USING METADATA TO FACILITATE UNDERSTANDING AND CERTIFICATION ABOUT THE PRESERVATION PROPERTIES OF A PRESERVATION SYSTEM

Jewel H. Ward, Hao Xu, Mike C. Conway, Terrell G. Russell, and Antoine de Torcy

CRADLE Seminar, 20 September 2013University of North Carolina at Chapel HillSchool of Information and Library Science

I. Introduction

II. Background

III. Method (Mapping a Data Grid to the OAIS Functional Model)

IV. Conclusion

V. Future Work

Introduction• Need to provide internal audit mechanisms to verify

assertions about preservation capabilities• OAIS RM TRAC TDR Certification Certifying the

Certifiers• This project grew out of Moore’s work, “Towards a Theory

of Digital Preservation” & work for SAA in 2010: • “A preservation environment manages communication from the past while

communicating with the future. Information generated in the past is sent into the future by the current preservation environment. The proof that the preservation environment preserves authenticity and integrity while performing the communication constitutes a theory of digital preservation. We examine the representation information that is needed about the preservation environment for a theory of digital preservation. The representation information includes descriptions of the preservation management policies, the preservation processes, and the state information that is needed to verify the correct working behavior of the system.” IJDC, 2008, Vol. 3, No. 1, pp. 63-75

Introduction• We propose to do this by:

• Metadata-as-a-preservation task: mapping computer functions and procedures to the OAIS model and ISO 16363 (TRAC)

• Metadata-as-state: use state transition systems to connect computer code & data management policies

• Our method bridges the gap between computer code & human-readable policies

• Facilitates certifying preservation repository properties• Not a funded project per se. Melding of dissertation (Jewel

Ward), Master’s (Mike Conway), and post-Doc (Hao Xu) work.

Background• Metadata

• Bibliographic, administrative• IP numbers, date, time• Event data, state

• The OAIS Composite of Functional Entities• Common Services, Administration, Ingest, Data Management,

Archival Storage, Preservation Planning, Access

• Human- vs Machine-readable Policies“The repository shall comply with Access Policies” (ISO 16363)

Vs.

acAclPolicy { msiAclPolicy(“STRICT”); } #computer code

• “Bottom Up” vs. “Top Down”

Background

Background

Background

Background

Method 1

Method 1

Method 2• State transition system captures

• State of data objects• Their transitions

Example: SIP AIP DIP

• Data management policies determine which sequences of states are compliant or not

• These refinements yield a formal structure for data management policies

• The state transition system thus obtained specifies which metadata are necessary if the preservation properties are going to be certified.

Method 2

Method 3• Data system consists of:

• Actions change states• Events that trigger rules• Rules that consist of actions

• Need to ID all states and actions, and the non-determinism• What events trigger rules?• Need a set of metadata attributes == states of the state transition

system

Method 3• Mapping

• States• State Transitions• Non-determinism

• Interpreting the components of the OAIS Reference Model as a state transition system allows us to map the high level recommendations to machine code in a rigorous manner

• State transitions provide log information; log information == metadata; these attributes are stored in the metadata catalog

Method 4• If not a 1:1 mapping, need additional metadata

• Example: SIP AIP; AIP AIP; AIP DIP

• Use the OAIS Composite of Functional Entities to create “policy domains” in the preservation system. E.g., the OAIS Reference Model as a “state transition system”.

• State transitions provide logging information about each transition that may be preserved as metadata• Example, can store whether or not an object is part of a SIP or an

AIP as a metadata attribute attached to that object• No change = compliant• Change = not compliant

Method 4• Attach metadata for each area of the data grid• Similar to the OAIS Composite of Functional Entities• Combined with Customized Policies = a “policy domain”

Method 4

Conclusion 1

“Basing policy domains on [the OAIS Reference Model Composite of Functional Entities] enables the development of assessment criteria that evaluate the recorded state of each object and allow automated validation of the properties such as authenticity, integrity, chain of custody, and trustworthiness. Our approach makes the assessment of the preservation state of the archive amenable to formal, automated validation via state transition events metadata.”

Summary• We examined the “state of the state”• We detailed a method for abstracting state transition

systems from data management policies

“…this approach bridged the gap between concrete computer code and human-readable, abstract standards such as the OAIS Reference Model Functional Model by using metadata. We posit that this method may be applied to any preservation system in order to facilitate the certification of a trustworthy digital repository. “

Future Work• I finish my dissertation, which examines the “state of the

state”.• Capture how information objects in the OAIS RM may be

transformed, combined, or divided• Capture the static and dynamic aspects of the OAIS RM• Map iRODS policy enforcement points to the OAIS RM

semantics (static vs. dynamic)• Classify the policies required for repositories to create a

library of policies by domain or function• Define a formalism to verify these

states/transitions/actions

AcknowledgementsThis research is partially supported by NSF grant #0940841 “DataNet Federation Consortium” and NSF grant #1032732 “SDCI Data Improvement: Improvement and Sustainability of iRODS Data Grid Software for Multi-Disciplinary Community Driv- en Application”.

Questions? Comments?