Using distributed object technologies in telecommunications network management

The integration of heterogeneous networks and systems is one of the more urgent requirements expressed by networks and computer users. ISO and ITU-T normalisation bodies have contributed in a significant manner to the definition of a global management framework called TMN (Telecommunication Management Network). TMN is an agreed framework that permitted to a number of public and private network operators to build their management system. However, these existing systems are confronted to the heterogeneity of emerging technologies. In fact, new equipment is built with specific management interfaces, which are not conforming, to the TMN one. The heterogeneity considered in this paper is the one that emerges from the OMG (Object Management Group) CORBA (Common Object Request Broker Architecture). In fact, a lot of CORBA based systems are emerging in the field of management. In this context, telecommunication operators are willing in the short term to use their existing management systems to control them in a uniform way. The aim of this paper is to propose solutions to these problems through the use of Q Adapter that permits to integrate CORBA based equipment into the global management framework based on TMN.KeywordsManagementCORBAOSIAdaptationObjectProtocolService

Describes the initial design work of the New Zealand Distributed Information Systems (NZDIS) research project, which seeks to develop an architecture for building distributed information systems from existing information resources, based on software agent and distributed object technologies. An agent-based architecture is used, with messages exchanged via the FIPA (Foundation for Intelligent Physical Agents) agent communication language (ACL). Novel features of this system include the use of standards from the object-oriented programming community, such as the Common Object Request Broker Architecture (CORBA) as a communications infrastructure, the Unified Modeling Language (UML), which is used as an ontology representation language, the Object Data Management Group's Object Query Language (OQL), which is used for queries, and the Object Management Group's Meta Object Facility (MOF), which is used as the basis for an ontology repository agent. 'Stringified' object references may be returned as the content of ACL messages, allowing query results to be made available via a variety of CORBA interfaces.

One of the most attractive aspects of the Common Object Request Broker Architecture (CORBA) lies in its open standard nature. Code that is based only on constructs described in the CORBA specification is portable between object request brokers (ORBs) without depending on any single ORB implementation. However, this portability feature is not completely achieved in real-world applications. This paper discusses CORBA portability issues through our experience in implementing a CORBA object group service (OGS) and porting it on different ORBs. In particular, we discuss some implementation choices we made with Orbix and VisiBroker, and we point out the impact of these choices on the service portability and interoperability. This sheds some light on whether the current CORBA specification is mature enough to be deployed in industrial systems that have requirements regarding portability and interoperability. We also present how new CORBA specifications solve part of the shortcomings mentioned in this paper.

The test and training enabling architecture (TENA) middleware is the result of a joint interoperability initiative of the Director, Operational Test and Evaluation (DOT&E) of the Office of the Secretary of Defense (OSD). The goals of the initiative are to enable interoperability among ranges, facilities, and simulations in a quick and cost-efficient manner, and to foster reuse of range assets and future range system developments. The TENA middleware uses Unified Modeling Language (UML)-based model-driven code generation to automatically create a complex Common Object Request Broker Architecture (CORBA) application. This model-driven automatic code-generation greatly reduces the amount of software that must be hand-written and tested. Furthermore, the TENA middleware combines distributed shared memory, anonymous publish-subscribe, and model-driven distributed object-oriented programming paradigms into a single distributed middleware system. This unique combination yields a powerful middleware system that enables its users to rapidly develop sophisticated yet understandable distributed applications. The TENA middleware offers powerful programming abstractions that are not present in CORBA alone and provides a strongly-typed application programmer interface (API) that is much less error-prone than the existing CORBA API. These high-level, easy-to-understand programming abstractions combined with an API designed to reduce programming errors enable users to quickly and correctly express the concepts of their applications. Re-usable standardized objects farther simplify the development of applications. The net result of this combination of features is a significant reduction of application programming errors yielding increased overall reliability and decreased overall development time. Distributed applications developed using the TENA middleware exchange data using the publish-subscribe paradigm. Although many publish-subscribe systems exist, the TENA middleware represents a significant advance in the field due to the many high-level, model-driven programming abstractions it presents to the programmer. The TENA middleware API relies heavily on compile-time type-safety to help ensure reliable behavior at runtime. Careful API design allows a great number of potential errors to be detected at compile-time that might otherwise go unnoticed until run-time - where the cost of an error could be extremely high! The implementation of the TENA middleware uses C++, as well as a real-time CORBA ORB. The TENA middleware is currently in use at dozens of Department of Defense (DoD) testing and training range facilities across the county and has been used to support major test and training events such as Joint Red Flag '05. The TENA Middleware is available at http://www.tena-sda.org/

Problem statement: This study presents an in-depth analysis of the performance of Software Communications Architecture (SCA) component-based waveform applications in terms of inter-component communications. The main limitation with SCA, in the context of embedded systems, is the additional cost introduced by the use of Object Request Broker (ORB) middleware. The ORB middleware handles the interaction between components and objects in SCA distributed environment. This interaction should be highly efficient, due to the real time nature of SCA systems and transparent to the application programmer. Approach: We can achieve high efficiency in SCA systems by enhancing the Inter-Process Communications (IPC) mechanisms in Operating systems (OS) micro kernels, while we achieve transparency through Interface Definition Language (IDL). Different encoding mechanisms like “External Data Representation (XDR), Network Data Representation (NDR) and Common Data Representation (CDR) facilitate inter-component communication transparently and efficiently”. Marshalling procedures format data from the local machine representation to common network representations. A most common encoding mechanism for Common Object Request Broker Architecture (CORBA) systems is CDR representation. Measurements have been performed with ORBExpress DSP as a CORBA distribution and Open Source SCA Implementation Embedded (OSSIE) for SCA implementation. In order to perform these measurements we proposed two metrics for profiling the ORB that are invocation and marshalling. In addition, we propose three elements of data types to evaluate the performance of ORB middleware that are, Basic, Array and Sequence data types. Results: The CORBA bus is really the part, which brings an overhead to the SCA radio systems. This overhead is due to method invocations that have been carried out by ORB middleware. Conclusion: Performance benchmarks of ORBExpress DSP middleware show that, although using CORBA for inter-component communications introduces delays and overheads, the overall effect can be reduced by sending packets of data instead of basic data type elements.

The authors discuss data communications networks (DCNs) used by operating telephone companies to interconnect large numbers of telecommunications network elements with operations systems and workstations to support and manage telecommunications networks, referred to by the international telegraph and telephone consultative committee (CCITT) as a telecommunications management network (TMN). The TMNs can include different types of DCNs such as private lines, circuit-switched networks, packet-switched networks, and integrated services digital networks (ISDNs). These can be divided into two classes: connection-mode and connectionless-mode networks. The authors briefly consider TMN concepts and implementation architectures. They then focus on TMN internetworking design alternatives, issues, and protocol stacks, in order to provide data network designers and implementors with the necessary fundamentals in considering and choosing interworking solutions for TMN applications. >

Distributed computing applications rely on transmissions of messages between processes. However, as workstations are not intended to manage this kind of communications, it is necessary to use some communication tools known as message passing libraries. Currently, MPI (Message Passing Interface) and PVM (Parallel Virtual Machine) are the most used. In addition, the need for interoperability among the rapidly proliferating amount of hardware and software led to the definition of CORBA (Common Object Request Broker Architecture), which standardizes the execution support of distributed object applications. This architecture offers good interoperability and encapsulation support. Moreover, its method invocation mechanism, offers several features and can be used as a good communication model. Consequently, the use of such an architecture for distributed and grid computing applications seems interesting and promising. However, CORBA is always criticized on the performance level. By taking account of all these elements, a performance evaluation of CORBA seems necessary. The aim of the paper is to present benchmark results of some CORBA implementations (ORBacus and TAO) and to compare them with those of the two message passing libraries MPI (MPICH and LAM) and PVM, by using a Network of WorkStations (NOW).

As telecommunications networks and services are getting larger and more complex, telecommunication service providers around the world are desperately looking for solutions to manage and control them. A telecommunications management network (TMN) has been envisioned to provide a framework for the operation, administration, maintenance and provisioning (OAM&P) of telecommunications networks and services in today's open, multi-vendor environment. Due to the inherent distributed nature of managing systems and managed systems, supporting distributed processing is an essential requirement in TMN. This paper examines the general requirements for supporting distributed processing for the purpose of open distributed management in TMN and proposes a solution which is based on the integrated use of two distributed processing technologies: the X.500 Directory Service and the ODP (Open Distributed Processing) Trader.

This paper describes an innovative framework for a scalable, secure, transparent and distributed medical image-database system which functions in a heterogeneous computer environment using CORBA and DCOM. The framework is designed for implementing telemedicine applications with maximal resource reusability and load balancing. This will enable an existing computer system to be adapted easily to the new system with minimal effort and cost. We have developed a heterogeneous distributed image-database system called MIRage, composed of three subsystems and ORB, based on the CORBA specification as underlying middleware. The ORB, which is a distributed demon structure, enables a cluster of heterogeneous computers to be seen as a single MIRage system, regardless of location and operating system.

This chapter introduces a programming environment for SCI clusters that takes advantage of both parallel and distributed programming paradigms. It aims at helping programmers to design high performance applications based on the assembling of generic software components. This environment is based on CORBA (Common Object Request Broker Architecture), with our own extensions to support parallelism across several cluster nodes within a distributed system. Our contribution concerns extensions to support a new kind of object, which we call a parallel CORBA object (or parallel object), as well as the integration of message-passing paradigms, mainly MPI, within a parallel object. These extensions exploit as much as possible the functionality offered by CORBA and require few modifications to an available CORBA implementation. This paper reports on these extensions and the description of a runtime system, called Cobra, which provides resource allocation services for the execution of parallel objects.

The robot middleware is a key concept in developing complex robot systems even in geographically distributed environment. Giving a handy API, reusable standardized components and communication channels together with some automatism, the robot middleware helps the user to build easily reconfigurable systems. The behavior of the components and the manner of interaction among them are standardized by the Robotic Technology Component (RTC) specification. One implementation of the RTC specification is the OpenRTM-aist. It is a well written and convenient modular system built upon the Common Object Request Broker Architecture (CORBA). The first version of CORBA is released in 1991. Nowadays the CORBA is getting more and more out of date. Our ultimate goal is developing a new robot middleware in which we apply a modern distributed framework instead of CORBA. As a first step of the substitution we suggest some practical extensions of the OpenRTM-aist by the adaptation of the Internet Communication Engine (ICE) for component communication and the introduction of the web application concept for system editing and control. Having these structural modifications the resulting system became more powerful than the original system has been. The chapter introduces some structural and implementation details of the OpenRTM-aist together with the results of the experiments done for the performance comparison of the original and extended system.

Robot systems are comprised of several elements working together as a whole. The specific task of the robot system determines which elements are required. These reusable, fungible elements can be implemented as components which connect each other via communication channels and well-defined interfaces. The behavior of the components and the manner of interaction among them can be standardized by the Robotic Technology Component (RTC) specification. One promising implementation of the RTC specification called OpenRTM-aist is a software platform assisting to the component-oriented robot system development. In OpenRTM-aist both the specification and the implementation is based on the Common Object Request Broker Architecture (CORBA) and its remote method invocation. The first version of CORBA was released in 1991. In spite of the updates CORBA is getting more and more out of date. Several solutions exist which can replace or extend CORBA. Our ultimate goal is replacing the CORBA and setting up a modern distributed robot system development framework which is based on the original OpenRTM-aist specification. To be the first step of this task in this paper we suggest some practical extensions of the existing OpenRTM-aist robot middleware. These modifications are the adaptation of the Internet Communication Engine (ICE) for inter-component communication and as a new scheme, the introduction of the web application concept. After these structural modifications the resulting system became more powerful, and thanks to the web application concept much more user friendly.

This tutorial addresses how both the Object Management Group (OMG) specifications and the implementation choices made by middleware providers and application developers affect Common Object Request Broker Architecture (CORBA) application scalability. We will cover a range of scalability issues, starting with Object Request Broker (ORB) internals and working outward to full-scale applications, addressing issues such as connection management, Portable Object Adapter (POA) scalability features, multithreading, object lifecycle issues, object location, system configuration, maintenance, and management, and common application architectures. This tutorial is not language-centric and is useful to developers using Java, C++, or any other language to develop CORBA-based applications.

A major concern when implementing SONET/SDH technology is the ability to effectively manage a constantly evolving network plus its elements along with new services that will be rapidly introduced. This paper describes our experience in implementing a telecommunications management network (TMN) compliant SONET/SDH network management system. The TMN concept is envisioned by the standard body as a promising approach to manage the operations, administration, maintenance and provisioning (OAM&P) functions in a multi-vendor telecommunication network. This paper presents the problems and pitfalls of TMN and outlines our TMN implementation experience in both domestic and Mexican networks.

A framework for the distribution of program objects in heterogeneous computer systems using Common Object Request Broker Architecture (CORBA) is described. Any load balancing algorithm can be integrated transparently into the existing CORBA infrastructure. The implementation was tested with different load balancing strategies on an algorithm performing an exhaustive search over all possible paths, over all interconnection topologies of n nodes. The goal is to find the topology yielding the minimal sum of average and maximal distances among all pairs of nodes in minimal execution time.