Kurt Geihs

Middleware challenges ahead

Middleware research and development has reached the end of its first major phase, and new requirements are arising that are so fundamentally different that they will lead to new-generation middleware systems. Facing dynamic modifications in distributed systems technology, middleware developers are striving to support applications that meet the technical challenges of ubiquitous computing.

A Generic Model for Fault Isolation in IntegratedManagement Systems

Distributed systems in enterprises as well astelecommunication environments strongly demand moreautomated fault management. A single fault in thesecomplex systems might cause a huge number of symptomatic error messages and side effects to occur. Thecommon root faults for these symptoms have to beidentified to start fault removal procedures as soon aspossible and to decrease system down-time. This paper presents a methodology for fault isolation inintegrated management systems. A generic model isdescribed that unifies the view of the management systemon the managed environment. It integrates the relevant aspects of network, system, and servicemanagement layers in order to perform integrated faultisolation. Our approach is based on a general dependencygraph model. It captures the information that isrequired to determine the root cause of a fault on theone hand, and the set of fault affected services andcustomers on the other hand. The layered TMNarchitecture serves as an example for an integratedmanagement environment throughout this paper.

A UML Meta-model for Contract Aware Components

We present an extension to the UML meta-model which allows modelling of contract aware components. Contracts are a novel way of describing the functional and non-functional behaviour of components. The usage of contracts in component diagrams allows tools to check whether all requirements for a successful assembly and deployment of the components are fulfilled. Furthermore, we investigate how components can be used in the different development phases and how design phase transitions can be managed.

Model metamorphosis

Model driven architectures (MDA) will become practical only if transformations from platform-independent to platform-specific models can be largely automated. Kafka, an extensible rule-based transformation language, and the Kase modeling tool enable automated, customized transformations that support round-trip engineering. With Kafka and Kase, developers can construct transformations without detailed knowledge of metamodels.

Efficient and Transparent Instrumentation of Application Components Using an Aspect-Oriented Approach

The increasing significance of Service Level Management (SLM) strongly requires an appropriate instrumentation of application components in order to monitor compliance with the defined Service Level Objectives (SLOs). The manual instrumentation of application components is very costly and error-prone and thus rather inefficient.

Distributed Systems, OSF DCE, and Beyond

This introduction paper presents basic foundations of distributed systems and applications and then shows how OSF DCE addresses the requirements imposed by distributed environments. The DCE architecture is illustrated, the basic functionality of the DCE components is explained, and the DCE RPC as the major base for client/server applications is presented in closer detail.

Unifying service level management using an MDA-based approach

Service level management (SLM) has gained more and more importance in the past few years. One of the biggest challenges is the integration of emerging new technologies such as Web services. A large number of different SLM approaches has been proposed which complicates an efficient SLM. This paper describes an SLM approach that is based on the model driven architecture (MDA). The first step is to specify abstract reusable SLA patterns which are bound later to a concrete management platform and are finally physically deployed into the managed environment. This approach benefits from the advantages of the MDA and provides a mechanism for transforming SLA patterns for different SLA management platforms. Our approach has been prototypically implemented for the Web services level agreement (WSLA) environment.

Security Requirements for Mobile Agents in Electronic Markets

In this article we identify security threats and requirements for software agent systems in the context of an electronic market. A short description of our own agent system AMETAS is given. It provides an infrastructure for a general multi-purpose agent system. We explain which security facilities need to be employed and how some of them were implemented in AMETAS.

Quality of service in middleware and applications: a model-driven approach

Quality of service (QoS) management has become an important requirement for middleware platforms and distributed applications. Early QoS engineering attempts focused on single-category extensions to standard middleware. In recent years generic middleware frameworks have been proposed in order to facilitate multicategory QoS management. Our experience with such a framework has revealed that QoS management cannot be shielded from the applications. Applications need to be designed in a QoS-aware manner and application QoS requirements need to be translated into appropriate middleware extensions. Therefore we propose a comprehensive, model-driven development process for QoS-enabled distributed applications on top of QoS-enhanced middleware platforms. Our approach builds on OMGs Model-Driven Architecture (MDA). We demonstrate the mapping from the platform-independent to the platform-specific model, and we show how the design approach is applied targeting a .NET-based QoS-enabled middleware.

Generic QoS Specifications for CORBA

Quality of Service (QoS) integration is a growing demand on nowadays networks and distributed systems. While QoS has originally been a domain of networking protocols and multimedia applications, a generalized view includes all aspects related to service quality that a client experiences. Object-oriented middleware like CORBA, DCOM or Java/RMI are popular but the current standards lack means for QoS integration. Some efforts have been made to integrate QoS in such middleware. But so far, all of them are restricted to specialized QoS categories like real-time, fault-tolerance or multimedia. A general approach is still missing. In this paper we present an approach how QoS definitions for a broad variety of QoS categories can be integrated into CORBA.