Abstract: The open distributed processing (ODP) standardisation initiative has led to a framework by which distributed systems can be modelled using a number of viewpoints. These include an enterprise viewpoint, which focuses on the objectives and policies of the enterprise that the system is meant to support. Although the ODP reference model provides abstract languages of relevant concepts, it does not prescribe particular techniques that are to be used in the individual viewpoints. In particular, there is a need to develop appropriate notations for ODP enterprise specification, in order to increase the applicability of the ODP framework. In this paper, we tackle this concern and develop a specification language to support the enterprise viewpoint. In doing so, we focus on the expression of enterprise policies that govern the behaviour of enterprise objects. The language we develop is a combination of structured English and simple predicate logic, and is built on top of the formal object-oriented specification language Object-Z. We illustrate its use with a case study that presents an enterprise specification of a library support system.

Abstract: The ODP Enterprise Language allows the rules and policies that characterize an organization to be brought together and used to guide the various stages of system design, development and operation. UML is one of the leading notations for system design and is likely to be the basis for a wide range of design tools. However, UML has a comparatively weak set of facilities for supporting the combination of existing, parameterized specifications and, in particular, for defining and managing policies. This paper discusses the requirements for defining communities and expressing policies within a UML environment, compares ways in which the existing notation might be used in enterprise specification, and indicates some of the implications this would have for system development tools.

Abstract: Presents extensions and refinements of those concepts that are pertinent to the ODP (open distributed processing) enterprise viewpoint. We first highlight the intricacies of enterprise modelling and then present key enterprise modelling concepts. These concepts represent both refinements to the existing ODP concepts and some new concepts that we propose for the ODP enterprise language standard currently being progressed. We then investigate how the relevant UML (Unified Modelling Language) constructs can be used to represent the enterprise language concepts and to support the enterprise specifications. We conclude by discussing various tools that are needed to facilitate the processes of enterprise modelling, verification and building of open distributed systems.

Abstract: CLF/Mekano is a distributed object infrastructure oriented towards the high-level coordination of coarse grain components. Unlike other infrastructures of the same class, such as CORBA or DCOM, coordination in CLF/Mekano is built-in at the lowest level, namely at the inter-component communication protocol level, and not as a side service (such as the event, transaction or negotiation services of Corba). Although the CLF protocol is "lightweight" (it relies on very few concepts and only 8 communication "verbs"), it makes the design and implementation of components more complex, but also more valuable if it can be reused. The Mekano library has been developed in order to deal with this complexity, targeting reusability. It provides ready-to-use generic classes of customizable components, as well as useful component parts which can be reassembled according to application specific needs. Of course, further layers of domain-specific libraries (so called business object libraries), can then be developed on top of Mekano, to provide ready-to-use components dedicated to specific business needs (in the line of Enterprise Java Beans).

Abstract: Specification is not a gimmick; it is a real discipline that offers many advantages to software developers. It is helpful for building, managing and describing applications. Specification standards are now available, such as the OMG (Object Management Group) adoption of the UML (Unified Modelling Language) notation and the RM-ODP (Reference Model for Open Distributed Processing) standards developed by ISO (International Standardisation Organisation) and ITU-T (International Telecommunication Union-Telecommunication Sector). However, these standards are totally independent, even though they deal with the same topic. In order to conciliate these two approaches, we propose a way to use the UML notation to express RM-ODP enterprise concepts.

Abstract: Groupware systems are designed to support the cooperation of people within and between enterprises. The development of groupware using component-based programming techniques has received a lot of attention recently. The commonly expected benefits are reduced development time, lower costs and higher product quality. Aiming at an additional benefit, the work presented in this paper makes use of the concept of software components after development in order to provide tailorability of already-deployed groupware systems. We describe the architecture of the Evolve platform, which permits one to maintain and manipulate nested component structures of distributed groupware systems at run-time. Apart from run-time tailorability, the architecture meets other groupware-specific (or relevant) requirements, namely support for synchronous and asynchronous cooperative tailoring, tailoring at different levels of complexity, and the flexible control of the scope of tailoring activities (i.e. the set of users affected by these activities). Evolve itself is application-independent and works with any set of software components complying with the FlexiBeans component model, which is an adaptation of the JavaBeans model. We demonstrate the object-oriented design behind Evolve with a simple example and give an overview of related and future work.

Abstract: The paper covers heterogeneous multi-tier environments based on CORBA and Java. On the client side there is a Web browser that connects to the middle tier through CORBA-based Java applets. The business logic is decoupled from the database server on the third tier. Access to the databases is made through a JDBC interface or with embedded SQL. We present considerations about the use of different browsers and multiple ORBs, concentrating on interoperability issues. We explore the problems that have to be faced and give practical advice on how to make things work.

Abstract: The problem of finding the position of a mobile agent in a wide distributed system still represents an open research area. In fact, although today several mobile agent platforms have been developed, each of them implements an ad hoc naming and location policy, suitably studied to address the specific requirements deriving from the design choices made. What is really needed is a naming and location scheme of general validity, able to effectively meet all the typical requirements of mobile agent environments and thus easy to integrate into different platforms. A first contribution of the paper is the identification of the main requirements which an agent naming scheme of general validity should meet. Then, some properties are suggested to be taken into account, in order to make a qualitative naming scheme classification. The second contribution of the paper is the proposal of a "human readable" agent naming scheme, based on the distributed environment outlined in MASIF, the standardization OMG proposal for mobile agent systems. In addition, two location protocols suitable for the proposed naming scheme are presented, which are particularly appropriate for Internet/intranet environments.

Abstract: The Internet has created a tremendous opportunity to conduct business electronically. Innovative business concepts, like virtual enterprises, supply chain management, or one-to-one marketing, as well as advanced competitive strategies encompassing these business concepts, like mass customization, may be followed-up much more efficiently. However, competitive strategies like mass customization require sophisticated information infrastructures to support the indispensable business to business electronic commerce-even for small and medium enterprises taking part in a virtual enterprise that pursues mass customization. Especially electronic data interchange (EDI), which is understood as a means to exchange business data, is crucial to set up and maintain virtual enterprises. Thus, there is high demand on inexpensive and easily employable software that allows platform-independent exchange of business data between companies. We present an approach to a component (application) framework that aims to achieve this goal. By using the extensible markup language (XML) as an important cross-platform technique, together with common business communication standards, we show how the border of heterogeneous (distributed) application systems can be overcome. With this, the business communication protocol is set up. Taking this protocol as a basis, we further present a component framework, which is implemented using the JavaBeans technology that supports efficient inter-company communication. In addition, we show how this approach may further develop to a means for inter-company coordination.

Abstract: There is growing interest in providing computer support for an organisation's business processes such as customer order processing, product support, stock taking and so forth. Workflow systems are normally used for this purpose to co-ordinate and monitor execution of multiple tasks arranged to form business processes. In this context, computer support for work activity co-ordination will be taken to mean tools and services made available to the employees of an organisation to enable them to carry out their tasks that form the part of these workflows. The paper illustrates how a transactional workflow system can be augmented with support for reliable management of worklists in an arbitrarily distributed environment. Ideally, the workflow enactment service should be neutral to the types of work activity coordination services to be made available to users. In this way, the needs of a wide variety of organisations can be supported by building organisation specific services. The approach taken here is to separate organisational aspects of workflow management from the workflow enactment service as much as possible.

Abstract: Members of the COTS-based system initiative at the Software Engineering Institute have developed the Generic Enterprise Ensemble (GEE), a generic approach to building distributed, transaction based, secure enterprise information systems (EIS) GEE is a tool to help in the selection of technologies and architectural choices when building enterprise information systems Enterprise JavaBeans/sup TM/ (EJB) is a specification from Sun Microsystems for an application server based on Java technology a comparison is made between GEE based solutions and off-the-shelf solutions based on the EJB specification

Abstract: The article proposes and evaluates some extensions to the CORBA event service, based on the use of the light-weight reliable multicast protocol (LRMP). These extensions address some limitations of the CORBA Event Service, namely multicasting, reliability and total ordering. The extensions were developed and tested in a prototype environment created for this purpose, and are transparent and fully compatible with the standard OMG event service, enabling the user to decide on the use of standard IIOP or IP multicasting.

Abstract: In our work with legacy information systems, we have found two prevalent anti-patterns-tight coupling and code pollution-which, if not addressed in replacement systems, could result in today's new systems simply becoming tomorrow's new legacy system. Tight coupling results from Explicit Invocation across collaborating components. Code pollution results from implicit (rather than explicit) reflection of time-ordered collaboration protocols. These anti-patterns diminish component maintainability, flexibility, and reusability. In response, we propose a synthesis of Implicit Invocation (which reduces tight coupling) and Statecharts (which reflect collaboration protocols directly). The paper describes the development of EventPorts, which realize this synthesis and thus encapsulate a novel and promising component collaboration technology.

Abstract: In building models for manufacturing, product information has most often been handled separately from process information. The integration of product and process models in a unified data model could provide the means by which information could be shared across a manufacturing enterprise throughout the system lifecycle from design to production. Recently, attempts have been made to integrate these two separate views of systems through identifying common data models. This paper relates description-driven systems to multi-layer architectures and reveals where existing design patterns facilitate the integration of product and process models and where patterns are missing or where existing patterns require enrichment for this integration. It reports on the construction of a so-called description-driven system which integrates product data management (PDM) and workflow management (WfM) data models through a common meta-model.

Abstract: Customer service management (CSM) offers a management interface between customers and a service provider, which enables the customers to individually monitor and control their subscribed service. Introducing CSM in the service provider's environment includes communicating and interacting with its service management. Considering the complexity of service management, the goal of this paper is to logically separate CSM and service management, from an enterprise point of view, by identifying specific CSM roles which describe the functions of service management that are relevant for CSM. By using the concepts of roles and associations, we abstract from the details of the underlying service management and identify the requirements that have to be met by the service management. The specific CSM roles and associations are formalized using the terms and concepts of the ODP (open distributed processing) enterprise viewpoint specification in order to ensure that the resulting specification can be applied to a wide range of scenarios. The instantiation of the proposed approach within a real-life scenario shows the applicability and the benefits of our approach.

Abstract: Business via the Internet is becoming very popular. A number of organizations doing business in the traditional way are extending to do business over the World Wide Web. This not only results in reaching a very large number of customers in a cost-effective way but also makes business transactions fast and efficient. Most business-to-business deals are done through value-added networks (VANs) but, for general consumer-to-business deals, the Internet provides a powerful base. However, customer confidence in Internet commerce needs to be further strengthened before large-scale Internet purchasing becomes a reality. In recent years, we have seen the emergence of cryptographic techniques to provide secure transactions, but security alone is not enough, unless the transacting parties also trust each other. Hence, the main ingredient missing is trust. Many attempts have been made to provide secure and trust-providing protocols but few have seen any practical use. In this paper, we show how trust can be provided through a network of trust service providers (TSPs). We provide a set of trust services of a very basic nature which can be deployed through such a network. Our solution is implemented in the form of distributed objects on a CORBA-based platform. The clients accessing the trust services are written as Java applets.

Abstract: The mainframe centered IT environment is still a common architecture in many large organizations, especially in the financial industry. But the increasing demand for new applications and integration of modern communication technology forces a paradigm change. The paper deals with the challenging task of defining and controlling a disciplined evolution of the existing centralized IT systems into a new integrated architecture. First an introduction into the problem domain of large scale IT systems and into the basic characteristics of mainframe computing is provided. Analyzing the characteristics of large scale systems leads to the concept of a managed evolution and a service architecture. The description of requirements for this new architecture is followed by a discussion of design guidelines and a detailed explanation of the mainframe implementation. The paper concludes with up-to-date testing results which prove the scalability of the implementation up to several thousand distributed clients.

Abstract: It is widely recognized that the scalable and efficient management of large, heterogeneous information technology infrastructures requires middleware that allows the extension of managed resources with new functionality at runtime. A recent and promising approach is the Java Dynamic Management Kit (JDMK) that relies on the JavaBeans component technology. Based on our experiences with a prototype implementation that provides an adaptable management instrumentation for an Internet Telephony Server, the paper analyses the suitability of JDMK for building scalable and flexible management systems. The results of our work allow us to evaluate JDMK regarding its suitability for the management of large-scale enterprise networks.

Abstract: Type compatibility is an important issue in the area of service type evolution as it is desirable for a new-version service to still be compatible with its old version in order that existing clients of the old service are affected by the change as little as possible. The paper introduces a new type relationship called an equivalence relationship which concerns functionality compatibility rather than interface signature compatibility when determining substitutability between two service versions. To support this kind of relationship, parts of the CORBA invocation model will be extended to allow information of equivalent service versions to be discovered at run time from the augmented CORBA Interface Repository. A client request to an old service will then be dynamically and transparently composed as a new-version invocation to a new-version service. The proposed extensions will be useful to provide compatibility not only between versions of the same service but also between two distinct services that have equivalent functionality.

Abstract: Business objects have become an important topic of the discourse on enterprise distributed object computing, but what is a business object, apart from a flabbergasting, seemingly oxymoronic juxtaposition of vocables from two spheres that are poles part, viz. that of management fads and that of software development? From a comprehensive study of the literature on the subject, we distinguish seven reasonably distinct strands of usage of the concept and also cast a glance at a number of closely related terms. Contemplating our terminological findings, we then try to reach out for the true essence of business objects, but fail insofar as we arrive at two separate, although interrelated essences. Of these two, which we thereinafter refer to as business objects in the core sense and business objects in the extended sense, we find the latter more interesting, for a number of reasons. Scavenging further for their quiddity, we contrast business objects in the extended sense with various concepts that, prima facie, seem related, such as components, ensembles, agents, actors and objects. Finally, we take advantage of a scheme suggested by B. Cox (1990, 1991) to synthesise our results into a layered model of software and to adumbrate why we believe that business objects in the extended sense will form the underpinnings of a new era of realistic computing.

Abstract: Long before middleware became a market topic and professional providers offered out of the box functionality, industry like Asea Brown Boveri (ABB), had to provide solutions, which were based on what we today call middleware. Consequently, many industrial firms developed their own solutions. We describe an ABB proprietary middleware product called Object Management Facility (OMF). We present all its architectural properties and functional features. Wherever meaningful, we compare OMF's abilities with those offered by DCOM and CORBA and for some aspects important to the domain of control systems, we show that even today, OMF can compete with commercially available middleware products.

Abstract: As manufacturing industry evolves, enterprise networking becomes more popular and important. At the same time, distributed object computing technology such as CORBA has been developed rapidly and taken into use in many fields. Since CORBA technology has its advantages in an enterprise network environment, a CORBA based integrated framework for manufacturing enterprises called CEIF (Concurrency Engineering Integrated Framework) is proposed. An ORB with essential services and facilities resides in the core of the framework to support its application module, which integrates a multiple view modeling/facilitating tool and key applications in a manufacturing enterprise, and its management module, which provides efficient management function for enterprise network and applications. The architecture of the integrated framework and its application module and management module are described in detail.

Abstract: The paper presents an ODP-based approach to modelling virtual enterprises using a business case from the maritime industry. By modelling this business case, focusing on enterprise modelling, engineering requirements for communication infrastructure in virtual enterprises are identified. These requirements are met with the Data Exchange and Management (DEM) architecture, which has been implemented during this work and is presented.

Abstract: A previous paper by B.P. Blackshaw and J.R. Ellwood (1997) examined the suitability of CORBA for building enterprise level distributed systems. A number of areas of concern were discussed, and the paper concluded that at the time of writing, mid-1997, CORBA was not sufficiently mature for the job, However optimism was expressed that within 2-3 years many of the issues raised would have been dealt with by vendors and the OMG. The article investigates the accuracy of that prediction. It re-visits the issues raised in 1997 and looks at what has changed. It also discusses how the continued Internet revolution and the emergence of Java have changed the distributed landscape, and how well CORBA has adapted to these challenges.

Abstract: The paper presents a novel approach to providing error feedback for distributed, component based applications. We describe HERCULE, a framework within which an existing application can execute, to enhance error feedback. HERCULE will collect data from user actions and server requests and provide context dependent feedback on errors. The strength of HERCULE is that the application will not have to be modified or transformed in any way to participate in the framework. Users of software systems often spend a great deal of time trying to work out how to use the system and, in particular, how to deal with errors. It is often difficult to find out what has caused an error, and how to recover from it. Sometimes users are even oblivious to the presence of errors. In component based applications, the constituent parts are developed independently, and consequently traditional methods for implementing global feedback mechanisms will not be feasible. We therefore propose the introduction of an error reporting framework which will provide the required level of feedback for component based systems.

Abstract: The DART (Distributed Adaptive Run-Time) project is developing an adaptive software environment for general-purpose distributed applications. The goal of the project is to provide a software run-time system that allows application authors to quickly develop distributed software, such as network or World Wide Web software, without having to deal with the details of the distribution technology. DART compile-time and run-time components configure the application execution environments depending on hints provided with the application. An essential feature of the run-time component is its ability to reconfigure, or adapt itself, both to the application requirements and to the system and networking environment. To achieve both distribution and adaptation, we use meta-level object programming techniques and run-time monitoring.