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.]

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:

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)