Contents
What is the CRiB?
The CRiB is a Service Oriented Architecture (SOA) designed to assist cultural heritage institutions in the implementation of migration-based preservation interventions. The CRiB system works by assessing the quality of distinct conversion applications or services to produce recommendations of optimal migration strategies. The recommendations produced by the system take into account the specific preservation requirements of each client institution.
The CRiB is currently being supported by Web services technology and is capable of carrying out the following activities:
- Recommendation of optimal migration alternatives that take into consideration the preservation requirements of the client institution;
- Convertion of digital objects to up-to-date encodings that most users will be capable of interpreting;
- Evaluation of migration's outcome by comparing the original digital object with its converted counterparts and identifying the significant properties that have not been correctly preserved;
- Generation of migration reports in appropriate forms for inclusion in the preservation metadata of migrated objects;
How does it work?
The general architecture of the CRiB system is depicted in Fig. 1. The Client-side layer illustrates client applications that may take advantage of the services provided by the CRiB. Examples of such applications might be: digital repository systems (e.g. DSpace, Fedora or Eprints) or custom applications developed by individual users.
Fig. 1 - Overview of the CRiB architecture.
The Server-side layer illustrates the whole set of components that constitute the CRiB system.
The Format Detector, as suggested by its name, is a service capable of identifying the underlying encoding of a digital object.
The Service Registry is responsible for managing information about existing conversion services. It stores metadata about its producer/developer (e.g. name, description and contact), about the service it self (e.g. name, description, the source/target formats that it is capable of handling, cost of invocation, etc.) and information on how the service should be invoked by a client application (i.e. its access point).
The Migration Broker is responsible for carrying out object migrations. In practice, this component is responsible for making sure that composite conversions are performed atomically from the point-of-view of the client application and the rest of the SOA components. Additionally, this component is responsible for recording the performance of each migration service. The results of these measurements are stored in the Evaluations Repository, a knowledge base that supports the recommendation system (see Migration Advisor).
The Format Evaluator provides information about the current status of file formats. This information enables the Migration Advisor to determine which formats are better candidates for accommodating the properties of source objects by looking at the characteristics of each pair of formats. This service is supported by a data store containing facts about formats (i.e. Format Knowledge Base), but could also exploit external sources of information such as the PRONOM registry or Google Trends, to automatically determine a format’s ubiquity and use trends.
The Object Evaluator is in charge of judging the quality of the migration outcome. It accomplishes this by comparing objects submitted to migration with its converted counterparts. Again, these evaluations will be performed according to multiple criteria. These criteria, also known as significant properties, constitute the set of attributes of an object that should be maintained intact during a preservation intervention.
The Migration Advisor produces recommensations of migration alternatives. In reality this component acts as a decision support centre for client institutions that is capable of determining the best possible option within a wide range of alternatives. It accomplishes this by confronting the preservation requirements outlined by client institutions with the accumulated knowledge about the behaviour of each accessible migration path.
Well, can I use it?
Yes you can. We have put up a small demonstrator for the CRiB platform called Migration Workbench. You may use it to convert digital objects from many different formats and obtain evaluation reports produced by the CRiB.
You may also develop your own clients by implementing the WSDL interfaces published here.
The CRiB's source-code is currently open for inspection. Please contact the authors for a working copy of the platform's source-code. Please read the following license to check if any restrictions are applicable.
/**
* CRiB | Conversion and Recommendation of Digital Object Formats
* Copyright(c) 2008 Miguel Ferreira <mferreira@dsi.uminho.pt>
* All Rights Reserved.
*
* This software was developed with the Department of Information Systems
* of the University of Minho, Portugal, under the supervision
* of Ana Alice Baptista <analice@dsi.uminho.pt> and JoséŽ Carlos Ramalho
* <jcr@di.uminho.pt>.
* ----------------------------------------------------------------------
* Permission to use, copy, or modify this software and its documentation
* for educational and research purposes only and without fee is hereby
* granted, provided that this copyright notice and the original authors'
* names appear on all copies and supporting documentation. This program
* shall not be used, rewritten, or adapted as the basis of a commercial
* software or hardware product without first obtaining permission of the
* authors. The authors make no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* THE NAME AND TRADEMARKS OF COPYRIGHT HOLDERS MUST ALWAYS BE INCLUDED
* OR ASSOCIATED TO ANY ADVERTISING, PUBLICITY OR DISTRIBUTION OF THIS
* SOFTWARE AND ITS DOCUMENTATION. TITLE TO COPYRIGHT THIS SOFTWARE AND
* ANY ASSOCIATED DOCUMENTATION WILL AT ALL TIMES REMAIN WITH THE
* COPYRIGHT HOLDERS.
* ---------------------------------------------------------------------
* This software is part of the CRiB platform. The CRiB is a Service
* Oriented Architecture (SOA) designed to assist cultural heritage
* institutions in the implementation of migration-based preservation
* interventions. The CRiB works by assessing the quality of distinct
* conversion services to produce recommendations of optimal migration
* strategies. The recommendations produced by the system take into
* account the specific preservation requirements of each client
* institution.
*
* For additional information, please refer to the following papers and
* Web sites:
*
* - Ferreira, M., Baptista, A. A., & Ramalho, J. C. (2007). An
* intelligent decision support system for digital preservation.
* International Journal on Digital Libraries, 6(4), 295-304.
*
* - Ferreira, M., Baptista, A. A. & Ramalho, J. C. (2006). A Foundation
* for Automatic Digital Preservation. Ariadne(48).
*
* - CRiB homepage: http://crib.dsi.uminho.pt
*
* - Author homepage: http://www.dsi.uminho.pt/~ferreira
* ----------------------------------------------------------------------
* Kindly report any suggestions or corrections to mferreira@dsi.uminho.pt
*/
What conversions are currently supported by the CRiB?
You may inspect which conversion services are being offered by the CRiB at the Migration Workbench's Supported Migrations page.
What criteria are being evaluated?
When a conversion executed by the CRiB, some evaluations are perfomed in order to access the quality of the invoked conversion service. Resulting objects are also evaluated in what concerns the preservation of its significant properties.
At the moment, the CRiB is capable of evaluating the follow three groups of criteria:
Process-related criteria
Criteria to evaluate the performance of the conversion process. These criteria are general for every available conversion services.
Technical criteria
The technical criteria are related to the current status of file formats and rendering software:
Object criteria
After a conversion the resulting objects will be compared with its original counterparts according to the following criteria:
Note: You need a XSLT enabled browser to see this the evaluation taxonomies as HTML. Any modern browser is capable of processing XSLT. You may save the evaluation taxonomies as XML. |
How can I participate?
You may contribute to the CRiB system in many different ways:
Development of conversion services
You may help to build a larger network of converters by developing your own converters or application wrappers (i.e. software layers that enable conversion applications to be invoked as Web services).
Construction of evaluation taxonomies
Evaluation taxonomies are quintessential to assess the quality of conversion applications. They define the criteria that will be evaluated by each of the following components: Migration Broker, Format Evaluator and Object Evaluator. You may contribute to the project by adding new criteria to existing taxonomies or creating new taxonomies for additional classes of objects.
We are currently working on taxonomies for Still-images and Text-documents. Available taxonomies may be inspected here.
Development of property extractors for different formats
Each criterion present in the evaluation taxonomies must be extracted from digital objects in order to be evaluated by the Object Evaluator. Property or criterion extractors for all sorts of formats need to be developed.
Development of object comparators
In order to assess the quality of a migration, significant properties from both source and targe objects must be compared. For example, to realise if the textual content of a document has been completely preserved during a migration intervention, one must be able to compare text. Similar comparison algorithms are needed all types of information, e.g. pixel data, voxel data, audio, video, etc.
Production of information for the Format Knowledge Base
The Format Evaluator, the component responsible for determining if two formats are compatible in terms of its properties, is supported by a knowledge base containing facts about recognised file formats. You may contribute with factual data about file formats so that a general knowledge base for supporting recommendation is created.
Are there any related publications?
Here is the list of publications related to the CRiB platform:
Ramalho, J. C., Ferreira, M., Faria, L., Castro, R., Barbedo, F., & Corujo, L. (2008). RODA and CRiB - A Service-Oriented Digital Repository. Paper presented at the International Conference on Preservation of Digital Objects (iPRES), London, UK [paper].
Becker, C., Ferreira, M., Kraxner, M., Rauber, A., Baptista, A. A., & Ramalho, J. C. (2008). Distributed Preservation Services: Integrating Planning and Actions. Paper presented at the European Conference on Research and Advanced Technology for Digital Libraries (ECDL), Aarhus, Denmark. [paper]
Ferreira, M., Baptista, A. A. & Ramalho, J. C. (2006). A Foundation for Automatic Digital Preservation. Ariadne(48). [paper]
Ferreira, M. (2006). Automatic Evaluation of Migration Quality in Distributed Networks of Converters. Bulletin of the IEEE Technical Committee on Digital Libraries (TCDL), 2(1). [paper]
Ferreira, M., Baptista, A. A. & Ramalho, J. C. (2006). CRiB: A service oriented architecture for digital preservation outsourcing. Paper presented at the XATA - XML: Aplicações e Tecnologias Associadas, Portalegre, Portugal. [paper]
Ferreira, M., Baptista, A. A. & Ramalho, J. C. (2005). Avaliação Automática de Migração em Redes Distribuídas de Conversores. Paper presented at the Conferência da Associação Portuguesa de Sistemas de Informação (CAPSI), Bragança, Portugal. [paper]
Summary of related links
Demonstrators
Evaluation taxonomies
Format Knowledge Base
How can I reach the CRiB team?
The CRiB team is mainly composed by the following people:
Some additional people have contributed to the project, namely:
Migration Broker team:
Migration Advisor evaluation:
Comments and suggestions are more than welcome at crib@dsi.uminho.pt.
Copyright © 2005-2007 University of Minho/Department of Information Systems
All rights reserved