Procedural meta-models for architectural design praxis

Jeff Magee and Jeff Kramer John Wiley and Sons, New York, NY, 1999, 374 pp. ISBN 0471987107, $64.99 The book is an introductory text to the ideas, concepts, and topics of concurrency. The text focuses on understanding concepts and techniques, and problems of concurrency, not on the implementation or language. The author's overall goal is that by a combination of learning and doing using Java should make the process of acquiring the skills relating to concurrency interesting, enjoyable, and challenging. The Java language is thus used only for illustration and programming experience of the reader. The book is intended for a computer science student or software developer. A background in programming is expected, as well as some familiarity with the essential concepts of object-oriented programming. Knowledge of the Java programming language and operating systems concepts is beneficial but not required. After reading the text, a reader can expect to have a broad understanding of the concepts of concurrency, the problems that arise, methods to emphasis desirable properties in a concurrent system, and ways to avoid the undesirable ones. The text provides a systematic treatment of concepts, as means to rigorously specify and model concurrent systems, with Java examples to animate and illustrate the concepts discussed. The book is organized into twelve chapters, with three appendices. The first eight chapters provide a concise and comprehensive foundation of concurrency, with the remaining four chapters focusing on more advanced concepts. The latter four chapters are somewhat supplemental and can be read at the discretion of the reader. The content of the text is self-contained, with no reliance upon external references. The authors provide a concluding set of notes and further topics which reference external works, but these are not used in the chapter contents. The introduction provides the foundation for the book, and an idea of what will follow in the rest of the text. The basics of modeling and Java are covered. Authors follow with the concepts of processes, threads and with the idea of concurrency. The emphasis is on using Java, and on the notation used to define a concurrent process or thread. The discussion continues covering interleaving and asynchronous concurrency. Various details about composition of parallel processes and finite state processing modeling are presented. The programming of concurrent execution using Java is then examined via the concept of multiple threads. Here, sharing objects among Java threads is also discussed. The concept of conditional synchronization is covered next, and is used to construct a monitor. The methods of the base object in Java is used, and a waiting queue associated with a Java object is discussed and implemented. This discussion is followed by introduction of deadlock. Authors show the conditions necessary for a deadlock to occur and present an analysis of a concurrent system establishing that such a system is deadlock-free. The classic Dining Philosopher's problem is used to illustrate the distinction between finding deadlocks in models and in programs. The presentation continues with the safety property (that asserts that nothing bad happens), and the liveliness property (that asserts that nothing good happens). Here, authors use the material on model-based design to consolidate many of the concepts previously discussed. No one modeling method or design methodology is emphasized. Then creation and elimination of threads in a running program is covered next. The dynamic starting and stopping of Java threads is presented. The discussion moves then to messaging passing. Asynchronous and synchronous messaging is presented with Java programming examples. The concept of a rendezvous, allowing for interaction in a messaging system, is also presented. Based on the concepts developed so far filter-pipeline, supervisor-worker, and announcer-listener concurrent architectures are examined. Java programs demonstrating how the elements of each model interact at runtime are developed. The presentation completes with modeling and implementing of timed systems. Time is signaled by the passage of successive time ticks. The authors then elaborate on a system that is event-based rather than thread-based. Java programs are used to illustrate in implementation the concepts discussed. The three appendices provide a reference, specification, and listing of semantics for the finite-state modeling algebra used by the authors throughout the book. The text is ideal for teaching in a classroom environment, or for a motivated reader to use for self-paced learning. Its organization follows a logical train of discussion and thought, with each chapter building successively on the other, with the more difficult concepts and topics withheld until later. This gradual approach makes the material flow smoothly and cohesively from the beginning to the end. The book is intended as a textbook, so does organize the material and discussion as one, but does not become too dry or bland to stifle the reader's interest in the material. The examples are inter-mixed with the discussion to highlight and emphasize essential points the authors make in each chapter. The text illustrates concepts well under discussion, and does not become a long-winded recital of theory. The topics examined are fundamental to concurrency, and are well illustrated and discussed, but no one topic is examined extensively. The code examples are well written concerning the programming style, indentation and comments. A CD is provided, containing the codes from the book. In addition supplementary material consisting of presentation slides and an errata is provided on the author's WWW site, as well as on the CD. The book is up to date both on the topics of concurrency, and with the Java applets, code, and programs used to illustrate them. Later, as the Java language evolves, the examples may need to be updated, but for the time being the text well represents that state of the Java language. William F. Gilreath, Micron Technology, Inc., Boise Idaho

Research on artificial neural networks (ANNs) has been carried out for more than five decades. A renewed interest appeared in the 80's with the finding of powerful models like J. Hopfield's recurrent networks, T. Kohonen's self-organizing feature maps, and the back-propagation rule. At that time, there was no platform that was at the same time versatile enough for any ANN model to be implemented and fast enough to solve large problems. Super-computers were the sole exception to this rule, but were prohibitively expensive for most applications. However, both research scientists and application engineers clearly identified the need for such a computing power. This triggered many projects in the field. In parallel, research on multi-processor systems started during the 60's. Systolic arrays have been proposed in 1979 as a means to fully exploit the possibilities of VLSI. Two previous theses, by F. Blayo and C. Lehmann, have studied the use of bi-dimensional systolic arrays for neural computation. At first, the presented system, called GENES, has been designed for the Hopfield model. Extensions to other ANNs have also been proposed. The goal of the present thesis is to study, design, build, and analyze an efficient accelerator for neural computation. In a first step, the GENES architecture has been extended towards generality and efficiency. This includes a thorough analysis of ANN models, of other neural computers, and of previous GENES implementations. The result of this work is the GENES IV integrated circuit, whose architecture has been co-designed by P. Ienne and the author. The main part of this thesis discusses the architecture, the design and the analysis of the MANTRA I machine, a neural computer based on a GENES IV array with up to 40 × 40 processing elements (PEs). The delta rule (and hence the Perceptron and Adaline rules), the back-propagation rule, the Hopfield model, and the Kohonen model can be implemented on this system. Although not a generic system, such a machine may be regarded as a multi-model neural computer. A prototype has been running for a year and is used daily by software designers. Several novel features distinguish the MANTRA I machine from other neural systems. First, it belongs to the few existing neural computers, contrary to the majority of implementations, which are specific to an application or to an algorithm. The machine does not hard-wire any algorithm, but provides the necessary primitives to implement the target models. This is a key feature for research, since several algorithms or versions of an algorithm can be tested on a problem. It is an important aspect for applications as well, because different ANN models are often cascaded to solve a problem. The GENES IV array — that is, the computing core of the MANTRA I machine — features synapse-level parallelism (i.e., one real or virtual PE is allocated per synapse or neural connection), while most other systems exploit only neuron-level parallelism (i.e., one PE per neuron). Hence, this system aims at a much finer parallelism grain and is well suited for massively parallel architectures. The problem size that can be computed by a neural accelerator should not be limited by the hardware (except for memory size). Therefore, it is essential to support time-sharing of PEs. On the MANTRA I machine, this is achieved by the concept of virtual arrays. Matrices are divided into sub-matrices that can be mapped onto the physical array, which is then time-shared among them. An efficient mechanism has been implemented to swap sub-matrices in background, while some other computation is performed. Since systolic arrays are pipelined systems, it is important to avoid emptying and re-filling them too often, in order to keep the hardware utilization rate high. Therefore, a systolic instruction flow has been implemented, so that each instruction follows the data for which it has been issued. Like any SIMD system, the MANTRA I machine is composed of a parallel or SIMD module and a control module. The SIMD module consists of the GENES IV array and a set of dedicated units designed for the computation that scales with the number of neurons and would poorly fit on a bi-dimensional array. A complex system of FIFOs and memories sustains the required input/output streams for the systolic array. The control module is a complete SISD system. Its tasks are (1) to control the SIMD module by dispatching instructions, (2) to manage data input and output, (3) to communicate with the external world, and (4) to perform data pre- and post-processing. The SIMD instructions are of the very long instruction word (VLIW) type. Synchronization between the two modules is achieved by an instruction FIFO. The performance of the MANTRA I machine has been analyzed using the delta rule. Measurements show that the sustained performance is very close to its peak value, as long as the problem fits in the memory banks connected to the GENES IV array. Experiments have also been run to investigate the impact of the constraints imposed by the hardware on the convergence of algorithms. Finally, the use of systolic arrays as neural accelerators is discussed in the light of the experience acquired with the GENES IV array and the MANTRA I machine. The weaknesses of the machine are analyzed, and several solutions are proposed to avoid them in a future design. A general discussion of the future of neural computers concludes this thesis.

Falls prevention education between older adults and healthcare providers during transition from hospital to community-living

A growing body of literature is beginning to examine how individuals engage and interact with others within group contexts. However, no research has examined how individuals’ orientations toward coordinating action in groups, their relational orientations, alter their behaviour within group interactions. This thesis asserts that this gap has potentially been driven by the absence of a framework that captures all facets of the relational modules individuals use to coordinate action in groups. In turn, existing measures of relational orientations cannot necessarily be applied within the intragroup domain. This thesis represents an attempt to bridge this gap. First, a description of individual differences in orientations towards coordinating action in groups informed by Durkheim (1893/2014) is presented. The description outlines that two distinct collections of relational orientations exist, mechanical and organic. Second, across five studies this thesis presents the development and preliminary evidence of a measure that may capture individual variation in people’s orientations toward coordinating action in groups according to a mechanical or organic relational module, the Mechanical and Organic Orientations Scales or MOOS for short. In an initial pilot study (Chapter 2) preliminary items created to capture mechanical and organic orientations are submitted to factor analytic methods to examine the underlying structure of the items. While the results of this pilot study were promising, a number of issues suggested that further refinement of the items was needed. A series of studies were then conducted using a revised set of items (Chapter 3). In Study 1, an exploratory factor analysis using the revised set of items was conducted. Although the item factor loadings were moderate, the results provided some support for a two factor model of relational group orientations reflecting the two predicted mechanical and organic orientations, with nine items in each factor. Study 2 then sought to confirm the factor structure observed in Study 1. The results demonstrated good indices of fit. The factor structure and loading of items were also shown to be consistent through a series of multigroup measurement invariance models. Study 2 also sought to establish the convergent and divergent validity of the MOOS from measures that capture people’s life-guiding principles. The results provided support for the validity of the MOOS, with associations demonstrating that the MOOS captures a dimension of sociality that is different to but nonetheless related to broad socially organising principles. Study 3 was then conducted to further establish the construct validity of the MOOS from existing measures of people’s relational orientations. Only tentative support for the MOOS was obtained in this study. While the patterns of convergence and divergence found in Study 3 suggested that the MOOS are related to existing relational orientation measures, the patterns of results were paradoxical to what theory outlined in Chapter 1 would suggest. A considerable discussion is also provided to discuss why these paradoxical patterns may have emerged. In Study 4, associations between the MOOS and the ties people seek to form with others in their own social networks were examined. Again, only weak support for the validity of the MOOS was obtained. Although the MOOS do appear to be associated with group level phenomena (i.e., how people form their interdependencies with others), some of these associations were non-significant. The results of Study 4 were taken to provide only preliminary support to the validity of the MOOS. Study 4 also noted that further research is needed before the MOOS can be fully utilised in contemporary research. The general discussion (Chapter 4) then draws upon the findings of the five studies to propose that while there is some evidence to suggest that people’s relational group orientations may be relevant to the way people coordinate action in groups, further research is necessary to establish the validity of the MOOS. With the recognition that further improvements are necessary, the theoretical and practical implications of an improved MOOS are then discussed. Specifically, this discussion draws attention to the relevance of these findings for research in relationship science and group dynamics, and provides examples of how an improved MOOS may be used to inform theory and practice within these domains. Limitations of the research program are discussed and suggestions for future research exploring mechanical and organic orientations are also outlined.

In this thesis, concepts for developing Spatial Data Infrastructures with an emphasis on visualizing 3D landscape and city models in distributed environments are discussed. Spatial Data Infrastructures are important for public authorities in order to perform tasks on a daily basis, and serve as research topic in geo-informatics. Joint initiatives at national and international level exist for harmonizing procedures and technologies. Interoperability is an important aspect in this context - as enabling technology for sharing, distributing, and connecting geospatial data and services. The Open Geospatial Consortium is the main driver for developing international standards in this sector and includes government agencies, universities and private companies in a consensus process. 
\n3D city models are becoming increasingly popular not only in desktop Virtual Reality applications but also for being used in professional purposes by public authorities. Spatial Data Infrastructures focus so far on the storage and exchange of 3D building and elevation data. For efficient streaming and visualization of spatial 3D data in distributed network environments such as the internet, concepts from the area of real time 3D Computer Graphics must be applied and combined with Geographic Information Systems (GIS). For example, scene graph data structures are commonly used for creating complex and dynamic 3D environments for computer games and Virtual Reality applications, but have not been introduced in GIS so far. 
\nIn this thesis, several aspects of how to create interoperable and service-based environments for 3D spatial data are addressed. These aspects are covered by publications in journals and conference proceedings. The introductory chapter provides a logic succession from geometrical operations for processing raw data, to data integration patterns, to system designs of single components, to service interface descriptions and workflows, and finally to an architecture of a complete distributed service network.
\nDigital Elevation Models are very important in 3D geo-visualization systems. Data structures, methods and processes are described for making them available in service based infrastructures. A specific mesh reduction method is used for generating lower levels of detail from very large point data sets. An integration technique is presented that allows the combination with 2D GIS data such as roads and land use areas. This approach allows using another optimization technique that greatly improves the usability for immersive 3D applications such as pedestrian navigation: flattening road and water surfaces. It is a geometric operation, which uses data structures and algorithms found in numerical simulation software implementing Finite Element Methods. 
\n3D Routing is presented as a typical application scenario for detailed 3D city models. Specific problems such as bridges, overpasses and multilevel networks are addressed and possible solutions described. The integration of routing capabilities in service infrastructures can be accomplished with standards of the Open Geospatial Consortium. An additional service is described for creating 3D networks and for generating 3D routes on the fly. Visualization of indoor routes requires different representation techniques.
\nAs server interface for providing access to all 3D data, the Web 3D Service has been used and further developed. Integrating and handling scene graph data is described in order to create rich virtual environments. Coordinate transformations of scene graphs are described in detail, which is an important aspect for ensuring interoperability between systems using different spatial reference systems. The Web 3D Service plays a central part in nearly all experiments that have been carried out. It does not only provide the means for interactive web-visualizations, but also for performing further analyses, accessing detailed feature information, and for automatic content discovery.
\nOpenStreetMap and other worldwide available datasets are used for developing a complete architecture demonstrating the scalability of 3D Spatial Data Infrastructures. Its suitability for creating 3D city models is analyzed, according to requirements set by international standards. A full virtual globe system has been developed based on OpenStreetMap including data processing, database storage, web streaming and a visualization client.
\nResults are discussed and compared to similar approaches within geo-informatics research, clarifying in which application scenarios and under which requirements the approaches in this thesis can be applied.
\n

Sustainable High-rises

Climate change, its causes and effects have become a topical issue in the world today. Universal increases in temperature and sea levels, are evidences of this global phenomenon. In the field of architecture, climate-resilient and climate-responsive domestic buildings are being developed to adapt to changing climates, while being socio-economically suited to their geographical contexts. Much research in this area has been carried out in developing tropical countries such as Nigeria. Most studies concentrate on passive optimisation of building envelopes to promote thermal comfort and reduce reliance on active mechanical controls which worsen climate change. Thus, it may be said that thermal comfort has been established as a link between climate change and housing. In south-west Nigeria, where an abundance of tropical rainforests engenders a hot-humid climate, achieving thermal comfort in buildings is a major need. Studies show that of all house envelopes in south-west Nigeria through time, two housing styles namely the pre-colonial traditional and colonial modernist styles best demonstrate effective use of climatic design principles in achieving thermally comfortable interiors. However, due to cultural changes over time, a third style of housing which is referred to as contemporary south-west Nigerian housing, is currently the most preferred form of housing. South-west Nigerian contemporary house shows considerable influence from the International Style. This housing style features envelopes with minimum use of climatic design principles and maximum reliance on mechanical cooling devices such as air conditioners, in providing indoor thermal comfort. These mechanical devices, however, are known for aggravating south-west Nigerian climate change. To reduce the aggravation of climate change caused by south-west Nigerian contemporary housing envelopes, this study proposes a free-running contemporary house envelope which promotes thermal comfort in present and future south-west Nigerian climates. As such, the study extensively reviewed climatic design principles and thermal standards applicable in tropical climates as well as material on chronological south-west Nigerian housing developments. The study modelled and evaluated the thermal performance of a free-running, base-case contemporary house envelope in present and future climates, using DesignBuilder’s dynamic thermal simulations. South-west Nigerian present and future climatic data used in the simulations, were generated by the climatic data source and calculation software Meteonorm. South-west Nigerian present climatic data was validated by readings from data loggers placed in a real-live contemporary base-case house in the region. The results of this study’s simulations confirmed that the free-running, base-case contemporary house envelope does not promote thermal comfort in present climates, hence the current supplementary mechanical thermal controls. Additionally, the results showed that the contemporary envelope would not promote thermal comfort in future south-west Nigerian climates. As such, this study then proceeded to optimise the contemporary house envelope to improve its thermal performance in south-west Nigerian present and future climates. This optimisation involved adjusting the envelope specifications under the following parameters: headroom height, external wall (thermal mass, insulation and thickness), internal ground floor (thermal mass, insulation and thickness), roof (thermal mass, pitch, structure, overhang length, covering), external window (size, type, glazing thickness and type), azimuth angle (building orientation) and ground floor elevation distance. These parameters were based on Szokolay’s (2014) climatic design principles. The results showed that optimising the south-west Nigerian contemporary envelope under those parameters improved its thermal performance, enabling it to provide indoor thermal comfort in present and future south-west Nigerian climates. Accordingly, this study’s main contribution is the proposal of a free-running climate-responsive south-west Nigerian contemporary house envelope which promotes indoor thermal comfort in present and future climates. It recommends that: 1. without any need for mechanical cooling devices, the specifications of this optimised contemporary house envelope can be used to reform housing design policies in south-west Nigeria, and 2. using the optimised envelope would reduce reliance on mechanical thermal controls and therefore mitigate climate change in the region.

In the ambiguous period of globalisation, the city of Istanbul has been facing a series of complex and uncertain problems by the emergence of neo-liberal urban policies, the continuing issues of the residential neighbourhoods of former internal migrants, and finally new challenges by the arrival of a massive number of transnational migrants. In this context of emerging urban polarization, urban design needs to develop the ability to communicate with different disciplines interwoven into a whole. A new understanding of the built environment and the ways of modifying urban design is needed. The design studio is the most popular and widespread method for teaching and training students at every level to work together for the emerging complex urban issues, to accept a dialectic exchange with instructors and classmates, and to acculturate students to the “real-world” environment with all of the noises, intrusions and nuisances of the city of Istanbul. To what extent can a graduate programme, and design studio, in particular, give an understanding of complex urban issues, and develop an ability to develop resilient projects and policies for the emerging contemporary urban problems? What are the benefits of using exchanged or integrated methods of landscape architecture, architecture and urban planning regarding resiliency? In the ambiguous globalising context, this paper aims at revealing the challenging milieu of an urban design studio at ITU Interdisciplinary Graduate Urban Design Programme. What makes the design studio extraordinary is not only the participation of three departments in conducting the studio, but also multi-departmental student profile to deal with and respond to complex contemporary urban issues. Consist of three designers (architects, planners and landscape architects); urban design studio aims at giving the students the ability to work in interdisciplinary groups with a high interaction and interdisciplinary dialogue. The studio works also provoke the students to interpret different views, combine and read undergraduate knowledge with new disciplines. In the paper, the methodology of the research is based on a literature review about “urban design education and studio culture.” Following a brief description of the programme, the paper, first of all, focuses on the interdisciplinary design and teaching approach in the studio to respond complex urban issues – evaluating ambiguous events concerning to urban design theories, resilient practices, methods and the process. Focusing on the aim of the studio, it secondly gives a description of the context of the design process. Thirdly, it provides abilities gained during the graduate education as an urban designer. Finally, it reveals concluding remarks on the graduate education of an urban designer under the theme of resiliency. This paper may provide a critical discussion for a broader understanding of the resiliency in the urban design education in Istanbul and Turkey. And it may relocate urban design training in the long journey of the planning history.

Metric-based Evaluation of Implemented Software Architectures

Hollandse Renaissance als bron van de Nieuwe Kunst

The article presents and investigates new possibilities of multivariate data visualization and their analytical convenience. We demonstrate elementary principles, algorithms and graphical outputs of modern visualization methods with particular focus on Bertin matrices, RADVIZ, Projection pursuit and parallel coordinates. Illustrative examples show their practical implementation into the process of multivariate data analysis, hence providing the reader with an idea of the wide range of their application.

In the last months a pandemic has changed the daily life of billions of people Among the efforts to reduce the impact of the disease, social distancing has had huge consequences and raised may concerns, from the inadequacy of contemporary urban design to the social inequality of national and regional lockdown This paper focuses on the consequences that this experience is having on the design of urban public and private areas Everybody admits that our cities are going to change but, beside the first quick adaptation to social distancing, it is unclear how to rethink today's urban areas We start from our previous work on the classification of architectural rules and on the study of how creativity is expressed via architectural rules, to discuss the principles and social aspects of newly proposed designs The motivation for this analysis is to investigate and raise awareness of the consequences of changes in social practices: given that we are in need for new structures and service organization, we can still make choices and should balance the positive and negative aspects of these design alternatives The community should be aware, as much as possible, of the intrinsic forces that novel solutions exert on our social system and urban environment This work shows just one way to analyse architectural design, and should be considered as a contribution to a much needed broad and inclusive discussion about how we want urban spaces to be

Software design issues can severely impede software development and maintenance. Thus, it is important for the success of software projects that developers are aware of bad smells in code artifacts and improve their skills to reduce these issues via refactoring. However, software refactoring is a complex activity and involves multiple tasks and aspects. Therefore, imparting competences for identifying bad smells and refactoring code efficiently is challenging for software engineering education and training. The approaches proposed for teaching software refactoring in recent years mostly concentrate on small and artificial tasks and fall short in terms of higher level competences, such as analysis and evaluation. In this paper, we investigate the possibilities and challenges of designing serious games for software refactoring on real-world code artifacts. In particular, we propose a game design, where students can compete either against a predefined benchmark (technical debt) or against each other. In addition, we describe a lightweight architecture as the technical foundation for the game design that integrates pre-existing analysis tools such as test frameworks and software-quality analyzers. Finally, we provide an exemplary game scenario to illustrate the application of serious games in a learning setting.

In 1998, Ian Foster and Carl Kesselman, together with thirty distinguished experts in high-performance computing and networking, laid the foundations of a new computing model called GRID. Their vision was introduced in the book, The GRID: Blueprint for a New Computing Infrastructure (see review, SCPE Vol. 3, No. 3 ). The editors wrote: … A computational grid is a hardware and software infrastructure that provides dependable, consistent, pervasive, and inexpensive access to high-end computational capabilities… allowing new classes of applications to emerge… as yet, we have only a preliminary understanding of what these new applications will look like. Over the next five years, Grid computing became the hottest R&D field. Academia and national labs built experimental infrastructures, new startups were established to develop Grid technologies, and the HPC giant vendors joined the party. Each one pushed in a different direction based on what and how he believed Grid computing should look. It was only a matter of time until people started to ask what the Grid is all about. A survey of ten Grid experts produced ten different answers. The question remains without a clear answer, leaving many people confused. Ian Foster picked up the gloves. In his article, What is the GRID? A three point checklist (GRIDtoday, July 22, 2002: Vol. 1, No. 6), he redefines the Grid model to reflect the trades and changes in the field during the past five years. According to Foster, a Grid is a system that: Coordinates resources that are not subject to centralized control. Uses standard, open, general-purpose protocols and interfaces. Delivers a nontrivial quality of service. But Foster's new definition could not encompass all of the Grid's approaches. Moreover, Foster explained by example what the Grid is not: A cluster management system such as Sun's Sun Grid Engine, Platform's Load Sharing Facility, or Viridian's Portable Batch System can, when installed on a parallel computer or local area network, deliver quality of service guarantees and thus constitutes a powerful Grid resource. However, such a system is not a Grid itself, due to its centralized control of the hosts that it manages Within a week the responses started to come in. The first one was from Wolfgang Gentzsch, Director of Grid computing at Sun Microsystems (GRIDtoday, August 5, 2002: Vol. 1, No. 8). Gentzsch wrote: I very much like Ian's two earlier definitions. Combined, they may provide a very generic Grid definition. The new checklist, however, reduces the potential of a wide and rich variety of Grids, with different architectures, operational models, and applications, and may miss the chance to becoming widely accepted as a standard definition of the Grid. Why do we need a definition for the Grid? Can the Grid be defined? Is a definition is necessary to the Grid's development? The Grid is an open vision and thus cannot be defined. An attempt to define the Grid can only reach the foreseen technology horizon, and this horizon is only one to two years ahead. Grid computing is a paradigm in shift. New architectures and standards are changing the shape and direction of the Grid's development. In the past year one such prominent architecture was Open Grid Services Architecture (OGSA). The OGSA is the first attempt to bridge the gap between two cyberspace worlds: the Internet and the Grid. The Internet and the Grid are two different computing models. There are people who believe that the Grid is the next generation of the Internet and the World Wide Web, saying that the Great Global Grid is still many years away. Others state that the Grid will complement, not replace, the Internet as we know it. In 1998, when the Grid blueprint was published, a new Internet language appeared called eXtensible Markup Language (XML). XML is a development tool for a new Internet computing model known as Web Services. At that time, nobody understood that there is a relationship between Web Services and the Grid. Three years past before Steve Tuecke from Argonne National Laboratory started to write a spec for Grid Services. Later, people from IBM joined the mission and together they created OGSA. The OGSA specification outlines interfaces to grid computing software that comply with Web Services standards. If adopted, Grid services such as job scheduling, authentication, failure-detection, staging of applications and data, and migration of applications and data, will all be accessed through standard Web Services architecture. OGSA is basically where Grid meets Web Services and maybe the first step towards full integration of the Internet and the Grid. The Internet appeared a decade ago. In the beginning, the Net offered primitive applications: a mailing system, ftp services, and a web of home pages. Nobody asked, What is the Internet? The years passed and new emerging Internet technologies were developed. Today we can talk on the phone over the Net, chat with friends, and video conference with colleagues on the other side of the world. New computing and business models were developed: e-commerce, e-learning, e-science, and e-you-name-it. And nobody asks what the Internet is. The Grid is a super-model, a bag of networking models associated with many types of architectures, software packages, applications, and standards. Today, when people talk about the Grid they mention Data Grids, Science Grids, and Campus Grids. And at the same time they mention Farm computing, Peer-to-peer computing, and Utility computing, among others. Ten years from now many of today's technologies will disappear and new ones will be developed. I don't know how Grid computing will look a decade from now, but I know that we will have g-commerce, g-learning, g-science, and g-chat. Nobody will ask what the Grid is. It will be obvious, just as the Internet is today. Ami Marowka The Computer Aided Design Laboratory School of Engineering and Computer Science Hebrew University of Jerusalem

Based on the words about why we must study software architecture, this article analyzed what the idea of building software architecture based on design patterns acts on the process of software development, discussed the development trend of software architecture and design patterns, and pointed to the problems which need to pay your attention during the term of building software architecture based on design patterns. In addition this paper described how the MVC pattern works in J2EE and explained what responsibilities the various parts in MVC have.