Persistent URI Service for EU institutions: proof-of-concept

Zakaria Arrassi – PwC EU ServicesStijn Goedertier – PwC EU ServicesStéphane Roulier – PwC EU Services

Persistent URI Task Force Meeting19 September 2014

HTTP URI: identifier and locatorDefinition

• A compact sequence of characters that identifies and/or locates a resource and that follows the HTTP URI scheme

• Double use:o as an identifier: to identify information resources,

physical resources or abstract resources o as a locator: to get (information about) a resource

(HTTP GET), possibly via redirection

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HTTP URI: identifier and locatorExamples

• A country, e.g. Belgiumhttp://publications.europa.eu/resource/authority/country/BEL

• A concept scheme, e.g. Countries Named Authority Listhttp://publications.europa.eu/resource/authority/country

• A pesticide substance, e.g. lepidopteran pheromoneshttp://ec.europa.eu/semantic_webgate/html/dataset/pesticides/resource/substances-1894

• A contract notice, TED notice 229842http://ted.europa.eu/udl?uri=TED:NOTICE:229842-2014:TEXT:EN:HTML

BE

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Existing problem: Fragmented namespaces - lack of coordination: EU institutions mint their own URIs. Fragmentation of effort: EU institutions use their own sub-domains, virtual folders, etc. No common infrastructure.Lack of service-level guarantees: EU institutions don’t commit to service levels (major barrier to reuse of URIs).

Proposed solution: common policy consisting ofInter-institutional governance: roles, responsibilities, and decision-making process.Design principles: strict rules and guidelines for IRI sets by EU institutions.Configurable, persistent URI service for europa.eu: service providing redirection and content negotiation mechanisms and enforcing common URI conventions (e.g. purl.europa.eu).

Benefits: Increased service levels: central, high-availability service Harmonisation and trustworthiness: good governance and change management Network effects: avoid duplication of resources and information… through the reliable reuse

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Persistent URI ServiceBusiness case

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Persistent URI ServiceExisting persistent URI services

• OCLC: purl.org• US Library of Congress: id.loc.gov• US Government Printing Office: purl.gpo.gov• W3ID: w3id.org• UK Gov: data.gov.uk• DBpedia: dbpedia.org• DOI handlers: doi.org

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PURI Service: Proof-of-conceptObjectives and approach

Objectives:o Demonstrate technical feasibility with exampleso Identify additional requirements or concerns

Approach:1. Requirement analysis2. Comparison of existing open-source software3. Deployment of PoC on http://uri.semic.eu4. Configuration of sample persistent URI namespaces

• One central register of URI namespaces: the Persistent URI Service manages the URI namespace.

• Many local registers of resources: the local registers contain the local identifier of resources for which information is kept in the register.

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URI namespacehttp://{subdomain}.europa.eu/{namespace}/

tail{local id}/{version}/{language}

Central register of URI namespaces Local register of resources

centrally decided Locally decided under central guidance

Persistent URI Service1. Requirement analysis

• Actors: user (HTTP client), PURI administrator (Persistent URI Service), namespace owner (local registry),

• Use cases:a) Request / approve a persistent URI namespaceb) Configure redirection rules for a URI namespacec) Submit HTTP requests on persistent URIs, which are

redirected to the right local registryd) Monitor HTTP requests

Persistent URI Service1. Requirement analysis

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Persistent URI Service1. Requirement analysis

User

Persistent URI ServiceBrowser / HTTP client local registry

PURI Administrator Namespace owner

“For data integration and application integration, I need HTTP URIs that are commonly used to identify and locate important EUI resources.”

“I want to provide a service that allows EUIs to request and manage persistent HTTP URI namespaces. I want to monitor service levels (incl. persistence).”

“I want to make resources in my registry available with persistent HTTP URIs that serve both as a common identifier and locator. ”

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Persistent URI Service1. Requirement analysis

User

Persistent URI ServiceBrowser / HTTP client local registry

PURI Administrator Namespace owner

a) Request / approve a persistent URI namespace

Use case:

1. Tenders Electronically Daily (TED) wants to have persistent URIs for contract notices (CN) and contract award notices (CAN). TED requests the persistent URI namespace http://data.europa.eu/contract-notice/

2. The PURI administrator verifies the request and approves the request, granting TED access to the persistent URI namespace.

Persistent URI Service1. Requirement analysis: user scenario

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Scope criteria Examples

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1.Authoritative source2.Commitment of persistence3.Inter-organisational4. Machine-readable

information5.Existing register

• Data models: INSPIRE data models?

• Reference data: EuroVoc, NALs, NUTs, GEMET?

• Registers: staff register, budget lines, TED, Trade Marks, FTS, Ship, …

• Documents: OJ, Eur-Lex, …• High-value datasets

Persistent URI ServiceScope criteria

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Persistent URI Service1. Requirement analysis

User

Persistent URI ServiceBrowser / HTTP client local registry

PURI Administrator Namespace owner

b) Configure redirection rules for a URI namespace

Use case:

3. TED configures a redirection rule on the URI namespace: http://data.europa.eu/contractnotice/{$local_id} redirect to http://ted.europa.eu/udl?uri=TED:NOTICE:{$local_id}.

4. 5 years later, TED is migrated to the CELLAR platform. TED re-configures the redirection rule http://data.europa.eu/contractnotice/{$local_id} redirect to http://cellar.europa.eu/TED:NOTICE:{$local_id}.

Persistent URI Service1. Requirement analysis: user scenario

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Persistent URI Service1. Requirement analysis

User

Persistent URI ServiceBrowser / HTTP client local registry

PURI Administrator Namespace owner

c) Submit HTTP requests on persistent URIs, which are

redirected to the right local registry

Use case:

HTTP Client Persistent URI Service

HTTP/1.1 GET http://data.europa.eu/contract-notice/229842-2014Accept: application/rdf+xml

HTTP/1.1 303 See OtherLocation: http://ted.europa.eu/udl?uri=TED:NOTICE:229842-2014

HTTP/1.1 GET http://ted.europa.eu/udl?uri=TED:NOTICE:229842-2014Accept: application/rdf+xml

HTTP/1.1 200 OKAccept-Ranges: bytesContent-Type: application/rdf+xml; charset=UTF-8Content-Length: 1821

local register

http://data.europa.eu/ http://ted.europa.eu/udl

Persistent URI Service1. Requirement analysis: user scenario

5.Each HTTP request on a persistent URI is redirected to the right local register (following the redirection rules).

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Persistent URI Service1. Requirement analysis

User

Persistent URI ServiceBrowser / HTTP client local registry

PURI Administrator Namespace owner

d) Monitor HTTP requests

Use case:

6.The PURI administrator uses the Persistent URI Application to monitor the incoming HTTP requests on the persistent URI namespace. The URI Technical Team discovers that URIs on the namespace of TED are no longer dereferenceable; an HTTP 404 error code is returned. The URI Technical Team reports this to the TED team. The TED team fixes these comments on the local registry.

Persistent URI Service1. Requirement analysis: user scenario

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Persistent URI Service2. Comparison of existing open-source software

Features

Apache HTTPD

PID

Purlz

NetKernel

Callimachus

URL shortener

1. Functionality            a) Request / approve URI namespace            b) Configure redirection rules for a URI namespace            - HTTP request parameters            - Input URI pattern            - Output URI pattern            - Internal redirection (proxy forwarding)            - External redirection            - Response status code            - HTTP response parameters            c) Redirection of HTTP requestsd) Monitor HTTP requests            

2. Open-source license (OSI approved)            3. Maturity            4. Maintained            

Persistent URI Service3. Deployment on http://uri.semic.eu

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• Using standard software (Apache HTTPD Server)

• Temporary domain (not data.europa.eu)

• Temporary server (Amazon Web Services micro-instance)

Persistent URI Service4. Configuration of sample persistent URI namespaces

• DG EMPLOYMENT: ESCO taxonomy

o E.g. http://uri.semic.eu/id/esco/occupation/506

• DG SANCO: PPP products

o E.g. http://uri.semic.eu/pesticide-substance/1894

• DG COMM: RAPID

o E.g. http://uri.semic.eu/press-release/IP-14-780/FR

• Publications Office: TED

o E.g. http://uri.semic.eu/contract-notice/229842-2014

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Persistent URI ServiceConclusion

• Demonstrated technical feasibility with standard Web software (Apache HTTPD Server)

• Benefits:o Guarantees for persistence: thanks to the policy, the

redirection rules, and the monitoring of service levels.o Flexibility: local registries keep managing own

resources (including the local id).o Speed and efficiency: easy to configure.o visibility: local register remains visible thanks to

redirection.

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Disclaimer

This presentation was prepared for the Persistent URI Task Force by PwC EU Services. It represents work that was commissioned by the ISA programme of the European Commission.The views expressed in this report are purely those of the authors and may not, in any circumstances, be interpreted as stating an official position of the European Commission.The European Commission does not guarantee the accuracy of the information included in this study, nor does it accept any responsibility for any use thereof.Reference herein to any specific products, specifications, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favouring by the European Commission.All care has been taken by the author to ensure that s/he has obtained, where necessary, permission to use any parts of manuscripts including illustrations, maps, and graphs, on which intellectual property rights already exist from the titular holder(s) of such rights or from her/his or their legal representative.

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