Message Oriented Middleware

Most of the electromagnetic problems can be reduced down to either integrating oscillatory integrals or summing up complex series. However, limits of the integrals and the series usually extend to infinity. In addition, they may be slowly convergent. Therefore, numerically efficient techniques for evaluating the integrals or for calculating the sum of infinite series have to be used to make the numerical solution feasible and attractive. In the literature, there are a wide range of applications of such methods to various EM problems. In this paper, our main aim is to critically examine the popular series transformation (acceleration) methods which are used in electromagnetic problems and compare them by numerical examples.

International Journal of Embedded Systems and Applications (IJESA) is a quarterly open access peer-reviewed journal that publishes articles which contribute new results in all areas of the Embedded Systems and applications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on understanding Embedded Systems and establishing new collaborations in these areas.

Layered sensing provides a hierarchical net-centric architecture for universal situational awareness with global coverage and persistent surveillance. Sensors in the layered hierarchy provide spatial, temporal, spectral, and polarization diversity with different scales and resolutions over different time horizons. Cooperative management of netted sensors is a successful strategy to achieve targeting performance and overall measures of merit (MOM) goals. After a brief introduction to issues in layered sensors, a resource management strategy based on geometry information is described so as to enhance performance in target detection (minimum detectable Doppler) and tracking accuracy (geometric dilution of precision). Preliminary simulation results are presented to illustrate this Geometric Approach to Layered Sensing (GALS) concept.

The middleware market represents a sizable segment of the overall Information and Communication Technology market. In 2005, the annual middleware license revenue was reported by Gartner to be in the region of 8.5 billion US Dollars. In this article we address the question whether research had any involvement in the creation of the technology that is being sold in this market? We attempt a scholarly discourse. We present the research method that we have applied to answer this question. We then present a brief introduction into the key middleware concepts that provide the foundation for this market. It would not be feasible to investigate any possible impact that research might have had. Instead we select a few very successful technologies that are representative for the middleware market as a whole and show the existence of impact of research results in the creation of these technologies. We investigate the origins of web services middleware, distributed transaction processing middleware, message oriented middleware, distributed object middleware and remote procedure call systems. For each of these technologies we are able to show ample influence of research and conclude that without the research conducted by PhD students and researchers in university computer science labs at Brown, CMU, Cambridge, Newcastle, MIT, Vrije, and University of Washington as well as research in industrial labs at APM, AT&T Bell Labs, DEC Systems Research, HP Labs, IBM Research and Xerox PARC we would not have middleware technology in its current form. We summarise the article by distilling lessons that can be learnt from this evidenced impact for future technology transfer undertakings.

A massively multiplayer online game (MMOG) lets thousands of players interact simultaneously within a virtual world via the Internet. Middleware plays an important role in the development of next-generation MMOGs, which must be built on platforms that address not only the service aspect, but also code maintainability and development for programmers. The authors' compact, highperformance message-oriented middleware has a code-generation programming model that is designed to address many of these problems. Online Gaming Architectures Support Services Algorithm/Protocol Design and Analysis Mobile Environment Mobile Communication Systems Applications Emerging Technologies IEEE Transactions on Mobile Computing revolutionary new quarterly journal that seeks out and delivers the very best peer-reviewed research results on mobility of users, systems, data, computing information organization and access, services, management, and applications. IEEE Transactions on Mobile Computing gives you remarkable breadth and depth of coverage …

The middleware market represents a sizable segment of the overall Information and Communication Technology market. In 2005, the annual middleware license revenue was reported by Gartner to be in the region of 8.5 billion US Dollars. In this article we address the question whether research had any involvement in the creation of the technology that is being sold in this market? We attempt a scholarly discourse. We present the research method that we have applied to answer this question. We then present a brief introduction into the key middleware concepts that provide the foundation for this market. It would not be feasible to investigate any possible impact that research might have had. Instead we select a few very successful technologies that are representative for the middleware market as a whole and show the existence of impact of research results in the creation of these technologies. We investigate the origins of web services middleware, distributed transaction processing middleware, message oriented middleware, distributed object middleware and remote procedure call systems. For each of these technologies we are able to show ample influence of research and conclude that without the research conducted by PhD students and researchers in university computer science labs at Brown, CMU, Cambridge, Newcastle, MIT, Vrije, and University of Washington as well as research in industrial labs at APM, AT&T Bell Labs, DEC Systems Research, HP Labs, IBM Research and Xerox PARC we would not have middleware technology in its current form. We summarise the article by distilling lessons that can be learnt from this evidenced impact for future technology transfer undertakings.

SIMD extensions are the most common technique used in current processors for multimedia computing. In order to obtain more performance for emerging applications SIMD extensions need to be scaled. In this paper we perform a scalability analysis of SIMD extensions for multimedia applications. Scaling a 1dimensional extension, like Intel MMX, was compared to scaling a 2-dimensional (matrix) extension. Evaluations have demonstrated that the 2-d architecture is able to use more parallel hardware than the 1-d extension. Speed-ups over a 2-way superscalar processor with MMX-like extension go up to 4X for kernels and up to 3.3X for complete applications and the matrix architecture can deliver, in some cases, more performance with simpler processor configurations. The experiments also show that the scaled matrix architecture is reaching the limits of the DLP available in the internal loops of common multimedia kernels.

A Real-Time Wireless Distributed Embedded System (RTWDES) is formed by a large quantity of small devices with certain computing power, wireless communication and sensing/actuators capabilities. These types of networks have become popular as they have been developed for applications which can carry out a vast quantity of tasks, including home and building monitoring, object tracking, precision agriculture, military applications, disaster recovery, industry applications, among others. For this type of applications a middleware is used in software systems to bridge the gap between the application and the underlying operating system and networks. As a result, a middleware system can facilitate the development of applications and is designed to provide common services to the applications. The development of a middleware for sensor networks presents several challenges due to the limited computational resources and energy of the different nodes. This work is related with the design, implementation and test of a micro middleware for RTWDES; the proposal incorporates characteristics of a message oriented middleware thus allowing the applications to communicate by employing the publish/subscribe model. Experimental evaluation shows that the proposed middleware J Intell Robot Syst provides a stable and timely service to support different Quality of Service (QoS) levels.

The middleware technology used as the foundation of Internet-enabled enterprise systems is becoming increasingly complex. In addition, the various technologies offer a number of standard architectures that can be used by designers as templates to build applications. However, there is little concrete understanding in the software industry on the strengths and weaknesses of competing technologies, and the different trade-offs that various component architectures impose. The SACT Group at CSIRO has qualitatively and quantitatively evaluated a number of commercially available Message-Oriented Middleware (MOM) systems. This paper focuses on the results obtained from the performance evaluation of the IBM's MQSeries V5.2. It presents an overview of the technology, and discusses the metric used in this study for performance measurement The test results related to the sustainable performance of the system using various test configurations are described and their implications discussed.

Narada is a distributed event brokering system designed to run on a large network of cooperating broker nodes. Narada supports heterogeneous client configurations that scale to arbitrary size and incorporates efficient routing algorithms to optimize disseminations to clients. Narada is failure resilient and guarantees delivery in the presence of failures. In this paper we provide an overview of the Narada event brokering system. The paper also describes the Java Message Service compliance process and support for peer-to-peer interactions in Narada. Finally, the paper outlines issues and entry points for supporting Web Services within Narada

This paper addresses a numerical electromagnetic analysis of the influence of installing passive shield wires "extra ground wires" (EGW) underneath the bottom phase conductor on the lightning shielding performance of 765-kV, 3-phase, double-circuit transmission lines. The method of moment (MOM) is employed to model the whole structure in three dimensions except the lightning channel. The lightning channel is simulated by the well-known transmission-line model (TLM), where the influence of the lightning-channel-generated electric and magnetic fields (EMF) are taken into account. The lightning shielding performance with and without EGW is introduced and discussed, without ac energization and due to three distinct lightning strokes, namely, the negative first, the negative subsequent and the positive strokes. The produced voltages and currents in the phase conductors and ground wires as well as the voltage across the insulators are computed, with and without the EGW, due to different lightning current waveforms, locations and inclination of the lightning channel, and return-stroke velocities. The introduction of such EGW results in a significant improvement of the shielding effectiveness by reducing the lightning-produced voltages and currents in the phase conductors as well as the voltage across the insulators. Accordingly, a much lower transient overvoltages can be expected with less inadvertent outages of the lines, where the probabilities of flashover and back-flashover decrease, and the reliability enhances. Index Terms-Electric and magnetic fields (EMF), extra ground wires (EGWs), insulator voltage, lightning shielding, numerical electromagnetic transient.

Software integration is a crucial aspect of collaborative software applications and systems. It enables a number of different software applications, created by different developers, using different programming languages, and even located at different places to work with each other collaboratively to achieve common goals. Nowadays, a number of techniques are available to enable software integration. Messaging is the most prominent technique in this respect. In this paper, two leading open-source messaging brokers, Apache ActiveMQ and Apache Apollo, have been experimentally compared with each other with regard to their messaging capabilities (message sending and receiving throughputs). Both brokers support exchanging messages between heterogeneous and distributed software applications using several messaging mechanisms including Java Message Service (henceforth JMS). A number of experimental test scenarios have been conducted to obtain the comparison results that indicate the one-to-one JMS messaging performance of each broker. Overall performance evaluation and analysis showed that Apache Apollo outperformed Apache ActiveMQ in all test scenarios regarding message sending throughputs. Whereas, Apache ActiveMQ outperformed Apache Apollo in most test scenarios regarding message receiving throughputs. Moreover, the evaluation methodology (test conditions, test scenarios, and test metrics) proposed in this paper has been carefully chosen to be adopted by software developers to evaluate other messaging brokers to determine the acceptable level of messaging capabilities in distributed environments of heterogeneous software applications.

The TJ-II remote participation system (RPS) is focused on providing remote access to elements that depend exclusively on characteristics of the TJ-II environment: data acquisition, diagnostics control systems and TJ-II operation tracking. Four key points were taken into account prior to starting the software design: access security, software execution platforms, software maintenance and distribution and delivery of operation events. The first, access security, was addressed by means of a distributed authentication and authorization system, PAPI. Regarding the other points, the development was based on the use of web servers (due to their standard character, flexibility and scalability) and Java technologies (due to their open nature, security properties and technological maturity). Software deployment was prepared to make use of the Java Network Launching Protocol (JNLP). On-line message distribution was planned according to a message oriented middleware. At present, the TJ-II RPS manages over 1000 digitization channels and 20 diagnostic control systems. The TJ-II RPS architecture is flexible, scalable and powerful enough to be applied to distributed environments and, in particular, it could be used in the ITER environment.

An approximate exprctssion is found for the joint probability of instants of occurrence of photoevents in the case of low-level light and short observation times. The use of this erpression in estimating the average couut rate and the bandwidth of Gaussian-hrentzian light is discussed.

Supervisory processes are fundamental when running data center operations striving for fault resilience: any downtime can directly affect the business's income and definitely its reputation. Current monitoring tools rely on experts to configure constant thresholds on single streams, which is not appropriated for dynamic systems and insufficient to capture complex patterns. We present HOLMES, built to support data center experts to anticipate failures with a solution that combines Event Driven Architecture, Complex Event Processing and an unsupervised machine learning algorithm. Based on rules created by the users, the system continuously checks for known problems. Meanwhile, for the unknown ones, we leverage the CEP engine for aggregating and joining streams of real-time data to feed normalized input to FRAHST, our machine learning algorithm that detects anomalous patterns across multivariate numerical streams. We describe how the UI module also operates within the publish/subscribe paradigm to enhance situational awareness. The system had very well acceptance and was successfully implemented at one of the largest Internet Service Providers in South America.

A mixed (scalar and vector) potential surface integral equation formulation, developed for microstrip antennas, is employed in conjunction with the method of moments to predict the radiated emission from arbitrarily shaped printed circuit traces. Computed currents and radiated fields for a typical trace configuration in the form of a rectangular loop loaded by low- or high-impedance lumped loads indicate good agreement with transmission line theory and/or elementary loop antenna analysis, when the trace size is electrically small. Computed results are presented to highlight the radiation and coupling due to common-mode currents

Common IT (information technology) concepts/notions are generally complex and rather difficult for new students to grasp. These include, for example, (a) OOP (object-oriented programming) notions of abstraction, encapsulation, inheritance and polymorphism or (b) those associated with ISO/OSI (International Standards Organization/Open System Interconnect) reference model such as the notions of protocols, services, and standards. The basic concepts of OOP in example (a), if well presented, will facilitate the understanding of other relevant concepts, e.g. class versus instance methods/data, method overloading and overriding, use of foundation classes and interfaces as well as OO program design. Similarly, the basic concepts of ISO/OSI in example (b) should be well understood before the introduction of other related concepts such as internetworking with circuit-switching or packet- switching, forward and reverse address resolution, hop, time-to-live, communications gateways, message-or...

We present the Message Bus (Mbus) , a lightweight, message oriented, infrastructure for ad-hoc composition of heterogeneous components. In this paper we describe the general Mbus architecture, the Mbus transport specification and higher-level services. It is shown how the Mbus fits into the multiparty multimedia conferencing architecture and can be used for decomposing conferencing applications.

We review several aspects of building real-time streaming data Grid applications. Building on general purpose messaging system software (NaradaBrokering) and generalized collaboration services (GlobalMMCS), we are developing a diverse set of interoperable capabilities. These include dynamic information systems for managing short-lived collaborative service collections (“gaggles”), stream filters to support the integration of Geographical Information Systems services with data analysis applications, streaming ...

Web Services hold the promise of a standards-based platform for automating the integration of applications over diverse networks, operating systems and programming languages. Reliable messaging is critical in this context; many enterprise systems require a messaging infrastructure that guarantees message delivery even in the presence of software and network failures. Using existing message-oriented middleware (MOM) for reliable Web services messaging seems natural. However, a variety of implementation challenges, including the support for specific reliable Web services messaging protocols, must be addressed. In this paper, we discuss the options for and implications of employing MOM to implement reliable messaging for Web services. In doing so, we contribute to the understanding of reliability for Web services in general.

The rapid growth of data exchange on the Internet has created many critical problems that require an answer. Traditional data exchange systems based on client/server communication models are less scalable and incur especially high maintenance cost in the data exchange domain. For these reasons, many researchers have switched their interest to asynchronous communication models. Although Message-Oriented Middleware (MOM) is a middle-tier infrastructure that links operating systems and applications, such asynchronous communication APIs supported by middleware vendors are usually hard to use. For these reasons, in this study, we present a new development environment for asynchronous communication platforms which we term Ghostwriter. The keyword for our development environment is 'easy', that is, easy to use, easy to develop, and easy to deploy. Therefore, many researchers have switched their interest to asynchronous communication models. In addition, learning about and implementing the functions of the asynchronous communication's clients in Ghostwriter environment is simple. Other benefits are a lower technical learning curve, help for concentrate on system design, has easily reusable components, and easily integrated applications.

In the last years, integrated hardware/software architectures for the remote and/or automatic management of WasteWater Treatment Plants have been developed using different approaches and techniques. In this paper, we propose a different modular infrastructure which extends a Service-Oriented Architecture with the concept of Complex Event Processing. Our proposal is based on an Enterprise Service Bus, a distributed message-oriented middleware, extended with a Rule Service, embedding a rule engine in the system, an Event Router and an Event Scheduler. The infrastructure is then used to implement a modular and flexible management system for a Sequencing Batch Reactor treatment plant: this system includes a database facility, a user interface, a temporized manager to schedule the different phases of the treatment process and, finally, a signal-aware realtime DSS used for an adaptive process control.

This paper describes the Maximum Likely Estimation (MLE) method and the Method of Moments (MOM) for wind speed modeling. The Weibull wind speed distribution models are fitted using the two methods and the wind data from a tall tower in the Midwestern United States, with seasonal wind speed variations also considered in the modeling. It turned out that both methods provide very similar results with comparable accuracy. The Monte Carlo simulation is used for obtaining expected wind energy production using a Weibull sampling technique.

The Weibull distribution has been found to be a suitable fit for the empirical distribution of the wind speed measurement samples. We discuss the application of the Maximum Likelihood Estimation (MLE) method and the Method of Moments (MOM) for fitting the 2-parameter Weibull distribution to wind speed measurements. We also prove that both the MLE and MOM yields unique parameter estimates.

This paper presents results of extensive computational experiments in which evolutionary multiobjective algorithms were used to find Pareto-optimal solutions to a complex structural design problem. In particular, Strength-Pareto Evolutionary Algorithm 2 (SPEA2) was combined with a mathematical programming method to find optimal designs of steel structural systems in tall buildings with respect to two objectives (both minimized): the total weight and the maximum horizontal displacement of a tall building. SPEA2 was employed to determine Pareto-optimal topologies of structural members (topology optimization) whose cross-sections were subsequently optimized by the mathematical programming method (sizing optimization). The paper also presents the shape of the Pareto front in this two-dimensional objective space and discusses its dependence on the building's aspect ratio. The results reported provide both qualitative and quantitative knowledge regarding the relationship between the two objectives. They also show the trade-offs involved in the process of conceptual and detailed design of complex structural systems in tall buildings.

This paper deals with the problem of the calculation of surface integrals for electromagnetic scattering in the case of the widely popular double-triangular basis functions first introduced by Rao, Wilton, and Glisson (1982). An entire set of formulas is obtained which overrides the difficulties inherent to the singularity of the integrands, and results showing the stability, accuracy, and efficiency of

In this paper we propose the main guidelines of a toolkit designed to allow the several different electronic devices (CPUs, microcontrollers, sensor DSPs, etc.) that compose a mobile robot and its environment to cooperate as members of a community. This idea would allow an easy modularization of complex systems that integrate robots and distributed sensors, taking an effective advantage of the newest data processing and communication technologies. The availability of many computing-capable sensing and actuating devices and of broadband communication channels allows us to find new ways of implementing physically distributed systems that can be used in the control of autonomous robots. Our research is aimed at creating an efficient and reliable layered middleware in the hardware-software structure, in order to allow each device to interact in a transparent way with all the others, on the same machine or elsewhere.

The middleware technology used as the foundation of Internet-enabled enterprise systems is becoming increasingly complex. In addition, the various technologies offer a number of standard architectures that can be used by designers as templates to build applications. However, there is little concrete understanding in the software industry on the strengths and weaknesses of competing technologies, and the different trade-offs that various component architectures impose. The SACT Group at CSIRO has qualitatively and quantitatively evaluated a number of commercially available Message-Oriented Middleware (MOM) systems. This paper focuses on the results obtained from the performance evaluation of the IBM's MQSeries V5.2. It presents an overview of the technology, and discusses the metric used in this study for performance measurement The test results related to the sustainable performance of the system using various test configurations are described and their implications discussed.

A lot of research works in different areas have been done on Interoperability frameworks. Each area of research has its own specification and requirements to manage a complex processing request. Interoperability framework is significantly important for utilizing heterogeneous communications and integrations in SOA systems. Various middleware technologies are often used as the communication and integration infrastructure for distributed system to ensure the interoperability. Nevertheless, different types of middleware have raise interoperability issues as well. One of the well known middleware architectures used for heterogeneous systems is Message Oriented Middleware (MOM). MOM is known as common attach technology for heterogeneous, distributed and loosely coupled software system. In this paper we explore and analyze studies related to cross-platform in communication and integration. In the end, we have proposed agent-based MOM interoperability framework and Ontology mapping conceptual model which is the key model to do message mapping for different applications in SOA system.

SIMD extensions are the most common technique used in current processors for multimedia computing. In order to obtain more performance for emerging applications SIMD extensions need to be scaled. In this paper we perform a scalability analysis of SIMD extensions for multimedia applications. Scaling a 1dimensional extension, like Intel MMX, was compared to scaling a 2-dimensional (matrix) extension. Evaluations have demonstrated that the 2-d architecture is able to use more parallel hardware than the 1-d extension. Speed-ups over a 2-way superscalar processor with MMX-like extension go up to 4X for kernels and up to 3.3X for complete applications and the matrix architecture can deliver, in some cases, more performance with simpler processor configurations. The experiments also show that the scaled matrix architecture is reaching the limits of the DLP available in the internal loops of common multimedia kernels.

Localization is one of the fundamental prob-lems in mobile robot navigation. In this paper a study is presented on a new methodology aimed at localizing a mobile robot in indoor and outdoor environments using active markers and commer-cial off-the-shelf webcams. The marker detection system is based on the dif-ference of working frequencies of the shutter of a webcam and of

A Peer-to-Peer (P2P) Grid would comprise services that include those of Grids and P2P networks and naturally support environments that have features of both limiting cases. Such a P2P grid integrates the evolving ideas of computational grids, distributed objects, web services, P2P networks and message oriented middleware. In this paper we investigate the architecture, comprising a distributed brokering system that will support such a hybrid environment. Access to services can then be mediated either by the middleware or alternatively by direct P2P interactions between machines.

Message-oriented middleware (MOM) is at the core of a vast number of financial services and telco applications, and is gaining increasing traction in other industries, such as manufacturing, transportation, health-care and supply chain management. Novel messaging applications, however, pose some serious performance and scalability challenges. In this paper, we present a methodology for performance evaluation of MOM platforms using the SPECjms2007 standard benchmark. SPECjms2007 is based on a novel application in the supply chain management domain designed to stress MOM infrastructures in a manner representative of real-world applications. In addition to providing a standard workload and metrics for MOM performance, the benchmark provides a flexible performance analysis framework that allows users to tailor the workload to their requirements. The contributions of this paper are: i) we present a detailed workload characterization of SPECjms2007 with the goal to help users understand the internal components of the workload and the way they are scaled, ii) we show how the workload can be customized to exercise and evaluate selected aspects of MOM performance, iii) we present a case study of a leading JMS platform, the BEA WebLogic server, conducting an in-depth performance analysis of the platform under a number of different workload and configuration scenarios. The methodology we propose is the first one that uses a standard benchmark providing both a representative workload as well as the ability to customize it to evaluate the features of MOM platforms selectively.

A lot of research works in different areas have been done on Interoperability frameworks. Each area of research has its own specification and requirements to manage a complex processing request. Interoperability framework is significantly important for utilizing heterogeneous communications and integrations in SOA systems. Various middleware technologies are often used as the communication and integration infrastructure for distributed system to ensure the interoperability. Nevertheless, different types of middleware have raise interoperability issues as well. One of the well known middleware architectures used for heterogeneous systems is Message Oriented Middleware (MOM). MOM is known as common attach technology for heterogeneous, distributed and loosely coupled software system. In this paper we explore and analyze studies related to cross-platform in communication and integration. In the end, we have proposed agent-based MOM interoperability framework and Ontology mapping conceptual model which is the key model to do message mapping for different applications in SOA system.

In message-oriented distributed object system, cooperating objects exchange messages and various functions are carried out as a side effect of message exchanges. As objects range from an icon on the screen to a full featured server, the set of messages they can understand is also different. An object may not know the properties of all the objects it is communicating with. Objects may acquire new functionality at runtime and this makes the problem even more difficult. This paper presents message handling in the Bond distributed object system. Bond uses KQML as a communication language allowing every object to parse every message. The solution for the semantic understanding of messages are the subprotocols-highly specialized, closed set of commands. Being object instances themselves, subprotocols can be generated dynamically or stored into persistent storage. Objects implement the handling of subprotocols in their class definitions. Objects can be extended at runtime with probes to understand new subprotocols or, in some cases, can dynamically generate or learn new subprotocols.

Common IT (information technology) concepts/notions are generally complex and rather difficult for new students to grasp. These include, for example, (a) OOP (object-oriented programming) notions of abstraction, encapsulation, inheritance and polymorphism or (b) those associated with ISO/OSI (International Standards Organization/Open System Interconnect) reference model such as the notions of protocols, services, and standards. The basic concepts of OOP in example (a), if well presented, will facilitate the understanding of other relevant concepts, e.g. class versus instance methods/data, method overloading and overriding, use of foundation classes and interfaces as well as OO program design. Similarly, the basic concepts of ISO/OSI in example (b) should be well understood before the introduction of other related concepts such as internetworking with circuit-switching or packetswitching, forward and reverse address resolution, hop, time-to-live, communications gateways, message-orie...

The narrowband frequency characteristics of straight-wire antennas can be overcome by proper loading of the antenna. The bandwidth characteristics of the loaded antennas are investigated through an optimization routine. A bandwidth ratio of 7.58:l is achieved with a 0.75 meter long capacitively loaded antenna and a simple matching network.

This paper presents one of the first applications of a novel message-oriented middleware, DCDT, that has been recently developed at University of Brescia in collaboration with Politecnico of Milano. This simple and low-cost experimental application is aimed at detecting and localizing a mobile robot in indoor environments using a commercial off-the-shelf webcam and a couple of active markers. The most

This paper describes an approach to enhance the resilience of message oriented middleware to faults and attacks. The system is designed to work with different message oriented middleware as long as the messaging system can supply the information and control API required. The structure of the system and the approach to handling link failures, broker failures and anomalous behaviour through the planning of mirroring and relaying mechanisms to suit the tolerable risk and the deployment context is the focus of the paper. Validation is through industrial case studies and end user assessment.

Diversity in distributed applications leads to diversity in distribution models, and hence in middleware. However, large systems may need different types of middleware and interoperability between them, requiring "Middleware to Middleware" architectures. We have introduced the schizophrenic middleware concept as a general solution for interoperability between distribution models. PolyORB, our implementation of a schizophrenic middleware, demonstrates full interoperability between CORBA, SOAP, and the Ada 95 Distributed System Annex (DSA). In this paper, we present an assessment of the usability of our platform to implement Message Oriented Middleware (MOM). We then study MOM and ORB interoperability, from both an architectural and a functional point of view, and finally discuss benefits provided by our architecture to implement middleware.

The middleware technology used as the foundation of Internet-enabled enterprise systems is becoming increasingly complex. In addition, the various technologies offer a number of standard architectures that can be used by designers as templates to build applications. However, there is little concrete understanding in the software industry on the strengths and weaknesses of competing technologies, and the different trade-offs that various component architectures impose. The SACT Group at CSIRO has qualitatively and quantitatively evaluated a number of commercially available Message-Oriented Middleware (MOM) systems. This paper focuses on the results obtained from the performance evaluation of the IBM's MQSeries V5.2. It presents an overview of the technology, and discusses the metric used in this study for performance measurement The test results related to the sustainable performance of the system using various test configurations are described and their implications discussed.