There is a growing tendency for people in the community of object-oriented methods to use preand post-conditions to write formal specifications for opera- tions （methods） of classes. The motivation for trying to tak...There is a growing tendency for people in the community of object-oriented methods to use preand post-conditions to write formal specifications for opera- tions （methods） of classes. The motivation for trying to take advantage of well established formalism in precisely defining the functionality of operations is laudable, but unfortunately this exercise may be flawed because the use of pre- and post-conditions containing method calls （or similar） with side effects are likely to cause confusion in the interpretation of specifications. This paper analyzes, with comprehensible examples, why using pre-post notation is not effective to specify operations in objectoriented systems in general, discusses existing approaches to using pre-post notation for object-oriented systems, and offers some solutions to the problem.展开更多
The advantage of COOZ (Complete Object-Oriented Z) is to specify large scale software, but it does not support refinement calculus. Thus its application is confined for software development. Including refinement calc...The advantage of COOZ (Complete Object-Oriented Z) is to specify large scale software, but it does not support refinement calculus. Thus its application is confined for software development. Including refinement calculus into COOZ overcomes its disadvantage during design and implementation. The separation between the design and implementation for structure and notation is removed as well. Then the software can be developed smoothly in the same frame. The combina- tion of COOZ and refinement calculus call build object-oriented frame, in which the specification in COOZ is refined stepwise to code by calculus. In this paper, the development model is established, which is based on COOZ and refinement calculus. Data refinement is harder to deal with in a refinement tool than ordinary algorithmic refinement, since data refinement usually has to be done on a large program component at once. As to the implemelltation technology of refinement calculus, the data refinement calculator is constructed and an approach for data refinement which is based on data refinement calculus and program window inference is offered.展开更多
Data integration requires managing heterogeneous schema information. A federated database system integrates heterogeneous, autonomous database systems on the schema level, whereby both local applications and global ap...Data integration requires managing heterogeneous schema information. A federated database system integrates heterogeneous, autonomous database systems on the schema level, whereby both local applications and global applications accessing multiple component database systems are supported. Such a federated database system is a complex system of systems which requires a well-designed organization at the system and software architecture level. A specific challenge that federated database systems face is the organization of schemas into a schema architecture. This paper provides a detailed, formal investigation of variability in the family of schema architectures, which are central components in the architecture of federated database systems. It is shown how the variability of specific architectures can be compared to the reference architecture and to each other. To achieve this, we combine the semi-formal object-oriented modeling language UML with the formal object-oriented specification language Object-Z. Appropriate use of inheritance in the formal specification, as enabled by Object-Z, greatly supports specifying and analyzing the variability among the studied schema architectures. The investigation also serves to illustrate the employed specification techniques for analyzing and comparing software architecture specifications.展开更多
实时获取农作物长势及产量等信息对于现代农业的发展具有重要意义。近年来,随着遥感技术(remote sensing,RS)和地理信息系统(geographic information system,GIS)广泛应用于农作物估产领域,相继出现了一些较为实用的估产方法,主要有结...实时获取农作物长势及产量等信息对于现代农业的发展具有重要意义。近年来,随着遥感技术(remote sensing,RS)和地理信息系统(geographic information system,GIS)广泛应用于农作物估产领域,相继出现了一些较为实用的估产方法,主要有结合辅助数据的估产方法、基于植被指数的估产方法、基于特定模型的估产方法和基于农作物估产平台(软件)的开发等。其中,基于植被指数的估产方法又分为单一和多植被指数估产2类方法。在对近年来该领域大量文献深入研究的基础上,着重就几类热点方法展开论述,并对每类方法的优势和缺陷进行了评述,最后对该领域需要进一步研究的方向进行了探讨和展望,以期为后续研究提供参考。展开更多
文摘There is a growing tendency for people in the community of object-oriented methods to use preand post-conditions to write formal specifications for opera- tions （methods） of classes. The motivation for trying to take advantage of well established formalism in precisely defining the functionality of operations is laudable, but unfortunately this exercise may be flawed because the use of pre- and post-conditions containing method calls （or similar） with side effects are likely to cause confusion in the interpretation of specifications. This paper analyzes, with comprehensible examples, why using pre-post notation is not effective to specify operations in objectoriented systems in general, discusses existing approaches to using pre-post notation for object-oriented systems, and offers some solutions to the problem.
基金the National Natural Science Foundation of China (No.69673006) and theNational Ninth Five-Year Project (98-780-01-07-06) of Ch
文摘The advantage of COOZ (Complete Object-Oriented Z) is to specify large scale software, but it does not support refinement calculus. Thus its application is confined for software development. Including refinement calculus into COOZ overcomes its disadvantage during design and implementation. The separation between the design and implementation for structure and notation is removed as well. Then the software can be developed smoothly in the same frame. The combina- tion of COOZ and refinement calculus call build object-oriented frame, in which the specification in COOZ is refined stepwise to code by calculus. In this paper, the development model is established, which is based on COOZ and refinement calculus. Data refinement is harder to deal with in a refinement tool than ordinary algorithmic refinement, since data refinement usually has to be done on a large program component at once. As to the implemelltation technology of refinement calculus, the data refinement calculator is constructed and an approach for data refinement which is based on data refinement calculus and program window inference is offered.
文摘Data integration requires managing heterogeneous schema information. A federated database system integrates heterogeneous, autonomous database systems on the schema level, whereby both local applications and global applications accessing multiple component database systems are supported. Such a federated database system is a complex system of systems which requires a well-designed organization at the system and software architecture level. A specific challenge that federated database systems face is the organization of schemas into a schema architecture. This paper provides a detailed, formal investigation of variability in the family of schema architectures, which are central components in the architecture of federated database systems. It is shown how the variability of specific architectures can be compared to the reference architecture and to each other. To achieve this, we combine the semi-formal object-oriented modeling language UML with the formal object-oriented specification language Object-Z. Appropriate use of inheritance in the formal specification, as enabled by Object-Z, greatly supports specifying and analyzing the variability among the studied schema architectures. The investigation also serves to illustrate the employed specification techniques for analyzing and comparing software architecture specifications.
文摘实时获取农作物长势及产量等信息对于现代农业的发展具有重要意义。近年来,随着遥感技术(remote sensing,RS)和地理信息系统(geographic information system,GIS)广泛应用于农作物估产领域,相继出现了一些较为实用的估产方法,主要有结合辅助数据的估产方法、基于植被指数的估产方法、基于特定模型的估产方法和基于农作物估产平台(软件)的开发等。其中,基于植被指数的估产方法又分为单一和多植被指数估产2类方法。在对近年来该领域大量文献深入研究的基础上,着重就几类热点方法展开论述,并对每类方法的优势和缺陷进行了评述,最后对该领域需要进一步研究的方向进行了探讨和展望,以期为后续研究提供参考。
