ISO Open Research Articles

Policy 2003: Workshop on Policies for Distributed Systems and Networks

Policy-based systems are the subject of a wide range of activities in universities, standardization bodies and within industry [1]. They have a wide spectrum of applications ranging from quality-of-service management within networks to security and enterprise modeling. Within the Internet community there is considerable interest in Policy Based Networking. A number of companies have announced tools to support the specification and deployment of policies. Much of this work is focused on policies for quality-of-service management within networks and the Internet Engineering and Distributed Management Task Forces (IETF/DMTF) are actively working on standards [2] related to this area. The Security community has focused on the specification and analysis of access control policy, which has evolved into the work on Role-Based Access Control (RBAC) [3]. There had been work over a number of years in the academic community on specification and analysis of policies for Distributed Systems [4], mostly concentrating on authorization polices. Although there are strong similarities in the concepts and techniques used by the different communities there is no commonly accepted terminology or notation for specifying policy. Several research groups are looking at high-level aspects of policy related to Enterprise Modelling. An ISO Open Distributed Processing (ODP) working group is defining Policy and Role concepts within the Enterprise Viewpoint [5]. Enterprise goals or Service Level Agreements can be considered as high-level abstract policies, which must be progressively refined into implementable policies. The work on the specification and analysis of Business Rule is also relevant.

An ODA‐like Multimedia Document System

A multimedia document is composed of different media objects. ISO's Open Document Architecture (ODA) proposes a standard multimedia document model. However, the current ODA profile only includes static media, e.g. text, geometric graphics and images. Because the future multimedia documents not only include static media but also continuous media, e.g. video and audio, continuous media document parts should be added to have a complete multimedia document model. In this paper, we propose a multimedia document model, which is derived from ODA's concept. The proposed model is based on the object-oriented approach. Objects in the proposed document model are divided into two types : data objects and pseudo objects. Data objects are data structures of a document ; pseudo objects are used to manage data objects. Based on the proposed model, a multimedia document authoring and presenting system (MMDS) is also developed on SUN SPARC workstations using the Solaris 2.X operating system

ODP viewpoints of IBCN service management

Service management is one of the key functional areas in the future telecommunications management network (TMN) for the integrated broadband communication network (IBCN). We describe the objectives and functions of service management. An experimental service management system has been designed by NEMESYS, a project within the European RACE programme. This service management will be implemented as part of an experimental study of TMN requirements and techniques in a simulated ATM environment. The design of the experimental Service Manager is discussed using the novel viewpoint approach that has emerged from ISO's Open Distributed Processing (ODP) standardization activities. We briefly review the ODP viewpoint concepts. The design aspects of the Service Manager are analysed with respect to the different viewpoints. We also evaluate the usefulness of the ODP viewpoints for the analysis and design of a rather complex distributed system.

A framework architecture for information networks

An overview of the INA Architecture, which builds on the current advances in broadband communication and distributed computing technologies and specifies an architecture for future information networks that are required to transport multimedia information and to manage multimedia communication, is presented. The key functional separations that have to be met in any INA-consistent network, the major components of an INA-consistent network, and the various levels in the architecture are described. The INA Architecture is compared with ISO's Open Systems Interconnection (OSI), ISO's Open Distributed Processing (ODP), and Bellcore's AIN architecture.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Fiber optic backbone boosts local-area networks

The evolving Fiber Distributed Data Interface (FDDI) for fiber optic networks, which greatly increases system capacity and flexibility, is discussed. The standard is described in terms of the ISO's Open Systems Interconnection (OSI) reference model. The initial FDDI standard defines four protocols: physical layer medium dependent, physical layer, media access control, and station management. Each of these is examined. Optical technology and the use of application-specific integrated circuits required by FDDI are discussed. Applications of FDDI and its future evolution are considered.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Telecommunication services and distributed applications

The issues involved in standardizing the seventh (application) layer of the Open Systems Interconnection model are examined. The status of the ISO Open Distributed Processing (ODP) reference model and of other models is summarized. Telecommunication service requirements are discussed within the context of these standardization efforts. >

A comprehensive security system— the concepts, agents and protocols

This paper presents an overview of a comprehensive security architecture for use within, and as a value-added enhancement to, the ISO Open System Interconnection model. The system is arranged basically as an application layer service but can allow all of the ISO-recommended security facilities to be provided at any layer of the model. It is suitable as an “add-on” service to existing arrangements or can be fully integrated into new applications. For large-scale, distributed processing operations, a network of “security management centres” is suggested, that can help to ensure that system misuse is minimized, and that flexible operations are provided in an efficient manner.

Future scientific networking

The scientific community currently uses a number of different computer networks, largely based on proprietary protocols and operated in an informal way. Collaborative research, across both national and subject boundaries, will only be able to benefit fully from the potential of computer communications if there is an infrastructure available based on a coherent architecture. ISO's Open Systems Interconnection provides the best technical solution to meet this requirement and the Eureka project COSINE is promoting the provision of the required infrastructure for Europe

A conformance tester for X.25 DTE implementations

The authors review briefly the testing architecture of ISO 9646, a standard for defining testing methodology and architecture for all of the ISO Open Systems Interconnection layers. They then describe the test systems of the US National Institute for Standards and Technology for both the link and packet layers, and, for vendors interfacing their data terminal equipment to DDN. They explain how conformance to the Defense Data Network (DDN) X.25 interface can be verified. They also discuss the possibility of porting the test system to other test equipment. >

Security of open systems

As an enhancement to ISO's Open Systems Interconnection Reference Model, ECMA defines a security framework for distributed systems which is based on the concepts of security domains and security facilities. This paper describes a functional decomposition of the security of distributed systems, thus providing building blocks which can be specified and analysed in detail and can be used to establish a secure distributed processing environment for both private application software and public communication services such as electronic mail. The aim is to achieve both interoperability (openness) and a high level of confidence.

An Approach to the Formal Description of Information-Management Networks

This report represents a part of the experiences on using formal description techniques in design of information-management systems and networks, performing in the Central Laboratory of Control Systems (Bulgaria) and in the Institute of Information Transmission Problems (U.S.S.R.) to support the development of computer-aided researches and design of information and automation systems. The information subsystem based on LAN “Izotring” is used as an example to illustrate the main principles of description and of transition from conceptual to formal description in terms of the ISO Open System Interconnections architecture. The nearest problems are discussed.

Service access procedure (SAP) for a transport layer protocol

The article presents the concept and design of a Service Access Procedure (SAP) for establishing transparent and reliable connections between the top three layer protocols of the ISO Open System Interconnection (OSI) and the corresponding bottom four layer protocols. The SAP allows a user to utilize network authentication services and accommodates for a single network login while establishing an active connection. Of the bottom four layers, the transport and network protocols are often selected to be the U. S. Department of Defense (DoD) standard Transmission Control Protocol (TCP) and Internet Protocol (IP), respectively. The upper layer protocols are usually a part of the host processor's software whereas the TCP/IP and the subsequent lower layer protocols might be resident in a physically distinct device such as an interface unit (IU). The rationale for residency of the TCP/IP in IUs, the concept and design of a TCP SAP, and the basis for selection of the lower layer protocols that constitute the host-front-end protocol set are presented in this article.

Dialogue management reference model

I would like to review and extend the discussion of the layered structure model similar to the ISO Open Systems Interconnect model in the Report on the SIGCHI Workshop on Planning for User Interface Standards published in the October, 1985 SIGCHI Bulletin . First, I would like to compliment the people who worked on the report. They produced a document which I regard as correct, however incomplete. Bullinger and Faehnrich in Germany have published papers on what they regard as the User Interface Management System. I have integrated Figure 3 and Figure 4 from the CHI '85 Report with the diagrams from Bullinger et al to produce Figure 1. The layers added---semantic, syntactic and lexical---are commonly used in the implementation of compilers and interpreters and are supported by many tools referred to as compiler compilers i.e., yacc and lex from the UNIX system. In the ISO OSI reference model, interfaces exist at the vertical arrows between adjacent layers, protocols exist between peer layers. The term "user interface" conflicts with the ISO usage of "interface." I will instead refer to "human-computer dialog rules." Human-computer dialog rules are the set of peer layer protocols along with the user feedback rules, and appear as horizontal arrows on Figure 1. It is the set of human-computer dialog rules that should be standardized by SIGCHI members. Interfaces between the adjacent layers are implementation details and should be standardized by implementors.

X.25 protocols in the airline industry

The requirements of a highly reliable data transport mechanism are outlined, and a practical implementation of the CCITT/ISO standards within the airline is demonstrated. An understanding of the ISO Open Systems Interconnection architecture, as well as CCITT recommendations such as X.25 and X.75, is assumed. The selection of various X.25 subsets and how they meet the data communications needs of a variety of interconnection structures are then described. Finally, the paper reviews the current work being undertaken with respect to the higher layers of the ISO OSI architecture.

A multilayered operating system for microcomputers

Traditionally, programs on microcomputers have been accessing the hardware through a simple monitor. Recent years, however, have seen the evolution of general operating systems for microcomputers. With these, microcomputer systems follow the history of the mainframes. General operating systems have several advantages. They enhance the possibilities of the hardware and define standard interfaces for application programs. However, the price one has to pay for these benefits is high. The operating system itself will take a large part of the available resources and, for many systems, it will hinder a user-oriented interface of the application programs. These disadvantages, which are serious enough for mainframes, can make the traditional general operating system unacceptable for microcomputer systems. As an alternative, we will propose a multi-level operating system, based on ideas from the ISO Open System Interconnection Basic Reference Model [1]. This system combines the advantages of having only a thin layer of software between application programs and the hardware, with the functionality offered by general operating systems.

Local area networks: Local area networks — An interconnection of computers and peripherals in adjacent rooms or buildings — Can provide cost-effective communications

Local area networks are defined, and the operation of ring, bus, and star networks is described and compared. The ISO Open System Interconnection Model is also described.

Software for interactive on-line conferences

A layered architecture for the implementation of real-time conferences is presented. In a real-time conference a group of users each at his or her own workstation, share identical views of on-line application information. The users cooperate in a problem solving task by interactively modifying or editing the shared view or the underlying information, and can use a voice communication channel for discussion and negotiation. The lower layer in this architecture, named Ensemble, supports the sharing of arbitrary application-defined objects among the participants of a conference, and the manipulation of these objects via one or more application-defined groups of commands called activities. Ensemble provides generic facilities for sharing objects and activities, and for dynamically adding and removing participants in a conference; these can be used in constructing real-time conferencing systems for many different applications. An example is presented of how the Ensemble functions can be used to implement a shared bitmap with independent participant cursors. The relation between this layered architecture and the ISO Open Systems Interconnection reference model is discussed. In particular, it is argued that Ensemble represents a plausible first step toward a Session-layer protocol for “multi-endpoint connections”, a neglected area of communication protocol development.

A Broadband Accelerator Control Network

A broadband data communications network has been implemented at BNL for control of the Alternating Gradient Synchrotron (AGS) proton accelerator, using commercial CATV hardware, dual coaxial cables as the communications medium, and spanning 2.0 km. A 4 MHz bandwidth Digital Control Channel using CSMA-CA protocol is provided for digital data transmission, with 8 access nodes available over the length of the RELWAY. Each node consists of an rf modem and a microprocessor-based store-and-forward message handler which interfaces the RELWAY to a branch line implemented in GPIB. A gateway to the RELWAY control channel for the (preexisting) AGS Computerized Accelerator Operating System has been constructed using an LSI-11/23 microprocessor as a device in a GPIB branch line. A multilayer communications protocol has been defined for the Digital Control Channel, based on the ISO Open Systems Interconnect layered model, and a RELWAY Device Language defined as the required universal language for device control on this channel.

Experiences with a Layered Approach to Local Area Network Design

The Nestar Plan 4000 network was designed using the ISO Open Systems Interconnection model. The Xerox Network Systems Internet Transport Protocols (XNS) were chosen for the network and transport layers, a token-passing protocol (Arcnet) for the physical and datalink layers, and existing Nestar server software for the highest layers. The physical and datalink layers are supported by a VLSI chip and their implementation was straightforward. In spite of their detailed specification, implementing the network and transport layers presented some unanticipated challenges. This paper discusses details of our experience in implementing the network with emphasis on the problems encountered and how they were solved.