3/24/051 Value-Added Surrogates for Distributed Content Establishing a Virtual Control Zone By: Sandra Payette & Carl Lagoze Presented By: Mohamed Elmiligui

3/24/052 Outline Introduction - What is a V-A surrogate? Virtual control zones Implementation of V-A surrogates using Fedora architecture 4 different roles that a V-A surroagte can play Experiments done using V-A surrogates Conclusion

3/24/053 What is a V-A Surrogate? Gates (surrogates) to distributed content Can be used to improve the quality of the content – a mean to perform special services and/or transformations to the content Services like data integration, access control, preservation monitoring, etc..

3/24/054 What is a V-A Surrogate? From a Technical perspective: –it is a mediator (resides between the raw data sources and end-user application) –integrates and transforms data to fit higher- level abstractions Extends mediator role from data conversion, exchange, integration into integrity requirements of distributed content in DL

3/24/055 What is a V-A Surrogate? V-A surrogates is a way to reach distributed content Do not store the content, they obtain it from the external source when needed No only that, its key advantage is its ability to provide special services on the content This paper focuses on services that facilitate integrity in DL.

3/24/056 Virtual Control Zone Non-virtual world, libraries defined there control zone physically (books are inside the library) Virtual world it is not that easy Repository of V-A surrogates, each mapping to an external resource, an institution can somewhat define the boundaries its virtual control zone

3/24/057 Cooperative Relationships Delegating Responsibility –Content providers sign licensing agreements with libraries –Provider grants access to a certified library server that stores V-A surrogates, which are capable of providing specific access controls per the license agreement

3/24/058 Cooperative Relationships Partitioning Responsibility: –Parties agree that the content provider will act only as a long-term holder of the data –Accessing institutions could use the V-A surrogates to tailor the interfaces to the content in a manner that satisfy the users need Sharing Standards: –V-A surrogates provide uniform linking functionality for distributed content

3/24/059 No Cooperative Relationships Monitoring & Logging: –V-A surrogates could collect data regarding the uptime and availability of distributed resources and log access errors Selective Actions: –V-A surrogates might monitor selected sites, that are important to the library & and take actions such as caching the content locally if it is unavailable X% of the time

3/24/0510 Architecture of V-A Surrogates Require an architecture that supports: –Aggregation of distributed content –Association of rich and extensible behaviors with that content –Mediation capabilities –Open interface Number of implementations are possible – paper chose Fedora

3/24/0511 Architecture of V-A Surrogates 3 main parts: –DataStreams : requests (pointers) to external sources –Primitive Disseminator : generic methods for the clients to interact with the DO –Typed Disseminators : means for providing content specific functionality (ex: Get Table of Contents  content is a book) Figure 1 of paper

3/24/0512 Architecture of V-A Surrogates Figure 2 of paper

3/24/0513 Roles of V-A Surrogates Booster: –Behavior-augmented surrogate –It boosts the functionality of the base content –Example : Provide on the fly conversion of images that are aggregated to form a journal article deliver multimedia views of a lecture content

3/24/0514 Roles of V-A Surrogates Guard : –Policy augmented surrogate –Enable the enforcement of fine-grained access control policies that are made to meet content-specific requirements

3/24/0515 Roles of V-A Surrogates Caretaker: –Preservation-augmented surrogate –Contribute to the long term management and care of distributed content –Example: Caretaker can perform tests on distributed content to asses its health, and at a minimum it could produce metadata about the condition, at a maximum it could take action to protect the content

3/24/0516 Roles of V-A Surrogates Auditor: –Inspection augmented surrogate –Purpose is to apply some kind of inspection over content that is not in ones control –Monitor resources and track events that may be leading indicators of potential problems –Example: Tracking the frequency of a “404” error

3/24/0517 Selected Experiments Paper talks about three experiments: –V-A surrogates for security and access control –V-A surrogates for reference linking –V-A surrogates for preservation

3/24/0518 V-A surrogate for security and access control Figure 3 of paper

3/24/0519 V-A Surrogates for Reference Linking GetReferenceList –returns a list of documents referenced by this document GetCurrentCiationList –returns a list of known citations of this document GetLinkedText –return full document content with embedded data about its references GetMyData –gets data in canonical format

3/24/0520 V-A surrogates for preservation Figure 5 of paper

3/24/0521 Conclusion V-A surrogate is a form of DO that can enhance the functionality of digital content that is not in ones direct reach Discussed 4 types of V-A surrogates –Booster –Guard –Caretaker –Auditor