FUNDAMENTALS AND CONCEPTS FOR LONG TERM … (Part 2) - Long-Term Archiving (LTA) of...VDA Part 2:...

VDA Recommendation 4958 Part 2, 1st Edition, June 2005 of 47

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Long term archiving (LTA) of digital product data, which are not based on technical drawings

VDA Part 2: LTA Reference Process

4958

This recommendation serves to establish basic, common requirements regarding the processes, data and organization of the long-term archiving of digital product data generated during product development.

It is the result of the project carried out by the VDA “Long-Term Archiving” project group, which is part of the VDA “CAD/CAM” working group. The VDA recommends its appliance.

Part 1 identifies requirements relating to the long-term archiving of product data that exists in digital form only and summarizes certain legal and technical aspects. Part 1 provides the basis for the other parts of the recommendation.

Part 2 describes typical application scenarios and provides recommendations for designing the processes used to prepare the data for long-term archiving, the archiving of the data itself, and the process steps required to access and reprocess the archived data. The primary goal is safeguarding the quality of the data and the documents.

Part 3 defines the minimum requirements to be satisfied by the archived information regarding the information in the 3D CAD representations and product structure descriptions from the user’s point of view and concerning the process definition.

Part 4 provides recommendations for the verification of reliable LTA workflows and data quality as a crucial part of any LTA architecture.

Work on Parts 3 ff. is currently in progress. They will be published once this work has been completed. Therefore modifications are possible.

1st Edition from June 2005

VDA Working Group "CAD/CAM"

Published by: Verband der Automobilindustrie Copyright

Westendstraße 61 Copies and any other form of

Postfach 17 05 63 duplication must include a correct 60079 Frankfurt citation of the source. Telefon 069/97507-284 Telefax 069/97507-300 Internet: [email protected]

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Disclaimer

The VDA recommendations “Long-Term Archiving (LTA) of digital Product Data, which are not based on technical drawings” are recommendations that are available for anyone to use. Anyone using these recommendations is responsible for ensuring that they are used correctly.

The VDA recommendations give due consideration to the prevailing state-of-the-art at the time of publication. Use of the VDA recommendations does not allow a person to avoid assuming responsibility for his or her actions. In this respect, everyone acts at their own risk. The VDA and the parties involved in drawing up the VDA recommendations assume no liability whatsoever.

We request that anyone encountering an error or the possibility of an incorrect interpretation when using the VDA recommendations contact the VDA immediately so that any errors can be rectified.

The document is a translated version of the German edition. Therefore the German document represents the original and shall be referenced in the case of discrepancies. Due to the translation it might be possible that the English text gives place for interpretations, because terms are often grounded deep in the original language and therefore it is not possible in any case to translate them uniquely into another language.


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Content

1 OBJECTIVE.............................................................................................................................9

2 SCOPE ....................................................................................................................................9

3 LIST OF ABBREVIATIONS, DEFINITIONS AND NORMATIVE REFERENCES.....................9

3.1 Abbreviations......................................................................................................................9

3.2 Definitions.........................................................................................................................10

3.3 Normative references .......................................................................................................10

3.4 Terms from OAIS (ISO 14721)..........................................................................................11

3.5 Role description ...............................................................................................................12 3.5.1 Role Data Creator........................................................................................................12 3.5.2 Role Preparer (Archive) ...............................................................................................12 3.5.3 Role Consumer............................................................................................................12 3.5.4 Role Administrator .......................................................................................................12 3.5.5 Role Management .......................................................................................................12 3.5.6 Role Examination team................................................................................................12 3.5.7 Role Archive ................................................................................................................12 3.5.8 Role Archive GUI.........................................................................................................12 3.5.9 Role Quality agent .......................................................................................................13 3.5.10 Role Validation agent...................................................................................................13

4 USAGE OF INTERNATIONAL STANDARDS .......................................................................13

5 FUNDAMENTALS AND CONCEPTS FOR LONG TERM ARCHIVING.................................13

5.1 OAIS Reference model .....................................................................................................13 5.1.1 OAIS environment .......................................................................................................13 5.1.2 Build up OAIS Data package .......................................................................................14 5.1.3 Differentiation OAIS – VDA4958-2...............................................................................15

5.2 Data verification and data validation...............................................................................15 5.2.1 Data verification...........................................................................................................15 5.2.2 Data Validation ............................................................................................................15 5.2.3 Approach to the accomplishment of a data validation ..................................................16

5.3 Definition core model .......................................................................................................17

5.4 Appliance of the core model............................................................................................18

6 PROCESS DESCRIPTION REFERENCE PROCESS ...........................................................20

6.1 Data Preparation...............................................................................................................21

Detailing of Data Preparation .....................................................................................................21 6.1.1 Preserved Data Selection ............................................................................................21 6.1.2 Initiate Quality Agent....................................................................................................21 6.1.3 Data Verification ..........................................................................................................21


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6.1.4 Automatic creation of Validation Properties possible?..................................................22 6.1.5 Automatic Creation of Validation Properties.................................................................22 6.1.6 Create Preservation Description Information (PDI) ......................................................22 6.1.7 Create Descriptive Information (DI)..............................................................................22 6.1.8 Create Submission Information Package (SIP)............................................................22 6.1.9 Manual Creation Validation Properties.........................................................................22 6.1.10 Error handling for data preparation ..............................................................................22 Detailing Data Verification..........................................................................................................23

6.2 Ingest.................................................................................................................................24

Detailing Ingest ...........................................................................................................................24 6.2.1 Submit for Ingest .........................................................................................................24 6.2.2 Receive Data...............................................................................................................24 6.2.3 Check Quality Assurance.............................................................................................24 6.2.4 Send Confirmation.......................................................................................................25 6.2.5 Generate Archival Information Package (AIP)..............................................................25 6.2.6 Examination Content Information (CI)..........................................................................25 6.2.7 Error Handling for denied Submission Information Package (SIP) ...............................25 6.2.8 Receive Confirmation ..................................................................................................25 Detailing Generate Archival Information Package (AIP) .............................................................25

6.3 Archival Storage ...............................................................................................................27

Detailing Archival Storage..........................................................................................................27 6.3.1 AIP Transfer to Main Storage ......................................................................................27 6.3.2 Initiate Digital Time Signature Process ........................................................................27 6.3.3 Set Digital Time Signature ...........................................................................................27 6.3.4 Store to Media .............................................................................................................27 6.3.5 Storage Assurance ......................................................................................................28 6.3.6 Update Descriptive Information (DI).............................................................................28 6.3.7 Update Meta Data Base ..............................................................................................28 6.3.8 Confirm the Archiving ..................................................................................................28 6.3.9 Generate Confirmation Report.....................................................................................28 6.3.10 Receive Confirmation ..................................................................................................28 6.3.11 Receive Confirmation ..................................................................................................28 6.3.12 Disaster Recovery .......................................................................................................28 6.3.13 Error Handling for Archival Storage .............................................................................28 6.3.14 Manual Edition of Descriptive Information (DI) .............................................................28

6.4 Retrieval ............................................................................................................................29

Detailing Retrieval.......................................................................................................................29 6.4.1 Request Retrieval Data................................................................................................29 6.4.2 Access.........................................................................................................................29 6.4.3 Data Selection .............................................................................................................29 6.4.4 Prepare Data for Dissemination...................................................................................29 6.4.5 Generate Dissemination Information Package (DIP)....................................................29 6.4.6 Provide Dissemination Information Package (DIP) ......................................................29 Detailing Data Selection.............................................................................................................30 Detailing Generate Dissemination Information Package (DIP) ...................................................31

6.5 Data usage ........................................................................................................................34

6.6 Optional: Remove............................................................................................................35


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Detailing Optional: Remove........................................................................................................35 6.6.1 Remove Request.........................................................................................................35 6.6.2 Initiate Remove Process..............................................................................................35 6.6.3 Access.........................................................................................................................36 6.6.4 Data Selection Removal ..............................................................................................36 6.6.5 Delete CI and PDI of AIP .............................................................................................36 6.6.6 Error Check Removal AIP............................................................................................36 6.6.7 Add Removal Information to Descriptive Information ...................................................36 6.6.8 Confirmation of Removal .............................................................................................36 6.6.9 Generate Confirmation Report.....................................................................................36 6.6.10 Receive Confirmation Report.......................................................................................36 6.6.11 Automatic Remove Request ........................................................................................36 6.6.12 Error Report of Removal..............................................................................................36 6.6.13 Error handling for AIP Deletion Failures.......................................................................36

6.7 Ingest of Pre-existing Data...............................................................................................38

7 DATA ELEMENTS.................................................................................................................38

7.1 AIP (Archival Information Package) ................................................................................38 7.1.1 OAIS Definition............................................................................................................38 7.1.2 Copy of AIP .................................................................................................................38

7.2 Authentication Secret Key ...............................................................................................38

7.3 Automatic remove request...............................................................................................38

7.4 CI (Content Information)...................................................................................................38 7.4.1 General definition ........................................................................................................38 7.4.2 CI in native format .......................................................................................................38

7.5 Data ...................................................................................................................................39 7.5.1 General definition ........................................................................................................39 7.5.2 Analysis results...........................................................................................................39 7.5.3 Formatting and documents standards..........................................................................39 7.5.4 In archive format..........................................................................................................39 7.5.5 In native format............................................................................................................39 7.5.6 In target format ............................................................................................................39 7.5.7 Process control data....................................................................................................39 7.5.8 Quality criteria..............................................................................................................39 7.5.9 Quality rules ................................................................................................................39 7.5.10 Validation property rules ..............................................................................................39

7.6 DI (Descriptive Information).............................................................................................39

7.7 DIP (Dissemination Information Package) ......................................................................39

7.8 Information........................................................................................................................40 7.8.1 Access granted information .........................................................................................40 7.8.2 Access input information..............................................................................................40 7.8.3 Access validation information ......................................................................................40 7.8.4 Access denied information...........................................................................................40 7.8.5 Authentication information ...........................................................................................40 7.8.6 Check digital signature information..............................................................................40 7.8.7 Confirmation information..............................................................................................40 7.8.8 Confirmation deletion Content Information...................................................................40


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7.8.9 Confirmation remove ...................................................................................................40 7.8.10 Descriptive Information error information .....................................................................40 7.8.11 Digital time signature ...................................................................................................40 7.8.12 Disaster recovery error information..............................................................................41 7.8.13 Error fix of meta information.........................................................................................41 7.8.14 Filter information for accessible data ...........................................................................41 7.8.15 Meta data base update information..............................................................................41 7.8.16 Reference information .................................................................................................41 7.8.17 Reset archiving trigger.................................................................................................41 7.8.18 Selection information ...................................................................................................41 7.8.19 Storage information .....................................................................................................41 7.8.20 Storage error information.............................................................................................41 7.8.21 Target format information.............................................................................................41 7.8.22 Technical error fixing information.................................................................................41 7.8.23 Trigger information ......................................................................................................41 7.8.24 Validation failure information........................................................................................41

7.9 Key data ............................................................................................................................41

7.10 Key ring..........................................................................................................................42

7.11 Data in native format.....................................................................................................42

7.12 New validation properties from archive formatted file ...............................................42

7.13 No...................................................................................................................................42

7.14 PDI (Preservation Description Information) ................................................................42 7.14.1 General definition ........................................................................................................42 7.14.2 PDI in target format......................................................................................................42

7.15 PI (Packaging Information) ...........................................................................................42

7.16 Report ............................................................................................................................42 7.16.1 General definition ........................................................................................................42 7.16.2 Confirmation report......................................................................................................42 7.16.3 Content error report .....................................................................................................43 7.16.4 Data preparation error report .......................................................................................43 7.16.5 Error report ..................................................................................................................43 7.16.6 Error report removal.....................................................................................................43 7.16.7 Error fixing report.........................................................................................................43 7.16.8 Integrity failure report...................................................................................................43 7.16.9 Meta data base update report......................................................................................43 7.16.10 Results report...........................................................................................................43 7.16.11 System error report ..................................................................................................43 7.16.12 Validation report.......................................................................................................43 7.16.13 Verification information report ..................................................................................43

7.17 Request..........................................................................................................................43 7.17.1 General definition ........................................................................................................43 7.17.2 Access request............................................................................................................43 7.17.3 Authentication..............................................................................................................44 7.17.4 Remove request ..........................................................................................................44 7.17.5 Time stamp..................................................................................................................44

7.18 Results ...........................................................................................................................44


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7.18.1 General definition ........................................................................................................44 7.18.2 Analysis results for validation properties......................................................................44 7.18.3 Check for removal information .....................................................................................44 7.18.4 Validation results .........................................................................................................44 7.18.5 Verification results .......................................................................................................44

7.19 Rules ..............................................................................................................................44 7.19.1 Access rules ................................................................................................................44 7.19.2 Automatic remove request...........................................................................................44 7.19.3 Validation rules ............................................................................................................44

7.20 Secret key......................................................................................................................44

7.21 Select source for validation properties .......................................................................45

7.22 Signature document order............................................................................................45

7.23 SIP (Submission Information Package).......................................................................45 7.23.1 General definition ........................................................................................................45 7.23.2 SIP data in archive format:...........................................................................................45

7.24 Support ..........................................................................................................................45

7.25 Time stamp....................................................................................................................45

7.26 Validation Properties ....................................................................................................45

7.27 Yes .................................................................................................................................45

APPENDIX A ................................................................................................................................46

1 METHODOLOGY OF PROCESS DESCRIPTION – SIMPLIFIED ACTIVITY DIAGRAM.......46

2 DOCUMENT STRUCTURE....................................................................................................47


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List of figures

Figure 1: OAIS environment .......................................................................................................13

Figure 2: Context Data object – representation information – Information object .................14

Figure 3: OAIS functional entities ..............................................................................................14

Figure 4: Build up of an OAIS Information package .................................................................14

Figure 5: Data verification and data validation .........................................................................15

Figure 6: General approach to a validation using Validation Properties (VP) illustrated by the example of a conversion from a SIP to an AIP...................................................................16

Figure 7: Example of the validation of information...................................................................17

Figure 8: Core model and extending possibilities schematically ............................................18

Figure 9: Appliance of the core model.......................................................................................19

Figure 10: Overview data flow ....................................................................................................20

Figure 11: Data Preparation........................................................................................................21

Figure 12: Data Verification ........................................................................................................23

Figure 13: Ingest .........................................................................................................................24

Figure 14: Generate AIP..............................................................................................................26

Figure 15: Archival Storage........................................................................................................27

Figure 16: Retrieval .....................................................................................................................29

Figure 17: Data Selection............................................................................................................30

Figure 18: Generate DIP..............................................................................................................31

Figure 19: Automatic Validation of Dissemination Information Package (DIP).......................32

Figure 20: Data Verification for DIP............................................................................................34

Figure 21: Optional: Remove......................................................................................................35

Figure 22: Data Selection Removal............................................................................................37

Figure 23: Example of a simplified activity diagram.................................................................46

Figure 24: Hierarchical structure of the process description ..................................................47


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1 Objective

The part 2 of VDA 4958 “Long term archiving (LTA) of digital product data, which are not based on technical drawings“ provides recommendations for the layout of LTA processes. Its validity is connected to the other parts of the recommendation.

2 Scope

The recommendations are relevant for development and documentation processes, which are based on 3D representations (3D master models). These representations give a description of the current existing, established and the technical status quo of the 2D archiving processes, which are no longer applicable, due to technical or economical reasons for the 3D-mastermodels.

The reference process description obtains to 3D CAD data within the scenarios written above. In case of the reference process implementation it is necessary to fulfil the common legal rules and recommendations of archiving, like security and backup services within the archiving system, for these digital data.

The used definitions do not represent a system description. The addressed systems are only described throughout their functionality, which are relevant for and necessary to the archiving and retrieval process.

3 List of abbreviations, definitions and normative references

3.1 Abbreviations

3D three Dimensional

AIC Application Interpreted Construct

AIP Archival Information Package

AP214 Application Protocol 214 – ISO 10303-214

CAD Computer Aided Design

CAx Computer Aided Technologies like CAD, CAM (Computer Aided Manufacturing), CAE (Computer Aided Engineering) or CAT (Computer Aided Testing)

CI Content Information

CRC Cyclic Redundancy Checks

DI Descriptive Information

DIP Dissemination Information Package

EDV Elektronische Daten Verarbeitung

EU European Union

GUI Graphical User Interface

HTML HyperText Markup Language

ID Identification

IDEF Integration DEFinftion for function modelling

ISO International Organization for Standardization

OAIS Reference Model for an Open Archiving Information System

PDI Preservation Description Information

PDM Product Data Management

PI Package Information


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SIP Submission Information Package

STEP STandard for the Exchange of Product Model Data

TDM Team Data Management

UML Unified Modelling Language

V Volume

VDA Verband der Automobilindustrie

VP Validation Properties

WORM Write once read many

3.2 Definitions

3D model: is a three dimensional representation of digital data which describe a product by defining the shape of the product.

Archiving: Certified processes for the writing, storing / retention and retrieval of information within the archive.

Core model: Identifies the necessary minimum of the data, rules and dependencies, which ensures the interpretability (concerning functionality and features) during the archiving period.

Digital engineering-signature: is a digital signature, which will be normally used to confirm of the correctness of the document. Important for the signature is the reference to the signing person.

Digital time- signature: normally an automatic created digital signature, which seals a document. Important for the signature is the time stamp.

Document: A document is a logical container for product defining data. A document may be associated to an item or another object and is either represented in physical (paper, microfiche) or digital form.

File: A file is an atomic container of data on a computer storage medium

Master model (also 3D Master): is a 3D model representation of a product and contains the detailed geometric description of the shape, but also information about e.g. mass, tolerance and further product defining data. A master model is normally used as the source for deriving further documents needed for the product description.

Meta data: combine all non geometric product data

Validation Properties: Predefined parameters which are used to check the validity of, for example, a geometric model or the hierarchy of a product structure after the conversion of Content Information. Validation properties examples include centre of gravity and number of assembly knots within a product structure.

Version: A version represents a specific stage of design or maturity of a part, document, or geometric model.

3.3 Normative references

The recommendation leans against existing standards with a high diffusion rate.

ISO 10303-214: Industrial automation systems and integration - Product data representation and exchange: Part 214 Application Protocol: Core data for automotive mechanical design processes

ISO 14721: Space data and information transfer systems - Open archival information system - Reference model


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3.4 Terms from OAIS (ISO 14721)

For the process description VDA4958-2 references the functional model of „Open Archival Information System – OAIS” of ISO 14721. Ensuring the greatest possible compatibility to OAIS and its terms and definitions this document refers to the detailed descriptions of the terminology used in ISO 14721 (see 5.1).

A selection of fundamental terms from ISO14721 (OAIS) will be explained as following:

Archival Information Package (AIP): The AIP consists of the following elements:

- Content Information (CI) (archiving formatted and optionally native formatted)

- Packaging Information (PI)

- Preservation Description Information (PDI) (Validation Properties, context information for the Content Information)

- Digital Signature Information

Archival Storage : The process comprises accompanying process steps of the archival storage process steps. This includes the update of the Descriptive Information (DI) (meta data for the AIP’s), the physical storage of the data as well as an examination for possible errors.

Content Information (CI): includes the set of information that is the original target of preservation.

Descriptive Information (DI): represents the meta data of the archiving system. The DI is the set of information, consisting primarily of Package Descriptions, which is provided to Data Management to support the finding, ordering, and retrieving by Consumers of archived information holdings. The descriptive information will be extended with the storage information (e.g. according to ISO9660).

Information package : are data packages used for the communication with and within the archival system

Ingest: During the Ingest process the role preparer submits the Submission Information Package (SIP) from the preparation environment into the archiving environment.

Package Information (PI): is used to bind and identify the components of an Information Package.

Provenance Information: Provenance describes the source of the Content Information, which has had custody of it since its origination, and its history (including processing history).

Preservation Description Information (PDI): is the information which is necessary for adequate preservation of the Content Information and which can be categorized as Provenance, Reference, Fixity, and Context information.

Remove: During the remove process the data will be deleted from the archival system. Data removal can be initiated either by the roles Administrator or by an automatic request generated by the archive.

Retrieval: Retrieval of archived data from the archive for a consumer. The process includes a recommended access check, provides functionality for a data search to select the required data and for converting them into the desired data format:

Presentation Information: is an information, which is necessary to make the information presentable for the consumer, (e.g. display presentation of a 3D CAD model)

Submission Information Package (SIP): consists of the following main information objects:

- Content (native formatted data)

- Preservation Descriptive Information (Validation Properties)

- Context information (regarding the content information)

- Packaging Information:


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3.5 Role description

The enlisted roles are part of the process description. The roles secure the assigned process steps as well as the relating functions. They can either be persons or system roles. They do not represent any system limits.

3.5.1 Role Data Creator

The data creator is an organization, person, or client system, which provides the information to be preserved. This can include other archives or internal archive personnel or system components. Typical roles of type "data creator" may be. System Designers, Design Engineers, Subcontractors, Manufacturers or Test Engineers

3.5.2 Role Preparer (Archive)

The preparer (Archive) is an organization, person, or IT-system, which prepares the information to be archived This can include other archives or internal archive personnel or system components. Preparation procedures include e.g. the Generation of AIP process.

3.5.3 Role Consumer

The consumer is an organization, person, or client system, which interacts with the services offered by the archive to find preserved information of interest and to access that information in detail. This can include other archives, as well as internal archive personnel or system components. Typical roles of type "consumer" may be Design Engineers, Suppliers, Manufactures, Customers, Regulatory and Certification Agencies or Quality Departments

3.5.4 Role Administrator

The Administrator is an organization or person, that is responsible for the management of the archive and daily operation. The role performs actions such as access control, monitoring and error handling. The role is not directly involved in the archiving and retrieval processes. The role may not be responsible for the administration of further external tools like quality agents, the evolved TDM, CAx, PDM or Data Exchange applications.

3.5.5 Role Management

Management represents a person or department, which is responsible for the management of the automotive product. The management makes strategic decisions, e.g. Removal of data from the archive.

3.5.6 Role Examination team

Represents the approving organizations or persons of a company. The approving team approves the AIP before the AIP is stored within the archive.

3.5.7 Role Archive

The Archive is the archiving environment, which usually supports at least the key functions of an archiving architecture according ISO 14721 (OAIS). Key functions are administration, data management, archival storage, access control, preservation planning.

3.5.8 Role Archive GUI

The Archive GUI represents a graphical user interface. The user of the archive will interact with the archive via the GUI.


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3.5.9 Role Quality agent

It is recommended that the Quality Agent is a system (tool set) but it may be an organization or person which is responsible for completeness, quality and consistency of the data to be retained according to a defined list of quality criteria.

3.5.10 Role Validation agent

The Validation agent is primary a system (tool set) or secondary an organization or person, which is responsible for verification of the validity of the data content.

4 Usage of international standards

To fulfil the long term archiving of product data in an adequate process and data quality, the reference process description, the used data formats and the data packages are based on international standardized methods, concepts and standards (see chapter 3.3 ff. and 6). The use of international standards raises the level of acceptance for the designated community and raises the level of interoperability between systems and data formats. Furthermore the usage of standards improves the length of time the data may be kept without a loss and simplifies the definition of processes, system architecture, implementation and certification.

5 Fundamentals and concepts for long term archiving

5.1 OAIS Reference model

5.1.1 OAIS environment

The OAIS environment is derived from the interaction of four roles: producers, consumers, management and the archive itself.

Figure 1: OAIS environment

Within the interaction information will be exchanged, which are relevant for the archiving inside the archiving system. These information are defined as the knowledge base. Data object can be information of any kind. They exist in two ways, in a physical representation (e.g., as a paper document) or in a digital representation. During the interaction (data exchange) between the roles the representation will change. This kind of alteration is combined under the term of Representation Information. The Representation Information is an information which is necessary to convert the received information into a user understandable form (e.g., display of a 3D CAD model on a screen). An information object is only interpretable by an IT- system. The following figure clarifies the context.


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Figure 2: Context Data object – representation information – Information object

The interactions within the OAIS environment are explicitly described using main functions, system data and data packages. The following figure gives an overview of the elements used in OAIS.

Figure 3: OAIS functional entities

OAIS focuses on the five main process modules: Preservation Planning, Data Management, Ingest, Archival Storage, Access and Administration.

5.1.2 Build up OAIS Data package

Within the information exchange (data to the Archive or data from the Archive to the target system) special data packages will be used. According to the relevant process the content of these data packages can differ, but the basic build up of the packages is independent from the relevant process. The following figure describes the basic build up of the information packages

Figure 4: Build up of an OAIS Information package

The Content Information (CI) represents the information which is the original target of preservation. The CI will be further described by the Preservation Description Information. The package may


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change during its generation and archiving process, e.g. the data will be packed. This kind of information, and further system relevant information, like the size of the package will be combined and stored within the Package Information. The Descriptive Information represents the meta data for the Archive. Part of the Descriptive Information could be a short title and description of the archived data as well as reference information e.g. storage place within the archive.

5.1.3 Differentiation OAIS – VDA4958-2

OAIS provides a detailed description of dependencies and interactions of the main functionalities within the archiving architecture. The basic functionality of e.g. the module Archival Storage shall be achieved by an implementation of a current existing archiving software and hardware. Therefore the module Archival Storage is out of scope of VDA4958-2. VDA4958-2 extends the functionality of the archival storage module about the usage of a digital time signature.

There are no recommendations regarding the definition of the archiving format or descriptions that ensures the data quality within OAIS. This will affect the definition of the minimum subset of information, which must at least be available ensuring that the data will be interpretable by a user after a retention period X.

5.2 Data verification and data validation

Source data Target dataValidation compares two models against each other

∆Vol < Toleranceif TRUE⇒validation passed

Volume1 = x m3 Volume1 = y m3conversionconversion

Verification: compares model against set of rules

Valid

ati

on

Veri

ficati

on

Verification rule:ARE THERE CRACKS WITHIN THE SHAPE?

Check resultFALSE ⇒verification passed

Check resultTRUE ⇒verification failed

Figure 5: Data verification and data validation

5.2.1 Data verification

The data verification ensures the data quality of the data to be archived. Verification rules shall ensure that a data representation meets the quality requirements within defined tolerances. A verification is successful if no verification rule is violated.

Only verification rules belonging to the core model (see chapter 5.3) are part of VDA4958-2.

5.2.2 Data Validation

Data validation aims at the examination, whether e.g. the prepared (converted) Content Information (CI) correspond to the Content Information, which were sent to the archive. Validating can be accomplished by a direct comparison based on pre-defined Validation Properties (VP). I.e.,


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the Validation Properties, which are created in the source system will be compared with the Validation Properties, which are created within the process based on the converted CI.

If a creation of new Validation Properties is not possible out of the converted CI, the following methods can be used as a substitute:

- conversion loop: data in the native data format are converted into a neutral data format and back again into the native format. Subsequently, the new Validation Properties are created out of the resulting native data from the loop and will be compared with the Validation Properties of the source data.

- verification of the archived data based on a set of rules

5.2.3 Approach to the accomplishment of a data validation

1. Creation of defined VP- generated by the

source system

3. Creation of defined VP-generated by the

target system

4. Comparison of validation properties

SourceDocument

Archive Document

SIP AIP

2. Transfer to Archive

5. Feedback to system

1. Creation of defined VP- generated by the

source system

3. Creation of defined VP-generated by the

target system

4. Comparison of validation properties

SourceDocument

Archive Document

SIP AIP

2. Transfer to Archive

5. Feedback to system

Figure 6: General approach to a validation using Validation Properties (VP) illustrated by the example

of a conversion from a SIP to an AIP

In step 1 pre-defined values for the examination (Validation Properties) are generated within the source system. The VP are stored in the SIP. Within step 2 the SIP is converted into an AIP during the transfer into the archive, i.e., into the LTA data format. In step 3 the generation of new VP out of the LTA data format of the AIP takes place. A comparison of the old and new VP is now possible within step 4. In a further step 5 the result of validation (feedback information) is made available. If the data validation is not successful the Producer or Preparer may have to improve the data quality on demand.

The following illustration shows an example, how to proceed the validation of the Validation Property V=1m³ of a 3D CAD model. A more detailed description of the elements used in Figure 7 follows in chapter 7.


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A I PS I P

Provenance: Result:

r Rejection/ Acceptance inf.

CATIA-FILE,

include Props. V=1M3

CI

CATIA-FILE,

include Props. V=1M3

CI

Fixitiy:Source

Val. Props: V=1M3

PDIFixitiy:Source

Val. Props: V=1M3

PDIG

ene

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ene

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STEP File, include Props.

V=1.001M3

CI

STEP File, include Props.

V=1.001M3

CI

Fixitiy:Target Val.

Props: V=1.001M3

Provenance:Source Val.

Props-> V=1M3

Archive Admin.dataPart Name, ID, ..

DI


DI


DI

PDI

Ge

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Archive Admin.dataPart Name, ID, Digital signature for AIP.

DI


DI


DI

ConversionConversion

Mapping

Validation of: SIP/ CI <-> AIP CI, by using Val. Props.Result: r between Val. Props., incl. Rejection/

Acceptance information

new entry

Figure 7: Example of the validation of information

The Validation Property V with its value 1m³ is defined within the producing system. This value is part of the Content Information of the SIP and is written into the PDI during data preparation. Within the Ingest process the SIP is converted into an AIP. Due to the conversion processes the value of the VP within the Content Information of the AIP can slightly differ from the original value (here: V=1,001m³). For validating purposes the Validation Property is newly generated out of the converted Content Information. This has the new value V=1,001m³ either. The value is stored within the PDI as fixity information. The original value of the Validation Property is additionally stored as provenance information within the PDI of the AIP. A comparison of the original and new Validation Property is now possible. The result of the investigation is also stored within the PDI of the AIP as provenance information. Thus the results are available for a later Retrieval process.

5.3 Definition core model

The core model identifies the necessary minimum of data, which is needed to preserve the interpretability of the designed model (concerning functionality and characteristics) during the retention period. The core model consists of defined data elements, the representations of the model and the requirements regarding the data quality1, which the data elements shall accomplish.

The use of a core model does not exclude the archiving of additional information or a redundant storage in an alternative format. These alternative formats can offer additional functionalities regarding, e.g., preservation of additional knowledge about the designed model or concerning a support of interoperability between the used systems. Nevertheless it should be taken into account that these additional information are exposed to an increased risk of becoming useless during the

1 The definition of data quality can base on e.g. following documents:

- VDA4955: Extent and quality of CAD/CAM-data

- SASIG - Product Data Quality (PDQ) Guidelines for the Global Automotive Industry, which are

currently submitted to the ISO as New Work Item Proposal (NWIP). They contain definitions of rules

regarding data quality (geometry).

- EN9300-110 of the AECMA-STAN LOTAR project describes a set of rules through the “Core Model

for 3D Explicit Geometry Data”, which is based on EXPRESS rules.


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retention period, since it does not have to correspond to the quality requirements of the LTA as, e.g., a representation in a standardized LTA conform data format. The extension of the archive packages concerning additional information must be specified in the agreements, which are made between the archive organization and its customer (Preparer, potential consumer).

The following illustration shows one possibility to extend the core model of a single geometrical part with additional information and formats.

Core Modelz.B. Advanced B-REP acc. toAIC 514ISO10303

Content Informatione.g. profile of a single part within the standard tolerances

Extension of formats

Ext

ensi

on

of

info

rma

tion Archived

STEP-File, contains created geometry definition and history

Archived CATIA Source-File

Archived Vismock-Up JT-File:TesselatedGeometry

AIP

Figure 8: Core model and extending possibilities schematically

The actual content of the core model is a geometrical model, represented by, e.g., an Advanced B-Rep model converted according to ISO10303-214 (AIC514). In this case additional content of the archive package could be a construction history, the proprietary CAD-file (CATIA source file) and/or a JT-file with the tessellated representation of the CAD geometry

5.4 Appliance of the core model

Within the data preparation process the data, which are to be archived, are prepared by the Preparer. Due to the conversion of the data into the LTA conform data representation it is in most cases not possible and often also not necessary (economically) to retain the entire spectrum of functionalities and intentions of the models. The Preparer shall prepare the data in a way that the fundamental functions remain, which are necessary, e.g., for the homologation of an assembly. It is ensured by the definition of the core model defining the relevant data extent for the LTA (see VDA4958-3).

The core model is represented first by data in the native format, which are converted into the LTA data format within the Ingest process. The examination of the correct conversion takes place via a data validation.


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Content Information

(Native Model)

SIP(Native Format)

ttIngest Retrieval

DIP (Native Format)

AIP(3DModel in LTA Format, e.g. STEP AP 214)

Core Model

Producer

Content Information relevant for retention

Other Content Information (not retained in the archive)

Consumer

LTA relevantDesign Content

Archive System

Represented by

Converter Converter

Represented by

Represented by

Controls Controls

Figure 9: Appliance of the core model

The applied neutral AIP data format should at least provide a level of stability preventing fundamental changes of the archived data across the retention period. Due to the long retention periods it can be possible that an archive data format will no longer be supported. This leads to the fact, that it could be necessary to convert the original data format into a new data format within the retention period. The use of standardized and revealed data representations however can provide protection against multiple iterated conversions.

Within the Retrieval process the archive data is converted into a further representation (DIP). This representation depends on the kind of the Retrieval. If an inspection of the data is sufficient, it is possible to use a Viewer Tool. Another case could be the import of the data into a current/future CAD system. For this purpose the data must be converted into the proprietary (native) data format of the target system.

The conversion steps are controlled by the core model and the Validation Properties.


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6 Process description reference process

In the following the LTA reference process is described according to the methodology and illustration in Appendix A.

Figure 10: Overview data flow

The process step "overview data flow" is organized along the life cycle of the data to be archived. For this the role "Producer" has to create the Content Information. Afterwards, the role "Preparer (archive)” has to prepare the created Content Information for archiving during the Data Preparation process . Afterwards the resulting Submission Information Package (SIP) will be sent during an Ingest process to the Archive System. Within the Archival Storage process the SIP will be converted into an Archival Information Package (AIP). This includes the conversion of native formatted product data into the archive format as well as the signing of the data with a digital time signature. The process Archival Storage contains the accompanying steps of the data archiving. For reuse or viewing, the data Consumer has the ability to retrieve the archived data. The archiving system provides in addition the optional Remove Process step.

The Ingest process for pre existing data describes the automatic process of conversion and storage of an already existing archive (and data) into the recommended archive format.

The phases 'Data Generation' and 'Data Usage' and enclosing Process steps are out of VDA-LZA. The phases and the process steps are only integrated for process modelling reasons.


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6.1 Data Preparation

Figure 11: Data Preparation

The data to be archived will be prepared by the Preparer. This includes a defined automated data verification, performed e.g. by the role Quality Agent. Data Preparation also includes the creation of Validation Properties. These process steps can be supported by the role Quality Agent too. If necessary the Preparer may perform an error handling, because only the role Preparer has the responsibility for the Content Information.

Detailing of Data Preparation

6.1.1 Preserved Data Selection

The Preparer selects data for archiving within a domain depended process. The process step represents the initial trigger for the archiving process. As an example, the selection can be performed by a product structure viewer of a CAD/PDM system or by a release trigger information coming from the Data Creator.

The selected e.g. CAD or Meta information defines the Content Information (CI) of the future SIP.

6.1.2 Initiate Quality Agent

The process is necessary due to special requirements of long term archiving. The Content Information must meet with the recommended data quality criteria, ensuring the readability and interpretation of the archived data by future systems. The process step is under the responsibility of the role Preparer.

6.1.3 Data Verification

The role Quality Agent performs a data verification. The data verification includes the analysis of the current data quality according to the recommended data quality demands. A verification is successful if no verification rule is violated.


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6.1.4 Automatic creation of Validation Properties possible?

The Preparer has to decide, if a manual or automatic creation of Validation Properties is performed.

6.1.5 Automatic Creation of Validation Properties

The Preparer (Archive) initiates the source system to generate Validation Properties automatically. The Validation Properties are used later on for validation within the process step "INGEST - Generate AIP".

Possible Validation Properties are:

- Validation Properties for 3D CAD Data, e.g. weight, centre of gravity.

- Validation Properties for meta data information, e.g. Hash code

It is recommended that Validation Properties shall be extracted from the Content Information directly. Alternatively Validation Properties can be generated manually and saved within the Preservation Description Information (PDI).

6.1.6 Create Preservation Description Information (PDI)

The Preparer (Archive) creates the Preservation Description Information (PDI). The PDI is the information which is necessary for adequate preservation of the Content Information and which can be categorized as Provenance, Reference, Fixity, and Context information. As an addition for VDA4958, the Producer shall integrate Validation Properties information into the PDI to ensure the existence of Validation Properties for later automatic validation processes.

6.1.7 Create Descriptive Information (DI)

The Preparer (Archive) creates a set of Descriptive Information (DI) which includes archive meta data meeting the archives requirements. The Descriptive Information includes a reference to the data verification results report.

6.1.8 Create Submission Information Package (SIP)

The Preparer creates a SIP by combining the DI, PDI and CI into one package, supported by the system. The SIP contains also Packaging Information (PI). The PI is that information which, either actually or logically, binds, identifies and relates the CI and PDI. The SIP will be transferred to the archive.

The formats of the packages are defined in a submission agreement between the Preparer and the archiving organization. After the preparation of the Information Package the source data may get the status “read only”, so that changes yield into a new version of the data.

6.1.9 Manual Creation Validation Properties

The Preparer may have the possibility to create a set of predefined Validation Properties manually, in the case that the producing system is not able to calculate the needed Validation Properties. The manual creation of Validation Properties must be documented within the archiving process for reasons of traceability. This includes the basis data for the Validation Properties and the expected results.

6.1.10 Error handling for data preparation

In case of defective Content Information the Producer is responsible for the analysis and error handling for the Data Preparation process.


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Detailing Data Verification

Figure 12: Data Verification

The role Quality Agent performs a data verification. The data verification includes the analysis of the current data quality according to the recommended data quality demands. A verification is successful if no verification rule is violated.

6.1.3.1 Load Set of Data Quality Rules

The Quality Agent loads the set of data quality rules relevant for the Content Information e.g. 3D CAD model.

6.1.3.2 Verifying Content Information (CI)

The Quality Agent verifies the Content Information against the relevant set of data quality rules.

6.1.3.3 Generate Verification Information Report

The Quality Agent generates a verification information report which contains the verification results.

6.1.3.4 Verification o.k.?

The Preparer (Archive) must decide whether the result of the verification corresponds to the recommended data quality rules. In the case of a positive decision the Data Preparation process is continued. In the case of a negative decision the Preparer (Archive) must again accomplish the Data Preparation process. This can lead to the fact that e.g. 3D CAD models must be revised or a further analysis concerning the data quality has to be conducted. The Preparer should come to the decision if necessary in consultation of the Producer.


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6.2 Ingest

Figure 13: Ingest

During the Ingest process the role Preparer submits the Submission Information Package (SIP) from the preparation environment into the archiving environment. The archive receives the data packages and checks if the SIP contains data of the recommended format and then generates the Archival Information Package (AIP).

Detailing Ingest

6.2.1 Submit for Ingest

The Preparer initiates the submission of the SIP from the working environment to the archive.

6.2.2 Receive Data

The archive receives the SIP. The SIP shall be kept within the archives working environment for further processing during the Ingest process, due to validation reasons.

6.2.3 Check Quality Assurance

The process step checks the quality of the ingested data. This includes the successful transfer of the SIP to the staging area. For digital submissions, these mechanisms might include Cyclic Redundancy Checks (CRCs), or Checksums associated with each data file, or the use of system log files to record and identify any file transfer, or checking for media read/write errors. In addition to OAIS recommendations, the function checks the types of data formats used and the existence of PDI within the received SIP.

The exchanged data and its representations must be stipulated in the submission agreement between the Archive and the Producer. Stipulations may cover aspects such as:

- CAD data formats and Model files

- PDM data formats such as STEP.


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6.2.4 Send Confirmation

The Archive creates a report of the successful receiving of the SIP into the archives working environment.

6.2.5 Generate Archival Information Package (AIP)

The Archive performs the generation of an Archival Information Package (AIP) automatically. This includes the conversion of the Content Information from the submitted native format into the archiving format, the validation of the converted data and generation of any additional Descriptive Information (the meta data for the Content Information).

6.2.6 Examination Content Information (CI)

This process step is optional and synchronizes with the Producer's digital engineering signature process, such that the examination team will check the Content Information. After the check the archive proceeds with the process. In exceptional cases that the Content Information does not pass the check, it has to be adapted within another Data Generation process. The process step Data Generation has to be restarted again.

6.2.7 Error Handling for denied Submission Information Package (SIP)

Within this process the Preparer has to perform an error handling procedure in the case of incomplete transition of the SIP. This includes that the process step Data Preparation has to be done again regarding the stipulation made between the Data Creator, the Preparer and the Archive.

6.2.8 Receive Confirmation

The Preparer receives the confirmation which includes the information about the SIP’s successful ingestion.

Detailing Generate Archival Information Package (AIP)


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Figure 14: Generate AIP

The archive performs the generation of an Archival Information Package (AIP) automatically. This includes the conversion of the Content Information from the submitted native format into the archiving format, the validation of the converted data and generation of any additional Descriptive Information (the meta data for the Content Information).

6.2.5.1 Check Current Format

The Archive checks and has to decide if the current data format of the SIP Content Information belongs to the agreed data formats. Possible data formats can be :

- CAD / Meta information in native data formats

- SIP in neutral data formats.

Based on the analysed SIP format, the archive initiates either the conversion of the native formatted content information into the archive format or the automatic validation of the SIP into the neutral data format.

6.2.5.2 Convert Content Information (CI)

The archives converts the native formatted Content Information into the recommended neutral archive format. The conversion will be supported by preservation planning.

6.2.5.3 Automatic Validation of SIP

The archive (or the validation agent) performs an automatic validation process. Aim of this process is to check if the converted content information accords with the original model representation. The validation will be done by the comparison of defined validation properties.

6.2.5.4 Provide Validation Report

The archive provides a validation report.

6.2.5.5 Validation ok?

The archive has to verify if the validation was performed according predefined rules supported from preservation planning.

If the validation was correct, the archive will perform the generation of the archive Information package.

In cases of occurring failures the archive creates an error report, which is related to the validation.

6.2.5.6 Generate Package

The Archive will generate the Information Package (IP) by adding Content Information and Preservation Descriptive Information into one package. The addition of Packaging Information finishes the generation of the Information Package.

6.2.5.7 Error Handling for Generate AIP

In cases of erroneous generation of Information packages the Preparer is responsible for the error handling.


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6.3 Archival Storage

Figure 15: Archival Storage

The process comprises accompanying process steps of the archival storage process steps. This includes the update of the Descriptive Information (DI) (meta data for the AIP’s), the physical storage of the data as well as an examination for possible errors. Each company should meet the general recommendations for an archive system and its security. These general recommendations are out of scope. Process Steps #4, #5, #7 and #12 are out of scope of VDA4958-2. They are only shown for completeness.

Detailing Archival Storage

6.3.1 AIP Transfer to Main Storage

The Archive transfers the AIP from the working environment to the physical storage environment and generates the Administrators trigger information for the generation of a digital time signature.

6.3.2 Initiate Digital Time Signature Process

The Administrator initiates the digital time signature process

6.3.3 Set Digital Time Signature

The Archive sets a digital (time) signature according to the applicable EU-digital signature law. This assures the data integrity, readability and exchangeability during the retention period, and may be used as evidence when identifying the provenance of the information.

6.3.4 Store to Media

The Archive stores the AIP physically onto a medium according to meet the requirements of long term archiving and the availability of the stored data.


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6.3.5 Storage Assurance

The storage assurance function validates the successful transfer of the AIP to the staging area. For digital submissions, these mechanisms might include Cyclic Redundancy Checks (CRCs) or checksums associated with each data file, or the use of system log files to record and identify any file transfer or media read/write errors.

6.3.6 Update Descriptive Information (DI)

The Archive updates the set of descriptive information regarding the storage assurance and digital time signature information.

6.3.7 Update Meta Data Base

The Archive generates a new entry within the archives meta data base. The new entry contains the descriptive information plus the reference information, which defines the storage location.

6.3.8 Confirm the Archiving

The archive confirms the archiving process after the update of the meta data base.

6.3.9 Generate Confirmation Report

The Archive generates a confirmation report which includes the feedback information.


The Administrator receives the archival confirmation which includes the information about the AIPs successful storage.


Optional the Preparer receives the archival confirmation, which includes the information about the AIPs successful storage.

6.3.12 Disaster Recovery

The archive duplicates the AIP and stores the duplicate in separately.

6.3.13 Error Handling for Archival Storage

Within this process the Administrator is responsible for the error fixing procedures in case of incorrect storage of archiving information packages, update of meta data base or preparation for disaster recovery.

6.3.14 Manual Edition of Descriptive Information (DI)

The Administrator must have the ability to edit and attach several descriptions to the AIPs. The additional Descriptive Information could be, for example, the end of production date for a product - this is not known at the time the data is stored. The changes must be marked and be traceable.


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6.4 Retrieval

Figure 16: Retrieval

The process includes a recommended access check, provides functionality for a data search to select the required data and the generation of a Dissemination Information Package (DIP). The generation of the DIP should meet the requirements of the data receiver (Consumer/ Administrator).

Detailing Retrieval

6.4.1 Request Retrieval Data

The role Consumer/ Administrator initiates a retrieval request for a data package. The request shall contain all information needed for the successful retrieval process i.e. selection of requested data.

6.4.2 Access

The Archive centrally supervises the access rights for each role. Access has to be documented.

6.4.3 Data Selection

The Archive provides the functions to search for the requested data. Simultaneously the user’s access rights are checked.

6.4.4 Prepare Data for Dissemination

The Archive prepares the data for the retrieval, which includes checks of the validity of digital time signatures and the provision of copies of the AIP for dissemination.

6.4.5 Generate Dissemination Information Package (DIP)

The archive generates the Dissemination Information Package (DIP), which is derived from one or more AIPs. The DIP generation includes any conversion of Content Information into the required data format and validates the converted data.

6.4.6 Provide Dissemination Information Package (DIP)

The Archive transfers the DIP from archive environment to consumer's working environment.


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Detailing Data Selection

Figure 17: Data Selection

The Archive provides the functions to search for the requested data. Simultaneously the user’s access rights are checked.

6.4.3.1 Check for References

This process step checks if the data has references to other archived data packages. In cases of positive results, i.e. the data is referenced or references another data package, the references are read out.

6.4.3.2 Perform Filter for Data Collection

The Archive performs a filter function for the requested data depending on the consumers innocuousness rating.

6.4.3.3 Readout of DI

The Archive has to read out the descriptive information for the requested data. In cases of complete request information (e.g. exact part number, product structure information) the archive just has to interpret the descriptive information for that part. In cases of only partly know request information by the consumer, the archive has to readout the descriptive information of all e.g. parts which belongs to that request information.

6.4.3.4 Provide Collection

The Archive provides the list of stored elements which belong to the request information and which accord to the access rights of the consumer.

6.4.3.5 Provide list of possible target formats for data

The Archive provides the list of possible target formats for data.


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6.4.3.6 Select Data

The consumer / administrator has to select that kind of information from archives provided list, which is of interest.

6.4.3.7 Receive Selection

The Archive receives the data selection of the consumer / administrator.

Detailing Generate Dissemination Information Package (DIP)

Figure 18: Generate DIP

The Archive generates the Dissemination Information Package (DIP), which is derived from one or more AIPs. The DIP generation includes any conversion of Content Information into the required data format and validates the converted data.

6.4.5.1 Analyze Content Information (CI)

The Archive analyses the content information within the AIP.

6.4.5.2 Convert Content Information to target format

The Archive performs a data conversion of Content Information from archive format into the target format.

6.4.5.3 Automatic Validation of Dissemination Information Package (DIP)

The Archive performs an automatic validation process. Aim of this process is to check if the converted content information accords with the origin (archived) model representation. The validation will be done by the comparison of defined validation properties, i.e. validation properties generated by the origin (archive) system and validation properties newly generated within this process step.

6.4.5.4 Receive Validation Failure Report

The administrator receives the validation failure report.


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6.4.5.5 Data Verification for Dissemination Information Packages (DIP)

The Archive (or the system role quality agent) performs a data verification. The data verification includes the analysis of the current data quality according to the recommended data quality demands. A verification is successful if no verification rule is violated.

6.4.5.6 Convert PDI into target format

Convert PDI into target format.

6.4.5.7 Generate Package

The archive will generate the Information Package (IP) by adding content information and preservation descriptive information into one package. The addition of packaging information finishes the generation of the information package.

Detailing Automatic Validation of Dissemination Information Package (DIP)

Figure 19: Automatic Validation of Dissemination Information Package (DIP)

The Archive performs an automatic validation process. Aim of this process is to check if the converted content information accords with the origin (archived) model representation. The validation will be done by the comparison of defined validation properties, i.e. validation properties generated by the origin (archive) system and validation properties newly generated within this process step.

6.4.5.3.1 Analyze Data for Validation Properties for Retrieval

The Archive analyzes the current data for the existence of validation properties which should either be either stored within the Content Information and/or the Preservation Description Information

6.4.5.3.2 Are Val. Props. within CI?

The Archive checks if validation properties are stored within the Content Information.

6.4.5.3.3 Select Validation Properties from Content Information


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The Archive has to select validation properties within the Content Information.

If no Validation Properties are found within the Content Information, the following process step will be conducted:

6.4.5.3.4 Select Validation Properties from PDI

The Archive has to readout the validation properties from the PDI in case of missing PDI in the Content Information.

6.4.5.3.5 Calculate new Validation Properties from Content Information

The validation agent calculates new validation properties from the analyzed contend information. The calculation of validation properties is predefined and have to be stored within the archive.

6.4.5.3.6 Start Automatic Validation for DIP

The Validation Agent performs the validation whereas the model representation of the stored and the converted model will be checked based on Validation Property values.

6.4.5.3.7 Validation o.k.?

The Archive has to verify if the validation was performed according predefined rules supported from preservation planning. If the validation was correct, the archive will perform the generation of the archive Information package.

In cases of occurring failures the archive creates a validation failure report..

6.4.5.3.8 Generate Validation Failure Report

The validation agent generates a validation failure report, which will be provided to the administrator.

6.4.5.3.9 Receive Validation Failure Report

The Administrator receives the validation failure report.

Detailing Data Verification for Dissemination Information Packages (DIP)


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Figure 20: Data Verification for DIP

The Archive (or the system role Quality Agent) performs a data verification. The data verification includes the analysis of the current data quality according to the recommended data quality demands. A verification is successful if no verification rule is violated.

6.4.5.5.1 Load Set of Data Quality Rules

The Quality agent loads the set of data quality rules relevant for the Content Information e.g. 3D CAD model.

6.4.5.5.2 Verifying Content Information

The Quality Agent verifies the Content Information against the relevant set of data quality rules.

6.4.5.5.3 Generate Verification Information Report

The Archive generates a verification information report which contains the verification results.

6.4.5.5.4 Data Verification for DIP ok?

The Administrator has to decide if the verification analysis results bears up against the recommended data quality criteria. In case of a positive decision the data verification process will be continued. In case of negative results the Administrator has to restart the data verification process.

6.4.5.5.5 Error Handling for Data Verification

The Administrator has to perform, if possible, an error handling for data verification process.

6.5 Data usage

The process step Data Usage includes the import of the content information and the preservation descriptive information out of the DIP into the (future) target system (viewer,...). The process step is out of scope for VDA4958-2.


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6.6 Optional: Remove

Figure 21: Optional: Remove

Data removal can be initiated either by the roles Administrator or by an automatic request generated by the archive. The removal can be performed in two ways:

- deletion of relevant data or

- outsourcing of data, for example into a (technical) museum, which does not meet the requirements of a long term archive.

The process includes access control functionality for security reasons and data selection functionality for manual selection. The Content Information of the AIP will be deleted from the archive, but the deletion information remains within the archive's meta data. The remove process checks afterwards the data is correctly deleted and provides a status report. Because data may be stored on permanent media, each company has to decide if a removal process of data be implemented.

The process steps #5 'delete CI and PDI of AIP' and #6 'error check removal AIP' are integrated for process modelling (completeness) reasons.

Detailing Optional: Remove

6.6.1 Remove Request

The management should decide on the length of retention periods and removal requirements. If data is declared as removable, the management initiates a remove request for the archive.

6.6.2 Initiate Remove Process

The administrator has to initiate the remove process for defined information after getting the managements notification of the removal or an automatic remove request generated by the archive.


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6.6.3 Access

The Archive centrally supervises the access rights for each role. Access has to be documented.

6.6.4 Data Selection Removal

The Archive provides functions to search for the requested data.

6.6.5 Delete CI and PDI of AIP

The Archive deletes the Content and Preservation Information from the physical storage. It is recommended that the AIP´s Descriptive Information will remain within the archives meta data base and will be updated with the deletion information of that AIP.

6.6.6 Error Check Removal AIP

The Archive checks the complete deletion of Content and Preservation Description Information from the archives physical storage.

6.6.7 Add Removal Information to Descriptive Information

The Archive logs the deletion of the Content Information and Preservation Description Information and updates its meta data base. The update can contain the following entries:

- Deletion of which AIP

- Deletion date and time

- Who initiated the deletion ...

6.6.8 Confirmation of Removal

The Archive confirms the complete deletion of the AIP and the update of its meta data base.

6.6.9 Generate Confirmation Report

The Archive generates a confirmation report which includes the feedback information for the administrator about the removal procedures.

6.6.10 Receive Confirmation Report

The Administrator receives the removal confirmation report.

6.6.11 Automatic Remove Request

The Archive may automatically generate a remove request. The request is based on domain dependent requirements, defined by the Management. This can include expired archiving periods for documents e.g. 50 years. After this archiving period the data could be deleted.

6.6.12 Error Report of Removal

In cases of partial deletion of AIP information, the Archive generates an error report for the Administrator.

6.6.13 Error handling for AIP Deletion Failures

The Administrator has to perform an error handling procedure in cases of partial deletion of AIP´s.


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Detailing Data Selection Removal

Figure 22: Data Selection Removal

6.6.4.1 Check for References

This process step checks if the removal data has references to other archived data packages. In cases of positive results, the removal process has to be stopped .

References from the data to be removed yielding to other information packages will be deleted together with the removal information packages.

6.6.4.2 Readout of DI

The Archive has to read out the descriptive information for the requested data. In cases of complete request information (e.g. exact part number, product structure information) the archive has just to interpret the descriptive information for that part. In cases of only partly known request information by the consumer, the archive has to readout the descriptive information of all e.g. parts which belongs to that request information.

6.6.4.3 Provide Collection

The Archive provides the list of stored elements which belongs to the request information and which accords to the access rights of the consumer.

6.6.4.4 Select Data

The Administrator has to select that kind of information from archives provided list, which is of interest.

6.6.4.5 Receive Selection

The Archive receives the data selection of the Administrator.

6.6.4.6 Check for Remove Confirmation

The Archive requests a safety confirmation for the deletion of the Content Information.

6.6.4.7 Confirm the Removal

The Administrator confirms the removal of the AIP within the archive.


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6.6.4.8 Receive Confirmation

The Administrator receives the confirmation which includes the archive information about the data selection of AIP to be deleted

6.7 Ingest of Pre-existing Data

Within the automatically controlled Ingest process for pre existing data, the pre existing data (archive) will be converted into the recommended archiving format and stored in the long term archive. This process step is only relevant for pre existing 3D product data, e.g. CAD and PDM data, which fulfil the defined data quality criteria of this reference process. This process step is out of scope for VDA4958-2.

7 Data elements

7.1 AIP (Archival Information Package)

7.1.1 OAIS Definition

The AIP consists of the following elements:

- Content Information

- Packaging Information

- Preservation Description Information

- Digital Signature Information

- The Content Information is the set of information that the producer requires to retain and has all the qualities needed for permanent storage. Packaging information is the information that is used to bind and identify the components of an Information Package. Preservation Description Information is the information which is necessary for adequate preservation of the Content Information and which can be categorized as Provenance, Reference, Fixity, and Context information. Digital Signature Information is the information about authenticity (identify the signature-key-owner), data integrity and time stamp.

7.1.2 Copy of AIP

Copy of stored AIP. The original AIP remains within the archive.

7.2 Authentication Secret Key

Represents the secret part of the information, which is necessary for the authentication of a digital time signature.

7.3 Automatic remove request

Specific rules and constraint information for the automatic generated removal of archive data.

7.4 CI (Content Information)

7.4.1 General definition

The Content Information includes the set of information that is the original target of preservation.

7.4.2 CI in native format

Represents the converted content information during the retrieval process. The native data format depends on the current or future origin systems.


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7.5 Data


Information flow between two systems.

7.5.2 Analysis results

Analysis result of e.g. data quality agent tool.

7.5.3 Formatting and documents standards

supporting data from preservation planning

7.5.4 In archive format

Data formatted in the recommended archiving format.

7.5.5 In native format

Content information which was provided from the archive within the origin format, e.g. 3D CAD or PDM-system formatted data

7.5.6 In target format

Information converted into the format of the target system.

7.5.7 Process control data

Control data for the relevant process steps, depending on the implemented system.

7.5.8 Quality criteria

Standard control factors for quality agent tool.

7.5.9 Quality rules

Set of rules needed for verification of data.

7.5.10 Validation property rules

Represents a rule framework which supports the automatic creation of validation properties

7.6 DI (Descriptive Information)

The set of information, consisting primarily of Package Descriptions, which is provided to Data Management to support the finding, ordering, and retrieving by Consumers of archived information holdings. The descriptive information will be extended with the storage information and additionally with reference information for the CAD model.

7.7 DIP (Dissemination Information Package)

The Information Package will be generated by the archive as an answer to a consumer's request. The DIP may contain collections of AIP’s. The AIP Content Information will be converted into the data format of the target system.


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7.8 Information

7.8.1 Access granted information

Contains the verification of the requester's access rights. Represents the input of the next step in a standardized process.

7.8.2 Access input information

User account information: e.g. account name, password, further identifier and belonging access rights.

7.8.3 Access validation information

contains the validated access information, represents the input information for the following decision if the requester will grant access or not.

7.8.4 Access denied information

Contains the information that the request was declined by the archive.

7.8.5 Authentication information

Represents the authentication information of the secret key, generated by the checker tool.

7.8.6 Check digital signature information

Contains the status quo information for the digital signature of the stored AIP, represents the input for the following check if the digital is still intact.

7.8.7 Confirmation information

Contains the information that the relevant process was performed.

7.8.8 Confirmation deletion Content Information

Contains the information that the removal of the AIP (´s) was performed.

7.8.9 Confirmation remove

Contains the information that the remove process was performed successfully.

7.8.10 Descriptive Information error information

The kind of information, generated within error handling for archival storage, belongs to a check if the descriptive information was created correctly. The descriptive information error describes the mistake.

7.8.11 Digital time signature

Information about authenticity (identify the signature-key-owner) and data integrity time stamp information. A digital signature is a sort of seal of digital data. It is produced by using mathematical algorithm with the help of a private cryptographic key. With the help of the associated public key the signature can be checked at any time to identify the signature-key-owner and to prove the integrity of the data. In addition, a time stamp is added to the digital signature and is stored within the signature.


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7.8.12 Disaster recovery error information

Represents error information which informs the role about the kind of error occurring during the disaster recovery process.

7.8.13 Error fix of meta information

Contains the information about the error fixing of the meta data.

7.8.14 Filter information for accessible data

Contains a list according the requesters reliability. the filter effect that the archive offers just the information that the requester is allowed to see.

7.8.15 Meta data base update information

Meta data base update information e.g. for new entries (AIP´s) within the archive or remove information for deleted content information.

7.8.16 Reference information

A reference is a means to identify a single instance or a group of related instances at object level.

7.8.17 Reset archiving trigger

Initialization (system trigger) information for the reset of the archiving process.

7.8.18 Selection information

Contains a list of selected documents by the requester.

7.8.19 Storage information

Contains the information where at which place (e.g. onto which WORM or DVD) the AIP is stored physically.

7.8.20 Storage error information

Represents a list of error notifications which AIP was not physically stored correctly within the archive.

7.8.21 Target format information

Contains the information which format will be accepted by the target (user) system.

7.8.22 Technical error fixing information

Represents the information which error was repaired by the administrator.

7.8.23 Trigger information

Represents the information which initiates a next system process step.

7.8.24 Validation failure information

Represents the information for the administrator or Producer which validation was not performed correctly or which single validation property resulted in an error.

7.9 Key data

Part of digital signature information process, not in scope of VDA4958-2.


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7.10 Key ring


7.11 Data in native format

Content Information which was provided from the archive within the origin format, e.g. 3D CAD or PDM-system formatted data.

7.12 New validation properties from archive formatted file

List of calculated parameters which are used to check the validity of e.g. a geometric model or the hierarchy information of a product structure information within comparison of validation properties.

7.13 No

Decision information

7.14 PDI (Preservation Description Information)


Preservation Description Information is the information which is necessary for adequate preservation of the Content Information and which can be categorized as Provenance, Reference, Fixity, and Context information.

In addition the PDI includes the validation properties.

The PDI can be described as follows:

- Provenance: Describes the Source of the Content Information. This includes information about the system, which administrates the Content Information since its origin as well as its history.

- Reference: Provides one or more characteristics or a pattern of characteristics by which the Content Information can be uniquely identified.

- Fixity: Provides information, which ensure the fixity (changelessness) of the archived data. A non-fix object can therefore be changed without any notice.

- Context: The Context describes the relations of the Content Information towards other objects outside the Information Package. This can contain the information e.g. in which System the Content Information were created.

7.14.2 PDI in target format

Relevant PDI in target format, extracted from CI during generate AIP for retrieval process.

7.15 PI (Packaging Information)

Administrative data needed for the archive data management. Packaging Information is that kind of information that is used to bind and identify the components of an Information Package.

7.16 Report


contains information about e.g. a role decision or results of an activity.

7.16.2 Confirmation report

Gives the role the information that the relevant process was performed successfully.


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7.16.3 Content error report

Represents an information resulting from e.g. analysis or check process, which contains additional input for the administrator/ producer/ consumer. In this case the report provides information about mismatches of the content Information regarding e.g. the data quality requirements.

7.16.4 Data preparation error report

Error information which provides information about the kind of error that occurred during the relevant process steps

7.16.5 Error report

Represents error information showing the kind of error occurring during relevant process steps.

7.16.6 Error report removal

Represents error information, which inform the involved role about occurred errors within the Removal process.

7.16.7 Error fixing report

Represents information resulting from error fixing activity.

7.16.8 Integrity failure report

Contains the information which part of the digital signature is incorrect.

7.16.9 Meta data base update report

Report information about changed meta data base update information.

7.16.10 Results report

Represents information resulting from e.g. analysis or check process.

7.16.11 System error report

Represents an information resulting from e.g. analysis or check process, which contains additional input for the administrator/ producer/ consumer. In this case the report provides information about malfunctions during e.g. an analysis process.

7.16.12 Validation report

Contains the results of a validation process.

7.16.13 Verification information report

Contains the results of a verification process.

7.17 Request


Request of a user or administrator for certain data.

7.17.2 Access request

Manually generated request from the Consumer, or Administrator which can consist, for example, of partial or full part number or assembly knot information. The access request will be transferred


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to the archive frontend. The request must contain the account information, such as name and /or password of the current user.

7.17.3 Authentication

Information for an inquiry within the set digital signature process for the validation of the digital signature.

7.17.4 Remove request

Remove request represents the management information for removal of an AIP within the archive.

7.17.5 Time stamp

Information for an automatic inquiry within the set digital time signature process, which will be validated by the signature system.

7.18 Results


Information resulting from, for example, an analysis or check process.

7.18.2 Analysis results for validation properties

The results could be provided in form of a list which contains information about relevant validation properties.

7.18.3 Check for removal information

The results for the check will be send to the next process step “Confirmation Removal”.

7.18.4 Validation results

Contains a detailed list of validation results.

7.18.5 Verification results

Contains a detailed list of verification results.

7.19 Rules

7.19.1 Access rules

Data domain specific rules and constrain information for the access to the archive system.

7.19.2 Automatic remove request

Specific rules and constraint information for the automatic generated removal of archive data.

7.19.3 Validation rules

Rules, constrains and information for the decision process "validation o.k.?" Rules are to be defined within the preservation planning.

7.20 Secret key

Created by the Trust Center. Part of digital signature information process, not in scope of VDA4958-2.


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7.21 Select source for validation properties

Input for the validation property selection either from Content Information or PDI.

7.22 Signature document order


7.23 SIP (Submission Information Package)


The SIP consists of following main information objects:

- Content (native formatted data): The set of information, which has all required qualities for a permanent keeping and on which archiving focuses on.

- Packaging Information: Set of information, which is necessary for identification and the connections of components within an Information Package.

- PDI: Information, which is necessary for an adequate keeping of the Content Information. PDI is categorized in Provenance, Reference, Fixity and Context information. In addition, Validation Properties are part of the PDI in VDA4958.

7.23.2 SIP data in archive format:

Content Information which was converted into or already provided the archive format.

7.24 Support

General support information coming from data management. i.e. rules and constrains for the process.

7.25 Time stamp

A time stamp is added to the digital signature in addition. Part of digital signature information process, not in scope of VDA4958-2.

7.26 Validation Properties

Predefined parameters which are used to check the validity of, for example, a geometric model or the hierarchy of a product structure after the conversion of Content Information. Validation properties examples include centre of gravity and number of assembly knots within an product structure.

7.27 Yes

Decision information


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Appendix A

1 Methodology of process description – simplified activity diagram

The following chapter deals with the applied methodology, which was used for the process description within this recommendation. The description is inevitable for a consistent understanding. The standardized and internationally accepted procedures the process description is based on had to be adapted and modified for satisfying the specific use case Long Term Archiving.

The process description is illustrated through a simplified activity diagram. The illustration rests on UML elements and IDEF0 methods.

The following elements are applied in the simplified activity diagram.

Activity (Process)

Role

Decision

Data

System role

Milestone

System Process

Supporting Process

Activity (Process)

Role

Decision

Data

System role

Milestone

System Process

Supporting Process

Figure 23: Example of a simplified activity diagram

Every process step is started by a milestone. The use of milestones allows the integration of required references to and from other processes. The simplified activity diagram identifies the participating roles via swim lanes. The swim lanes differentiate the various roles (persons) and systems (e.g. CAD system or the archive). The interaction between single activities within the process chain is represented by the data flow. In cases of decisions, the role has the chance to take corrective action. For single process steps, a supporting process gives further information, e.g. about archiving policies for “generate package information”.

To reduce the amount of information within one description level, the simplified activity diagrams are based on a hierarchical structure, following IDEF0. A shadow behind a process element indicates a further detailed description for this specific process.

The hierarchy structure is displayed within the following figure.


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Figure 24: Hierarchical structure of the process description

2 Document structure

The process descriptions are arranged into several levels. Part of the document is the process figure, as a visualization of the process, e.g. process step level 1 overview data flow. A further component is the detailed description of the level overview process(overview data flow) and its single sublevel process descriptions (data preparation, ingest,… ).

The marked process steps indicate the sub process steps, which are within the scope of this recommendation. There are detailed descriptions for the marked process step which lay under further level. The resulting structure for the process description is the basis for the document structure.

The document structure looks like as following:

1. level: overview data flow (marked sub process: e.g. Ingest), description of the process “overview data flow “ and the sub processes

2. level: Ingest (marked sub process: e.g. Generate AIP) description of the process “Ingest“ and the sub processes

3. level: Generate AIP: description of the process “Generate AIP“ and the sub processes

FUNDAMENTALS AND CONCEPTS FOR LONG TERM … (Part 2) - Long-Term Archiving (LTA) of...VDA Part 2:...

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