XML-based Network Management

nervousripΑσφάλεια

5 Νοε 2013 (πριν από 3 χρόνια και 5 μήνες)

77 εμφανίσεις

XML
-
based Network Management

Hong
-
Taek Ju (
주홍택
)


Dept. of Computer Science and Engineering

Keimyung University, Daegu Korea

Tel: +82
-
53
-
580
-
5234


Email: juht@kmu.ac.kr

http://comnet.postech.ac.kr/~juht

POSTECH

DP&NM Lab.

(
2
)

XML
-
based Network Management

KNOM 2002 Tutorial

Preliminary


Expected Audience


Some knowledge

on network management.


Basic understanding of Web technology.


Graduate students, Researchers, Software Engineers.


Tutorial Scope


Introduction on XML technologies.


Focus on Internet management.


Focus on element and network, not on service and business management.


State of the art for research work and standard activities


Tutorial Objectives


Precise understanding on what is XML
-
based network management.


Concrete examples for applying XML to network management.


Future research topics on XML
-
based network management.

POSTECH

DP&NM Lab.

(
3
)

XML
-
based Network Management

KNOM 2002 Tutorial

Contents

1.
Introduction

2.
What is XML?

3.
Applicability of XML

4.
State of the Art for XML
-
based Network
Management

5.
Closing Remarks

POSTECH

DP&NM Lab.

(
4
)

XML
-
based Network Management

KNOM 2002 Tutorial

1. Introduction


XML is an emerging technology for Web
-
based applications
and has been in the spotlight.


XML has many advantages


Simplicity, openness, extensible, inexpensive


Most people believe that XML will succeed much more than
HTML, HTTP, Web, Java


Advantages in XML
-
based network management


Easy to learn
: not management domain specific technology


Large supporting tools and technology
: Low development cost


High compatibility with legacy management technology
: Integrated
management.


Low footprint on device
: applicable to the network devices.

POSTECH

DP&NM Lab.

(
5
)

XML
-
based Network Management

KNOM 2002 Tutorial

1. Introduction


My definition of XML
-
based Network Management:



All alternative or complimentary approaches for the
current management framework in order to solve
the problems of current network management or
improve the management environment by taking
advantages of XML technologies



POSTECH

DP&NM Lab.

(
6
)

XML
-
based Network Management

KNOM 2002 Tutorial

2.
XML: What is XML?


What does


XML” stands for?


eXtensible
: not a fixed format, customizable.


Markup
: used to define things.


Language
: used to communicate or describe and encapsulate its
information and pass it.


XML was designed to describe data.


Document Type Definition

(DTD) or
XML Schema

is used.


XML is self
-
descriptive.


XML is free and extensible.


XML allows the author to define his own tags.


XML is a compliment to HTML.


XML will be used for describing data and HTML for displaying same data.


XML is a future Web technology.


Quick standard process, large support by vendor.


Common tool for all data manipulation and data transmission.

POSTECH

DP&NM Lab.

(
7
)

XML
-
based Network Management

KNOM 2002 Tutorial

2. XML: Technology Map

XML

Program

Scripts

Database

Editor(file)

Input

Generate

DTD, XML Schema

Define

Validate

DOM

Dump

Parse

Program

Process

WAP, XHTML

Standard

XSL

XSLT

XPath

Input

Web

Brower

Input

SOAP

Remote

System

Exchange

Input

POSTECH

DP&NM Lab.

(
8
)

XML
-
based Network Management

KNOM 2002 Tutorial

3. Applicability of XML


Basic management tasks


Management Information
Modeling
.


Description framework for managed resource to managed object.


Management Information
Realization
.


Guarantees of consistency between managed resource and managed
object.


Management Information
Distribution
.


Exchange of management information between management
applications.


Management Information
Analysis
.


Process of management information production from collected
information.


Management Information
Presentation
.


User interface for display management information or taking
management command from operators.

POSTECH

DP&NM Lab.

(
9
)

XML
-
based Network Management

KNOM 2002 Tutorial

3. Basic Management Tasks

Modeling

Realization

Distribution

Analysis

Presentation

Agent

Manager

POSTECH

DP&NM Lab.

(
10
)

XML
-
based Network Management

KNOM 2002 Tutorial

3. Management Information Modeling


Standard Information model






XML Schema

for management information modeling


Advantages


Easy to learn, not domain specific technology.


Use of powerful and convenient graphical XML editor.


Modeling result is concise and easy to read.


Secondary benefits


validation, sample data generation.


Disadvantage


No standard models, but easy to translate from standard information models.

SNMP

TMN

DMTF

XML

Tool

SMI

GDMO

CIM

XML Schema

Models

MIB
-
II

G.721

CIM v.6

No standard yet

Approach

Object
-
based

Object
-
oriented

Object
-
oriented

Object
-
oriented

POSTECH

DP&NM Lab.

(
11
)

XML
-
based Network Management

KNOM 2002 Tutorial

3. Management Information Realization


Standard management frameworks leave it completely
unspecified
-

viewed as a “local matter”.


Model specification serves as a starting point for the coding of
the agents.


For Web interface and CLI, the model specification was not provided.


For SNMP, MIB compilers have been used to generate MIB stubs.


The stubs are supplemented with the code for actual access to resources.


There is no common interface or data format between managed
resource and management agents such as CLI, SNMP, Web.


Large development cost and footprint.


Consistency problem by multiple access to single managed resource.


XML for management information realization


XML can be used for middleware between agents and managed resources.


Low footprint solution.


Various method can be used for XML generation.

POSTECH

DP&NM Lab.

(
12
)

XML
-
based Network Management

KNOM 2002 Tutorial

3. Management information distribution


Communication between management applications


Agent


Manger, Manager


Manager


Standard management communications








North bound interface is usually based on CORBA.


XML and CORBA are interoperable technologies.


XML does not say anything about communication protocol,
Implicitly HTTP is used.


Reliable, efficient by compression, highly secure, high connectivity.


Flexible by use of SOAP.

SNMP

TMN

DMTF

XML

Protocol

SNMP/UDP

CMIP

Operations/HTTP

SOAP or HTTP

Operation

Get, Set,

GetNext,
Response

M
-
Get, M
-
Set , M
-
Create, M
-
Delete,
M
-
Action

GetInstance,
SetInstance, GetClass,
etc. (23 Operations)

Unspecified

Notification

Trap

M
-
Event_Report

Unspecified

Unspecified

Encoding

ASN.1

ASN.1

XML

XML

POSTECH

DP&NM Lab.

(
13
)

XML
-
based Network Management

KNOM 2002 Tutorial

3. Management Information Analysis


This has not been standardized and based on data processing
such as sorting, filtering, logging and correlating.


Management platforms

provide basic management
functionality and development environment.


Their price is usually very expensive.


Customization requires large amount of time and effort.


In most cases, they do not depend on standard technology.


Recently,
CORBA

has been used widely as an implementation
platform for management systems.


XML for management information analysis.


XML is a standard data processing tool.


Many supporting tools (such as database) are available.


Lots of developers having XML knowledge.

POSTECH

DP&NM Lab.

(
14
)

XML
-
based Network Management

KNOM 2002 Tutorial

3. Management Information Presentation


This allows user interactive access to the management system.







+
:

Include telnet connection.


#: MS
-
Windows or X
-
Windows


*: Without use of XML techno
logies.


XML for management information presentation


Separation with display and data in Web environment.


Platform independent standard display technology.


Device dependant display support.


Ubiquitous management user interface.


User
-
friendly graphic interface.

Text
+

Windows
#

Web
*

XML

Ubiquity

Best

Bad

Good

Good

Interactivity

Bad

Best

Good

Good

Development cost

Low

High

Middle

Low

User
-
friendliness

Worst

Good

Best

Best

POSTECH

DP&NM Lab.

(
15
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. State of the Art for XML
-
based NM


Research work


Complimentary approaches to SNMP


eXtensible Network and Application

Management Instrumentation.


SNMP to XML translator


XML/SNMP Gateway


Improvement approaches to Web
-
based network management


Direct Web Interface for Device Configuration


XML
-
based Device Configuration


New Management Architectures


XML
-
based Service Configuration


Web
-
based Integrated Management Architecture


XML
-
based Network Management Architecture


Standard Activities


Web Based Enterprise Management (WBEM)

POSTECH

DP&NM Lab.

(
16
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. XNAMI


eXtensible Network and Application Management
Instrumentation (XNAMI)


A. John, et al., Bell Labs, 1999


A method for dynamic MIB expansion.


XML is used for information modeling.

1. GetRequest (x.y.z)

2. GetResponse (no such object)

3. SetRequest (
XML Definition

and Java Code for x.y.z)

4. GetResponse ( ok )

5. GetRequest (x.y.z)

6. GetResponse ( value of x.y.z )

7. GetRequest (OID for x.y.z definition)

8. GetResponse (
XML Definition

of x.y.z )

9. SetRequest (Delete x.y.z)

10. GetResponse ( ok )

POSTECH

DP&NM Lab.

(
17
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. SNMP to XML Translator (1)


Automatic translation from SNMP MIB definition to XML.


Model
-
level mapping & Metamodel
-
level mapping.


J.P. Martin
-
Flatin, EPFL, Aug. 2000


Gave only idea and examples for the two approaches


The two approaches were implemented in
libsmi

package.


But there was no validation or application for the approaches.


SNMP MIB to XML Schema mapping


J. H. Yoon, DPNM Lab., POSTECH, Oct. 2001


Formalized the two approaches into a
concrete algorithm
.


Reduced information loss in the translation process by taking
advantages of XML Schema.


Validated its completeness by developing a simple SNMP MIB browser
based on XML.

POSTECH

DP&NM Lab.

(
18
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. SNMP to XML Translator (2)


Model
-
level mapping


SNMP MIB to DTD/XML Schema and XML documents

ifTable

OBJECT
-
TYPE


SYNTAX SEQUENCE OF
IfEntry

::= { interfaces 2 }

ifEntry

OBJECT
-
TYPE


SYNTAX IfEntry


::= { ifTable 1 }

IfEntry ::=


SEQUENCE {


ifSpeed

Gauge32

}

ifSpeed

OBJECT
-
TYPE


SYNTAX Gauge32


::= { ifEntry 5 }

<
ifTable>


<ifEntry>


<ifSpeed>


</ifSpeed>


</ifEntry>

<ifTable>

<!ELEMENT
ifTable

ifEntry
* >

<!ELEMENT
ifEntry

ifSpeed

>

<!ELEMENT
ifSpeed

(#PCDATA) >

SNMP MIB

XML DTD

XML Document

POSTECH

DP&NM Lab.

(
19
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. SNMP to XML Translator (3)

<
table name=“
ifTable
”>


<column name=“
ifEntry
”>


<scalar name=“
ifSpeed
”>


</scalar>


</column>

</table>

<!ELEMENT table column* >

<!ATTRIBUTE table name CDATA >

<!ELEMENT column scalar+>

<!ATTRIBUTE column name CDATA>

<!ELEMENT scalar (#PCDATA)>

<!ATTRIBUTE scalar name CDATA>


Metamodel
-
level mapping


SNMP MIB to XML documents


ifTable

OBJECT
-
TYPE


SYNTAX SEQUENCE OF
IfEntry

::= { interfaces 2 }

ifEntry

OBJECT
-
TYPE


SYNTAX IfEntry


::= { ifTable 1 }

IfEntry ::=


SEQUENCE {


ifSpeed

Gauge32

}

ifSpeed

OBJECT
-
TYPE


SYNTAX Gauge32


::= { ifEntry 5 }

SNMP MIB

XML DTD

XML Document

POSTECH

DP&NM Lab.

(
20
)

XML
-
based Network Management

KNOM 2002 Tutorial


Applications of SNMP to XML translator

1.
Encoding SNMP MIB data



2. Information analysis or presentation for SNMP MIB data




3. Specification translation for SNMP to XML gateway

4. SNMP to XML Translator (4)

XML/HTTP

SNMP

SNMP

GW

XML

SNMP
Agent

Web
Server

POSTECH

DP&NM Lab.

(
21
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. XML/SNMP Gateway


What is XML/SNMP Gateway?


Relays management information and operations

between SNMP
agent and XML
-
based manager system.


While preserving the
legacy SNMP agent
, one can develop
XML
-
based
manager

by using XML technology.


Two basic requirements for the gateway


Specification translation
: SNMP MIB


XML


For understanding the management information exported by SNMP agent.


Interaction translation
: SNMP Operations


XML Operations


For supporting interaction between two management applications


XML/SNMP Gateway


Y. J. Oh, DPNM Lab., POSTECH, May 2002


For specification translation, Yoon’s SNMP to XML translator is used .


For interaction translation


XML does not specify the standard communication protocol.


Proposed three levels of interaction translation methods:
Process, Message,
Protocol

POSTECH

DP&NM Lab.

(
22
)

XML
-
based Network Management

KNOM 2002 Tutorial

SNMP Agent

XML
-
based Manager

SNMP Stack

XML/SNMP

Gateway

DOM

HTTP Server

SNMP Request

SNMP Response


HTTP Request
& Reponse

Trap Receiver

XPath Handler

XSL

Generator

MIB to XML

Translator

SNMP Trap

DOM

value

Target node

Trap node

Direct Call of
DOM Interface

Request Parser

SOAP Server

SOAP Request
& Reponse

4. XML/SNMP Gateway Architecture

HTTP

Client

DOM Event

Notification

DOM Interface Call

POSTECH

DP&NM Lab.

(
23
)

XML
-
based Network Management

KNOM 2002 Tutorial


Traditional Approach




Result of embedding small Web server into network device.


Ubiquitous, simple but powerful, user
-
friendly device management user
interface.


XML Approach (EmWeb XML parser)





XML generation by program is enough small solution to be embedded.


Separate display format and data generation.


XML parser can save development cost by generating backend stub
code based on XML schema.

4. Direct Web Interface to Managed Devices

Embedded
Web Server

HTML or Java / HTTP

Embedded
Web Server

XML & XSL / HTTP

POSTECH

DP&NM Lab.

(
24
)

XML
-
based Network Management

KNOM 2002 Tutorial


Today’s configuration management.


SNMP is hardly used.


Weak in information modeling power


Action in side effect, simple MIB structure, etc,


The CLI and direct Web interface are mostly used.


Proprietary:


Different from vendor to vendor, product to product, release to release.


Disadvantage in scalability.


XML
-
based device configuration


From Juniper Networks JUNOScripts


and Cisco Configuration Register


Proprietary


But scalable


And extensible

4. XML
-
based Device Configuration

XML RPC


<SetConfiguration><bgp>

<port>10.0.0.1</port>

<neighbor> 10.0.0.2</neighbor>

</bgp></SetConfiguration>


POSTECH

DP&NM Lab.

(
25
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. XML
-
based Application Management


C. Ensel & A. Keller, IBM Research, May 2001


Apply
XML, Xpath and RDF

to describe, query and
compute the
service

dependencies
, respectively.


RDF (Resource Description Framework)


A general framework for how to describe any Internet resource such
as a Web site and its content.


XML is used for describing the resources.

e
-
business application

Customer database

e
-
business application

Service Dependency

e
-
business application

Service dependency

RDF description

RDF Schema

Xpath

Query

POSTECH

DP&NM Lab.

(
26
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. WIMA


Web
-
based Integrated Management Architecture (WIMA).


J.P. Martin
-
Flatin, Ph.D Thesis, EPFL, Aug. 2000.


HTTP
-
based management communication model.


Dissociation of communication and information model


URL encoding of management operation.


Specifying information model and encoding in the MIME header.


XML was suggested as one of encoding format.


For notification delivery, reverse the HTTP client and server

roles
.




manager

agent

HTTP Server

HTTP Client

http://agent.domain:280/snmpv1/mib2/get?oid=a.b.c

HTTP/1.1 200 OK

Content
-
Type:”application/mgmt”;


mapping=“SNMPv1
-
to
-
XML

<?xml version=“1.0” ?>

<data> …</data>

HTTP Client

HTTP Server

HTTP/1.1 POST /agent.domain:280/trap?oid=a.b.c

Content
-
Type:”application/mgmt”;


mapping=“SNMPv1
-
to
-
XML

<?xml version=“1.0” ?>

<data> …</data>

HTTP/1.1 200 OK



POSTECH

DP&NM Lab.

(
27
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. XNM


XML
-
based Network Management architecture (XNM)


H. T. Ju, Ph.D Thesis, POSTECH, Oct. 2001


Extended the use of EWS from direct Web user interface to Web
-
based
management agent by using standard Web and XML technologies.


Management information model


Use
XML schema

for management information model


Standard management information models does not cover a significant amount
of managed resource to be managed.


XML Schema is a widespread approach in many application areas.


Utilize the advantages of XML schema for modeling.


Management communication model


Uses HTTP for management protocol without any extension.


Uses the
XPath

standard for addressing managed objects


Standard XML technology for addressing parts of an XML document.


Effectively query the managed objects (Scoping and Filtering).


Implemented the manager and agent system based on proposed architecture.


Developed a management system for a commercial high density Linux
server clusters based on our proposed architecture.

POSTECH

DP&NM Lab.

(
28
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. WBEM Architecture


Web
-
Based Enterprise Management (WBEM) Initiative.


WBEM Architecture

Data Description

CIM

</
xmlCIM>

Transport
Encoding

CIM Ops.

HTTP

Access

POSTECH

DP&NM Lab.

(
29
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. WBEM Example

M
-
POST

/cimom HTTP/1.1

HOST: www.xyz.com

Content
-
Type: application/xml; charset="utf
-
8"

73
-
CIMOperation: MethodCall

73
-
CIMMethod:
GetClass

<?xml version="1.0" encoding="utf
-
8" ?>

<CIM CIMVERSION="2.0" DTDVERSION="2.0">


<MESSAGE ID="87872" PROTOCOLVERSION="1.0">



<SIMPLEREQ>



<IMETHODCALL NAME="
GetClass
">



<LOCALNAMESPACEPATH>



<NAMESPACE NAME="root"/>



<NAMESPACE NAME="cimv20"/>



</LOCALNAMESPACEPATH>



<IPARAMVALUE NAME="ClassName">


<CLASSNAME NAME="
Joke
"/>


</IPARAMVALUE>



</IMETHODCALL>



</SIMPLEREQ>


</MESSAGE>

</CIM>


HTTP
/1.1 200 OK

Content
-
Type: application/xml; charset="utf
-
8"

73
-
CIMOperation:
MethodResponse

<?xml version="1.0" encoding="utf
-
8" ?>

<CIM CIMVERSION="2.0" DTDVERSION="2.0">


<MESSAGE ID="87872" PROTOCOLVERSION="1.0">



<SIMPLERSP>



<IMETHODRESPONSE NAME="GetClass">



<IRETURNVALUE>



<CLASS NAME=

Joke
" SUPERCLASS="CIM_SoftwareElement">



...








</CLASS>



</IRETURNVALUE>



</IMETHODRESPONSE>



</SIMPLERSP>


</MESSAGE>

</CIM>

POSTECH

DP&NM Lab.

(
30
)

XML
-
based Network Management

KNOM 2002 Tutorial

4. WBEM


WBEM standards are being implemented now by several groups
as open source.


The WBEMsource initiative is an umbrella organization for providing
coordination between open source WBEM projects


The Open Group's Pegasus project



OpenWBEM


Sun WBEM Services


B4wbem


SNIA Open Source CIMOM


Equipment vendors and operating system suppliers begin to support WBEM.


Cisco


Microsoft


Sun


Can WBEM replace SNMP?


This was the panel topic in IM 2001, Seattle.


Panel chair: J. P. Martin
-
Flatin


Panelists: James W. K. Hong (POSTECH), Aiko Pras (U. of Twente), Jürgen
Schönwälder (U. Braunschweig), Andrea Westerinen (Cisco), Jim Davis (Sun)

POSTECH

DP&NM Lab.

(
31
)

XML
-
based Network Management

KNOM 2002 Tutorial

5. Concluding Remarks


XML provides a standard way to manage data on the
Web
-

describe, process, exchange and display data.


It has many advantages and become ubiquitous
technology.


There has been many activities for improving today’s
network management environment by taking
advantages of XML.


But not enough yet.


Also, XML is no silver bullet, it a only tool, whose
benefits lie primarily in the manner of its usage.

POSTECH

DP&NM Lab.

(
32
)

XML
-
based Network Management

KNOM 2002 Tutorial

Thank you

POSTECH

DP&NM Lab.

(
33
)

XML
-
based Network Management

KNOM 2002 Tutorial

Useful References (1)

1.
General information about XML


Recommendations



w3c XML Recommandation


Annotated, http://www.xml.com/axml/testaxml.htm


w3c XSL version 1.0 Recommendation, http://www.w3.org/TR/xsl/


w3c XSLT version 1.0 Recommendation, http://www.w3.org/TR/xslt.html


w3c XSLT version 1.1 Working Draft, http://www.w3.org/TR/xslt11/


Portal Sites



A Technical Introduction to XML


http://www.XML.com


The XML Cover Pages


Oasis, http://www.oasis
-
open.org/cover/sgml
-
xml.html


XML Portal, http://www.xmlportal.co.kr/


W3C, XML, http://www.w3c.org/xml


XMLHack
-

developer news from the XML community, http://www.xmlhack.com


Tutorials


XML Introduction
-

Database Lab. Univ. Chung Nam, Korean,
http://dblab.comeng.chungnam.ac.kr/%7Edolphin/xml/atoz/xml
-
9710/xml
-
9710.html


Java Technology & XML Tutorial, http://java.sun.com/xml/tutorial_intro.html


Tutorials XML/HTML, http://www.zvon. org/index.php?nav_id=tutorials&mime=html

2
. Web and XML
-
based Management


DPNM, POSTECH: http://dpnm.postech.ac.kr/xbm/index2.xml


WBEM, http://www.dmtf.org/wbem


EmWeb, http://www.emweb.com


Juniper, http://www.juniper.net


POSTECH

DP&NM Lab.

(
34
)

XML
-
based Network Management

KNOM 2002 Tutorial

Useful References (3)

3. Papers for XML
-
based network management


John, A.; Vanderveen, K.; Sugla, B., A Java based SNMP agent for dynamic MIBs , Global Telecommunications
Conference, 1999. GLOBECOM '99 , Volume: 1a , 1999. Page(s): 396
-
400 vol. 1a


Festor, O.; Festor, P.; Ben Youssef, N.; Andrey, L., Integration of WBEM
-
based management agents in the OSI
framework , Integrated Network Management, 1999. Distributed Management for the Networked Millennium.
Proceedings of the Sixth IFIP/IEEE International Symposium on , 1999. Page(s): 49
-
64


Imamura, T.; Maruyama, H., Mapping between ASN.1 and XML , Applications and the Internet, 2001. Proceedings.
2001 Symposium on , 2001. Page(s): 57
-
64


Tellez, J.; Meriem, T.B., Management solutions for WDM networking , Networks, 2000. (ICON 2000). Proceedings.
IEEE International Conference on , 2000. Page(s): 120
-
124


John, A.; Vanderveen, K.; Sugla, B., XNAMI
-
An extensible XML
-
based paradigm for network and application
management instrumentation , Networks, 1999. (ICON '99) Proceedings. IEEE International Conference on , 1999.
Page(s): 115
-
124


Natarajan, R.; Mathur, A.P.; McKee, P., A XML based policy
-
driven management information service , 2001 IEEE/IFIP
International Symposium on Integrated Network Management Proceedings, Seattle, May 2001, pp. 277
-
280


Lewis, D.; Mouritzsen, J.D., The role of XML in TMN evolution , 2001 IEEE/IFIP International Symposium on
Integrated Network Management Proceedings, Seattle, May 2001, pp. 689
-
702


Ensel, C.; Keller, A., Managing application service dependencies with XML and the resource description framework ,
2001 IEEE/IFIP International Symposium on Integrated Network Management Proceedings, Seattle, Mya 2001, pp. 661
-
674


Hong
-
Taek Ju, Mi
-
Jung Choi, Sehee Han, Yunjung Oh, Jeong
-
Hyuk Yoon, Hyojin Lee and James W. Hong, "An
Embedded Web Server Architecture for XML
-
Based Network Management", Proc. of the IEEE/IFIP Network
Operations and Management Symposium (NOMS 2002), Florence, Italy, April 2002, pp. 5
-
18.