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1.
Roles and role models have received much attention as useful concepts for developing highly reusable and dynamically evolvable systems. Role models belong to the category of collaboration‐based development techniques, but most of the existing approaches to role models do not explicitly incorporate the core principle of collaboration‐based developments as an essential property of their primary design goals. Consequently, the existing approaches still suffer from a problematic phenomenon that the structural and behavioral constraints defined in a role system can be violated during the role‐binding stage. We call such a problematic phenomenon the role‐binding anomaly. In order to alleviate the role‐binding anomaly, we propose an enhanced role model, in which all role instances and core objects can exist by themselves, namely, they can be developed, executed, and tested independently. Roles and core classes can be bound to each other at the instance level. In addition, the role system describes and encapsulates the behavior for dynamic reconfigurations among role instances. The enhanced role model is designed so as to be meaningful with respect to software engineering principles, rather than dynamic evolution. It also facilitates role model implementation using general programming languages (i.e. not supporting dynamic specialization) such as Java. To illustrate how the proposed role model makes such benefits, we develop a set of Java classes necessary for implementing the enhanced role model in the form of a Java package role, and present a simplified automatic teller machine system as an example application. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
2.
Joseph R. Laracy 《Software》2009,39(1):105-110
As the use of computer simulation grows in a variety of science and engineering fields, the quality of random variate generators becomes increasingly important. Unfortunately, a number of standard implementations are grossly inadequate and exhibit poor statistical properties. This paper presents a software pattern for efficiently implementing an extensible, high‐quality random variate generator. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
3.
The need for multiple views of an object is often encountered in software practice. This paper presents our experience in addressing this need under a software architecture known as the law‐governed architecture. We introduce the notion of a surrogate object which allows an object to appear different and behave differently when used from different parts of a system. This concept requires some minor modifications to the classical inheritance‐based object‐oriented systems, mostly involving a judicious use of delegation. A concrete implementation of surrogates under the law‐governed architecture is described and some applications of surrogates are briefly discussed. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
4.
Guillermo Jimenez‐Diaz Pedro A. Gonzalez‐Calero Mercedes Gomez‐Albarran 《Software》2012,42(2):235-253
The use of game technology for building virtual learning environments is intended to improve the motivation and engagement of the student, borrowing such properties from their entertaining counterparts. Nevertheless, wrapping pedagogical contents in a virtual environment is no simple achievement, and requires a rigorous process of designing and validating the metaphors and mechanics included in the virtual learning system. In this paper we describe such design process exemplified in the construction of consecutive versions of ViRPlay, a 3D role play virtual environment for teaching object‐oriented design. We show how main mechanics were transferred from experiments in the real world and how such mechanics were evolved based on empirical evaluations. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
5.
For many years systems engineers have produced traditional system requirements specifications containing shall‐statement requirements. The rapid adoption of use case modeling for capturing functional requirements in the software community has caused systems engineers to examine the utility of use case models for capturing system‐level functional requirements. A transition from traditional shall‐statement requirements to use case modeling has raised some issues and questions. This paper advocates a hybrid requirements process in which use case modeling and traditional shall‐statement requirements are applied together to effectively express both functional and nonfunctional requirements for complex, hierarchical systems. This paper also presents a practical method for extracting requirements from the use case text to produce a robust requirements specification. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 303–319, 2004 相似文献
6.
Local search is an emerging paradigm for combinatorial search which has recently been shown to be very effective for a large number of combinatorial problems. It is based on the idea of navigating the search space by iteratively stepping from one solution to one of its neighbors, which are obtained by applying a simple local change to it. In this paper we present LOCAL++, an object‐oriented framework to be used as a general tool for the development and implementation of local search algorithms in C++. The framework comprises a hierarchy of abstract template classes, one for each local search technique taken into account (i.e. hill‐climbing, simulated annealing and tabu search). Each class specifies and implements the invariant part of the algorithm built according to the technique, and is supposed to be specialized by a concrete class once a given search problem is considered, so as to implement the problem‐dependent part of the algorithm. LOCAL++ comprises also a set of abstract classes for creating new techniques by combining different search techniques and different neighborhood relations. The architecture of LOCAL++ provides a principled modularization for the solution of combinatorial search problems, and helps the designer deriving a neat conceptual scheme of the application, thus facilitating the development and debugging phases. LOCAL++ proved to be flexible enough for the implementation of the algorithms solving various scheduling problems. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
7.
Raed Shatnawi Wei Li James Swain Tim Newman 《Journal of Software: Evolution and Process》2010,22(1):1-16
An empirical study of the relationship between object‐oriented (OO) metrics and error‐severity categories is presented. The focus of the study is to identify threshold values of software metrics using receiver operating characteristic curves. The study used the three releases of the Eclipse project and found threshold values for some OO metrics that separated no‐error classes from classes that had high‐impact errors. Although these thresholds cannot predict whether a class will definitely have errors in the future, they can provide a more scientific method to assess class error proneness and can be used by engineers easily. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
Content‐based image retrieval (CBIR) is a process of retrieving images from an image database by exploiting the content of the images (typically the querying of an image). CBIR avoids many problems associated with traditional ways of retrieving images by keywords. Thus, a growing interest in the area of CBIR has been established in recent years. In this paper, a novel object‐oriented framework (CBIRFrame) is built for CBIR applications development. We discuss the motivations for CBIRFrame before discussing its design in detail. Two applications of CBIRFrame are also briefly discussed to show the effectiveness of applying CBIRFrame to real applications. Finally, we outline the possible uses of the design of CBIRFrame for other types of domains, such as content‐based retrieval of video clips. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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10.
Object oriented (OO) techniques are proving useful in software engineering for dealing with complex systems and for increasing the ease of code development and maintainability. However, their application to electromagnetic modeling is still in its infancy. A brief introduction for microwave engineers to OO paradigms is made. A review of the state of the art in OO full‐wave electromagnetic modeling is made, an illustrative example is shown, and likely future trends are discussed. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 341–353, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mmce10031 相似文献
11.
This paper argues for the adoption of object‐oriented design and UML tools for nonsoftware designs, i.e., systems, hardware and algorithms: This is a controversial position. It presents a case study, the design of a heating, ventilation, and air conditioning system, using UML tools. This case study also shows the incremental elaboration used to progress from the requirements model, to the analysis model, to the design model, etc. The paper finally discusses some difficulties that must be overcome in order to apply UML tools to system designs. © 2002 Wiley Periodicals, Inc. Syst Eng 6: 28–48, 2003. 相似文献
12.
Jakob Axelsson 《Systems Engineering》2002,5(3):165-179
Modeling languages intended for capturing essential properties of complex technical systems need to cover both software and physical components in a holistic framework. Object‐oriented modeling languages are often used for software, and possess many features that are attractive also in a general modeling notation for systems engineering. However, software oriented languages lack certain features that are essential when modeling physical components, in particular the ability to deal with the continuous‐time relationships needed to describe the dynamics of such components. In this paper, we investigate how the expressiveness of the Unified Modeling Language (UML) can be increased to make it suitable also for describing physical components. A case study of an automotive mechatronic system is elaborated to show the practical usefulness of the results. © 2002 Wiley Periodicals, Inc. Syst Eng 5: 165–179, 2002 相似文献
13.
Heterogeneous objects are objects composed of different constituent materials. In these objects, multiple desirable properties from different constituent materials can be synthesized into one part. In order to obtain mass applications of such heterogeneous objects, efficient and effective design methodologies for heterogeneous objects are crucial.In this paper, we present a feature based design methodology to facilitate heterogeneous object design. Under this methodology, designers design heterogeneous objects using high-level design components that have engineering significance. These high level components are form features and material features. In this paper, we first examine the relationships between form features and material features in heterogeneous objects. We then propose three synthesized material features in accordance with our examination of these features. Based on these proposed features, we develop a feature based design methodology for heterogeneous objects. Two enabling methods for this design methodology, material heterogeneity specification within each feature and combination of these material features, are developed. A physics (diffusion) based B-spline method is developed to (1) allow design intent of material variation be explicitly captured by boundary conditions, (2) ensure smooth material variation across the feature volume. A novel method, direct face neighborhood alteration, is developed to increase the efficiency of combining heterogeneous material features.Examples of using this feature based design methodology for heterogeneous object design, such as a prosthesis design, are presented. 相似文献
14.
The recent emergence of object‐relational technology into the commercial database market has caused new challenges for the implementation of conceptual database designs. This paper presents our experience with using the Oracle 8 object‐relational data model in the implementation of an engineering application described using the EXPRESS conceptual modeling language. EXPRESS is part of the engineering community's Standard for the Exchange of Product Data and can be characterized as a structurally object‐oriented modeling language, supporting the notion of entities, entity hierarchies, complex constraints on entity hierarchies, relationships and inverse relationships between entities, and user‐defined types. As a result, EXPRESS provides an excellent framework for studying the mapping of conceptual modeling concepts into an object‐relational model. In this paper, we describe the way in which the features of EXPRESS can be mapped into object‐relational features such as object tables, object references, and nested tables. We also describe the manner in which features such as member functions on object types, triggers, and stored procedures can be used to support the implementation of constraints associated with a conceptual schema. Although the mappings presented are specific to EXPRESS and Oracle 8, the mappings are generalizable to conceptual modeling languages and object‐relational models with similar features. Our work defines how traditional mapping concepts must be revised in order to make adequate use of the features now found in object‐relational models. As part of this paper, we also compare our mapping approach using Oracle 8 to mapping issues for the PostgreSQL object‐relational model and the Objectivity/DB object‐oriented data model. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
15.
In previous work, we have modeled a vocabulary given as a semantic network by an object‐oriented database (OODB). The OODB schema thus obtained provides a compact abstract view of the vocabulary. This enables the fast traversal of the vocabulary by a user. In the semantic network vocabulary, the IS‐A relationships express the specialization hierarchy. In our OODB modeling of the vocabulary, the SUBCLASS relationship expresses the specialization hierarchy of the classes and supports the inheritance of their properties. A typical IS‐A path in the vocabulary has a corresponding shorter SUBCLASS path in the OODB schema. In this paper we expose several cases where the SUBCLASS hierarchy fails to fully correspond to the IS‐A hierarchy of the vocabulary. In these cases there exist traversal paths in the semantic network for which there are no corresponding traversal paths in the OODB schema. The reason for this failure is the existence of some IS‐A relationships between concepts of two classes, which are not connected by a SUBCLASS relationship. This phenomenon weakens the accuracy of our modeling. To rectify the situation we introduce a new OODB semantic relationship IS‐A to represent the existence of IS‐A relationships between concepts of a pair of classes which are not connected via a SUBCLASS relationship. The resulting schema contains both SUBCLASS relationships and IS‐A relationships which completely model the IS‐A hierarchy of the vocabulary. We define a mixed‐class level traversal path to contain either SUBCLASS or IS‐A relationships. Consequently, each traversal path in the semantic network has a corresponding mixed traversal path in the OODB schema. Hence the introduction of the semantic OODB IS‐A relationship improves the modeling of semantic network vocabularies by OODBs. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
16.
领域概念知识建模是构建信息系统分析的关键技术和任务之一,同时也是知识工程的瓶颈问题,其难点在于如何正确完整地捕捉和验证领域专家的知识。ER和UML等有属性特性的建模方法能够很好地描述领域知识,但却难以让领域专家确认知识的正确性和完整性。面向事实的信息建模(FOM)是一种完全面向自然语言交流的领域概念知识建模方法,是一种理想的概念建模和本体工程辅助工具。简要分析了概念建模过程,比较了不同概念建模方法,介绍了FOM的技术演化过程,从业务规则、动态建模、模型抽象机制、模型转换和工程应用等方面评述了FOM的研究现状和待研究问题。 相似文献
17.
Michael Halper Li‐min Liu James Geller Yehoshua Perl 《Concurrency and Computation》2003,15(15):1337-1362
A semantic relationship is a data modeling construct that connects a pair of classes or categories and has inherent constraints and other functionalities that precisely reflect the characteristics of the specific relationship in an application domain. Examples of semantic relationships include part–whole, ownership, materialization and role‐of. Such relationships are important in the construction of information models for advanced applications, whether one is employing traditional data‐modeling techniques, knowledge‐representation languages or object‐oriented modeling methodologies. This paper focuses on the issue of providing built‐in support for such constructs in the context of object‐oriented database (OODB) systems. Most of the popular object‐oriented modeling approaches include some semantic relationships in their repertoire of data‐modeling primitives. However, commercial OODB systems, which are frequently used as implementation vehicles, tend not to do the same. We will present two frameworks by which a semantic relationship can be incorporated into an existing OODB system. The first only requires that the OODB system support manifest type with respect to its instances. The second assumes that the OODB system has a special kind of metaclass facility. The two frameworks are compared and contrasted. In order to ground our work in existing systems, we show the addition of a part–whole semantic relationship both to the ONTOS DB/Explorer OODB system and the VODAK Model Language. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
18.
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. 相似文献
19.
对象关系的外连式实现方法 总被引：1，自引：0，他引：1
对象间关系的重要性已经得到广泛重视，但在现行程序语言中尚示获得全面支持，本文在论述了对象间关系的描述特性，分析了内嵌式和外连式两种关系实现方法的特点后，提出并深入讨论了外连式对象间关系的程序描述和实现方法，本文提出的方法已经通过基于C＋＋的程序转换的方法得到实现。 相似文献
20.
A number of activities involved in testing software are known to be difficult and time consuming. Among them is the definition and coding of test oracles and the isolation of faults once failures have been detected. Through a thorough and rigorous empirical study, we investigate how the instrumentation of contracts could address both issues. Contracts are known to be a useful technique in specifying the precondition and postcondition of operations and class invariants, thus making the definition of object‐oriented analysis or design elements more precise. It is one of the reasons the Object Constraint Language (OCL) was made part of the Unified Modeling Language. Our aim in this paper is to reuse and instrument contracts to ease testing. A thorough case study is run where we define OCL contracts, instrument them using a commercial tool and assess the benefits and limitations of doing so to support the automated detection of failures and the isolation of faults. As contracts can be defined at various levels of detail, we also investigate the cost and benefit of using contracts at different levels of precision. We then draw practical conclusions regarding the applicability of the approach and its limitations. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献