Re-engineering structures from web documents

To realise a wide range of applications (including digital libraries) on the Web, a more structured way of accessing the Web is required and such requirement can be facilitated by the use of XML standard. In this paper, we propose a general framework for reverse engineering (or re-engineering) the underlying structures i.e., the DTD from a collection of similarly structured XML documents when they share some common but unknown DTDs. The essential data structures and algorithms for the DTD generation have been developed and experiments on real Web collections have been conducted to demonstrate their feasibility. In addition, we also proposed a method of imposing a constraint on the repetitiveness on the elements in a DTD rule to further simplify the generated DTD without compromising their correctness

TimeLine: A High Performance Archive for a Distributed Object Store

This paper describes TimeLine, an efficient archive service for a distributed storage system. TimeLine allows users to take snapshots on demand. The archive is stored online so that it is easily accessible to users. It enables "time travel" in which a user runs a computation on an earlier system state. Archiving is challenging..

Lazy Modular Upgrades in Persistent Object Stores Chandrasekhar Boyapati, Barbara Liskov, Liuba Shrira

Abstract Persistent object stores require a way to automatically upgrade persistent objects, to change their code and storage representation. Automatic upgrades are a challenge for such systems. Upgrades must be performed in a way that is efficient both in space and time, and that does not stop application access to the store. In addition, however, the approach must be modular: it must allow programmers to reason locally about the correctness of their upgrades similar to the way they would reason about regular code. This paper provides solutions to both problems. The paper first defines upgrade modularity conditions that any upgrade system must satisfy to support local reasoning about upgrades. The paper then describes a new approach for executing upgrades efficiently while satisfying the upgrade modularity conditions. The approach exploits object encapsulation properties in a novel way. The paper also describes a prototype implementation and shows that our upgrade system imposes only a small overhead on application performance

Snapshots in a Distributed Persistent Object Storage System

The ability to take transaction-consistent snapshots of a distributed persistent object store is useful for online data archive, backup, and recovery. However, most modern snapshot utilities such as those in file systems and database systems are not designed for distributed environments and directly applying these methods to a distributed environment results in poor performance. This thesis describes an e#cient snapshot scheme for a distributed persistent object store

DTD-miner: A tool for mining DTD from XML documents

The World-Wide Web (WWW) is one of the richestrepositories of information in the world today. People no longer use the Web simply for browsing but also for nu-merous E-Commerce applications like making airline ticket and hotel reservations, and performing banking transac-tions. Nevertheless, for Web based E-commerce to be successful, one has to overcome the interoperability issues be-tween different E-commerce sites. At present, most of the E-commerce sites present their products and services inWeb documents that are not very well structured

ConChord: Cooperative SDSI Certificate Storage and Name Resolution

We present ConChord, a large-scale certificate distribution system built on a peer-to-peer distributed hash table. ConChord provides load-balanced storage while eliminating many of the administrative difficulties of traditional, hierarchical server architectures. ConChord is specifically designed to support SDSI, a fully-decentralized public key infrastructure that allows principals to define local names and link their namespaces to delegate trust. We discuss the particular challenges ConChord must address to support SDSI efficiently, and we present novel algorithms and distributed data structures to address them. Experiments show that our techniques are effective and practical for large SDSI name hierarchies

Lazy Modular Upgrades in Persistent Object Stores

Persistent object stores require a way to automatically upgrade persistent objects. Automatic upgrades are a challenge for such systems. Upgrades must be performed in a way that is efficient both in space and time, and that does not stop application access to the store. In addition, however, the approach must be modular: it must allow programmers to reason locally about the correctness of their upgrades similar to the way they would reason about regular code. This paper provides solutions to both problems. The paper first defines upgrade modularity conditions that any upgrade system must satisfy to support local reasoning about upgrades. The paper then describes a new approach for executing upgrades efficiently while satisfying the upgrade modularity conditions. The approach exploits object encapsulation properties in a novel way. The paper also describes a prototype implementation and shows that our upgrade system imposes only a small overhead on application performance