This paper reviews the characteristics and methodologies developed by the programmable network and active network communities as complementary approaches making a significant contribution to the development of new arc...
详细信息
ISBN:
(纸本)0780370473
This paper reviews the characteristics and methodologies developed by the programmable network and active network communities as complementary approaches making a significant contribution to the development of new architectures. One such architecture is developed in the IST Project FAIN. FAIN is a three-year project, whose main task is to develop and validate an open, flexible, programmable and dependable network architecture based on novel active node concepts.
We present an approach to building multicast services at the network layer using unicast forwarding and two additional building blocks: ephemeral state probes, i.e. extremely lightweight distributed computations based...
详细信息
ISBN:
(纸本)0780370643
We present an approach to building multicast services at the network layer using unicast forwarding and two additional building blocks: ephemeral state probes, i.e. extremely lightweight distributed computations based on a time-bounded associative memory; and the ability to inject or enable packet processing functions that modify router behavior in a very limited way. In our approach, senders and receivers use ephemeral state probes to determine where to inject functionality. A special function that duplicates packets matching a particular pattern and forwards them to a specific destination is then instantiated at the desired network location. Our approach eliminates the need for sophisticated multicast routing protocols and gives the end-systems control over the multicast service, allowing the application to tailor the service to its needs. At the same time, our approach creates efficient forwarding paths by using ephemeral state probes to determine (only) the relevant aspects of the network and group topology. We present two multicast implementations: one builds a multicast tree with centralized control, another provides the traditional IP multicast abstraction. Both implementations can be done in a simple and scalable manner with minimal added functionality in the routers beyond unicast forwarding.
As network technology has become more powerful and complex, it has become increasingly difficult to monitor the well-being of a network. Failure semantics, media, network equipment, and topologies are quickly evolving...
详细信息
ISBN:
(纸本)0780370643
As network technology has become more powerful and complex, it has become increasingly difficult to monitor the well-being of a network. Failure semantics, media, network equipment, and topologies are quickly evolving towards greater sophistication and lesser serviceability. We often wish that the locus of our network supervision were inside the network, as close as possible to the suspect faulty equipment, in order to perform unit verification and real-time in situ repairs of network equipment. Unlike simple end-to-end "pings", this directional, sub-end-to-end supervision requires a wide range of data concerning topologies, type of network nodes, node contingencies, and proven test suites for them. Our "Regatta" framework makes supervision of network nodes (for example, switches, routers, firewalls) and node aggregates (clouds) practical by automating the acquisition and utilization of this data. The resulting platform marries the ease of end-to-end monitoring (the operator does not know about intervening network nodes or topologies) with the merits of unit supervision into the network (highly specialized coverage). Regatta overcomes key weaknesses in both end-to-end monitoring (wherein a whole end-to-end extent is the sole testing scope of choice) and unit supervision into the network (that is, multi-dimensional dependencies on the network itself). A Regatta's limiting factor is in the availability of Java runtimes inside the network - such runtimes are required in order to dynamically inflate and customize Regatta's artifacts. Short of active networks or mobile agents infrastructures supporting Regatta's widespread application, the Regatta framework already yields an appealing supervision resolution when attached to actual networks, and scales up to the finest resolution in experimental settings with all Java-enabled network nodes.
Over the last couple of years we have been working on the development of mobile agents systems and their application to the areas of telecommunications and network management. This work has produced positive results: ...
详细信息
ISBN:
(纸本)0780370643
Over the last couple of years we have been working on the development of mobile agents systems and their application to the areas of telecommunications and network management. This work has produced positive results: a competitive mobile agent platform was built, the run-time benefits of mobile agents were proved, and our industrial partners have developed practical applications that are being integrated into commercial products. However, despite the positive results, we feel that mobile agent technology is still not ready to enter the path of mainstream software development. In our perspective, one of the main reasons for this situation arises from the traditional approach to mobile agent technology. This approach, based on the familiar concept of the mobile-agent distributed platform as an extension of the operating system, focuses too much on the mobile agents and associated issues (mobility, agent lifecycle, security, coordination, etc.) and provides poor support for the development of applications where mobile agents are just one of several available technologies. Learning from past experience, we are now working on a new approach where the focus is brought back to the applications and mobile agents become just one the tools available to develop distributed systems. This provides a much lighter framework for application-based mobile agent systems. This paper presents the lessons learned from our previous project and discusses the new concept we are developing: application-centric mobile agent systems.
Motion integration issues have come to the forefront, along with maintainability and connectivity to automation solutions. For this standards are needed. PLCopen has generated such a standard. A standard in programmin...
详细信息
ISBN:
(纸本)0780367367
Motion integration issues have come to the forefront, along with maintainability and connectivity to automation solutions. For this standards are needed. PLCopen has generated such a standard. A standard in programming languages, to harmonize the access of motion control functionality across platforms. In this way, the generated application program is much more hardware independent, and re-usable across platforms. The provided standard, the PLCopen Motion Control Profile, is based on IEC 61131-3 Function Blocks. With the standardization of the interfaces and the functionality, and implementation on multiple platforms, it provides a programming standard that is widely supported by the industry. The stated goals of this standardization are simplicity, efficiency, consistency, universality, flexibility and completeness. Due to the data hiding and encapsulation, it is usable on different architectures, for instance ranging from centralized to distributed control. It is also important to say that it is not specifically designed for a certain range of applications e.g. packaging industry but it will serve as a basic layer for ongoing definitions in these areas. As such it is open to existing and future technologies.
This article presents an investigation into the possibilities of using Voyager/sup TM/ for efficient distributed programming. Voyager is a complex Java tool, made by Objectspace. It integrates different technologies s...
详细信息
This article presents an investigation into the possibilities of using Voyager/sup TM/ for efficient distributed programming. Voyager is a complex Java tool, made by Objectspace. It integrates different technologies such as RMI, CORBA, and mobile agent technology. During the work I have created an isolated local network, written a test application and databases and made some efficiency tests. I have compared two different kinds of communication between hosts (different and the same architectures) with databases based on standard ORB communication and by introducing mobility for objects. The purpose of the investigation is to find out if and when mobility is better than the classical client-server model for communication.
The Model/View/Controller design pattern is very useful for architecting interactive software systems. This design pattern is partition-independent, because it is expressed in terms of an interactive application runni...
详细信息
The Model/View/Controller design pattern is very useful for architecting interactive software systems. This design pattern is partition-independent, because it is expressed in terms of an interactive application running in a single address space. Applying the Model/View/Controller design pattern to web-applications is therefore complicated by the fact that current technologies encourage developers to partition the application as early as in the design phase. Subsequent changes to that partitioning require considerable changes to the application's implementation-despite the fact that the application logic has not changed. This paper introduces the concept of Flexible Web-Application Partitioning, a programming model and implementation infrastructure, that allows developers to apply the Model/View/Controller design pattern in a partition-independent manner Applications are developed and tested in a single address-space; they can then be deployed to various client/server architectures without changing the application's source code. In addition, partitioning decisions can be changed without modifying the application.
TRACY is a prototype of a middleware architecture that supports the migration of agents (in our definition: self contained, autonomous objects) in heterogeneous networks with the aim to complement more traditional dis...
详细信息
ISBN:
(纸本)0769510868
TRACY is a prototype of a middleware architecture that supports the migration of agents (in our definition: self contained, autonomous objects) in heterogeneous networks with the aim to complement more traditional distributed architectures. TRACY supports a weak form of (optimized) agent migration in a network of agent servers and implements local message passing between agents. Derived from a concise evaluation of requirements, mostly targeted towards eCommerce and Intranet applications, TRACY is based on a three layer architecture model that supports a clean separation of concerns. A fully functional prototype of TRACY is by now ready for a first release and will be offered to system developers on the basis of an open-source venture. Currently, we are developing an industrial strength reference installation with a partner in the transport and logistics domain. The focus of this paper are the lessons learned during requirements analysis and system design, and the architecture of TRACY.
Existing active networkarchitectures depend on using statically typed languages for protection and performance. Unfortunately, this limits some of the more dynamic features of an active network. In this paper, we pre...
详细信息
暂无评论