, list of contents, page-able, prior states)
– content negotiation – Turtle, RDF/XML, JSON/LD, HTML
• entity lookup
– return what registry knows about any URI
• validate
– test a set of URIs to see they are known and Accepted
(within a register sub-tree)
• search
– free text search (within a register sub-tree)

19. UKGovLD Registry
Demo
• Browse of colours register
• RDF of colours register and a colour

20. UKGovLD Registry
Functions: Registration
• single entity
– POST simple entry to register
– basic metadata created automatically
– UI allows for extensible forms to create entries
• entity with metadata
– include explicit RegisterItem to annotate
– allows you to register an external URI
– can register multiple entries at once this way
• batch registration
– register a complete collection – register + contents
– e.g. upload a complete skos:ConceptScheme or skos:Collection
– can configure bulk types

21. UKGovLD Registry
Status and validation
• some automated checks at registration
– minimal properties of entity (label, type)
– type matches one of (optional) allowed types for this register
– register can specify SPARQL ASK queries for validation
• item status
– default is “Submitted”
– can set initial status in API or explicit metadata, if you have the
authority
– can change status through API or UI following the lifecycle
– administrators can force a status change outside lifecycle
• approval process
– is outside the registry itself
– just have property to state the policy and API/UI to do the updates
– some operations may have their own complex workflow

22. UKGovLD Registry
Versioning and history
• changes to an item generates new version
– metadata record is versioned _red:1 _red:2 ....
– separate copy of entity (separate named graph)
• Register is versioned if items added
– or their status is changed
• API supports
– list versions
– version at point in time (including for Register)
– get version

23. UKGovLD Registry
Demo
• Add a new colour via form
• Change its status
• Update it
• View history
• Upload a complete concept scheme
• Show registration of referenced entities

24. UKGovLD Registry
Outline
• Background and motivation
• Details
– information model
– core functionality
– advanced topics
– status
• Applying it
• Discussion and next steps

25. UKGovLD Registry Federation, delegation and namespaces
reg:Delegated
reg:delegationTarget
reg:NamespaceForward
reg:forwardingCode [0..1]
reg:DelegatedRegister
reg:enumerationSubject [0..1]
reg:enumerationPredicate [0..1]
reg:enumerationObject [0..1]
reg:Register
reg:FederatedRegister
reg:forwardingCode [0..1]

26. UKGovLD Registry Federation, delegation and namespaces
Case 1: External entities
– identifier published in different namespace
– want to include it in authoritative list
Solution:
– just register as a referenced entity
– already seen this
– authoritative because it’s on the list
– can record properties of the entity, and maintain
history
– no namespace management involved

27. UKGovLD Registry
Referenced entities
/local
/id
/local-authority
Registry External service
e.g. opencommunities.org
Hosted by LA directly

28. UKGovLD Registry
Case 2: Namespace allocation
– want someone else to serve part of the registry
namespace
– might be a single item or a complete register sub tree
– e.g. allocating namespace in location.data.gov.uk for
serving INSPIRE spatial object identifiers
Solution:
– reg:NamespaceForward
– can be a redirect (30X) or proxy (200)
– no constraints on whether target acts like a Registry
– target ought to serve linked data with URIs in the right
namespace, but not required
Federation, delegation and namespaces

29. UKGovLD Registry
Namespace forward
/local
/id
/local-authority
Registry External web site
could be anything

30. UKGovLD Registry Federation, delegation and namespaces
Case 3: Federated register
– want someone else to run part of the registry
infrastructure but act like one big registry
– integrated search, validation etc
Solution:
– reg:FederatedRegister
– can be a redirect (30X) or proxy (200)
– target endpoint must comply with Registry API at
least for search, validation and entity lookup

31. UKGovLD Registry
Federated register
/local
/id
/local-authority
Registry
Federated registry
/local-authority
/id

32. UKGovLD Registry Federation, delegation and namespaces
Case 4: Delegating a register
– some one else to serve the list of contents of the
register
– but they only have triple store, not full registry
implementation
Solution:
– solution eg:DelegatedRegister
– specify SPARQL endpoint and triple
pattern to enumerate members
reg:DelegatedRegister
reg:delegationTarget [1]
reg:enumerationSubject [0..1]
reg:enumerationPredicate [0..1]
reg:enumerationObject [0..1]

33. UKGovLD Registry
Delegated register
/local
/id
/local-authority
Registry
External SPARQL service

34. UKGovLD Registry
Demo
• Proxy namespace
• Delegated register (if time)

35. UKGovLD Registry
Security model
• authentication
– OpenID (e.g. Google, Google profile)
• authorization
– permissions
• Register, Update, StatusUpdate, Force, Grant, GrantAdmin
• inherit down the tree
• e.g.: Register,Update:/example/local
– can grant to known user or anyone authenticated
– bundled into roles
• Maintainer – Update, Grant
• Manager – Register, StatusUpdate, Update, Grant
• Authorized – Register, Update, StatusUpdate - for experimental areas
• Administrator - anything

36. UKGovLD Registry message queue infrastructure (tbd)
• publish/subscribe on notification of changes
– plug in audit trail recording
– replicate to duplicate stores for read-only load
balance
– hook for workflow
• scheduling analysis of registrations
– e.g. analyse registered datasets to map and
visualize identifier usage

37. UKGovLD Registry
Status
• Proof of concept
– API implementation build on top of Jena and Lucene
– everything except federated search
– UI based on simple templating
– proxy mode handled by dynamic reconfig of external nginx
– open source (license details to be agreed)
• Remaining planned work
– notification
– registration of datasets
– packaging and deployment instructions
– optional: some GML rendering support?
• Next steps
– pilot applying it

38. UKGovLD Registry
Conceptual architecture
router
renderer
request
processor
user
credentials
roles and
bindings
auth
registry
core
logic
Registry
RDF store
text index
style and
templates
external
UI
admin
UI
log
audit
trail
storeAPI
nginx
proxy
conf
API

39. UKGovLD Registry
Outline
• Background and motivation
• Details
– information model
– core functionality
– advanced topics
– status
• Applying it
• Discussion and next steps

40. UKGovLD Registry
Local authorities example
• illustrated various options
– maintain list in register
• some might be managed in registry, LA can edit
• some might be served by LA
• some might be served by DCLG
• single list supporting search, validation
– DCLG run a registry service and federated (or just
forward) part of namespace
– DCLG maintain master list in triple store, use
delegated register

41. UKGovLD Registry
Dataset registration
• would like to know how identifiers are being used
and how they connect data sets
• support registration of RDF data sets
– queue separate analysis suite to extract usage
information
– create metadata
– add these back into the registry record
– support visual browse
• POC does not include analysis and visualization
but provides hooks to third party modules
• e.g. Epimorphics InfoMap visualizer

42. UKGovLD Registry
Dataset analysis

43. UKGovLD Registry
WMO application of Registry
publishing existing authoritative
code-tables as web-accessible
resources
43

44. UKGovLD Registry WMO data exchange governance
WMO No. 306 Manual on Codes: the ‘crown-jewels’ of WMO … decades
of expert effort in developing and maintaining a ‘shared language’ for
describing meteorological phenomena.
44

45. UKGovLD Registry Model-driven data exchange standards
WMO data product specifications are being updated in line with
community best practice ; a model driven approach based on the ISO
19100-series of International Standards enables a semantic model to be
encoded in a variety of formats – including GML.
This is very similar to the approach taken within INSPIRE.
45
GML/XML
data products
«conformsto»
XML Schema 1.0
Schematron .
Validation schema
and rules
Validatable
data products
********
****
*******
*********
*********
********
**
*******
**********
**
«derivedfrom»
Application Schema
(aka ‘conceptual model’)
Technology independent description of
content and structure of information to
be exchanged for a given application
FullMoon

46. UKGovLD Registry Binding data model to WMO code-tables
46
Excerpt from BUFR edition 4 Code- and Flag-tables
IWXXM METAR/SPECI
«CodeList»
RunwayDeposits
URI: http://codes.wmo.int/bufr4/codeflag/0-20-086
tagged values:
vocabulary = “http://codes.wmo.int/bufr4/codeflag/0-20-086”
extensibility = “none”
«DataType»
AerodromeRunwayState
+ runway : Runway [0..1]
+ cleared : Boolean [0..1]
+ contamination : RunwayContamination [0..1]
+ snowClosure : Boolean [0..1]
+ depositType : RunwayDeposits [0..1]
+ depthOfDeposit : DepthOfDeposit [0..1]
+ brakingAction : BrakingAction [0..1]
+ frictionCoefficient : FrictionCoefficient [0..1]

47. UKGovLD Registry Code-table as web-accessible register
47

48. UKGovLD Registry Referencing terms from data products
48

49. UKGovLD Registry
NAMESPACE FORWARD:
publishing a simple ontology within
the namespace of the registry
49

50. UKGovLD Registry Pre-determined properties
WMO code-tables (e.g. Common code-table
C-6: List of units) have a number of specific
properties defined …
50

51. UKGovLD Registry Published definitions required
To represent the information from the code-tables in RDF we need to
reference definitions of those properties …
51

52. UKGovLD Registry A simple ontology
As the properties support the definition of the code-tables themselves,
the definitions are published within the namespace of the registry …
52

53. UKGovLD Registry A simple ontology (with #frag IDs)
Following de facto practice, the definitions are published using the
#fragment identifier pattern …
53

54. UKGovLD Registry Namespace forward (proxy)
The #fragment identifier pattern means that the registry’s “/ID”
‘containment’ pattern is not applicable – therefore we register the
entire ontology as a single DELEGATED resource using a PROXY pattern
54

55. UKGovLD Registry Namespace forward: configuration
The NAMESPACE FORWARD is configured using the web UI by an
authenticated user with appropriate permissions …
(but can also be done programmatically via the RESTful API)
55

56. UKGovLD Registry Externally managed HTTP server
54.246.66.105 is an anonymous HTTP server (hosted on Amazon EC2)
with content negotiation configured for HTML, RDF/XML and TTL – all of
which are provided as static resources …
56
UKGovLD Registry
ukgovld-registry.dnsalias.net
Apache2 +
mod_negotiation
54.246.66.105
NGINX

57. UKGovLD Registry Tracking changes; version & history
This approach enables one to track changes as new versions of the
ontology are published; with each new version published to a new
directory one can amend the delegation target to update the registry.
57

58. UKGovLD Registry
Discussion
• use cases for where to apply this?
• missing features needed for these?
• what would it take to pilot one?

59. UKGovLD Registry
Links
• Design notes and API details
https://github.com/der/ukl-registry-poc/wiki
• Proof of concept deployment
http://ukgovld-registry.dnsalias.net/
No service guarantees

60. UKGovLD Registry

61. UKGovLD Registry
Convenient views
• full RegisterItem/Register structure complex
• versioning makes that a lot worse
//registry
Register
VersionedThing
//registry:1
Register
Version
//registry/_reg
RegisterItem
VersionedThing
//registry/_reg:1
RegisterItem
Version
//registry/reg
Register
VersionedThing
//registry/reg/_foo
RegisterItem
VersionedThing
//registry/reg/foo
(entity)//registry/reg:1
Register
Version
//registry/reg/_foo:1
RegisterItem
Version
dct:versionOf
dct:versionOf dct:versionOf
dct:versionOf
reg:register
reg:register
reg:definition
reg:definition
//registry/_reg:2
RegisterItem
Version
//registry:2
Register
Version
//registry/reg:2
Register
Version
//registry/reg/_foo:2
RegisterItem
Version