120699
Enhancements to the Voting Algorithm
There are several consistency control algorithms for managing replicated files in the face of network partitioning due to site or communication link failures. In this paper, we consider the popular voting scheme along with three enhancements: voting with a primary site, dynamic voting, and dynamic voting with linearly ordered copiee. We develop a stochastic model which compares the file availabilities afforded by each of these schemes. We show that in this model dynamic voting with linearly ordered copies provides the greatest availability.
17317346
Representative instances and γ-acyclic relational schemes
In this paper, we study under what conditions will a pairwise inconsistent relational database ≪R,r≫ have a universal/representative instance L. If R is γ-acyclic and r satisfies all existence constraints, then it is possible to construct a universal instance L, using unmarked nulls, whose total projections onto R yield exactly the relations in r. We show that L would actually be a representative instance under a set of functional dependencies if R satisfies the additional mild condition: for any functional dependency X → A where A is a single attribute, whenever XA is contained in two relation schemes R and R' of R, it follows that R ∩R' is a relation scheme of R, having X as one of its keys.
13942242
A Scheme of Parallel Processing for MIMD Systems
This paper presents a recognition procedure for parallel tasks in the user program written in a conventional programming language. To establish our program model, it describes the parallelism of the program in tenns of a process flow graph in which the relationships among processes are of predecessors and successors. And finally it presents a parallel processing scheme which realizes automatically the recognition of parallel tasks and schedules these tasks for parallel execution.
8520486
Local Area Networks: Software and Related Issues
In this paper, we present a review of the issues that affect the software requirements for a local area network. We introduce protocols for the local area networks and characterize their software needs. Two approaches to operating systems are outlined and examples of each approach are presented. Various applications which use local area networks and performance issues are also discussed.
45139817
Alternative methods for the reconstruction of trees from their traversals
It is well-known that given the inorder traversal of a binary tree's nodes, along with either one of its preorder or postorder traversals, the original binary tree can be reconstructed using a recursive algorithm. In this short note we provide a short, elegent, iterative solution to this classical problem.
21910023
On Universal and Representative Instances for Inconsistent Databases
1002176
An adaptive data replication algorithm
This article addresses the performance of distributed database systems. Specifically, we present an algorithm for dynamic replication of an object in distributed systems. The algorithm is adaptive in the sence that it changes the replication scheme of the object i.e., the set of processors at which the object inreplicated) as changes occur in the read-write patern of the object (i.e., the number of reads and writes issued by each processor). The algorithm continuously moves the replication scheme towards an optimal one. We show that the algorithm can be combined with the concurrency control and recovery mechanisms of ta distributed database management system. The performance of the algorithm is analyzed theoretically and experimentally. On the way we provide a lower bound on the performance of any dynamic replication algorith.
18523825
Secure Locking Protocols for Multilevel Database Management Systems
While there are several secure concurrency control protocols for multilevel database management systems, most of them employ timestamp ordering or multiple versions of data or a hybrid protocol that utilizes both. The only known secure locking protocol that maintains single version data and can guarantee serializability, immediately aborts a higher level transaction whenever any of its locks at the lower levels is broken.
12121717
ADAM: a testbed for exploring the use of data mining in intrusion detection
Intrusion detection systems have traditionally been based on the characterization of an attack and the tracking of the activity on the system to see if it matches that characterization. Recently, new intrusion detection systems based on data mining are making their appearance in the field. This paper describes the design and experiences with the ADAM (Audit Data Analysis and Mining) system, which we use as a testbed to study how useful data mining techniques can be in intrusion detection.
44653286
Panel Discussion on the Polyinstantiation Problem: A Position Paper
7507605
Secure Dynamic Fragment and Replica Allocation in Large-Scale Distributed File Systems
We present a distributed algorithm for file allocation that guarantees high assurance, availability, and scalability in a large distributed file system. The algorithm can use replication and fragmentation schemes to allocate the files over multiple servers. The file confidentiality and integrity are preserved, even in the presence of a successful attack that compromises a subset of the file servers. The algorithm is adaptive in the sense that it changes the file allocation as the read-write patterns and the location of the clients in the network change. We formally prove that, assuming read-write patterns are stable, the algorithm converges toward an optimal file allocation, where optimality is defined as maximizing the file assurance.