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Slides form the tutorial on the ResourceSync Framework presented at Open Repositories 2013 in Charlottetown, PEI on 8 July 2013. The latest set of ResourceSync tutorial slides are available at http://www.slideshare.net/OpenArchivesInitiative/resourcesync-tutorial
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync:A Web-Based
Resource SynchronizationFramework
ResourceSync is funded by The Sloan Foundation & JISC
#resourcesync
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync Tutorial History
Simeon WarnerCornell [email protected]@zimeon
• First outing: OAI8, Geneva, Switzerland, June 2013• Second run: Open Repositories, here and now
• Most recent version of these tutorial slides is available at: http://www.slideshare.net/OpenArchivesInitiative/resourcesync-tutorial
Presenter
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Martin KleinLos Alamos National Laboratory<[email protected]>
@mart1nkle1n
ResourceSync Tutorial Contributors
3
Simeon WarnerCornell University
[email protected]@zimeon
Herbert Van de Sompel Los Alamos National Laboratory
<[email protected]>@hvdsomp
Robert SandersonLos Alamos National Laboratory
<[email protected]>@azaroth24
Richard JonesCottage Labs
<[email protected]>@cottagelabs
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSyncCore Team
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OAI
Herbert Van de SompelMartin KleinRobert Sanderson(Los Alamos National Laboratory)
Simeon Warner(Cornell University)
Berhard Haslhofer(University of Vienna)
Michael L. Nelson(Old Dominion University)
Carl Lagoze(University of Michigan)
NISO
Todd CarpenterNettie Lagace
Lyrasis
Peter Murray
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync Technical Group
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JISC
Richard JonesGraham Klyne
Stuart Lewis
OCLC
Jeff Young
LOCKSS
David Rosenthal
RedHat
Christian Sadilek
Ex Libris Inc.
Shlomo Sanders
Library of Congress
Kevin Ford
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
1. ResourceSync: Problem Perspective & Conceptual Approach
2. Motivation & Use Cases
3. Framework Walkthrough
4. Framework (Technical) Details
5. Implementation
6. Q&A
6
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
1. ResourceSync: Problem Perspective & Conceptual Approach
2. Motivation & Use Cases
3. Framework Walkthrough
4. Framework (Technical) Details
5. Implementation
6. Q&A
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Synchronize What?
• Web resourceso things with a URI that can be dereferenced
• Focus on needs of research communication and cultural heritage organizationso but aim for generality
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Synchronize What?
• Small websites/repositories (a few resources) to large repositories/datasets/linked data collections (many millions of resources)
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sync
sync
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Synchronize What?
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• Low change frequency (weeks/months) to high change frequency (seconds)
sync
sync
sync
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Synchronize What?
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• Synchronization latency and accuracy needs may vary
sync
Sync ???
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Why?
… because lots of projects and services are doing synchronization but have to resort to ad-hoc, case by case, approaches!
• Project team involved with projects that need this
• Experience with OAI-PMH: widely used in repos buto XML metadata onlyo Attempts at synchronizing actual content via OAI-PMH
(complex object formats, dc:identifier) not successful.o Web technology has moved on since 1999
• Devise a shared solution for data, metadata, linked data?
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync Problem
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• Consideration:• Source (server) A has resources that change over time: they
get created, modified, deleted• Destination (servers) X, Y, and Z leverage (some)
resources of Source A.• Problem:
• Destinations want to keep in step with the resource changes at Source A: resource synchronization.
• Goal:• Design an approach for resource synchronization aligned
with the Web Architecture that has a fair chance of adoption by different communities.• The approach must scale better than recurrent HTTP
HEAD/GET on resources.
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Source: Four CoreSynchronization Capabilities
1. Describing content – publish a list of resources available for synchronization to enable Destinations to perform an initial load or catch-up with a Source
2. Packaging content – bundle resources to enable bulk download for destinations
3. Describing changes – publish a list of resource changes to enable destinations to stay synchronized and decrease latency
4. Packaging changes – bundle resource changes for bulk download for destinations
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Source: Synchronization Features
5. Linking to related resources – provide links from to be synchronized resources to related resources
applicable to all core capabilities (1..4)
6. Access to historical data – provide archives of 1..4
7. Discovery of capabilities – support Destinations in discovering all offered capabilities 1..4
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Destination: Synchronization Needs
1. Baseline synchronization – A destination must be able to perform an initial load or catch-up with a source
- avoid out-of-band setup
2. Incremental synchronization – A destination must have some way to keep up-to-date with changes at a source
- subject to some latency; minimal: create/update/delete- allow to catch-up after destination has been offline
3. Audit – A destination should be able to determine whether it is synchronized with a source
- subject to some latency
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
1. ResourceSync: Problem Perspective & Conceptual Approach
2. Motivation & Use Cases
3. Framework Walkthrough
4. Framework (Technical) Details
5. Implementation
6. Q&A
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Cases – The Basics
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a)
b)
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Cases – The Basics
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c)
d)
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Cases – The not-so-Basics
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e)
f)
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Cases – The not-so-Basics
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g)
h)
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Case 1: arXiv Mirroring and Data Sharing
• Repository of scholarly articles in physics, mathematics, computer science, etc.
• > 850k articles• approx. 1.5 revisions per article on
average• approx. 75k new articles per year• Each article has full-text and separate
metadata record• approx. 3.8M resources
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Case 1: arXiv Mirroring and Data Sharing
• 2,700 updates dailyo at 8pm ESTo Currently using homebrew mirroring
solution (running with minor modifications since 1994!)
o occasional rsync (file system-specific, auth issues)
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Mirroring arXiv: 1994 - 2013
• Operated since the very early days of the Web!
1. HTTP trigger from the main site
2. HTTP pull update specific to mirror site
3. HTTP download of the resources
4. HTTP trigger to main site when mirror process complete
5. HTTP verification (via HEAD) by the main site which updates the update list specific to mirror site
6. periodic repeat as long as there are updates in the inventory for that mirror
• Requires trusted set of servers operating with the same internal organization
• Does not support synchronization check (so rsync is used periodically)
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Case 1: arXiv
Mirroring
• GOAL: Keep mirror sites synchronized with daily changes
• WANT:o high consistencyo moderate latencyo robustness to global network outages (low admin effort)o ability to verify sync status in case of questions
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Case 1: arXiv
Data Sharing
• GOAL: Make resources and update information publicly available so that any other service may synchronize at the frequency it needs, e.g.o Math Front at UC Daviso EprintWeb from IOP in UKo Data for bibliometric and scientometric analysis
• WANT:o low admin effort (i.e. standard approach, standard tools)o reasonable consistency, latency, efficiency
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Case 2: DBpedia Live Duplication
• Average of 2 updates per second• Low latency desirable => need for a push technology
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Case 2: DBpedia Live Duplication
• Initial experiment with distributed infrastructure
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Case 2: DBpedia Live Duplication
• Daily traffic:o 99% updateso 0.6% deletionso 0.03% creations
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Use Case 2: DBpedia Live Duplication
• # of content transfer events in two 8 hour intervals
• Max, queue size of remote duplication process
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
1. ResourceSync: Problem Perspective & Conceptual Approach
2. Motivation & Use Cases
3. Framework Walkthrough
4. Framework (Technical) Details
5. Implementation
6. Q&A
31
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Source Capability 1: Describing Content
In order to advertise the resources that a source wants destinations to know about, it may describe them:
o Publish a Resource List, a list of resource URIs and possibly associated metadata- Destination GETs the Content Description- Destination GETs listed resources by their URI
o Describes state of set of resources at one point in time (snapshot)
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Source Capability 2: Packaging Content
By default, content is transferred in response to a GET issued by a destination against a URI of a source’s resource. But a source may support additional mechanisms:
o Publish a Resource Dump, a document that points to packages of resource representations and necessary metadata- Destination GETs the package- Destination unpacks the package- ZIP format supported
o Packages set of resources at one point in time (snapshot)
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Source: Modular Capabilities
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Source Capability 3: Describing Changes
In order to achieve lower latency and/or greater efficiency, a source may communicate about changes to its resources:
o Publish a Change List, a list of recent change events (created, updated, deleted resource)- Destination acts upon change events, e.g. GETs
created/updated resources, removes deleted resources.o Describes changes to resources that occurred in a temporal
interval with a start- and an end-date
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Source Capability 4: Packaging Changes
In order to reduce the number of requests to obtain resource changes, a source may provide packaged bitstreams for changed resources:
o Publish a Change Dump, a document that points to packages of recently changed resource representations and necessary metadata - Destination GETs the package- Destination unpacks the package- ZIP format supported
o Packages resources that changed in a temporal interval with a start- and an end-date
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Source: Modular Capabilities
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
FrameworkStructure
(light)
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
FrameworkStructure
(complete)
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Destination: Key Processes
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
1. ResourceSync: Problem Perspective & Conceptual Approach
2. Motivation & Use Cases
3. Framework Walkthrough
4. Framework (Technical) Details
5. Implementation
6. Q&A
51
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
4. Framework (Technical) Details
1. Sitemaps
2. Pull method
3. Linking between resources
4. Discovery
5. Push method
6. Archives
52
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
4. Framework (Technical) Details
1. Sitemaps
2. Pull method
3. Linking between resources
4. Discovery
5. Push method
6. Archives
53
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
So Many Choices
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XMPP
AtomPub
SDShare
RSS
Atom
PubSubHubbub
Sitemap
XMPP
rsync
OAI-PMH
WebDAV Col. Syn.
OAI-ORE
DSNotify
RDFsync
Crawl
Push
Pull
SWORD
SPARQLpush
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
So Many Choices
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XMPP
AtomPub
SDShare
RSS
Atom
PubSubHubbub
Sitemap
XMPP
rsync
OAI-PMH
WebDAV Col. Syn.
OAI-ORE
DSNotify
RDFsync
Crawl
Push
Pull
SWORD
SPARQLpush
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
A Framework Based on Sitemaps
• Modular framework allowing selective deployment
• Sitemap is the core format throughout the framework
o Introduce extension elements and attributes: - In ResourceSync namespace (rs:) to
accommodate synchronization needso Reuse Sitemap format for all capability documents:
Resource List, Resource Dump, Change List, Change Dump, as well as for manifest in Dumps
o Utilize Sitemap index format where needed/allowed
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Sitemap Format
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9”>
<url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> </url>
<url> <loc>http://example.com/res2</loc> <lastmod>2013-01-02T14:00:00Z</lastmod> </url> …</urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Sitemap Index Format
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9”>
<sitemap> <loc>http://example.com/sitemap1.xml</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> </sitemap>
<sitemap> <loc>http://example.com/sitemap2.xml</loc> <lastmod>2013-01-02T14:00:00Z</lastmod> </sitemap> …</sitemapindex>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync Sitemap Extensions
<urlset xmlns=http://www.sitemaps.org/schemas/sitemap/0.9 xmlns:rs="http://www.openarchives.org/rs/terms/”> <rs:ln …/> <rs:md …/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:ln …/> <rs:md …/> </url> <url> … </url></urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync Sitemap Extensions
<sitemapindex xmlns=http://www.sitemaps.org/schemas/sitemap/0.9 xmlns:rs="http://www.openarchives.org/rs/terms/”> <rs:ln …/> <rs:md …/><sitemap> <loc>http://example.com/sitemap1.xml</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:ln …/> <rs:md …/> </sitemap>…</sitemapindex>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
4. Framework (Technical) Details
1. Sitemaps
2. Pull method
3. Linking between resources
4. Discovery
5. Push method
6. Archives
62
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Capability 1: Resource List
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Capability 1: Resource List
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability="resourcelist" from="2013-01-03T09:00:00Z"/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md hash="md5:1584abdf8ebdc9802ac0c6a7402c03b6" length="8876" type="text/html"/> </url> <url> … </url></urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Resource List
• Describe Source’s resources that are subject to synchronization• At one point in time (snapshot)
• Typical Destination use: Baseline Synchronization, Audit
• Each URI typically listed only once• Might be expensive to generate• Destinations use @from to determine freshness• Issue GETs against URIs to obtain resources• Very similar to current Sitemaps
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
What if I have a million resources?
• Current sitemap limit is 50k resources (or maximum document size of 50MB)
• Break complete list of resources into 50k-resource chunks, each on a Resource List document
• Create a Resource List Index document to group them:o Based on <sitemapindex>o May have up to 50k component Resource Listso Extends capacity to 2,500,000,000 resources within current
community practices
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Resource List Index <resourcelist_index.xml>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”resourcelist" from="2013-01-02T09:00:02Z”/> <sitemap> <loc>http://example.com/resourcelist1.xml</loc> <lastmod>2013-01-02T11:00:00Z</lastmod> <rs:md type="application/xml"/> </sitemap> <sitemap> <loc>http://example.com/resourcelist2.xml</loc> <lastmod>2013-01-02T11:00:01Z</lastmod> <rs:md type="application/xml"/> </sitemap></urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Resource List <resourcelist1.xml>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs=http://www.openarchives.org/rs/terms/> <rs:ln rel=”up” href=”http://example.com/resourcelist_index.xml”/> <rs:md capability=”resourcelist" from="2013-01-02T09:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T08:07:06Z</lastmod> <rs:md hash="md5:1584abdf8ebdc9802ac0c6a7402c03b6" length="8876" type="text/html"/> </url> ...</urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Capability 2: Resource Dump
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Capability 2: Resource Dump
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”resourcedump" from="2013-01-02T09:00:00Z”/> <url> <loc>http://example.com/resourcedump_part1.zip</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md length=”97553" type=”application/zip"/> </url> <url> <loc>http://example.com/resourcedump_part2.zip</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md length=”21294" type=”application/zip"/> </url></urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Resource Dump Manifest
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”resourcedump-manifest" from="2013-01-02T09:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md type="text/html" path=”/resources/res1"/> </url> <url> <loc>http://example.com/res2</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md type=”application/pdf” path=”/resources/res2"/> </url></urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Resource Dump
• Package Source’s resourcesthat are subject to synchronization• At one point in time (snapshot)
• Points to ZIP packages• Mandatory, even for only one ZIP• ZIP package contains manifest, listing contained bitstreams• Typical Destination use: Baseline Synchronization, bulk
download
• Each URI typically listed only once• Might be expensive to generate• Destinations use @from to determine freshness• GETs against individual URIs from Resource List achieves the
same result (ignoring varying freshness)
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Capability 3: Change List
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Capability 3: Change List
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated" hash="md5:1584abdf8ebdc9802ac0c6a7402c03b6" length="8876" type="text/html"/> </url> <url> … </url></urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Change List
• Describe Source’s resource changes• Occurring during temporal interval with start- and end-date
• Typical Destination use: Incremental Synchronization, Audit
• Changes are listed in chronological order• Multiple changes to one URI may result in multiple listing of
same URI• Source determines duration of temporal interval• Destinations use @from and @until to determine freshness• Issue GETs against URIs to obtain changed resources
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Capability 4: Change Dump
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Capability 4: Change Dump
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changedump" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/change_dump_part1.zip</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md length="887" type=”application/zip"/> </url> <url> <loc>http://example.com/change_dump_part2.zip</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md length=”9767" type=”application/zip"/> </url></urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Change Dump Manifest
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changedump-manifest" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated" length=”2887” type=”text/html” path=”changes/res1”/> </url> <url> … </url></urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Change Dump
• Package Source’s resources that have changed• during temporal interval with start- and end-date
• Points to ZIP packages• Mandatory, even for only one ZIP• ZIP package contains manifest, listing contained bitstreams• Typical Destination use: Incremental Synchronization, bulk
download of changes
• Changes in Change Dump Manifest listed in chronological order• Same URI can be listed multiple times• Might be expensive to generate• Destinations use @from and @until to determine freshness
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Recall… *Index
<changelist_index.xml>
<changelist1.xml>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Change List Index <changelist_index.xml>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <sitemap> <loc>http://example.com/changelist1.xml</loc> <lastmod>2013-01-02T11:00:00Z</lastmod> <rs:md type="application/xml"/> </sitemap> <sitemap> <loc>http://example.com/changelist2.xml</loc> <lastmod>2013-01-02T23:00:00Z</lastmod> <rs:md type="application/xml"/> </sitemap></urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Change List <changelist1.xml>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs=http://www.openarchives.org/rs/terms/> <rs:ln rel=”up” href=”http://example.com/changelist_index.xml”/> <rs:md capability="changelist" from="2013-01-02T09:00:00Z” until="2013-01-02T21:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated" hash="md5:1584abdf8ebdc9802ac0c6a7402c03b6" length="8876" type="text/html"/> </url></urlset>
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Resource Metadata SummaryElement/Attribute Description Defined by
<loc> Resource URI (identity) sitemaps
<lastmod> Timestamp of last change sitemaps
<changefreq> Expected update frequency sitemaps
<rs:md> ResourceSync
change Change type (Change List & Change Dump Manifest only) ResourceSync
encodingHTTP Content-Encoding header value RFC2616
hashOne or more content digests (md5, sha-1, sha-256)
Atom Link Ext.
lengthHTTP Content-Length header value RFC4287
pathPath in ZIP package (Dump Manifests only)
ResourceSync
typeHTTP Content-Type header value RFC4287
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
4. Framework (Technical) Details
1. Sitemaps
2. Pull method
3. Linking between resources
4. Discovery
5. Push method
6. Archives
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Supported Linking Use Cases
The web is based on links between resources, many of which are important to understand for synchronization.
1. Mirrored content with multiple download locations
2. Alternate representations of the same content
3. Patching content rather than replacing
4. Resources and their metadata
5. Prior versions of resources
6. Collection membership of resources
7. Republishing synchronized resources
All cases are handled with a <rs:ln> element referring to the remote resource
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Notes about Linked Resources
Some important things to keep in mind about linked resources:
• They may also be subject to synchronization• They may be updated in a very different schedule to the
resource it is linked from• Therefore, it is recommended to convey metadata about the
linked resource too• Links can be bi-directional – the linked resource can link back to
the linking resource
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Linking #1 - Mirror
1. Mirrored content with multiple download locations
This might occur due to:• Content distribution networks• Mirror sites• Backup locations• Load balancing
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Linking #1 - Mirror
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated”/> <rs:ln rel=”duplicate” pri=”1” href=”http://mirror1.example.com/res1"/> <rs:ln rel=”duplicate” pri=”2” href=”http://mirror2.example.com/res1"/> </url></urlset>
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Linking #2 – Alternate Representations
2. Alternate representations of the same content
This might occur due to:• Server supports HTTP content negotiation• Multiple copies of the same resource• Format migration for preservation reasons • Different clients wanting different formats• Multiple languages of the content
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Linking #2 – Alternate Representations
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<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated”/> <rs:ln rel="alternate" type="text/html" href="http://example.com/res1.html"/> <rs:ln rel="alternate" type=“application/pdf" href=”http://example.com/res1.pdf"/> </url></urlset>
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Linking #2 – Alternate Representations
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/res1.html</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated”/> <rs:ln rel=”canonical” href="http://example.com/res1"/> </url></urlset>
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Linking #3 – Patching Content
3. Patching content rather than replacing
This might occur due to:• Resources are very large and server wishes to conserve
bandwidth where possible• Changes are frequent and small• Changes are managed in a CMS that tracks differences• Format exists or can be described that is machine
processable to replicate the change
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Linking #3 – Patching Content
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<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/res1.json</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated” length=“398723”/> <rs:ln rel=”http://www.openarchives.org/rs/terms/patch” type=”application/json-patch” modified=“2013-01-02T17:00:00Z” length=“58” href=”http://example.com/res1-patch.json"/> </url></urlset>
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Linking #4 – Metadata about Resources
4. Resources and their metadata
This might occur due to:• Resources have additional metadata records, which are
useful for understanding the resource• Such as cultural heritage images, audio, video• Collections with descriptive metadata• Resources with technical metadata• Administrative or Rights metadata
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Linking #4 – Metadata about Resources
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<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated”/> <rs:ln rel=”describedby” type=”application/xml” href=”http://example.com/metadata/res1.xml"/> </url></urlset>
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Linking #4 – Metadata about Resources
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/metadata/res1.xml</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated”/> <rs:ln rel=”describes” type=”text/html” href=”http://example.com/res1"/> </url></urlset>
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Linking #5 – Prior Versions of Resources
But first…
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Memento Intermezzo
http://www.mementoweb.org/
URI for Original, URI for Version
URI-M - http://web.archive.org/web/20010911203610/http://www.cnn.com/
Web Archive
URI-R - http://www.cnn.com/
URI for Original, URI for Version
URI-M - http://en.wikipedia.org/w/index.php?title=September_11_attacks&oldid=282333
CMS
URI-R - http://en.wikipedia.org/wiki/September_11_attacks
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Linking #5 – Prior Versions of Resources
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<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated”/> <rs:ln rel=”memento” href=”http://example.com/past/20130102130000/res1"/> <rs:ln rel=”timegate” href=”http://example.com/timegate/res1"/> <rs:ln rel=”timemap” href=“http://example.com/timemap/res1” type=“application/link-format”/> </url></urlset>
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Linking #6 – Collection Membership
6. Collection membership of resources
A source might want to express this because:• Resources are part of OAI-ORE aggregations• Resources are part of OAI-PMH sets• Or to indicated any other type of collections of resources
Collections are named with URIs and can then be linked to with rel=“collection”
• Nice if the collection URI resolves to a useful description
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Linking #6 – Collection Membership
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated”/> <rs:ln rel=”collection” href=”http://example.com/aggregation/allres"/> </url></urlset>
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Linking #7 – Republishing Resources
7. Republishing synchronized resources
This might occur due to:• Aggregator systems that harvest resources from remote
sites and then republish them at new URIs• Examples include Blog republishing, content distribution
networks, mirrored or combined collections• Hypothetical scenario: Lots of little museums with small
collections, and a large European/American aggregating digital library system that wants to provide fast, combined access to the content (with permission)
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Linking #7 – Republishing Resources
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> <rs:md change=”updated”/> <rs:ln rel=”via” modified=“2013-01-02T10:00:00Z” href=”http://original.example.org/res1"/> </url></urlset>
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Linking #7 – Republishing Resources
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist" from="2013-01-02T09:00:00Z” until="2013-01-03T09:00:00Z”/> <url> <loc>http://aggregator.example.com/res1</loc> <lastmod>2013-01-02T18:00:00Z</lastmod> <rs:md change=”updated”/> <rs:ln rel=”via” modified=“2013-01-02T13:00:00Z” href=”http://example.org/res1"/> <rs:ln rel=”via” modified=“2013-01-02T10:00:00Z” href=”http://original.example.org/res1"/> </url></urlset>
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Link Relation Summary
Relation Use in ResourceSync Defined in
rel="alternate"Link from generic to specific URI HTML 5
rel="canonical"Link from specific to generic URI RFC6596
rel="collection"Resource is member of collection RFC6573
rel="describedby" Has metadata Protocol for Web Description Resources (POWDER): Description Resources
rel="describes" Is metadata for The 'describes' Link Relation Type
rel="duplicate" Mirror or alternative copy RFC6249
rel=".../rs/terms/patch"A patch -- efficient change information This specification
rel="memento" Link to time-specific URI Memento Internet Draft
rel="timegate" Link to timegate Memento Internet Draft
rel="via" Provenance chain, came from RFC4287
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Related Resource Metadata Summary
• Attributes of the <rs:ln> element; c.f. resource metadata + pri
Element/Attribute Description Defined by
<rs:ln> ResourceSync
encoding HTTP Content-Encoding header value RFC2616
hash One or more content digests (md5, sha-1, sha-256) Atom Link Ext.
href Related resource URI (identity) RFC4287
length HTTP Content-Length header value RFC4287
modified Timestamp of last change (c.f. <lastmod>) Atom Link Ext.
path Path in ZIP package (Dump Manifests only) ResourceSync
pri Priority of link RFC6249
rel Relation - IANA registered or URI RFC4287
type HTTP Content-Type header value RFC4287
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
4. Framework (Technical) Details
1. Sitemaps
2. Pull method
3. Linking between resources
4. Discovery
5. Push method
6. Archives
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Discovery ofCapabilities
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Discovery of Capability Documents
Requirements:• Need to discover capability documents, i.e. Resource List,
Resource Dump, Change List, Change Dump, Archives• Need to know the type of capability each document
represents.
Approach:• The Capability List provides links to these capability documents,
if the Source supports them.• These links have appropriate relation types, e.g.
“resourcelist”, “changelist”, etc.
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Capability List
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”capabilitylist”/> <rs:ln rel=“resourcesync” href=“http://example.com/.well-known/resourcesync”/> <url> <loc>http://aggregator.example.com/dataset1/resourcelist.xml</loc> <rs:md capability=”resourcelist”/> </url> <url> <loc>http://aggregator.example.com/dataset1/changelist.xml</loc> <rs:md capability=”changelist”/> </url></urlset>
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Requirements:• Need to discover a Capability List
Approach:• HTTP Link header from resources subject to synchronization,
relation type “resourcesync”• Links from HTML document <head>, relation type
“resourcesync”• Links from Capability documents, relation type “up”
Link header on example.com/res1.pdf
Link: <example.com/dataset1/capabilitylist.xml>;rel=“resourcesync”
Discovery of Capability Lists
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Discovery ofCapabilities
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Discovery: ResourceSync Description
Requirements:• Support for multiple Capability Lists, one per “set of
resources”• Need to discover these Capability Lists• Need descriptive information about each set of resources
that a Capability List pertains to• Useful to have descriptive information about the Source itself
Approach:• The ResourceSync Description document meets these
requirements. • It should be at a particular location to avoid having registries:
http://(hostname)/.well-known/resourcesync• It can be linked to from the Capability Lists as well.
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Discovery ofCapabilities
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ResourceSync Description
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”resourcesync”/> <rs:ln rel=“describedby” href=“http://example.com/info_about_source.xml”/> <url> <loc>http://aggregator.example.com/dataset1/capabilitylist.xml</loc> <rs:md capability=”capabilitylist”/> <rs:ln rel=“describedby” href=“http://example.com/dataset1/info_about_dataset1.xml”/> </url> <url> <loc>http://aggregator.example.com/dataset2/capabilitylist.xml</loc> <rs:md capability=”capabilitylist”/> <rs:ln rel=“describedby” href=“http://example.com/dataset2/info_about_dataset2.xml”/> </url></urlset>
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Discovery ofCapabilities
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ResourceSync - Agenda
4. Framework (Technical) Details
1. Sitemaps
2. Pull method
3. Linking between resources
4. Discovery
5. Push method
6. Archives
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Motivation for a Push Component in ResourceSync
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• Reduce synchronization latency by having the Source push out resource change information• To avoid continuous pull of Change Lists by Destinations
• Share information about changes to the Source’s ResourceSync implementation, e.g. announcement of new Resource List, new Capability List, etc.• To avoid continuous polling of e.g. Resource Lists,
ResourceSync Description
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Notification Types
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• Events pertaining to a resource• updated | created | deleted for a resource• 3rd party defined events
• Events pertaining to a set of resources• updated | created | deleted for a Resource List, Resource
Dump, Change List, Change Dump, Archives• 3rd party defined events
• Events pertaining to the overall ResourceSync implementation• updated | created | deleted for a Capability List,
ResourceSync Description• 3rd party defined events
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Possible Push Technology: XMPP PubSub
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Other technologies: WebSockets, HTTP callback
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Notification Payload
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• Payload the same irrespective of transport protocol• Use <urlset> as encapsulating element• One <url> element per notification
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Notification Payload – Resource Update (XMPP)
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<xmpp:iq from=“[email protected]” to=“[email protected]” type=“set” id=“liAJUz3S”> <xmpp:pubsub> <xmpp:publish node=“resource_notification_channel”> <xmpp:item id=“1234577”> <sm:urlset xmlns:sm=“http://www.sitemaps.org/schemas/sitemap/0.9” xmlns:rs=“http://www.openarchives.org/rs/terms/”> <sm:url> <sm:loc>http://example.com/res1</sm:loc> <sm:lastmod>2013-01-02T14:00:00Z</sm:lastmod> <rs:md change=“updated” hash=“md5:12324324jhhjl234234” length=“987665” type=“application/pdf”/> </sm:url> </sm:urlset> </xmpp:item> </xmpp:publish> </xmpp:pubsub></xmpp:iq>
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Notification Payload – Capability Update (XMPP)
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<xmpp:iq from=“[email protected]” to=“[email protected]” type=“set” id=“liAJUz3S”> <xmpp:pubsub> <xmpp:publish node=“changelist_notification_channel”> <xmpp:item id=“1234577”> <sm:urlset xmlns:sm=“http://www.sitemaps.org/schemas/sitemap/0.9” xmlns:rs=“http://www.openarchives.org/rs/terms/”> <sm:url> <sm:loc>http://example.com/dataset1/changelist.xml</sm:loc> <sm:lastmod>2013-01-02T14:00:00Z</sm:lastmod> <rs:md capability=“changelist” change=“updated”/> </sm:url> </sm:urlset> </xmpp:item> </xmpp:publish> </xmpp:pubsub></xmpp:iq>
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Push Technology Considerations
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• Notification channels• Multiple channels per Source to divide up notifications, e.g.
• a channel for changes pertaining to all resources that belong to a set of resources
• a channel for changes to capabilities for a set of resources
• Server-side filtering preferred over client-side
• Authentication/Authorization• To subscribe/create channels
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Push Technology Considerations
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• Delayed notification• Insurance that Destination does not miss anything
• Discovery• Links to channels e.g. from a Capability List• Links from channels to other channels• Provide channel metadata (transport protocol info etc.)
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
<urlset xmlns=“http://www.sitemaps.org/schemas/sitemap/0.9” xmlns:rs=“http://www.openarchives.org/rs/terms/”>… <url> <loc>xmpp:pubsub.example.com/dataset1?;node=resource_notification_channel</loc> <rs:md capability=“resource-notification”/> <rs:ln rel=“alternate” href=“ws://example.com/dataset1/meta_notification_channel”/> </url> <url> <loc>xmpp:pubsub.example.com/dataset1?;node=capability_notification_channel</loc> <rs:md capability=“capability-notification”/> </url> <url> <loc>xmpp:pubsub.example.com/dataset1?;node=resourcesync_notification_channel</loc> <rs:md capability=“resourcesync-notification”/> </url></urlset>
Push Channel Discovery
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ResourceSync - Agenda
4. Framework (Technical) Details
1. Sitemaps
2. Pull method
3. Linking between resources
4. Discovery
5. Push method
6. Archives
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ResourceSync Framework Component: Archives
In order to allow a Source to hold on to historical data and Destinations to catch up with events it has missed:
o Publish a - Resource List Archive, - Resource Dump Archive,- Change List Archive, and/or a - Change Dump Archive
o Documents, listing historical capability documents
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Resource List Archive
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<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability="resourcelist-archive" from="2013-01-09T13:00:00Z"/> <url> <loc>http://example.com/resourcelist1.xml</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> </url> <url> <loc>http://example.com/resourcelist2.xml</loc> <lastmod>2013-01-09T13:00:00Z</lastmod> </url> <url> … </url></urlset>
Resource List Archive
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Resource Dump Archive
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<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability="resourcedump-archive" from="2013-02-10T03:00:00Z"/> <url> <loc>http://example.com/resourcedump1.xml</loc> <lastmod>2013-01-10T03:00:00Z</lastmod> </url> <url> <loc>http://example.com/resourcedump2.xml</loc> <lastmod>2013-02-10T03:00:00Z</lastmod> </url> <url> … </url></urlset>
Resource Dump Archive
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Change List Archive
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<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changelist-archive" from="2013-02-01T23:00:00Z until="2013-02-03T23:00:00Z"/> <url> <loc>http://example.com/changelist1.xml</loc> <lastmod>2013-02-01T23:00:00Z</lastmod> </url> <url> <loc>http://example.com/changelist2.xml</loc> <lastmod>2013-02-02T23:00:00Z</lastmod> </url> <url> <loc>http://example.com/changelist3.xml</loc> <lastmod>2013-02-03T23:00:00Z</lastmod> </url></urlset>
Change List Archive
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Change Dump Archive
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<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability=”changedump-archive" from="2013-02-10T03:00:00Z until="2013-02-17T03:00:00Z"/> <url> <loc>http://example.com/changedump1.xml</loc> <lastmod>2013-02-10T03:00:00Z</lastmod> </url> <url> <loc>http://example.com/changedump2.xml</loc> <lastmod>2013-02-17T03:00:00Z</lastmod> </url> <url> … </url></urlset>
Change Dump Archive
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ResourceSync - Agenda
1. ResourceSync: Problem Perspective & Conceptual Approach
2. Motivation & Use Cases
3. Framework Walkthrough
4. Framework (Technical) Details
5. Implementation
6. Q&A
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Implementation #1:The Metadata Harvesting Use Case
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The Metadata Harvesting Use Case
1. Identification of metadata records within a service
2. Use of standards in metadata formats
3. Incremental updates
4. Create, Update, Delete
5. Sets
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The Metadata Harvesting Use Case
1. Identification of metadata records within a service
2. Use of standards in metadata formats
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ResourceSync does not specifically care about metadata records, only resources. It is up to the server to identify which of those resources are metadata.
We are free to annotate a resource's entry with appropriate metadata to indicate the format.
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
The Metadata Harvesting Use Case
3. Incremental updates
4. Create, Update, Delete
5. Sets
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All resources that can be obtained from a change list will be annotated with the kind of change that happened to them.
ResourceSync allows the server to publish lists of resources and changes and indexes of those lists all annotated with metadata.
ResourceSync publishes changes as static documents. The client is then free to walk up and down the change lists provided by the server.
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
(Required) Documents formetadata harvesting use case
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Describing Metadata Resources
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<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability="resourcelist" from="2013-05-05T13:00:00Z"/> <url> <loc>http://mydspace.edu/dspace-rs/resource/123456789/7/qdc</loc> <lastmod>2013-05-01T19:09:35Z</lastmod> <changefreq>never</changefreq> <rs:md type=”application/xml”/> <rs:ln href="http://mydspace.edu/bitstream/123456789/7/1/bitstream.pdf" rel="describes"/> <rs:ln href="http://mydspace.edu/bitstream/123456789/7/2/image.jpg" rel="describes"/> <rs:ln href="http://mydspace.edu/123456789/3" rel=”collection"/> </url></urlset>
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Describing Bitstream Resources
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<urlset … <url> <loc>http://mydspace.edu/bitstream/123456789/7/1/bitstream.pdf</loc> <lastmod>2013-05-01T19:09:35Z</lastmod> <changefreq>never</changefreq> <rs:md hash="md5:75d0ea94097a05fce9aca5b079e2f209" length="419805" type="application/pdf"/> <rs:ln href="http://mydspace.edu/dspace-rs/resource/123456789/7/qdc" rel="describedby"/> <rs:ln href="http://mydspace.edu/dspace-rs/resource/123456789/7/mets" rel="describedby"/> <rs:ln href="http://mydspace.edu/dspace-rs/resource/123456789/12/qdc" rel="describedby"/> <rs:ln href="http://mydspace.edu/123456789/2" rel=”collection"/> </url></urlset>
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Serving Metadata Resources
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http://mydspace.edu/dspace-rs/resource/123456789/7/qdc
ResourceSync webapp Item handle Metadata Format
metadata.formats = \ qdc = http://purl.org/dc/terms/, \ mets = http://www.loc.gov/METS/
metadata.types = \ qdc = application/xml, \ mets = application/xml
<loc>http://mydspace.edu/dspace-rs/resource/123456789/7/qdc<loc> <rs:md type="application/xml”/> <rs:ln href="http://purl.org/dc/terms/" rel="describedby"/>
<loc>http://mydspace.edu/dspace-rs/resource/123456789/7/mets</loc> <rs:md type="application/xml”/> <rs:ln href="http://www.loc.gov/METS/" rel="describedby"/>
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Generating Documents1. Initialise
Creates initial Capability List and Resource List documents
[dspace]/bin/dspace dsrun org.dspace.resourcesync.ResourceSyncGenerator -i
2. Update
Creates a new Change List which covers the period since the last Change List was created
[dspace]/bin/dspace dsrun org.dspace.resourcesync.ResourceSyncGenerator -u
3. Rebase
A combination of both Initialise and Update.
[dspace]/bin/dspace dsrun org.dspace.resourcesync.ResourceSyncGenerator -r
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Usage of Resources by clients
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Impact on DSpace
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URLs• Stable identifiers for archived items• Stable identifiers for unarchived items• Stable identifiers for metadata resources (in their various formats)• Stable identifiers for previous versions
Provenance• History of changes to an item/bitstream• Item/bitstream deletions (vs withdraw)• Bitstream create/update dates• Item create/update dates
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Versioning• Access of previous versions of both metadata and bitstreams• Stable identifiers for previous versions of both metadata and
bitstreams
Metadata Resources• Metadata in a variety of formats• Metadata as file/bitstream
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ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Admin Files• ResourceSync documents (Resource Lists, Change Lists, etc)• ResourceSync exports - Resource Dumps, Change Dumps• Metadata exports in a number of formats
Scheduled Tasks• Regular generation of RS documents
Complex Objects• Item/bitstream relationships• Collections of content
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Dspace Module:https://github.com/CottageLabs/DSpaceResourceSync
depends on the common java library:https://github.com/CottageLabs/ResourceSyncJava
PHP client:https://github.com/stuartlewis/resync-php
depends on the SWORDv2 clienbt library:https://github.com/swordapp/swordappv2-php-library/
Get the software!
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Implementation #2:ResourceSync at arXiv.org
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ResourceSync @ arXiv
• Use ResourceSync for both mirroring and public data accesso efficient updateso ability to do periodic auditso public synchronization capabilityo reduce admin burden
• Likely start with metadata + source for mirroring use case (doing experiments now)
• Open access use cases requires processed PDF also• Some concerns about likely use/load…
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Alternate download location
• Likely want to separate machine accesses from human accesses to preserve response time on main server
=> Use Mirrored Content part of spec
o <loc> specifies canonical URI - e.g. http://arxiv.org/pdf/1306.1073v1.pdf
o <rs:ln rel=“duplicate”> specifies preferred download location- e.g. http://export.arxiv.org/pdf/1306.1073v1.pdf
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<url> <loc>http://arxiv.org/pdf/1306.1073v1.pdf</loc> <lastmod>2013-06-06T00:57:12Z</lastmod> <rs:md hash="md5:e08e0c4e4d7b0895120014f0aa09e7c4" length="287714” type=”application/pdf"/> <rs:ln rel="duplicate” pri="1" href="http://export.arxiv.org/pdf/1306.1073v1.pdf" modified="2013-06-06T02:00:59Z"/></url>
Alternate download location
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Getting a copy of arXiv
It might be as easy as:
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(of course, you probably have to wait a while but it is nice to know ResourceSync is stateless so one can efficiently restart)
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
Python Library and Client
• Aim to provide library code implementing all ResourceSync facilities for use in both source and destination implementationso Designed for python 2.6 (RHEL6) and 2.7o Will not work with python <= 2.5
• Client (resync) supports many destination operations, inspired by the common Unix rsync program
• Client also supports some operations that might be useful in a source, such as generation of static Resource Lists, or periodic Change Lists (used in arXiv experiments)
• Explorer (resync-explorer) intended to allow easy inspection of a source’s resource sets and capabilities
• Developed since ResourceSync v0.5, updated for v0.9
http://github.org/resync/resync
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync Source Simulator
• Python code using Tornado server• Provides random set of resources of different sizes updated at a
particular rate• Very useful for testing Destination code
http://github.com/resync/simulator
ResourceSync TutorialJuly 8, 2013, Open Repositories 2013, PEI, Canada
ResourceSync - Agenda
1. ResourceSync: Problem Perspective & Conceptual Approach
2. Motivation & Use Cases
3. Framework Walkthrough
4. Framework (Technical) Details
5. Implementation
6. Q&A
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Timeline
• June 2013o Version 0.9 of ResourceSync framework specification releasedo Soliciting broad feedback
• July 2013o Version 0.x of Push-based methods for ResourceSync
• Fall 2013o Specification becomes NISO standard
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Pointers
• Specification
http://www.openarchives.org/rs/http://www.openarchives.org/rs/0.9/resourcesynchttp://www.openarchives.org/rs/0.9/archives
• List for public comment
https://groups.google.com/d/forum/resourcesync
• Client and simulator code
http://github.org/resync/resynchttp://github.org/resync/simulator
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ResourceSync:A Web-Based
Resource SynchronizationFramework
ResourceSync is funded by The Sloan Foundation & JISC
#resourcesync
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