We investigate the optimization of language-level checkpointing of Java programs. First, we describe how to systematically associate incremental checkpoints with Java classes. While being safe, the genericness of this...
详细信息
We investigate the optimization of language-level checkpointing of Java programs. First, we describe how to systematically associate incremental checkpoints with Java classes. While being safe, the genericness of this solution induces substantial execution overhead. Second, to solve the dilemma of genericness versus performance, we use automatic program specialization to transform the generic checkpointing methods into highly optimized ones. Specialization exploits two kinds of information: structural properties about the program classes; knowledge of unmodified data structures in specific program phases. The latter information allows us to generate phase-specific checkpointing methods. We evaluate our approach on two benchmarks, a realistic application which consists of a program analysis engine, and a synthetic program which can serve as a metric. Specialization gives a speedup proportional to the complexity of the object structure and the modification pattern. Measured speedups for the program analysis engine are up to 1.5, and for the synthetic program are up to 15.
This paper presents a load management concept for distributed object-oriented environments. The focus is on system level load management, i.e. the integration of load management into the runtime system or the middlewa...
详细信息
This paper presents a load management concept for distributed object-oriented environments. The focus is on system level load management, i.e. the integration of load management into the runtime system or the middleware. This paper discusses the special requirements of load management for distributed object-oriented environments. Based on the requirements, the components of a load management service are explained. Finally, an implementation of the load management concept for the CORBA middleware architecture is presented.
The authors discuss a discretionary access control model to realize secure object-oriented systems. An object is manipulated only through methods supported by the object. Classes and objects are hierarchically structu...
详细信息
The authors discuss a discretionary access control model to realize secure object-oriented systems. An object is manipulated only through methods supported by the object. Classes and objects are hierarchically structured in generalization (is-a) and aggregation (part-of) relations. We discuss how to authorize and inherit access rights on classes and objects in the hierarchical structure.
The paper discusses a Web-based application that serves as a leading resource for linking educators to the community. This Web site provides individual teachers and school organizations a simple and effective means to...
详细信息
The paper discusses a Web-based application that serves as a leading resource for linking educators to the community. This Web site provides individual teachers and school organizations a simple and effective means to communicate school/course-related information to the education community and also provides a means for interested parties to interact with the classroom and give feedback to the instructor online. The paper shows the feasibility of developing Web-based applications using several new application tools from the Java 2 Enterprise Edition and demonstrates some of the features of this new technology.
The peculiar characteristics of distribution systems require the development of specific load flow models and solving techniques. The aim of the studies presented in literature is usually to enhance computational effi...
详细信息
The peculiar characteristics of distribution systems require the development of specific load flow models and solving techniques. The aim of the studies presented in literature is usually to enhance computational efficiency and convergence characteristics of the algorithms. Yet, thanks to the increase of the capacity of modern computing environments, new approaches can be adopted that give preference to flexibility, extensibility and maintainability of the software rather than to computational efficiency. In the paper, the object-oriented paradigm is applied to distribution load flow. The electrical system modeling is structured in a hierarchy of classes; for each class, data and methods are defined to implement local processing of a Newton-Raphson distribution load flow algorithm decomposed into modules; information hiding guarantees modularity and flexibility. The features of a software tool implemented in an open software CAD environment are presented. Numerical applications to a test system evidence the convergence characteristics of the algorithm.
In order to improve reliability and quality, software systems should be tested. The testing of object-oriented software systems is more complex than that of traditional programming. Recently, we have proposed an appro...
详细信息
In order to improve reliability and quality, software systems should be tested. The testing of object-oriented software systems is more complex than that of traditional programming. Recently, we have proposed an approach to select a finite number of representative equivalent pairs as test cases from the infinite set of all equivalent pairs. The approach is based on the concept of equivalent fundamental pairs. We analyze the effectiveness of this approach using a class graph. A class graph can be derived from the syntax declaration of the algebraic specification for the given class under test. Using the class graph, we show that our approach omits many testing paths in the class graph but doesn't reduce the testing effect. Hence, the testing efficiency is improved greatly.
Aiming at improving the reconfiguration capability of an automatic testing system for turbine machinery, the method of object orientation is employed to develop its software. Since the project size is small, we adopt ...
详细信息
Aiming at improving the reconfiguration capability of an automatic testing system for turbine machinery, the method of object orientation is employed to develop its software. Since the project size is small, we adopt a compact and pragmatic approach to construct this object-oriented application instead of using complicated commercial object-oriented methods. Although the method is simple, it covers all phases from collecting customer requirements to testing the code. In this paper, the five main phases of the object-oriented method (requirements capture, analysis, design, programming and testing) are presented. The successful practical application proves that the adopted object-oriented method is efficient for this software development.
This author has mathematically correlated specific development practices to defect density and probability of on time delivery. She summarizes the results of this ongoing study that has evolved into a software predict...
详细信息
This author has mathematically correlated specific development practices to defect density and probability of on time delivery. She summarizes the results of this ongoing study that has evolved into a software prediction modeling and management technique. She has collected data from 45 organizations developing software primarily for equipment or electronic systems. Of these 45 organizations, complete and unbiased delivered defect data and actual schedule delivery data was available for 17 organizations. She presents the mathematical correlation between the practices employed by these organizations and defect density. This correlation can and is used to: predict defect density; and improve software development practices for the best return on investment.
A criticism that may, with some justification, be levelled at many visual programming languages is that they are simply not scalable to real world problems. In creating a visual language capable of handling multiple c...
详细信息
A criticism that may, with some justification, be levelled at many visual programming languages is that they are simply not scalable to real world problems. In creating a visual language capable of handling multiple concurrent threads of control in addition to a graphical depiction of data, we were acutely confronted with such difficulties. The language we devised, based on the Petri net model, incorporates an objectoriented view of data which, together with a number of innovations designed to alleviate screen contention and complexity, has helped to address the scalability issue.
Dynamic memory management (DMM) has been a high cost component in many software systems. In particular, the use of object orientation often results in an intensive use of dynamic memory, making the dynamic memory perf...
详细信息
Dynamic memory management (DMM) has been a high cost component in many software systems. In particular, the use of object orientation often results in an intensive use of dynamic memory, making the dynamic memory performance problem worse. The paper presents a profile based strategy to improve the performance of DMM. The performance improvement comes from a segregated strategy without splitting and coalescing cost. This modification is made feasible by preallocating the free-list based on the profile data of heap memory usage. In this research, the empirical study shows that the maximum number of live objects of each size is independent of the input; this data provides a profile and estimate for the amount of memory the application will need to run and can be preallocated to give great improvement in performance. Compared to the average performance of well known algorithms, the profile based approach is about 3.9 times to 6.5 times faster.
暂无评论