The RACE Open Services Architecture project - the Research and Development in Advanced Communications in Europe program's open architecture for integrated broadband communications services project - Technical

IBM Systems Journal,  Dec, 1992  by Abimbola O. Oshisanwo,  Martin D. Chapman,  Malcolm Key,  Alvin P. Mullery,  Jacques Saint-Blancat

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The specification and Implementation of current telecommunication services tend to be intimately bound to a specific network architecture. Moreover, within the eervlce software, interactions between the logical modules are not always explicit, accessible, or uniform, and tend to be optimized for a particular eervice. This is exemplified by the difficulty experienced in Integrating equipment from multiple vendors, and has resulted in telecommunicatlon systems that cannot rapidly exploit the advantages of new technology or respond to changing customer requirements. In addition, current telecommunication service a tend not to be viewed as an Integral whole, whereby user, control, and management aspects of a service are develoned independently from one another. Separate development can lead to problems of inconsistency if shared data are not updated correctly. The RACE Open Services Architecture (ROSA) project was established to address these problems. This paper presents an overview of the approach taken' In the' ROSA project.

The objective of the RACE[1] Open SeNices Architecture (ROSA) project is the definition of an open architecture for integrated broadband communications (IBC) senaces.

To understand the need for an open service architecture, it is necessary to examine the current situation in telecommunication networks and services. Today's telecommunication networks are not flexible with respect to changes in service requirements or to the introduction of new serices because of a number of factors, including:

* The lack of a network-wide architecture and thus the coexistence of node-bound architectures

* The limited capability for interworking between services

* The close coupling between service management and network management

* The complexity of the interworking of subnetworks based on different architectures

All of these factors make the introduction of service or its modification complex and expensive because of the redesign that is necessarily involved.

For example, the Intelligent Network (IN)2 platform is a means by which network operators provide advanced telephony services such as FreePhone and premium rate telephony. The IN platform is overlaid on the basic network architecture, extending the architecture for those serices that require the added IN functionality. While the basic principles and architecture of IN are being standardized, a number of vendors are offering platforms that have very limited interworking. As a result, it is currently not possible to construct a service out of components from the IN platforms of different vendors.

In the view of both the standardization bodies and relevant RACE functional specification projects, integrated broadband communication networks (IBCN) should support an extremely wide range of services. This view is supported by the adoption of asynchronous transfer mode (ATM), a flexible and service-independent transfer technique, as the future standard for the transport infrastructure. To support this view in the higher layers of the network, a service-independent organization of functions should be pursued as far as possible to achieve the maximum flexibility with respect to service evolution during the lifetime of the mc system.

Within the above perspective, ROSA aims at providing an architecture for the specification, design, and implementation of "open" services. Such an architecture must support the smooth introduction of new services, the graceful evolution of existing services, interworking between existing and new services, and an increased independence of the architecture and services from new and evolving network technologies.

This paper describes ROSA, the principles on which it is based, and the service specification methodology that has been developed for effective use of the architecture components. The paper is based on the results reported in the ROSA deliverables. 3-7 Although the ROSA project ends in December 1992, the definition of the ROSA architecture is being continued in a companion RACE project called CASSIOPEIA.8

The scope of the ROSA project

The terms open, service, and architecture are now defined with the aim of characterizing the objectives, the field of applicability, and the meaning of the ROSA architecture. 4

Open. The IBC environment will have to meet the need for rapid changes in software, equipment, and network structures due to advances in technology and to an ever-increasing demand for new types of services by users and operators. An open system of services is one in which such changes can be executed in the most efficient and costeffective manner. Such flexibility can only be achieved by creating a system in which:

Introduction of new services will be significantly faster than current techniques allow and will have a minimal impact on existing services. Elements of existing service specifications will be easy to reuse in new designs. Any change in implementation technology will not impact the existing services, provided that it is performed by respecting some predefined criteria. Interaction between services will be easier to identify and define than it is today. Service and network management will be treated in a way that is compatible with the principles laid down by the Telecommunications Management Network (TMN). 9