5860034
Achieving undo in bitmap-based collaborative graphics editing systems
Bitmap-based collaborative graphics editing systems are a special class of real-time collaborative editing systems. Undo is an important and difficult problem in these systems. Existing solutions show low efficiency because additional space cost should be added to achieve the function of undo. In this paper, we propose a new solution to resolve the undo problem. The basic idea is to reduce space cost through exploring relations among operations. The algorithm given in the paper can undo any operation at any time, and can greatly reduce the space cost while increasing a few time cost. The issues about undo scope and undo mode are also discussed in the paper.
34312633
Research on Reliable Communication in Real-Time Collaborative Designing Systems
Real-time collaborative designing systems allow users to view and design the same document from geographically distributed sites connected by web. In these systems, each action should be transferred to other sites correctly, timely and orderly. While a lot of researches focus mainly on providing reliable network environment to support collaborative works, we propose a new kind of reliable communication architecture for collaborative group. This architecture is based on UDP protocol for end-to-end transmission, and adopts a new Site-based Reliable Communication Protocol (SRCP) that depends on collaborative site itself to choose reliable communication channel and provide reliable transmission. Each site checks the connection status and chooses reliable path to transfer actions dynamically. Lost actions can be detected and retransferred faster when comparing to other architectures. The protocol and algorithms are given in detail in this paper.
26169252
Multicast Internet protocol
In this paper, we first review the existing IPv4 based multicast protocols and identify their shortcomings. We then proposed a new multicast protocol, called Multicast Internet Protocol (MIP), which is both scalable and flexible. The design principle of MIP is fundamentally different from the existing IPv4 based multicast protocols. The issues related to MIP routing and implementations are also studied in this paper.
269391
Integrated coverage and connectivity configuration in wireless sensor networks
An effective approach for energy conservation in wireless sensor networks is scheduling sleep intervals for extraneous nodes, while the remaining nodes stay active to provide continuous service. For the sensor network to operate successfully, the active nodes must maintain both sensing coverage and network connectivity. Furthermore, the network must be able to configure itself to any feasible degrees of coverage and connectivity in order to support different applications and environments with diverse requirements. This paper presents the design and analysis of novel protocols that can dynamically configure a network to achieve guaranteed degrees of coverage and connectivity. This work differs from existing connectivity or coverage maintenance protocols in several key ways: 1) We present a Coverage Configuration Protocol (CCP) that can provide different degrees of coverage requested by applications. This flexibility allows the network to self-configure for a wide range of applications and (possibly dynamic) environments. 2) We provide a geometric analysis of the relationship between coverage and connectivity. This analysis yields key insights for treating coverage and connectivity in a unified framework: this is in sharp contrast to several existing approaches that address the two problems in isolation. 3) Finally, we integrate CCP with SPAN to provide both coverage and connectivity guarantees. We demonstrate the capability of our protocols to provide guaranteed coverage and connectivity configurations, through both geometric analysis and extensive simulations.
52804588
Cryptanalysis of the Full HAVAL with 4 and 5 Passes
HAVAL is a cryptographic hash function with variable digest size proposed by Zheng, Pieprzyk and Seberry in 1992. It has three variants, 3-, 4-, and 5-pass HAVAL. Previous results on HAVAL suggested only practical collision attacks for 3-pass HAVAL. In this paper, we present collision attacks for 4 and 5 pass HAVAL. For 4-pass HAVAL, we describe two practical attacks for finding 2-block collisions, one with 243 computations and the other with 2 36 computations. In addition, we show that collisions for 5-pass HAVAL can be found with about 2 123 computations, which is the first attack more efficient than the birthday attack.
28581906
Design of an OGSA-Based MetaService Architecture
This paper proposes a MetaService-based architecture for dealing with the problem of services management in grid systems. We introduce the basic idea of MetaService, and then discuss MetaService classification, new MetaService construction, and the MetaService working mechanism. A graph and a tree can be used for the optimization function of MetaService. An example from real life is used to explain the role of MetaService. We give an overview of a grid prototype system which has incorporated some of the ideas presented. A brief comparison is given between MetaService and other related work.
1958263
On zone-balancing of peer-to-peer networks: analysis of random node join
Balancing peer-to-peer graphs, including zone-size distributions, has recently become an important topic of peer-to-peer (P2P) research [1], [2], [6], [19], [31], [36]. To bring analytical understanding into the various peer-join mechanisms, we study how zone-balancing decisions made during the initial sampling of the peer space affect the resulting zone sizes and derive several asymptotic results for the maximum and minimum zone sizes that hold with high probability.