Post on 27-Dec-2015
The Handle System: and its role in a Digital Object Architecture
Robert E. KahnCNRI
Workshop on Frontiersin Distributed Information Systems
Presidio of San FransiscoJuly 31 – August 1, 2003
Objective of the Framework
Internet objectiveBest-effort Packet Delivery
Heterogeneous
Networks Information Systems
Seamless Interoperability
Networks InformationSystems
Federating Heterogeneous Systems
Internet Comparison
• IP Addresses Machines
• Gateways (now routers) help with access
• TCP handles end-end issues– Remove duplicate packets– Restructure the arriving fragmented stream– Perform end-end error detection & retransmission– Provide flow control
Further Scoping the Problem
Complexity of Query
Time toResolve Query
Initial Focus on Querieswith Complexity = Zero
Literary Music Video Financial Grid Enum RFID
“SimpleLookup URL IPaddresses “Unfederated Databases”
Basic Attributes of the Approach
• Digital Objects (i.e. Data Structures)• Unique Identifiers Digital Objects• Resolution & Administration Mechanism
– Maintains Uniqueness of Ids DOs as long as they persist
– Maps Ids Useful State Information– Is distributed and scaleable– Does not involve complete search
Digital Object
• Set of elements, each of <Type, Value>
• Parsable across heterogeneous platforms
• One element must be the unique identifier
• Properties Record contains metadata
• Transaction Record records usage
• Most users wish to access its Essence
• Key Metadata is part of the Essence
Internal Data Structure
MethodsDisseminators
Digital Object
Access to the object is subject tocontrol by the owner. For example,a market in disseminators is possible.
The internal data structureis not directly accessibleby the programmer
Purposely Silent about
• What Types
• What Type of Types
• What Values
• What metadata or metadata schema
• What state information in Handle Records
• Policies and Procedures in general
• There are policies for Global, however
A Range of Possibilities
• Identifiers are persistent – e.g. DOIs
• Identifiers are transient – e.g. Grid
• Identifiers are resolvable
• Resolution information is not accessible
• Digital Objects are fixed, unchangeable
• Access to Digital Objects is fixed, even if DOs are changeable
Repository Notion
Any Hardware & SoftwareConfiguration
Logical External Interface
RAP
Nesting of Repositories
CoreStructureContentAggregation &De-aggregation
Core Interface must be present at each levelOther levels could be separately defined later
Federated Repositories• Key issue is commonality of interests in accessing
information from multiple repositories.• Financial Information is prime applications area• Metadata Registries allow for searching based on
“user-supplied” inputs. The use of handles (however branded) can simplify access.
• Access via local repositories is an operational desirable capability.
MetaObjects & Metadata Registries
• MetaObjects provide a structural basis for indirection and for organizing information
• Metadata is used to characterize digital objects, to access their identifiers and to assist in cross referencing
• Metadata Registries provide uniform access to metadata.
Handle Format
Naming Authority
Item ID(any format)
Prefix Suffix
In use, a Handle is an opaque string. Corporation For National
Research Initiatives
2304568.40/12345678
Handles Resolve to Typed Data
Handle data
2304568.40/12345678 URLhttp://www.loc.gov/.....
Handle Data type
RAPloc/repository
URLhttp://www.loc2.gov/..
Extensible Data Types XYZ1001110011110
Just one example - also looks like a digital object
Handles can also have semantics butwe frown on it! Resolution is independentof semantics in every instance
Handle Record
Allocation of Prefixes
1 - System Uses2 - High Fan in/out Organizations3 “4 - Businesses and formal organizations5 “6 - Individuals and anything that cant fit above7 “8 “
Creating & Resolving Type Information Dynamically
• Prefixes of the form 0.X are reserved for defining resolvable “system information” such as types and naming authorities
• 0.type/<type> is a handle for the type in brackets
• 0.na/<na> is a handle for a particular na• Non-system types can also be created by
individual users
Global Handle Resolution
HS1 HS2 HPS3 HS4
HANDLE ADMINISTRATION
HANDLE RESOLUTION
Handle Servers
(Handles are uniformly spread by hashing)
Multiple Handle Servers
Global & Local Handle Resolution
HS1 HS2 HPS3 HS4
HANDLE ADMINISTRATION
HANDLE RESOLUTION
Handle ServersGlobal
Local
HANDLE RESOLUTION
How do handles resolve...
Two steps to resolve a handle - -• Client queries GHR: “Which Handle Service has 1895.22/1011?”• GHR responds with a “map” showing the client which servers within
the responsible LHS it can query for that handle .
Handle Client
GHR
LHS A
LHS C
LHS ..n
LHS B
LHS D
Handle System
1. Where is 1895.22/1011?
Map of LHS B
2. Give me all data for 1895.22/1011
Handle Data
Administration of Handle Records
univ/thesis.txt 1217/4913527 univ/4913527 1217/thesis.txt
univ.csl.17.2
(the handles shown above identify digital objects)
univ 1217
univ.csl.17
univ.csl 1217.34
1217.34.1
The Global Handle Registry
• The GHR is a unique handle service used to store the identity and location of all local handle services (LHS), and tells a handle client which service to query to resolve a handle.
• All handle clients (for resolution or administration) know how to contact and query the GHR.
GlobalHandle Registry
DOI HandleService
LOCHandle ServiceCMU
Handle Service
DTIC HandleService
Korean Ctrl LibHandle Service
Nat’l Lib AustraliaHandle Service
Twin BaysHandle Service
Liqid KrystalHandle Service
MITHandle Service
Groups of Handle Servers
P
S
S
S
S
Group A Group B
Group C Group D
Handle ClientsAdministration
Use the Java™ HandleClient Tool provided inthe distribution for creatingor updating handles one-at-a-time or via a batch.
Develop your own administration client.
or
Handle ClientsResolutionDownload web browser plug-in which enables browsersto recognize the handle protocol.
or
Append a handle to proxy servere.g http://hdl.handle.net/<handle>)which understands both HTTP and HDL protocols.
or
Develop your own resolution client.
Setting up a Local Handle Service...
• Download the software from
http://www.handle.net.
• Follow the instructions in the installation script.
• Send your “site bundle”, containing the IP address
of your server and your administrator information,
to the Global Handle Registry (GHR)
administrator.
Organization of the International DOI Foundation
IDF
IDF is a non-profitorganization with offices in
Washington, DC (AAP) Geneva, Switzerland (IPA)
Members areMostly Book &
Journal Publishers Membership Dues
- Policies & Procedures- Licensing the DOI TM- Qualifying RAs- Marketing the DOI brand
4¢ per DOI on deposit – 1X; min $20K/yr1¢ per DOI in CDD on 12/31 – annual½¢ per DOI in CDD after $50K per RA
CDD
Business Potential
• Enabling new forms of Creativity – New forms of expression– Representing value as Digital Objects
• Selling infrastructure technology & services• Enabling Third Party value-added capabilities• Helping organizations manage their own information
better & offer new types of services• Stimulating access to “surface information” and
“embedded information” with appropriate access controls and conditions of use
Evolution of Policy for Global
• Original Policy– Best efforts service; run in-house– Cost paid by the Government– Available to the research community for free
• Current Policy (still in flux)– Best efforts service; run 7x24 with backup– Free to the research community; commercial users pay
after a period of experimentation– Handle System Advisory Committee oversees costs and
evolution.
Cost of Global Services
• IPv4 several million addresses; about 50M TLDs (excluding CCs)
• At say $20 per year per TLD, the cost of global registration and resolution services is about $1B per year – this is inefficient, very profitable or both
• The handle system is almost as large as DNS (there are over 10M DOIs alone) and costs about $250K per year at present.
• The DNS can be run within the handle system, if desired; but the handle system can support IPv4 and IPv6 without DNS
Applications of the Technology
• Identity Management (DHS)• PKI Infrastructure• Personal Locator Information• Efficient Communications• Steganography• Managing Digital Cash• Managing Business Transactions (e.g. email)• Learning of more up to date Publications• Cataloguing and Indexing