Overview

From TAPAS Wiki

Contents 1 Brief Introduction 2 Project Motivation 3 Vision and missions 4 Concept 5 TAPAS architecture 6 TAPAS System Management Architecture

Brief Introduction

The TAPAS project (TAPAS = Telematics Architecture for Play-based Adaptable Systems*) is a research project which aims at developing an architecture for network-based service systems with adaptability properties that are A): flexibility and adaptability, B): robustness and survivability, and C): QoS awareness and resource control (See Adaptability Properties). The goal is to enhance the flexibility, efficiency and simplicity of system installation, deployment, operation, management and maintenance by enabling dynamic configuration of network components and network-based service functionality.

Another objective is to gain experiences and knowledge by implementing those various features, both for demonstrating the implementation possibility and for validating the feature applicability. The goal is not to develop a complete executing architecture, but is to set the various features coming from the above defined requirements in a context related to totality.

The TAPAS architecture requires a support system for software development, deployment, execution and management. Moreover, the support is also needed for generic user functionality to enable the flexibility features of the system. This support system is denoted as the TAPAS Platform. Parts of the specified support functionality have been implemented using Java RMI, socket networking, and Web Services as a means for service definition, update and discovery. The TAPAS Platform is using XML as a common representation language. It extends also the applicability of the architecture concepts to handheld devices and java-enabled mobile phones.

* The previous name of TAPAS was Telematics Architecture for Plug-and-Play System

Project Motivation

Adaptable networking means that the provided network-based services are capable of handling dynamic changes in both time and position related to resources, users and changed service requirements. Adaptability implies flexibility, and comprises features related to various aspects of the functionality of a network-based service system such as:

1. Software flexibility, Adaptability and Mobility,
2. Personal Mobility,
3. Dynamic Configuration of resources and service software, and
4. Flexibility in the Interoperability with other architectures.

Vision and missions

TAPAS vision is to develop an architecture concept for Plug-and-Play telecommunication equipment and services. This architecture concept should meet the outlined requirements on flexibility and adaptively, as well as specified requirements with respect to robustness and survivability, and QoS and resource control. One objective of the project is to demonstrate the feasibility of the basic results by trial implementations and experiments using the TAPAS platform, which is a support system for the above architecture concept.

The project will have emphasis on PhD and Master degree education and scientific results meant for publication. The ongoing topics are:

• Plug-and-Play for Telecommunication Services To define a framework for service execution and methods for service design and composition that enables services to be constructed separately and then composed dynamically using Plug-and-Play techniques. The work has been concluded and successfully presented in a dissertation for the PhD degree program.

• Adaptive Fault-Tolerance in dynamic Plug-and-Play Systems Make the dynamic Plug-and-Play system fault tolerant, where the various elements are replicated and reconfigured dynamically depending on their dependability requirements and the semantics of the function. Several publications and results have been accomplished, and results are being finalised.

• Plug-and-Play for Wireless Components To design and specify the needed functionality for the handling of TAPAS components in a wireless network with respect to the TAPAS architecture. Validation of results by implementation and experimentation in the demonstrator will be carried out. New architectural concept and components, as well as extensions to the basic architecture, have been worked out. A set of various applications and experimental results have documented and presented in papers and Master degree theses.

• Dynamic Configuration To design and implement an architecture for the dynamic (re)configuration of nodes and service components, taking into consideration the dynamic availability of nodes in the network as well as changes in their capabilities and status.

• Adaptive Service Infrastructure In a global-scale, heterogeneous network environment as the web, sevices are increasingly comples and diverse in terms of availability, capabilities, platforms and technologies. The task is to give a foundation of an infrastructure that is capable of providing a set of well-established interfaces and enables dynamic and cross-platform composition, instantiation and interoperation of heterogeneous, adaptive services regardless of their programming languages and operating environments.

Concept

TAPAS as a concept is based on the theatre metaphor, where actors perform roles according to predefined manuscripts, and a director manages their performance. Actors are software components, which represent functionality to be executed at different nodes within the network. Roles are modelled as Extended Finite State Machines. A director is an actor with supervisory status regarding all other actors’ plug-in and plug-out phases. A director also represents a domain, which is a set of nodes managed by a single director.

Accordingly, TAPAS views service systems as predefined plays that consist of manuscripts defining roles. Service components, as the constituents of service systems, will correspond to actors that execute certain functionality.

TAPAS aims at developing an architecture for network-based service systems with

• flexibility and adaptability,
• robustness and survivability, and
• QoS awareness and resource control.

The goal is to enhance the flexibility, efficiency and simplicity of system installation, deployment, operation, management and maintenance by enabling dynamic configuration of network components and network-based service functionality.

TAPAS architecture

TAPAS architecture is separated into a system management architecture and a computing architecture as follows:

• The system management architecture is an architecture showing the structure of services and services components

• The computing architecture is a generic architecture for the modelling of any service software components

TAPAS System Management Architecture

The TAPAS System Management Architecture consists of four different platforms:

• TAPAS basic architecture: (is also called the TAPAS Core Platform) is the basis for all dynamic behaviour functionality, which is based on generic actors in the nodes of the network that can download manuscripts defining roles to be played. The model is founded on a theatre metaphor, where actors perform roles according to predefined manuscripts, and a director manages their performance. The roles are modelled as Extended Finite State Machines.

• TAPAS mobility architecture: is the basis for all mobility related issues that provide flexibility in Actor, Terminal, and Personal movement. This architecture is based on the basic architecture, but is also enhancing the functionality in the basic architecture by functionality to meet the requirements A)-B) as defined in the overview.

• TAPAS dynamic configuration architecture: is the basis for the framework for dynamic configuration and reconfiguration of Plug-and-Play systems. It provides representation, computation, and reasoning mechanisms for semantic description and matching of capabilities and status information. This architecture, as the mobility architecture, is enhancing the basic architecture functionality to meet the requirements A)-B) as defined in the overview.

• TAPAS capability architecture: defines essentials functionalities of the capability management in TAPAS. The architecture propose an ontological capability model that is well-prepared in a machine understandable manner. A capability model is defined in each individual domain. However, the model can be later exchanged with the provided capability transformation functionality. This architecture employs Semantic Web and Web Services technologies to manipulate capabilities and their ontologies.

• TAPAS adaptive service architecture: handles the complexity and diversity issues of nowadays services as viewed in the global-scale, i.e. availability, capabilities, platforms and technologies, decomposition and distribution of services. The realisation of these issues demands a well-established infrastructure which provides a set of well-defined interfaces and enables dynamic and cross-platform composition, instantiation and interoperation of heterogeneous, adaptive services regardless of their programming languages and operating environments. This architecture studies such an infrastructure by adopting the emerging Semantic Web and Web services technologies.