resourcesync quick overview
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Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
http://www.openarchives.org/rs #ResourceSync
Herbert Van de SompelLos Alamos National Laboratory@hvdsomp - herbertv@lanl.gov
ResourceSyncA Quick Overview
The ResourceSync editors are: Martin Klein (LANL), Robert Sanderson (LANL), Herbert Van de Sompel (LANL), Simeon Warner (Cornell U.), Graham Klyne (Oxford U.), Bernhard Haslhofer (U. of Vienna), Michael L. Nelson (Old Dominion U.), Carl Lagoze (U. of Michigan)
ResourceSync was funded by the Sloan Foundation & JISC
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
ResourceSync
• Collaboration between NISO and the Open Archives Initiative, 2012-2013
• Funded by the Sloan Foundation and JISC
• Goal: Devise a specification for web-based resource synchronization• Subjects of synchronization: web resources identified by HTTP
URIs• HTTP as the communication protocol for synchronization• Servers involved in synchronization are on the web
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Problem Statement
• Consideration:• Source (server) has resources that change over time: they
get created, modified, deleted• Destinations (servers) leverage (some) resources of the
Source
• Problem:• Destinations want to keep in step with the resource changes
at the Source
A Source’s Resources
A Source’s Resources Evolve over Time
A Source’s Resources Evolve over Time
A Source’s Resources Evolve over Time
A Source’s Resources Evolve over Time
A Source’s Resources Evolve over Time
A Source’s Resources Evolve over Time
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Problem Statement
• 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
• Goal:• Design an approach for resource synchronization aligned
with the Web Architecture that has a fair chance of adoption by different communities
One to Many – Master Copy
Many to One - Aggregator
Metadata Harvesting
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Solution Perspective
• Source communicates about the state of its resources:
• Publish inventory: snapshot of the state of resources at a moment in time
• Publish changes: enumeration of resource changes that occurred during a temporal interval
• Notify about changes: send notifications as changes occur
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Solution Perspective – Communication Payload
• Payload of the communications:
• Always: HTTP URI of the resource
• For change communications: change type (create | update | delete) & datetime of change
• As needed: metadata and links pertaining to the resource
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
ResourceSync is Based on Sitemaps
• Sitemap is the document format used throughout the frameworko Used widely by web servers to advertise their resources to
search engines
<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>
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
ResourceSync Extends Sitemaps
• Extensions to Sitemaps to support synchronizationo <rs:ln> for linkso <rs:md> for metadata
<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> …</urlset>
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Publish Resource List: Inventory at Tx
• In order to meet a Destination’s need for baseline synchronization, the Source may publish a Resource List
• A Resource List is an inventory, a snapshot of existing resources
• Per resource, it minimally provides the resource’s URI
• Process:- Destination obtains the Resource List- Destination obtains listed resources by their URI
Publish Resource List: Inventory at Tx
Resource List @Tx = { A ; B ; C }
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability="resourcelist" at="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"/> <rs:ln href="http://example.com/meta/dc/res1" rel=”describedby” type=”application/xml"/> </url> …</urlset>
Resource List
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Send Change Notification: Resource Changes as they Occur
• In order to meet a Destination’s need for incremental synchronization and low latency, the Source may send Change Notifications
• A Change Notification conveys resource change events as they occur
• For each event, it minimally lists the URI of the resource, the nature of the change, the datetime of the event
- Process:- Destination receives Change Notification- Destination obtains created/updated resources, removes
deleted resources
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Send Change Notification: Resource Changes at Ta
Change Notification @Ta = { A updated @Ta }
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Send Change Notification: Resource Changes at Tb
Change Notification @Tb = { D updated @Tb }
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Send Change Notification: Resource Changes at Tc
Change Notification @Tc = { A updated @Tc ; B updated @Tc }
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
ResourceSync Notifications are Based on the PuSH Protocol
• ResourceSync builds on the PubHubsHubbub protocol (PuSH) used for syndication of Atom/RSS feeds
• Destination subscribes to a Source’s notifications via an intermediate Hub
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Modular Framework
• ResourceSync specifies additional synchronization capabilities• Source decides which capabilities to support based on local
and community requirements
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Follow Your Nose Discovery
• ResourceSync specifies mechanisms for Destinations to determine whether and how a Source supports the framework• Based on conventions for web discovery and documents
that detail the level of support
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Follow Your Nose Document Navigation
• ResourceSync specifies mechanisms to navigate the various documents involved in the framework• Based on following typed links
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Status
• Core specification (pull) is ANSI/NISO Z39.99-2014
• Notification (push), Archives specifications in beta
• Growing implementation interest motivated by the need to move beyond metadata (OAI-PMH)
• Tools will be listed at http://www.openarchives.org/rs/toc
Herbert Van de Sompel - ResourceSyncNISO Annual Update, ALA, Las Vegas, NV, 29 June 2014
Specifications: http://www.openarchives.org/rs
Herbert Van de SompelLos Alamos National Laboratory@hvdsomp - herbertv@lanl.gov
ResourceSyncA Quick Overview
The ResourceSync editors are: Martin Klein (LANL), Robert Sanderson (LANL), Herbert Van de Sompel (LANL), Simeon Warner (Cornell U.), Graham Klyne (Oxford U.), Bernhard Haslhofer (U. of Vienna), Michael L. Nelson (Old Dominion U.), Carl Lagoze (U. of Michigan)
Google Group: https://groups.google.com/d/forum/resourcesync
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