View operations on objects with roles for a statically typeddatabase language

To deal with the evolution of data and applications and with the existence of multiple views for the same data, the object data model needs to be extended with two different sets of operations: object extension operations, to allow an object to dynamically change its type; and object viewing operations, to allow an object to be seen as if it had a different structure. Object extension and object viewing operations are related in that they are both identity-preserving operations, but different in that object extension may modify the behavior of the original object while object viewing creates a new view for the original object without modifying its behavior. A set of object viewing operations is defined in the context of a statically and strongly typed database programming language which supports objects with roles, and the relationships with object extension and role mechanisms are discussed. We then show how the object viewing operations can be used to give the semantics of a higher level mechanism to define views for object databases. Examples of the use of these operations are given with reference to the prototype implementation of the language Galileo 97     

A set‐oriented method definition language for object databases and its semantics

In this paper we propose a set‐oriented rule‐based method definition language for object‐oriented databases. Most existing object‐oriented database systems exploit a general‐purpose imperative object‐oriented programming language as the method definition language. Because methods are written in a general‐purpose imperative language, it is difficult to analyze their properties and to optimize them. Optimization is important when dealing with a large amount of objects as in databases. We therefore believe that the use of an ad hoc, set‐oriented language can offer some advantages, at least at the specification level. In particular, such a language can offer an appropriate framework to reason about method properties. In this paper, besides defining a set‐oriented rule‐based language for method definition, we formally define its semantics, addressing the problems of inconsistency and non‐determinism in set‐oriented updates. Moreover, we characterize some relevant properties of methods, such as conflicts among method specifications in sibling classes and behavioral refinement in subclasses. Copyright © 2003 John Wiley & Sons, Ltd.     

Semantic sampling of existing databases through informative Armstrong databases

Functional dependencies (FDs) and inclusion dependencies (INDs) convey most of data semantics in relational databases and are very useful in practice since they generalize keys and foreign keys. Nevertheless, FDs and INDs are often not available, obsolete or lost in real-life databases. Several algorithms have been proposed for mining these dependencies, but the output is always in the same format: a simple list of dependencies, hard to understand for the user. In this paper, we define informative Armstrong databases (IADBs) from databases as being small subsets of an existing database, satisfying exactly the same FDs and INDs. They are an extension of the classical notion of Armstrong databases, but more suitable for the understanding of dependencies, since tuples are real-world tuples. The main result of this paper is to bound the size of an IADB in the case of non-circular INDs. A constructive proof of this result is given, from which an algorithm has been devised. An implementation and experiments against a real-life database were performed; the obtained database contains 0.6% of the initial database tuples only. More importantly, such semantic sampling of databases appear to be a key feature for the understanding of existing databases at the logical level.     

Databases with uncertainty and lineage

This paper introduces uldbs, an extension of relational databases with simple yet expressive constructs for representing and manipulating both lineage and uncertainty. Uncertain data and data lineage are two important areas of data management that have been considered extensively in isolation, however many applications require the features in tandem. Fundamentally, lineage enables simple and consistent representation of uncertain data, it correlates uncertainty in query results with uncertainty in the input data, and query processing with lineage and uncertainty together presents computational benefits over treating them separately. We show that the uldb representation is complete, and that it permits straightforward implementation of many relational operations. We define two notions of uldb minimality—data-minimal and lineage-minimal—and study minimization of uldb representations under both notions. With lineage, derived relations are no longer self-contained: their uncertainty depends on uncertainty in the base data. We provide an algorithm for the new operation of extracting a database subset in the presence of interconnected uncertainty. We also show how uldbs enable a new approach to query processing in probabilistic databases. Finally, we describe the current state of the Trio system, our implementation of uldbs under development at Stanford. This work was supported by the National Science Foundation under grants IIS-0324431, IIS-1098447, and IIS-9985114, by DARPA Contract #03-000225, and by a grant from the Boeing Corporation.     

Ordered functional dependencies in relational databases

We extend the relational data model to incorporate linear orderings into data domains, which we call the ordered relational model. The conventional Functional Dependencies (FDs) are examined in the context of ordered relational databases by using the notion of System Ordering Independence (SOI), which refers to the desirable scenario that the ordering of tuples in a relation is independent of the implementation of the underlying DBMS. We also extend Armstrong's axiom system for FDs to object relations, which are a subclass of ordered relations that allow us to view tuples as objects. We formally define Ordered Functional Dependencies (OFDs) for the extended model by means of two possible extensions of domains, pointwise-orderings and lexicographical orderings. We first present a sound and complete axiom system for OFDs in the case of pointwise-orderings and then establish a sound and complete set of chase rules for OFDs in the case of lexicographical orderings. Our main result shows that the implication problems for both cases of OFDs are decidable, and that it is linear time for the case of pointwise-orderings.     

一种面向对象程序自动化方法的研究

构造性类型理论可作为研究程序自动化的理论基础．本文根据一种支持面向对象计算的类型理论，探讨了面向对象程序自动化的途径．面向对象程序的程序单位是类，它是数据和一组相关操作的统一体，程序开发的关键在于开发这些操作，本文重点讨论了开发这些操作的方法.     

A Temporal Logic for Supporting Historical Databases

Tackling data with gap-interval time is an important issue faced by the temporal database community. While a number of interval logics have been developed, less work has been reported on gap-interval time. To represent and handle data with time, a clause ‘when’ is generally added into each conventional operator so as to incorporate time dimension in temporal databases, which clause ‘when’ is really a temporal logical sentence. Unfortunately, though several temporal database models have dealt with data with gap-interval time, they still put interval calculus methods on gap-intervals. Certainly, it is inadequate to tackle data with gap-interval time using interval calculus methods in historical databases. Consequently, what temporal expressions are valid in the clause ‘when’ for tackling data with gap-interval time? Further, what temporal operations and relations can be used in the clause ‘when’? To solve these problems, a formal tool for supporting data with gap-interval time must be explored. For this reason, a gap-interval-based logic for historical databases is established in this paper. In particular, we discuss how to determine the temporal relationships after an event explodes. This can be used to describe the temporal forms of tuples splitting in historical databases. Received 2 February 1999 / Revised 9 May 1999 / Accepted in revised form 20 November 1999     

The verification and synthesis of data structures

Summary The concept of machine extension is a commonly used technique for implementing complex software: sets of object classes and operations on these objects are defined and used, often in a layered fashion, to construct the system. This paper addresses the adaptation of this technique to automatic programming. It discusses how such sets of data structures may be precisely specified, presents an axiomatization of a programming language suitable for machine verification, and shows how programs which realize these data structures may be proved correct. A range of data type classes is treated—including arrays, records, and pointers. Some new verification rules are presented to handle programs which use assignments and structured objects.     

Query processing over object views of relational data

This paper presents an approach to object view management for relational databases. Such a view mechanism makes it possible for users to transparently work with data in a relational database as if it was stored in an object-oriented (OO) database. A query against the object view is translated to one or several queries against the relational database. The results of these queries are then processed to form an answer to the initial query. The approach is not restricted to a ‘pure’ object view mechanism for the relational data, since the object view can also store its own data and methods. Therefore it must be possible to process queries that combine local data residing in the object view with data retrieved from the relational database. We discuss the key issues when object views of relational databases are developed, namely: how to map relational structures to sub-type/supertype hierarchies in the view, how to represent relational database access in OO query plans, how to provide the concept of object identity in the view, how to handle the fact that the extension of types in the view depends on the state of the relational database, and how to process and optimize queries against the object view. The results are based on experiences from a running prototype implementation. Edited by: M.T. ?zsu. Received April 12, 1995 / Accepted April 22, 1996     

Ontology oriented programming in go!

In this paper we introduce the knowledge representation features of a new multi-paradigm programming language called go! that cleanly integrates logic, functional, object oriented and imperative programming styles. Borrowing from L&O [1] go! allows knowledge to be represented as a set of labeled theories incrementally constructed using multiple-inheritance. The theory label is a constructor for instances of the class. The instances are go!’s objects. A go! theory structure can be used to characterize any knowledge domain. In particular, it can be used to describe classes of things, such as people, students, etc., their subclass relationships and characteristics of their key properties. That is, it can be used to represent an ontology. For each ontology class we give a type definition—we declare what properties, with what value type, instances of the class have—and we give a labeled theory that defines these properties. Subclass relationships are reflected using both type and theory inheritance rules. Following [2], we shall call this ontology oriented programming. This paper describes the go! language and its use for ontology oriented programming, comparing its expressiveness with Owl, particularly Owl Lite[3]. The paper assumes some familiarity with ontology specification using Owl like languages and with logic and object oriented programming.     

Spatio-Temporal Tube data representation and Kernel design for SVM-based video object retrieval system

In this article, we propose a new video object retrieval system. Our approach is based on a Spatio-Temporal data representation, a dedicated kernel design and a statistical learning toolbox for video object recognition and retrieval. Using state-of-the-art video object detection algorithms (for faces or cars, for example) we segment video object tracks from real movies video shots. We then extract, from these tracks, sets of spatio-temporally coherent features that we call Spatio-Temporal Tubes. To compare these complex tube objects, we design a Spatio-Temporal Tube Kernel (STTK) function. Based on this kernel similarity we present both supervised and active learning strategies embedded in Support Vector Machine framework. Additionally, we propose a multi-class classification framework dealing with unbalanced data. Our approach is successfully evaluated on two real movies databases, the french movie “L’esquive” and episodes from “Buffy, the Vampire Slayer” TV series. Our method is also tested on a car database (from real movies) and shows promising results for car identification task.     

Knowledge discovery from spatial transactions

We propose a general mechanism to represent the spatial transactions in a way that allows the use of the existing data mining methods. Our proposal allows the analyst to exploit the layered structure of geographical information systems in order to define the layers of interest and the relevant spatial relations among them. Given a reference object, it is possible to describe its neighborhood by considering the attribute of the object itself and the objects related by the chosen relations. The resulting spatial transactions may be either considered like “traditional” transactions, by considering only the qualitative spatial relations, or their spatial extension can be exploited during the data mining process. We explore both these cases. First we tackle the problem of classifying a spatial dataset, by taking into account the spatial component of the data to compute the statistical measure (i.e., the entropy) necessary to learn the model. Then, we consider the task of extracting spatial association rules, by focusing on the qualitative representation of the spatial relations. The feasibility of the process has been tested by implementing the proposed method on top of a GIS tool and by analyzing real world data.     

一种基于PC的新型过程监测软件

介绍一种过程监测软件,由于其采用面向对象的可视化编程技术,以及采用了自定义控件、动态数据交换、抗干扰和数据缓存等技术措施,可使监测系统实时性强,可靠性高,操作方便.     

A comparison of two approaches to utilizing XML in parametric databases for temporal data

The parametric data model captures an object in terms of a single tuple. This feature eliminates unnecessary self-join operations to combine tuples scattered in a temporal relation. Despite this advantage, this model is relatively difficult to implement on top of relational databases because the sizes of attributes are unfixed. Since data boundaries are not problematic in XML, XML can be an elegant solution to implement parametric databases for temporal data. There are two approaches to implementing parametric databases using XML: (1) a native XML database with XQuery engine, and (2) an XML storage with a temporal query language. To determine which approach is appropriate in parametric databases, we consider four questions: the effectiveness of XML in modeling temporal data, the applicability of XML query languages, the user-friendliness of the query languages, and system performances of two approaches. By evaluating the four questions, we show that the latter approach is more appropriate to utilizing XML in parametric databases.     

Expert' voice: The BabyUML discipline of programming

I want increased confidence in my programs. I want my own and other people's programs to be more readable. I want a new discipline of programming that augments my thought processes. Therefore, I create and explore a new discipline of programming in my BabyUML laboratory. I select, simplify and twist UML and other languages to demonstrate how they help bridge the gap between me as a programmer and the objects running in my computer The focus is on the run time objects; their structure, their interaction, and their individual behaviors. Trygve Reenskaug is professor emeritus of informatics at the University of Oslo. He has 40 years experience in software engineering research and the development of industrial strength software products. He has extensive teaching and speaking experience including keynotes, talks and tutorials. His firsts include the Autokon system for computer aided design of ships with end user programming language, structured programming, and a data base oriented architecture from 1960; object oriented applications and role (collaboration) modeling from 1973; Model-View-Controller, the world's first reusable object oriented framework, from 1979; OOram role modeling method and tool from 1983. Trygve was a member of the UML Core Team and was a contributor to UML 1.4. The goal of his current research is to create a new, high level discipline of programming that lets us reclaim the mastery of software.     

Navigational accesses in a temporal object model

A considerable research effort has been devoted in past years to query languages for temporal data in the context of both the relational and the object oriented model. Object oriented databases provide a navigational approach for data access based on object references. We investigate the navigational approach to querying object oriented databases. We formally define the notion of temporal path expression, and we address on a formal basis issues related to the correctness of such expressions. In particular, we focus on static analysis and give a set of conditions ensuring that an expression always results in a correct access at runtime     

DSM-CC编解码的C++实现

利用面向对象的方法，提出了在数字电视发送和接收系统中实现DSM-CC中数据下载协议的一种规律化的伪C代码到C 语言的映射规则，这一规则利用C 面向对象的语言特点，结合DSM-CC协议栈语义定义有很大相似性的特点，充分利用了多态和继承等面向对象的思想。利用这一规则，给出了一种自顶向下的DSM-CC的C 语言实现。这一实现具有对数据转盘（DC）和对象转盘（OC）兼容，可扩展性强，发送端（编码端）与接收端（解码端）通用的特点。     

A flexible and easy to use molecular biology workbench efficiently developed in Tcl/Tk

We describe the design and implementation of a workbench for molecular biology that allows the easy integration of analysis tools. The software is implemented in Tcl/Tk using the [incr Tcl] extension that provides object‐oriented programming. The program is called tkGDE and consists of four main parts. The sequence editor allows the user to perform basic editing operations on biomolecule sequences. The graphical annotation editor gives the user a graphical overview of all annotated features of a sequence. The output manager retains information on the results produced by the analysis tools. The bundle control allows several tools to run automatically, passing data from one tool to the next. Tools are integrated into the system by describing their properties in a configuration file, which drastically reduces the time needed for integration. We present results proving that Tcl/Tk has been misjudged to be slow and unsuited for large projects. To achieve sufficient performance we exploited special features of Tcl/Tk, namely idle tasks and the capabilities built into the Tk canvas widget. The system consists of more than 34000 lines of [incr Tcl] code in 182 classes. The whole development process took about one person‐year. Copyright © 2000 John Wiley & Sons, Ltd.