4b. OAIS Reference Model:

The Reference Model for an Open Archival Information System attempts to comprehensively identify the responsibilities and components of an archival system, including:

>> the roles of people and institutions that interact in an archive. These appear in the model as: Producer, Management, and Consumer
>> the digital objects that are managed by OAIS, called information packages
>> the major functions (things that happen or that should be done) of a fully-functioning OAIS. The six higher-level functions, which appear in the model as Ingest, Data Management, Archival Storage, Access, Preservation Management, and Administration, actually represent thirty-three lower-level functions.

OAIS Model

The OAIS diagram (above) shows the relationships among the functions. It looks a lot like a system architecture diagram, so many people understand it as such. But it is not. The rounded rectangles identify groups of related functions, not components in an implementation. In the real world, the functions do not have to reside on the same server or within the same organization. The groups can be broken apart and their functions can be distributed in many configurations.


The story of "O": A Digital Object in an
OAIS-compliant System

Information packages have different names at different stages in the archival process, representing the nature of the object at that point in the process.

A digital object comes into the system as a Submission Information Package (SIP), consisting of the object and a required set of metadata. The Producer is responsible for passing the SIP off to Management.

The SIP goes through the Ingest functions where it is processed and accepted into the system in accordance with accepted practice and rules and becomes an Archival Information Package (AIP). The AIP then contains the content of the SIP plus any additional metadata the system requires in the way of preservation elements. From that point on, metadata is added to the AIP for every action that affects the object.

In addition to ingesting the SIPs into the system, Management is responsible for being able to steward the AIPs over time and enable the delivery of AIPs to the Consumer as Dissemination Information Packages (DIP).

Most systems require the successful implementation of several functions—Administration, Data Management, and Common Services (which are not represented in the model)—to operate smoothly. An OAIS adds two key functions: Archival Storage and Preservation Planning, which identify and apply appropriate preservation strategies to move the AIPs into the future in a way that maintains them as readable, usable, and understandable objects.

The Consumer appears at the end of the model and may appear to simply request and receive DIPs. Understanding the interests, needs, and priorities of the Consumer as reflected by the kinds of queries submitted and the kinds of DIPs expected—both of which are likely to change over time—may have significant implications for the range of digital objects that are ingested. It may also be the basis for a truly successful OAIS, one that performs the preservation functions well and is actively used by target consumers.