Synchronization of multiple threads in a java program using the built-in features of the language has serious pitfalls for the programmer, particularly if a thread is interrupted while waiting inside a monitor. These ...
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Synchronization of multiple threads in a java program using the built-in features of the language has serious pitfalls for the programmer, particularly if a thread is interrupted while waiting inside a monitor. These concerns have lead to a movement to avoid java monitors altogether and use message passing instead. This paper visits the field of concurrent programming to show that replacing all java monitors with message passing is an overreaction to these problems.
Jcon is a new, full-featured, java-based implementation of the Icon programminglanguage. The compiler, written in Icon, generates an intermediate representation that is optimized and then used to produce classfiles o...
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Jcon is a new, full-featured, java-based implementation of the Icon programminglanguage. The compiler, written in Icon, generates an intermediate representation that is optimized and then used to produce classfiles of java bytecode. A four-chunk control-flow model handles goal-directed evaluation and produces constructs not expressible as java code. The runtime system, written in java, finds object-oriented programming a great advantage in implementing a dynamically typed language, with method calls replacing many conditional tests. An all-encompassing descriptor class supports values, references, and suspended operations. The procedure call interface is simple and incurs overhead for generator support only when actually needed. Performance is somewhat disappointing, and some limitations are annoying, but in general java provides a good implementation platform.
The shift from interpretation to Just-In-Time compilation has improved java's performance largely. However, further amelioration is still possible. A new execution model of java - hybrid concurrent compilation mod...
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The shift from interpretation to Just-In-Time compilation has improved java's performance largely. However, further amelioration is still possible. A new execution model of java - hybrid concurrent compilation model (HCCM) is proposed in this paper, which possesses the potential to surpass JIT by overlapping the production of native code with program execution through multithreaded control. We also present the design of our ongoing HCCM-based java Virtual Machine, discuss some new-emerged technical issues in the implementation of such a java VM and make some prediction about its performance.
Complex graphical user interfaces (GUIs) that support a large amount of user interaction require a fast response time, a rich set of building blocks for an esthetic look-and-feel, and a development environment that su...
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Complex graphical user interfaces (GUIs) that support a large amount of user interaction require a fast response time, a rich set of building blocks for an esthetic look-and-feel, and a development environment that supports ongoing change. On the World Wide Web, client-side technologies offer more of these features than do server-side solutions. java and javaScript are the two most popular languages used for client-side GUI implementations. java implementations require a user to download a plug-in that contains a virtual machine to execute the java byte-code. The installation and maintenance of this plug-in is sometimes an unsurmountable barrier to using java. javaScript lacks some of the desirable features of java, such as easy to use object-oriented features and having a GUI class library, but does not require a plug-in. We have enhanced javaScript by implementing a new language Object-javaScript (OJS) and by providing an OJS library of GUI components, thus making it a viable alternative to java.
If the first chapter of the Internet was about the dissemination of information, chapter two is about services. In the past, the Internet strategy of a company was about using a web site for advertising products. Toda...
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If the first chapter of the Internet was about the dissemination of information, chapter two is about services. In the past, the Internet strategy of a company was about using a web site for advertising products. Today the concept of product becomes almost indistinguishable from the concept of service, and the Internet becomes a key component of any type of channel. Electronic marketplaces and e-services are two of the main drivers for the change from chapter one to chapter two for the Internet, both from a business and technology perspective. E-services are about assets made available efficiently over the Internet. Electronic marketplaces are about demand for services being put in contact with the best offer. The two concepts naturally complement each other. The objective of this paper is to introduce the concepts behind both e-services and electronic marketplaces, and to show an example of the use of java as enabling technology. The example focuses on a novel approach to mediated service delivery, and the java-based prototype developed to implement it.
In general, performance analysis tools deal with large volumes of highly complex data of varying types and at varying levels of granularity. The result is that it is common for there to be many different tools and com...
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In general, performance analysis tools deal with large volumes of highly complex data of varying types and at varying levels of granularity. The result is that it is common for there to be many different tools and components that implement performance data collection, recording, and reporting in an analysis environment. This variety complicates communication within a group and makes cross-group communication about specific performance findings even more difficult. The analysis of the performance of javaTM virtual machines and java applications introduces additional complexity. We describe an approach that unifies the recording and reporting components of performance analysis into a single data model and standard set of reports. We have employed this model with significant success in the analysis of IBM's Developer Kits for the java virtual machine.
A java-Internet computing environment (JICE) with mulithreading and remote method invocation (RMI) mechanisms is designed as a computing platform to utilize a large collection of computing resources on the Internet fo...
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A java-Internet computing environment (JICE) with mulithreading and remote method invocation (RMI) mechanisms is designed as a computing platform to utilize a large collection of computing resources on the Internet for a distributed parallel computing. This research is intended to exploit the networked idle resources, to develop an infrastructure of global computing platform for applications in the heterogeneous Internet environment, and to evaluate its standard environment to support parallel and distributed computing efficiently. In general, the performance of communications on parallel applications causes a significant impact on the overall performance under the network-based environment. A method of system configuration is proposed to decrease communication time, which is a major bottleneck of performance enhancement. System configuration method (SCM) is a technique to divide a set of distributed nodes into several working groups based on the optimal communication time. Performance of the SCM is evaluated through analysis of communication time under JICE, and verified through the simulation. According to the analysis, the effective number of groups can be determined according to the ratio of shared memory write references. The SCM can enhance the performance of JICE by about two to three times in those applications with a reasonably high ratio of shared-memory references.
The paper presents the advantages of using javaScript functions in interaction with scriptable applets. The concept was tested on JxyZET simulation applet which was developed as a platform independent complement to xy...
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The paper presents the advantages of using javaScript functions in interaction with scriptable applets. The concept was tested on JxyZET simulation applet which was developed as a platform independent complement to xyZET. The later is an authoring tool for the development and visualization of various phenomena in physics. It runs under Motif environment and permits the simulation of flexible bodies built from particles interconnected with springs. In the first part of the paper a short history of JxyZET is given. The original JxyZET was expanded with some scriptable functions. This permits the definition of more complex elastic bodies built from several hundreds or even thousands of particles and springs. These bodies can be easily modified just by changing some parameters within the javascript code included in the parent hypertext. The simulation of complex dynamic systems is investigated. One such system is given by a ball bouncing on an elastic canvas. The introduction of libraries of reusable javaScript function was proposed. The usage of javascript permits the interaction of an user defined algorithm with the simulation tool, in our case JxyZET. The concept of dynamically conditioned simulation runs is explained and the possibilities of dynamically restructured simulation models are demonstrated. This means that during the simulation runs not only the parameters but also the structure of the simulation model can be modified, depending on programmable preconditions written in javaScript. The explained concepts of flexible scriptable functions can be implemented by other similar simulation applets too. In such a way the known nuclear fission reaction was simulated. In the presented example practically all the simulation algorithm was written in javascript. The presented approach permits very flexible simulations of large dynamic systems. The major limiting factor is presented by the capabilities of currently available computer technology, in particular their spee
We describe a java toolkit that is designed to support the creation of powerful and extensible GUI interfaces during the first year computer science course. The goals of this toolkit are to provide: an infrastructure ...
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We describe a java toolkit that is designed to support the creation of powerful and extensible GUI interfaces during the first year computer science course. The goals of this toolkit are to provide: an infrastructure for creating well designed programs that illustrates the concepts of computer science and its practical applications an environment for learning the basic ideas of interface design and for experimenting with a variety of designs a paradigm for building interfaces in java that scales from individual data items to large structures, using recursively displayable container classes. Additionally, the toolkit classes themselves can be studied as examples of proper object oriented design, and of building event listeners.
A problem solving environment (PSE) is a complete, integrated computing environment for composing, compiling and running applications in a specific problem area or domain. A visual programming composition environment ...
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A problem solving environment (PSE) is a complete, integrated computing environment for composing, compiling and running applications in a specific problem area or domain. A visual programming composition environment (VPCE) is described, which serves as a user interface for a PSE, and uses java and CORBA to provide a framework of tools to enable the construction of scientific applications from components. The VPCE consists of a component repository, from which the user can select off-the-shelf or in-house components, a graphical composition area on which components can be combined, various tools that facilitate the configuration of components, the integration of legacy codes into components and the design and building of new components. The VPCE produces output using dataflow techniques in the form of a task graph, annotated with a performance model plus constraints for each component, expressed in XML. In addition, the VPCE supports a domain specific expert system based on JESS (Ernest Friedman-Hill, JESS: The java Expert System Shell. See web site at: http://***/jess/, 1999) to guide the user in component selection and to perform integrity checking.
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