Development and Implementation of a Service Access Concept

Table of Contents

1 Introduction

1.1 Topic

1.2 Content

1.3 How to Read This Paper

2 General

2.1 Introducing Reflections

2.1.1 A Possible Scenario

2.1.2 Ad Hoc Networking

2.1.3 State of the Art

2.1.4 Future Situation

2.1.5 Reflections About Service Discovery, Description and Access

2.2 The Problem of automated Interaction

2.3 Use Cases

2.3.1 Service Discovery

2.3.2 Service Access

2.4 URLs/URIs/URNs, Namespaces

2.4.1 URI

2.4.2 URL

2.4.3 URN

2.4.4 Comparison URN - URL

2.5 Overview of the Different Techniques

2.5.1 SLPv2

2.5.2 UPnP

2.5.3 Jini

2.5.4 Salutation

2.5.5 JetSend

2.5.6 Inferno

2.5.7 SDP (Bluetooth)

3 Service Description

3.1 SLPv2

3.1.1 The Service-URL, Accessing SLP

3.1.2 Abstract Service Types

3.1.3 Definition of Attributes

3.1.4 Mandatory Attributes

3.1.5 Registration and Standardization of New Service Types

3.1.6 Explanatory Example

3.2 UPnP

3.2.1 Device Description

3.2.2 Service Description

3.2.3 Template Design Process

3.2.4 Example

3.3 Jini

3.3.1 Service Architecture

3.3.2 Remarks

3.3.3 Description

3.4 Salutation

3.4.1 Architecture

3.4.2 Service Description/Capability Exchange

3.4.3 Functional Unit Description

3.4.4 Attribute Description

3.4.5 Description Format

3.5 JetSend

3.6 Inferno

3.7 SDP (Bluetooth)

3.7.1 Structure

3.7.2 Discovery

3.7.3 Service Record

3.7.4 UUIDs

3.7.5 Data Elements

3.7.6 Universal Attributes

4 Service Access

4.1 SLPv2

4.2 UPnP

4.2.1 Control

4.2.2 Example for Control: Action:Invoke

4.2.3 Eventing

4.2.4 Example for an Event:Notify

4.2.5 Security

4.2.6 Summary

4.3 Jini

4.3.1 Considerations

4.3.2 Features

4.3.3 Security

4.3.4 Implementation Example

4.4 Salutation

4.4.1 Open Service

4.4.2 Transfer Data

4.4.3 Close Service

4.4.4 Summary of RPC Calls of the SLM-API

4.4.5 Salutation Architecture

4.5 JetSend

4.6 Inferno

4.6.1 General

4.6.2 External Environment

4.6.3 Styx

4.6.4 Security

4.7 SDP (Bluetooth)

5 Comparison of the Different Protocols

5.1 Features

5.2 (Dis)Advantages of the Protocols

5.2.1 SLPv2

5.2.2 UPnP

5.2.3 Jini

5.2.4 Salutation

5.2.5 JetSend

5.2.6 Inferno

5.2.7 SDP (Bluetooth)

6 Implementation of the SAP Project

6.1 Overview

6.1.1 Motivation

6.1.2 Features

6.1.3 Used Technologies

6.2 SAP Protocol Specification

6.2.1 Common Topics

6.2.2 Answer Message

6.2.3 Features and Limitations

6.2.4 The Tags

6.3 Architecture

6.3.1 External Architecture

6.3.2 Internal Architecture

6.4 Integration with Service Discovery

6.4.1 Common Integration Topics

6.4.2 SLP Integration

7 Conclusions and Outlook

7.1 Conclusions

7.2 Further Development

B Userguide

B.1 User Guide

B.2 General

B.3 Compiling

B.3.1 Compiling the Java Sources

B.3.2 Compiling the C Client

B.3.3 Creating the Documentation

B.4 Running

B.4.1 Easy Approach

B.4.2 Manual Approach

B.5 Usage

B.5.1 Serverside Programs

B.5.2 Clientside Programs

B.6 Usage in External Software

B.7 Module Programming

B.7.1 Modules Written in Java

B.7.2 Modules in Other Languages

B.7.3 Binding Modules to the SAS

B.8 Examples

B.8.1 Addierer

B.8.2 Print

B.8.3 Parport

Objectives and Topics

This thesis investigates technologies for automated service discovery and access in network-centric computing environments, addressing the challenges of heterogeneous systems and proprietary interfaces. The research focuses on designing and implementing a middleware-based Service Access Protocol (SAP) to enable seamless, scalable, and modular access to diverse network services without requiring complex manual configuration.

• Analysis and comparison of existing service discovery and access protocols (e.g., SLP, UPnP, Jini, Salutation).
• Exploration of service description methodologies and templates for cross-platform interoperability.
• Development of the Service Access Protocol (SAP) architecture and its server-side implementation in Java.
• Evaluation of middleware approaches for translating between common protocols and native device-specific interfaces.
• Creation of a documentation framework for protocol specification and software deployment.

Excerpt from the Book

Summary of Chapters

1 Introduction: Provides the context of network-centric computing, defines the scope of service discovery and access, and outlines the thesis structure.

2 General: Discusses the theoretical framework, including service discovery concepts, use cases, and URI/URL/URN naming schemes.

3 Service Description: Details the methodologies and templates used by various protocols, such as SLPv2, UPnP, Jini, and Bluetooth, to describe service capabilities.

4 Service Access: Examines techniques for interacting with services, focusing on control and eventing mechanisms across different network protocols.

5 Comparison of the Different Protocols: Compares the features, advantages, and disadvantages of the discussed protocols, providing a foundation for selecting appropriate solutions.

6 Implementation of the SAP Project: Describes the design, architecture, and implementation of the custom Service Access Protocol (SAP) and its Java-based server environment.

7 Conclusions and Outlook: Reflects on the future of automated device interaction and suggests potential improvements for the SAP project, such as enhanced event mechanisms.

Keywords

Service Discovery, Service Access, Service Description, Network-Centric Computing, UPnP, SLPv2, Jini, Salutation, Bluetooth, SAP, Middleware, Java, XML, Ad Hoc Networks, Protocol Implementation.

Frequently Asked Questions

What is the core focus of this thesis?

The thesis focuses on the challenges of automated service discovery and service access in network-centric environments, specifically proposing a middleware-based solution to bridge proprietary interface differences.

What are the primary thematic areas covered?

The work covers service description technologies, service access protocols (such as SLP, UPnP, Jini, and Salutation), protocol comparison, and the implementation of a new Service Access Protocol (SAP).

What is the main objective of the proposed SAP?

The objective of SAP is to serve as a scalable and simple middleware protocol that translates generic access requests into the native protocols required by various underlying devices.

Which scientific or technical methods are applied?

The work uses analytical methods to compare existing protocol specifications and utilizes object-oriented design and Java programming to implement the Service Access Server (SAS) and modules.

What is discussed in the main implementation chapter?

Chapter 6 details the SAP architecture, the motivation for its design, the technical features of the SAS, and the integration of services through a modular, driver-like interface.

Which keywords characterize this work?

Key terms include Service Discovery, Service Access, Middleware, SAP, UPnP, SLPv2, Jini, and Ad Hoc Networking.

How does UPnP handle service description?

UPnP uses XML-based descriptions, partitioned into a device description (containing metadata and a list of services) and individual service descriptions (containing actions, state variables, and arguments).

What role does the Service Access Server (SAS) play in the SAP architecture?

The SAS acts as a middleware entity that receives client requests via the SAP protocol, translates these into the specific commands required by target devices or services, and returns the results to the client.