Designing wrapper components for e-services in integrating heterogeneous systems

Component-based approaches are becoming more and more popular to support Internet-based application development. Different component modeling approaches, however, can be adopted, obtaining different abstraction levels (either conceptual or operational). In this paper we present a component-based architecture for the design of e-applications, and discuss the concept of wrapper components as building blocks for the development of e-services, where these services are based on legacy systems. We discuss their characteristics and their applicability in Internet-based application development. Received: 30 October 2000 / Accepted: 9 January 2001 Published online: 28 June 2001     

An authorization system for digital libraries

Digital Libraries (DLs) introduce several challenging requirements with respect to the formulation, specification, and enforcement of adequate data protection policies. Unlike conventional database environments, a DL environment typically is characterized by a dynamic subject population, often making accesses from remote locations, and by an extraordinarily large amount of multimedia information, stored in a variety of formats. Moreover, in a DL environment, access policies are often specified based on subject qualifications and characteristics, rather than subject identity. Traditional authorization models are not adequate to meet access control requirements of DLs. In this paper, we present a Digital Library Authorization System (DLAS). DLAS employs a content-based authorization model, called a Digital Library Authorization Model (DLAM) which was proposed in previous work [1]. Edited by Y. Yesha. Received: 21 December 2000 / Accepted: 6 March 2002 Published online: 14 May 2002     

XML-enabled workflow management for e-services across heterogeneous platforms

Advanced e-services require efficient, flexible, and easy-to-use workflow technology that integrates well with mainstream Internet technologies such as XML and Web servers. This paper discusses an XML-enabled architecture for distributed workflow management that is implemented in the latest version of our Mentor-lite prototype system. The key asset of this architecture is an XML mediator that handles the exchange of business and flow control data between workflow and business-object servers on the one hand and client activities on the other via XML messages over http. Our implementation of the mediator has made use of Oracle's XSQL servlet. The major benefit of the advocated architecture is that it provides seamless integration of client applications into e-service workflows with scalable efficiency and very little explicit coding, in contrast to an earlier, Java-based, version of our Mentor-lite prototype that required much more code and exhibited potential performance problems. Received: 30 October 2000 / Accepted: 19 December 2000 Published online: 27 April 2001     

基于WS-Security构筑安全的SOAP消息调用

介绍了Web—Security框架以及Web Service安全体系,通过一个简化的电子商务场景,详细展示了如何使用WS—Security规范,实现安全的SOAP消息调用。指出了使用WS—Security时,防范重传攻击的各种措施,并提出了一个简化的挑战响应模型。最后介绍了WS—Security的实现和开发工具。     

基于SOAP消息扩展的服务访问权限控制

简单对象访问协议(SOAP)是面向服务架构(SOA)中实现远程服务调用的协议,但是它没有定义标准的服务访问控制规范。本文提出了一种符合SOAP消息中XML语法的服务访问控制结构,并以此结构为基础,构建了一个动态细粒度基于角色的服务访问控制模型DFG-RBAC(Dynamic Fine Grain Role-based Access Control)。同时,利用目录服务器设计了服务访问权限数据存储与查询机制,实现了精确、高效的服务访问控制。     

PBAC: Provision-based access control model

Over the years a wide variety of access control models and policies have been proposed, and almost all the models have assumed “grant the access request or deny it.” They do not provide any mechanism that enables us to bind authorization rules with required operations such as logging and encryption. We propose the notion of a “provisional action” that tells the user that his request will be authorized provided he (and/or the system) takes certain actions. The major advantage of our approach is that arbitrary actions such as cryptographic operations can all coexist in the access control policy rules. We define a fundamental authorization mechanism and then formalize a provision-based access control model. We also present algorithms and describe their algorithmic complexity. Finally, we illustrate how provisional access control policy rules can be specified effectively in practical usage scenarios. Published online: 22 January 2002     

The OODB path-method generator (PMG) using access weights and precomputed access relevance

A path-method is used as a mechanism in object-oriented databases (OODBs) to retrieve or to update information relevant to one class that is not stored with that class but with some other class. A path-method is a method which traverses from one class through a chain of connections between classes and accesses information at another class. However, it is a difficult task for a casual user or even an application programmer to write path-methods to facilitate queries. This is because it might require comprehensive knowledge of many classes of the conceptual schema that are not directly involved in the query, and therefore may not even be included in a user's (incomplete) view about the contents of the database. We have developed a system, called path-method generator (PMG), which generates path-methods automatically according to a user's database-manipulating requests. The PMG offers the user one of the possible path-methods and the user verifies from his knowledge of the intended purpose of the request whether that path-method is the desired one. If the path method is rejected, then the user can utilize his now increased knowledge about the database to request (with additional parameters given) another offer from the PMG. The PMG is based on access weights attached to the connections between classes and precomputed access relevance between every pair of classes of the OODB. Specific rules for access weight assignment and algorithms for computing access relevance appeared in our previous papers [MGPF92, MGPF93, MGPF96]. In this paper, we present a variety of traversal algorithms based on access weights and precomputed access relevance. Experiments identify some of these algorithms as very successful in generating most desired path-methods. The PMG system utilizes these successful algorithms and is thus an efficient tool for aiding the user with the difficult task of querying and updating a large OODB. Received July 19, 1993 / Accepted May 16, 1997     

Managing One’s Availability to Telephone Communication Through Mobile Phones: A French Case Study of the Development Dynamics of Mobile Phone Use

This paper provides empirical results concerning the negotiation of access and joinability by mobile phone users. It shows how access is embedded in a gift-giving economy (giving one’s number for example). It also shows that the more users make themselves available on the mobile phone, the more their mobile phone traffic increases (both incoming and outgoing). This remarkable result is discussed in terms of the reciprocity involved in the management of mobile phone relationships.     

Axis上SOAP数字签名的实现

现有的SOAP引擎都没有提供对SOAP数字签名的支持,介绍了一种利用第三方API在Axis上实现SOAP数字签名的方法。这种方法可以提高系统的安全性。     

Management of access through biometric control: A case study based on automatic signature verification

The idea of the information society is pervasive and varied and, in this context, universal access is itself a multi-faceted concept. However, the notion of universality presupposes an analysis and understanding of what both unifies and discriminates among different individual members of a community of technology users. This paper addresses these ideas and, in particular, seeks to illustrate some techniques which can support such an analysis in a variety of task domains. Of special interest here is a specific case study which examines the use of biometric processing as a means of managing access in the broadest sense. It is argued that not only is the field of biometric measurement one where understanding similarities and differences is the essence of what is required, but also that this offers the opportunity to establish and explore a variety of practical techniques of very wide significance in the context of universal access. Published online: 18 May 2001     

一种基于SOAP的WebGIS系统

通过讨论SOAP的特性，探讨了采用SOAP技术解决WebGIS中的互操作问题的可行性，并提出了一种基于SOAP的空间信息服务功能的命令体系和WebGIS的结构，最后讨论了这种结构的优缺点。     

基于差分编码和压缩的SOAP优化

针对SOAP在序列化和反序列化过程中效率低及消息自身的冗余问题,提出在．NET框架下使用SOAP扩展以优化SOAP消息。对于SOAP请求消息,采用增加消息模版的方式实现差分编码,对于SOAP响应消息,根据消息的长短分别采用压缩或差分的方法来优化,减少带宽占用,使Web服务得到优化。     

Concurrency and recovery for index trees

Although many suggestions have been made for concurrency in B-trees, few of these have considered recovery as well. We describe an approach which provides high concurrency while preserving well-formed trees across system crashes. Our approach works for a class of index trees that is a generalization of the B-tree. This class includes some multi-attribute indexes and temporal indexes. Structural changes in an index tree are decomposed into a sequence of atomic actions, each one leaving the tree well-formed and each working on a separate level of the tree. All atomic actions on levels of the tree above the leaf level are independent of database transactions, and so are of short duration. Incomplete structural changes are detected in normal operations and trigger completion. Edited by A. Reuter. Received August 1995 / accepted July 1996     

A digital rights management scheme for broadcast video

Many watermarking techniques have been proposed for digital video and digital broadcast video. In general, they address the seller's or broadcaster's concerns, such as copyright-violation deterrence, copyright-violation detection and copy protection. Some of them provide for data integrity (tamper proofing), which is a shared concern of both subscriber and broadcaster. In all these cases, the watermark generation and embedding is performed or controlled by the seller or broadcaster. Therefore, a broadcaster with malicious intentions could, with manipulation, falsely implicate an innocent subscriber in copyright violation. This could be a major concern for subscribers. In this paper, we propose an integrated solution to manage the broadcaster's copyright and subscriber's false-implication concern (subscriber's rights) for digital video broadcasts. The proposed novel approach makes use of interactive watermarking techniques and protocols to help protect digital rights of all parties involved in video broadcasting.     

A configurable type hierarchy index for OODB

With respect to the specific requirements of advanced OODB applications, index data structures for type hierarchies in OODBMS have to provide efficient support for multiattribute queries and have to allow index optimization for a particular query profile. We describe the multikey type index and an efficient implementation of this indexing scheme. It meets both requirements: in addition to its multiattribute query capabilities it is designed as a mediator between two standard design alternatives, key-grouping and type-grouping. A prerequisite for the multikey type index is a linearization algorithm which maps type hierarchies to linearly ordered attribute domains in such a way that each subhierarchy is represented by an interval of this domain. The algorithm extends previous results with respect to multiple inheritance. The subsequent evaluation of our proposal focuses on storage space overhead as well as on the number of disk I/O operations needed for query execution. The analytical results for the multikey type index are compared to previously published figures for well-known single-key search structures. The comparison clearly shows the superiority of the multikey type index for a large class of query profiles. Edited by E. Bertino. Received October 7, 1996 / Accepted March 28, 1997     

An asymptotically optimal multiversion B-tree

In a variety of applications, we need to keep track of the development of a data set over time. For maintaining and querying these multiversion data efficiently, external storage structures are an absolute necessity. We propose a multiversion B-tree that supports insertions and deletions of data items at the current version and range queries and exact match queries for any version, current or past. Our multiversion B-tree is asymptotically optimal in the sense that the time and space bounds are asymptotically the same as those of the (single-version) B-tree in the worst case. The technique we present for transforming a (single-version) B-tree into a multiversion B-tree is quite general: it applies to a number of hierarchical external access structures with certain properties directly, and it can be modified for others.     

Drag-and-drop multimedia: ¶an interface framework for digital libraries

In this paper, we describe a new interface for querying multimedia digital libraries and an interface building framework. The interface employs a drag-and-drop style of interaction and combines a structured natural-language style query specification with reusable multimedia objects. We call this interface DanDMM, short for “drag-and-drop multimedia”. DanDMM interfaces capture the syntax of the underlying query language, and dynamically reconfigure to reflect the contents of the data repository. A distinguishing feature of DanDMM is its ability to synthesize integrated interfaces that incorporate both example-based specification using multimedia objects, and traditional techniques including keyword, attribute, and free text-based search. We describe the DanDMM-builder, a framework for synthesizing DanDMM interfaces, and give several examples of interfaces that have been constructed using DanDMM-builder, including a remote-sensing library application and a video digital library. Received: 15 December 1997 / Revised: June 1999     

Access cost for asynchronous Byzantine quorum systems

Summary. Quorum systems have been used to implement many coordination problems in distributed systems. In this paper, we study the cost of accessing quorums in asynchronous systems. We formally define the asynchronous access cost of quorum systems and argue that the asynchronous access cost and not the size of a quorum is the right measure of message complexity of protocols using quorums in asynchronous systems. We show that previous quorum systems proposed in the literature have a very high asynchronous access cost. We propose a reformulation of the definition of Byzantine quorum systems that captures the requirement for non-blocking access to quorums in asynchronous systems. We present new Byzantine quorum systems with low asynchronous access cost whose other performance parameters match those of the best Byzantine quorum systems proposed in the literature. In particular, we present a construction for the disjoint failure pattern that outperforms previously proposed systems for that pattern. Received: September 1999 / Accepted: September 2000     

基于SOAP安全扩展的Web服务研究

SOAP(Simple Object Access Protocol,简单对象访问协议)是一种基于XML的通信协议。本文在分析基于SOAP的Web服务结构以及SOAP消息构成后,提出了一种加强Web服务安全的SOAP数字签名技术,确保了Web服务完整性和安全性。     

Video OCR: indexing digital news libraries by recognition of superimposed captions

The automatic extraction and recognition of news captions and annotations can be of great help locating topics of interest in digital news video libraries. To achieve this goal, we present a technique, called Video OCR (Optical Character Reader), which detects, extracts, and reads text areas in digital video data. In this paper, we address problems, describe the method by which Video OCR operates, and suggest applications for its use in digital news archives. To solve two problems of character recognition for videos, low-resolution characters and extremely complex backgrounds, we apply an interpolation filter, multi-frame integration and character extraction filters. Character segmentation is performed by a recognition-based segmentation method, and intermediate character recognition results are used to improve the segmentation. We also include a method for locating text areas using text-like properties and the use of a language-based postprocessing technique to increase word recognition rates. The overall recognition results are satisfactory for use in news indexing. Performing Video OCR on news video and combining its results with other video understanding techniques will improve the overall understanding of the news video content.