8,604 research outputs found
A semi-formal comparison between the Common Object Request Broker Architecture (COBRA) and the Distributed Component Object Model (DCOM)
The way in which application systems and software are built has changed dramatically over the past few
years. This is mainly due to advances in hardware technology, programming languages, as well as the
requirement to build better software application systems in less time. The importance of mondial (worldwide)
communication between systems is also growing exponentially. People are using network-based
applications daily, communicating not only locally, but also globally. The Internet, the global network,
therefore plays a significant role in the development of new software. Distributed object computing is one
of the computing paradigms that promise to solve the need to develop clienVserver application systems,
communicating over heterogeneous environments.
This study, of limited scope, concentrates on one crucial element without which distributed object computing
cannot be implemented. This element is the communication software, also called middleware, which allows
objects situated on different hardware platforms to communicate over a network. Two of the most important
middleware standards for distributed object computing today are the Common Object Request Broker
Architecture (CORBA) from the Object Management Group, and the Distributed Component Object
Model (DCOM) from Microsoft Corporation. Each of these standards is implemented in commercially
available products, allowing distributed objects to communicate over heterogeneous networks.
In studying each of the middleware standards, a formal way of comparing CORBA and DCOM is presented,
namely meta-modelling. For each of these two distributed object infrastructures (middleware), meta-models
are constructed. Based on this uniform and unbiased approach, a comparison of the two distributed object
infrastructures is then performed. The results are given as a set of tables in which the differences and
similarities of each distributed object infrastructure are exhibited. By adopting this approach, errors caused
by misunderstanding or misinterpretation are minimised. Consequently, an accurate and unbiased
comparison between CORBA and DCOM is made possible, which constitutes the main aim of this
dissertation.ComputingM. Sc. (Computer Science
Software engineering and middleware: a roadmap (Invited talk)
The construction of a large class of distributed systems can be simplified by leveraging middleware, which is layered between network operating systems and application components. Middleware resolves heterogeneity and facilitates communication and coordination of distributed components. Existing middleware products enable software engineers to build systems that are distributed across a local-area network. State-of-the-art middleware research aims to push this boundary towards Internet-scale distribution, adaptive and reconfigurable middleware and middleware for dependable and wireless systems. The challenge for software engineering research is to devise notations, techniques, methods and tools for distributed system construction that systematically build and exploit the capabilities that middleware deliver
Towards Adaptable and Adaptive Policy-Free Middleware
We believe that to fully support adaptive distributed applications,
middleware must itself be adaptable, adaptive and policy-free. In this paper we
present a new language-independent adaptable and adaptive policy framework
suitable for integration in a wide variety of middleware systems. This
framework facilitates the construction of adaptive distributed applications.
The framework addresses adaptability through its ability to represent a wide
range of specific middleware policies. Adaptiveness is supported by a rich
contextual model, through which an application programmer may control precisely
how policies should be selected for any particular interaction with the
middleware. A contextual pattern mechanism facilitates the succinct expression
of both coarse- and fine-grain policy contexts. Policies may be specified and
altered dynamically, and may themselves take account of dynamic conditions. The
framework contains no hard-wired policies; instead, all policies can be
configured.Comment: Submitted to Dependable and Adaptive Distributed Systems Track, ACM
SAC 200
A QoS-Control Architecture for Object Middleware
This paper presents an architecture for QoS-aware middleware platforms. We present a general framework for control, and specialise this framework for QoS provisioning in the middleware context. We identify different alternatives for control, and we elaborate the technical issues related to controlling the internal characteristics of object middleware. We illustrate our QoS control approach by means of a scenario based on CORBA
A Framework for Evaluating Model-Driven Self-adaptive Software Systems
In the last few years, Model Driven Development (MDD), Component-based
Software Development (CBSD), and context-oriented software have become
interesting alternatives for the design and construction of self-adaptive
software systems. In general, the ultimate goal of these technologies is to be
able to reduce development costs and effort, while improving the modularity,
flexibility, adaptability, and reliability of software systems. An analysis of
these technologies shows them all to include the principle of the separation of
concerns, and their further integration is a key factor to obtaining
high-quality and self-adaptable software systems. Each technology identifies
different concerns and deals with them separately in order to specify the
design of the self-adaptive applications, and, at the same time, support
software with adaptability and context-awareness. This research studies the
development methodologies that employ the principles of model-driven
development in building self-adaptive software systems. To this aim, this
article proposes an evaluation framework for analysing and evaluating the
features of model-driven approaches and their ability to support software with
self-adaptability and dependability in highly dynamic contextual environment.
Such evaluation framework can facilitate the software developers on selecting a
development methodology that suits their software requirements and reduces the
development effort of building self-adaptive software systems. This study
highlights the major drawbacks of the propped model-driven approaches in the
related works, and emphasise on considering the volatile aspects of
self-adaptive software in the analysis, design and implementation phases of the
development methodologies. In addition, we argue that the development
methodologies should leave the selection of modelling languages and modelling
tools to the software developers.Comment: model-driven architecture, COP, AOP, component composition,
self-adaptive application, context oriented software developmen
OpenPING: A Reflective Middleware for the Construction of Adaptive Networked Game Applications
The emergence of distributed Virtual Reality (VR) applications
that run over the Internet has presented networked game
application designers with new challenges. In an environment
where the public internet streams multimedia data and is
constantly under pressure to deliver over widely heterogeneous
user-platforms, there has been a growing need that distributed VR
applications be aware of and adapt to frequent variations in their
context of execution. In this paper, we argue that in contrast to
research efforts targeted at improvement of scalability, persistence
and responsiveness capabilities, much less attempts have been
aimed at addressing the flexibility, maintainability and
extensibility requirements in contemporary distributed VR
platforms. We propose the use of structural reflection as an
approach that not only addresses these requirements but also
offers added value in the form of providing a framework for
scalability, persistence and responsiveness that is itself flexible,
maintainable and extensible. We also present an adaptive
middleware platform implementation called OpenPING1 that
supports our proposal in addressing these requirements
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