Factory Pattern Research Articles

Ownership and immutability in generic Java

The Java language lacks the important notions of ownership (an object owns its representation to prevent unwanted aliasing) and immutability (the division into mutable, immutable, and readonly data and references). Programmers are prone to design errors, such as representation exposure or violation of immutability contracts. This paper presents Ownership Immutability Generic Java (OIGJ), a backward-compatible purely-static language extension supporting ownership and immutability. We formally defined a core calculus for OIGJ, based on Featherweight Java, and proved it sound. We also implemented OIGJ and performed case studies on 33,000 lines of code. Creation of immutable cyclic structures requires a "cooking phase" in which the structure is mutated but the outside world cannot observe this mutation. OIGJ uses ownership information to facilitate creation of immutable cyclic structures, by safely prolonging the cooking phase even after the constructor finishes. OIGJ is easy for a programmer to use, and it is easy to implement (flow-insensitive, adding only 14 rules to those of Java). Yet, OIGJ is more expressive than previous ownership languages, in the sense that it can type-check more good code. OIGJ can express the factory and visitor patterns, and OIGJ can type-check Sun's java.util collections (except for the clone method) without refactoring and with only a small number of annotations. Previous work required major refactoring of existing code in order to fit its ownership restrictions. Forcing refactoring of well-designed code is undesirable because it costs programmer effort, degrades the design, and hinders adoption in the mainstream community.

Profiles for conveying the secure communication requirements of Web services

AbstractA fundamental theme of the services‐oriented Grid paradigm is the collaboration of participants from different administrative and security domains. As such, constructing meaningful, interoperable security that brokers interorganizational trust as well as token syntax and semantics is crucial for fostering Grid adoption and buy‐in. This is a lofty goal that must be tackled together by standards communities, middleware and platform software architects, and domain administrators. A crucial first step toward realizing this goal is the ability to normatively describe the secure communication requirements that affect message format. As such, we present two new OGF security profiles that provide guidance for the expression and conveyance of secure communication requirements. The Secure Communication Profile 1.0 is a refinement of the WS‐SecurityPolicy specification. The goals of this profile are to impose more restrictive conformance requirements on the WS‐Security mechanisms described by WS‐SecurityPolicy assertions, to facilitate key distribution and policy timestamping, and to profile normative ‘well‐known’ policy documents that identify commonly used security mechanisms. The Secure Addressing Profile 1.0 refines the WS‐Addressing specification in order to profile the inclusion of security policy within endpoint references (EPRs). This approach of conveying security policy within EPRs is well suited to the Grid paradigms of stateful Web service resources and factory patterns. Copyright © 2009 John Wiley & Sons, Ltd.

Three-Tier Knowledge Management System Based on .NET

Three-tier knowledge management system based on .NET architecture is designed according to requirement specification, characteristics of and relationship between enterprise electronic archives and knowledge management. This system using three-tier design based on factory pattern has good encapsulation and portability, with clearer and more concise structure. It degrades the costs of system development and maintenance and upgrades system’s high reusability and development efficiency.

Complexity in Scalable Computing

The rich history of scalable computing research owes much to a rapid rise in computing platform scale in terms of size and speed. As platforms evolve, so must algorithms and the software expressions of those algorithms. Unbridled growth in scale inevitably leads to complexity. This special issue grapples with two facets of this complexity: scalable execution and scalable development. The former results from efficient programming of novel hardware with increasing numbers of processing units (e.g., cores, processors, threads or processes). The latter results from efficient development of robust, flexible software with increasing numbers of programming units (e.g., procedures, classes, components or developers). The progression in the above two parenthetical lists goes from the lowest levels of abstraction (hardware) to the highest (people). This issue's theme encompasses this entire spectrum. The lead author of each article resides in the Scalable Computing Research and Development Department at Sandia National Laboratories in Livermore, CA. Their co-authors hail from other parts of Sandia, other national laboratories and academia. Their research sponsors include several programs within the Department of Energy's Office of Advanced Scientific Computing Research and its National Nuclear Security Administration, along with Sandia's Laboratory Directed Research and Development program and the Office ofmore » Naval Research. The breadth of interests of these authors and their customers reflects in the breadth of applications this issue covers. This article demonstrates how to obtain scalable execution on the increasingly dominant high-performance computing platform: a Linux cluster with multicore chips. The authors describe how deep memory hierarchies necessitate reducing communication overhead by using threads to exploit shared register and cache memory. On a matrix-matrix multiplication problem, they achieve up to 96% parallel efficiency with a three-part strategy: intra-node multithreading, non-blocking inter-node message passing, and a dedicated communications thread to facilitate concurrent communications and computations. On a quantum chemistry problem, they spawn multiple computation threads and communication threads on each node and use one-sided communications between nodes to minimize wait times. They reduce software complexity by evolving a multi-threaded factory pattern in C++ from a working, message-passing program in C.« less

Application of refactoring and design pattern in land information system development

The unceasing change problem of land information systems can be resolved through the refactoring and design pattern. To promote the implementation of design pattern and refactoring methods in developing land information systems reusing software design, applying refactoring methods to the abstract factory and decorator design patterns in land information system development is discussed.

Ownership confinement ensures representation independence for object-oriented programs

Representation independence formally characterizes the encapsulation provided by language constructs for data abstraction and justifies reasoning by simulation. Representation independence has been shown for a variety of languages and constructs but not for shared references to mutable state; indeed it fails in general for such languages. This article formulates representation independence for classes, in an imperative, object-oriented language with pointers, subclassing and dynamic dispatch, class oriented visibility control, recursive types and methods, and a simple form of module. An instance of a class is considered to implement an abstraction using private fields and so-called representation objects. Encapsulation of representation objects is expressed by a restriction, called confinement, on aliasing. Representation independence is proved for programs satisfying the confinement condition. A static analysis is given for confinement that accepts common designs such as the observer and factory patterns. The formalization takes into account not only the usual interface between a client and a class that provides an abstraction but also the interface (often called “protected”) between the class and its subclasses.

Teaching inter-object design patterns to freshmen

The benefits of object-oriented programming apply only to programs consisting of multiple objects. Inter-object design patterns make it, in theory, possible for beginning programmers to create well-understood forms of such programs. However, their descriptions have been targeted at experienced programmers with knowledge, for instance, of the implementation of compilers. We show that it is possible to explain and motivate several of these patterns including the iterator, model-view-controller, model-interactor, observer, façade, composite, and factory patterns by showing them working "in the small" in simple examples. We have effectively used this approach to teach an undergraduate class including several college freshmen and one high-school junior, who were able to exercise the patterns "in the medium.

Design patterns for parsing

We provide a systematic transformation of an LL(1) grammar to an object model that consists of an object structure representing the non-terminal symbols and their corresponding grammar production rules, a union of classes representing the terminal symbols (tokens). We present a variant form of the visitor pattern and apply it to the above union of token classes to model a predictive recursive descent parser on the given grammar. Parsing a non-terminal is represented by a visitor to the tokens. For non-terminals that have more than one production rule, the corresponding visitors are chained together according to the chain of responsibility pattern in order to be processed correctly by a valid token. The abstract factory pattern, where each concrete factory corresponds to a non-terminal symbol, is used to manufacture appropriate parsing visitors.Our object-oriented formulation for predictive recursive descent parsing eliminates the traditional construction of the predictive parsing table and yields a parser that is declarative and has minimal conditionals. It not only serves to teach standard techniques in parsing but also as a non-trivial exercise of object modeling for objects-first introductory courses.

Defect frequency and design patterns: an empirical study of industrial code

Software "design patterns" seek to package proven solutions to design problems in a form that makes it possible to find, adapt, and reuse them. A common claim is that a design based on properly applied patterns will have fewer defects than more ad hoc solutions. This case study analyzes the weekly evolution and maintenance of a large commercial product (C++, 500,000 LOC) over three years, comparing defect rates for classes that participated in selected design patterns to the code at large. We found that there are significant differences in defect rates among the patterns, ranging from 63 percent to 154 percent of the average rate. We developed a new set of tools able to extract design pattern information at a rate of 3/spl times/10/sup 6/ lines of code per hour, with relatively high precision. Based on a qualitative analysis of the code and the nature of the patterns, we conclude that the Observer and Singleton patterns are correlated with larger code structures and, so, can serve as indicators of code that requires special attention. Conversely, code designed with the Factory pattern is more compact and possibly less closely coupled and, consequently, has lower defect numbers. The Template Method pattern was used in both simple and complex situations, leading to no clear tendency.

Design and Development of a Cross Search Engine for Multiple Heterogeneous Databases Using UML and Design Patterns

As the popularity and complexity of Internet search engines increase, the design, development and maintenance of large, complex web-based Information Retrieval (WIR) systems become a challenge. The difficulty of designing a WIR system is compounded by information overload triggered from various different information sources. From a standpoint of the search engine users, it is more usable for the WIR to provide a single search point to multiple databases. To tackle this issue, we present the design and implementation of a cross-search component for the CS-Engine (Cross-Search Engine). The CS-Engine allows the user to search heterogeneous, multiple databases with one command. The CS-Engine is also distinguished from meta-search engines in that the CS-Engine does not need to trigger other search engines and translate a query for other search engines. Our performance benchmark tests show that the CS-Engine is scalable and usable. We also compare CS-engine with other search engines such as Google and AltaVista. The CS-Engine was developed with UML and design patterns including: (1) use case diagram, (2) class diagram, (3) package diagram, (4) interaction diagram, (5) Factory pattern, and (6) Strategy patterns. We conclude our paper with technical lessons learned as well as organizational issues encountered during the development phase.

디자인 패턴을 적용한 위성영상처리를 위한 군집화 분류시스템의 설계

본 논문에서는 위성영상을 처리하기 위한 무감독분류 기법인 군집분류 시스템을 설계하고 구현하였다. 구현된 시스템은 새로운 위성영상 포맷과 군집분류 기법의 지원이 용이하고, 확장성 있는 시스템의 설계를 위하여 팩토리 패턴과 전략적 패턴 등 다양한 디자인 패턴을 적용하였다. 군집분류 시스템은 순차군집분류 기법, K-Means 군집분류 기법, ISODATA 기법, Fuzzy C-Means군집분류 기법을 설계, 구현하였으며 Landsat TM 위성영상을 분류기의 입력영상으로 실험하였다. 그 결과 군집분류 기법은 사전지식이 없는 위성영상의 분류를 위한 표본영역의 추출작업과 위성영상의 실시간 분류에 효과적인 사용이 가능함을 보였으며, 재사용성 및 확장성이 우수한 시스템을 개발하였다. In this paper, we have designed and implemented cluttering classification systems- unsupervised classifiers-for the processing of satellite remote sensing images. Implemented systems adopt various design patterns which include a factory pattern and a strategy pattern to support various satellite images'formats and to design compatible systems. The clustering systems consist of sequential clustering, K-Means clustering, ISODATA clustering and Fuzzy C-Means clustering classifiers. The systems are tested by using a Landsat TM satellite image for the classification input. As results, these clustering systems are well designed to extract sample data for the classification of satellite images of which there is no previous knowledge. The systems can be provided with real-time base clustering tools, compatibilities and components' reusabilities as well.

A design method of Business Application Framework based on software patterns

This paper discusses design and implementation method of Business Application Framework based on software patterns, and then presents MVC pattern, of architecture and the method of dynamical update promulgation for Business Application Framework. We discuss adaptation of Abstract Factory for the kernel functionality of Business Application Framework, such as data creation, manipulation, composition, etc. It also presents class model and its class structure of Abstract Factory pattern. Finally, we briefly discuss the update, modification, and reconstruction method of Business Application Framework.

Implementation of a database factory

Object oriented software systems that utilize relational databases for data-store have to deal with the problem of interfacing to the relational data. This aspect of the software is more relevant to the solution domain rather than the problem domain i.e., the business requirements of an application do not dictate that there be a mechanism that allows the application to store and retrieve relational data. Hence, de-coupling the application from the database and its interface is relevant from the perspective of portability that of the application to other kinds of databases. For example, it is conceivable the application may be required to work with relational databases from different vendors. This article shows an adaptation of the Factory Method Pattern and the Abstract Factory Pattern [1] as a generic solution to the problem of de-coupling application code from the underlying database and its associated interface mechanisms.

Design of cellular manufacturing systems in tandem configuration

This paper develops a cell formation approach for a class of cellular manufacturing systems in which intercell moves are restricted to flow in one direction from one cell to the cell immediately downstream, without backtracking. An optimal zero-one integer programming model is used to determine which machines and parts should be assigned to cells and to specify the relative position of the cells on the factory material flow pattern. The model subdivides, the underlying manufacturing system into cells based on an intercell traffic minimization criterion and subject to machine capacity and operations sequence constraints. The model also considers part setup and run times for the evaluation of capacity requirements.

An economic assessment of electricity for industrial space heating in the United Kingdom

The potential for increased use of electricity for space heating in industry in the United Kingdom is investigated. Two presently available technologies are considered the most likely candidates: electricaire (storage-based warm air heating on a restricted hour tariff) and air-to-air heat pumps. A simulation modeling approach is employed to examine the economic feasibility of the two electricity-based heating systems. The central component of the model is a simple industrial building with known thermal characteristics. The technical performance of the heating system installed in the model factory is assessed over the period of a year, while the economic performance is evaluated over the lifetime of the heating system. The economic competitiveness of electricaire and heat pump space heating is assessed by comparison with gas-fired warm air heating for different sizes of factory and shift patterns. The future prospects of the heating systems are examined under various scenarios. It is concluded that electricaire looks most favourable in small single shift factories because of its low capital cost, while heat pump heating looks most attractive in factories operating longer shifts, particularily if advantage can be taken of restricted hour tariffs. Greater penetration of heat pump heating systems is only likely if reductions in the capital cost of heat pumps and/or improvements in the coefficient of performance are achieved.

Dialectics and Hope

1. Mankind, as it is, has been called a premature birth. The human being comes into the world more helpless and less finished than any animal, takes considerably longer to mature, and is threatened in the process even by itself. It wavers and makes mistakes which would never occur to a young animal in its innate environment. It is in the dark, does not know up from down, seldom or only indistinctly has in its body the infallible guide which leads a horse to water, or even a returning swallow to its nest from last year. It comes into unforeseen circumstances, such as the animal seldom experiences, must find its way in situations which have never existed before, and with which it is consequently not acquainted; whereas the young animal is soon whistled to a stop. The finished armor of the animal's species is soon hung around its shoulders, and its face, which in young animals often resembles a human baby's face, soon ossifies. The form of many hundred thousands of years triumphs; the curtain soon falls decisively over its potentiality for development. Of necessity animals repeat the proven factory pattern of their body and life, hence, they are beings but also very narrowly bound. Human beings can participate only very approximately in this boundedness; they do so as the usual mass-produced goods; they did so in a different way, fertilely and distinctly, in the earlier peasant class. But mass-produced goods themselves are historical, and what fit the average yesterday no longer fits today, for uniformity, at least, has its fashions. It is great that we humans are born unfinished as a species, not only as children. But it is also a hard lot to be engaged in a development which proceeds so slowly, since it is trapped over and over again by deceivers. Socialist society has been a practical possibility for at least a hundred years; and how many among the educated, of whom there is always ample number, do not even know its ABC's today. Mankind is the animal who takes detours, yet often in an obdurate and flagrantly foolish way, not just cunningly. Otherwise, all of outward life would run as easily and peacefully as now happens, at best, among friends. 2. All being is still built around the Not which induces hunger. There does not yet exist a food which could calm and fill up the lack entirely, or the boon

Housing the Worker: The Employment Linkage as a Force in Urban Structure

I NDUSTRIAL localization is a term widely employed by geographers and economists when they set out to explain the location in space of manufacturing activity. Observation of practice and assessment of census data have yielded certain generalizations as to where particular types of industry are found. From these generalizations several theories seeking to explain the causation of factory patterns have been devised. Without trying to catalogue or compare explanations we should note that the search for understanding began some 75 years ago and continues to the present time. During that period the quest has been for organizing concepts of industrial location that help us understand where plants will be located in terms of a generalized view of the geographical structure of manufacturing. Cooley' was the first to propose notions of transportation con-