Digital-Archiving Information Services Reference Model
Lou Reich
Computer Sciences Corporation
louis.i.reich@gsfc.nasa.gov
+1-301-794-1859
Don Sawyer
NASA Goddard Space Flight Center
don.sawyer@gsfc.nasa.gov
+1-301-286-2748
1. Definitions
2. Scope of this Reference Model
3. Dimensions of model
3.1 Classes of archives
3.2 Service Interfaces
3.2.1 Ingest
3.2.2 Storage
3.2.3 Metadata Management
3.2.4 Access
3.2.5 Dissemination
3.2.6 Operations and Policy
4. Services organized by interface
4.1 Ingest Services
3.2.2 Storage Services
3.2.3 Metadata Management Services
3.2.4 Access Services
3.2.5 Dissemination Services
5. Issues
1. Definitions
- Archived Data:
- Digital data that is being preserved for public access
over the long (indefinite) term. There is no presumption of any
understanding of what the bits represent. If any of the bits are changed,
there has been failure of the archive function.
- Archived Information:
- Information, represented by digital data, that is
being preserved for public access over the long (indefinite) term. The
information is deemed to be understandable to one or more segments of the
public. The underlying bits may be changed as long as the information is
not lost.
- Information Granule:
- For a given information product, the smallest
collection of information to which the archive provides standard external-
user identification and access services.
- Reference Model:
- A reference model is intended to establish a framework for
the development of consistent standards or specifications. A reference
model is based on a small number of unifying concepts and may be used as a
basis for education and explaining standards to a non-specialist. (A
reference model should be compatible with other, existing, reference models
to the extent practical.)
2. Scope of this Reference Model
The ISO Reference Model for Archival Information Services (AIS) provides a
framework for a series of standards for application and user interfaces to
open archival systems. The AIS Model identifies a high-level abstraction
that underlies current archival systems. It defines common terminology and
concepts that allow the architectures of existing and future systems to be
described and compared. The AIS Model provides a conceptual and functional
framework within which independent teams of experts may proceed with
detailed AIS definitions.
3. Dimensions of model
3.1 Classes of archives
[This is only a list of characteristics that may
be used to classify archives; it is not a classification scheme at this
point.]
- Expertise level of the expected customers
- Active (high ingest rate possibly driving factor) vs. static (low
ingest rate)
- Short-term vs. long-term storage requirements
- On-line WWW/FTP delivery vs. media delivery
- Size of data granules
- Total size of archive
- Complexity of subject area (e.g. single project vs. Multidiscipline)
- Centralized vs. distributed
3.2 Service Interfaces
The Archival Information Services may be broken into a number of categories
and related interfaces as shown in Figure 3-1. The numbered arrows
indicate the specific interfaces and do not indicate data flows. The
identified interfaces are:
1 Ingest
2 Access
3 Dissemination
4 Metadata Management
5 Data Storage
----------- -------------- -------------
| | | | | |
| | | |<--4---| ACCESS |<--2
| | | | | |
| | | | -------------
1-->| INGEST |---4-->| METADATA |
| | | MANAGEMENT |
| | | | -------------
| | | | | |
| | | |<--4---|DISSEMINATION|<--3
| | | | | |
----------- -------------- -------------
| | |
| 5 |
| | |
| v |
| -------------- |
| | | |
+---------5-->| DATA |<--5--------+
| STORAGE |
| |
--------------
Figure 3-1: Archival Information Services Interfaces and Relationships
3.2.1 Ingest
The external interface which accepts information into
the archive. This may include staging of information in preparation for
full acceptance, confirmation of receipt, and validation. [Key technology
areas include data packaging and metadata. Existing standards include
SFDU, BENTO(OpenDoc),FGDC metadata standards.]
3.2.2 Storage
The internal interface for storage and retrieval of
data products from long-term stores (i.e. media). This may include
transfer from staging storage to long term storage, and management of
multiple types of media. [Key technology areas include file storage
management systems (FSMS), media evolution, data compression, and database
management systems (DBMS). Existing standards include the IEEE Mass Storage
Reference Model , POSIX, and SQL92 (and SQL3).]
3.2.3 Metadata Management
The internal interface for populating and
maintaining catalogs, directories, inventories and related metadata stores.
[Key technology areas include database management systems, metadata,
hypertext, data modeling. Existing standards include SQL, HTML,
POSC,STEP/EXPRESS.]
3.2.4 Access
The external interface for querying, browsing and
product ordering by information consumers including other archive sites.
[Key technology areas include request brokers, WWW browsers, WAIS, DBMS,
data mining(AI), human machine interface(HMI) and data modeling. Existing
standards include SQL, Z39.50, and OMG CORBA and services.]
3.2.5 Dissemination
The external interface which sends copies of
requested information to information consumer. This may include staging to
on-line storage, notification to users of availability or direct
dissemination via a protocol such as http. [Key technology areas include
transportable media, network, file transfer protocols, and data/object
packaging techniques and relocatable code (e.g. Java).Existing standards
include CDF, HDF, BENTO, SFDU, SDTS, TCP/IP, FTP,OMG CORBA and services,
and Remote Data Access(RDA).]
3.2.6 Operations and Policy
[Some topics that may be addressed here
include:
- Costing policies
- Media monitoring for degradation
- Provision for backups
- Product identification
- Interactions with other archives - e.g. federations
- Preserving information under impending archive dissolution]
3.3. Services organized by interface
[The idea here is to identify and
describe categories of services at each interface.]
3.3.1 Ingest Services
3.3.2 Storage Services
3.3.3 Metadata Management Services
3.3.4 Access Services
3.3.5 Dissemination Services
4. Issues (TBD)
Wider Views
Overview of the First US Workshop
Overview of US Effort
Overview of the First International Workshop
Overview of International Effort
URL: http://ssdoo.gsfc.nasa.gov/nost/isoas/us01/p004.html
A service of
NOST at
NSSDC.
Access statistics for this web are available.
Comments and suggestion are always welcome.
Content Author: Don Sawyer/NASA GSFC (sawyer@ncf.gsfc.nasa.gov) +1.301.286.2748
and Lou Reich/CSC (louis.i.reich@gsfc.nasa.gov) +1.301.794.1859
Curator: John Garrett (garrett@ncf.gsfc.nasa.gov) +1.301.441.4169
Responsible Official: Code 633.2 / Don Sawyer (sawyer@ncf.gsfc.nasa.gov) +1.301.286.2748
Last Revised: September 14, 1995, Don Sawyer and Lou Reich
(January 30, 1997, John Garrett)