The Ultimate Web: Preparing for the Next Generation of the WWW

1

The Ultimate Web:Preparing for the Next Generation

of the WWW

Jim CarpenterBureau of Labor Statistics

November 1999

Draft: 04/20/23 03:33 PM

2

Objectives

• Describe the Ultimate Vision of the Web

• Describe its key technologies and standards

• Suggest how data managers can prepare

3

Personal Objectives

• Promote more data modeling– Resistant Culture: process oriented– The other category of physical-independent-thing:

object– Basic duality of knowledge representation:

• an individual physical thing is both object and process

• the difference is scope of time in the context of the thing

(see Knowledge Representation by John Sowa, p. 71 ff.)

• Promote ISO Metadata Standards– A key part of the semantic revolution

4

Outline

• Some basic ideas about UML and Modeling• Understanding information resource webs • Semantic web• Conclusion: focus on your own metadata

5

UML in a Nutshell

• UML contains a fixed set of elements (approx. 100)

• Each element has – Concept– Term– Syntax role– Graphic representation

• Elements are grouped into 9 types of diagrams

• Diagrams can describe anything - a metalanguage

6

Some Basic Ideas• A model is a set of concepts with notation and

syntax

• Types of models– human language programming language– scientific language protocol, format– architectural design template– computer system music, dance, DNA, atom, ...

• There is a map between any two models– not necessarily 1-1 or onto (remember set theory?)

• Work is the process of mapping models

7

Work Examplestranslating models

• Lecturing Speaker Listener

• Writing a book Writer Word Processor

• Building a house Owner Architect Contractor Craftsman House

• Building a system Owner Analyst Designer Programmer System

A house and a system as models!Remember, Zachman describes the system as the “ultimate model”

8

Understanding Webs

9

Example: The Web of Pages• Type of resource on WWW Server: WWW Page

– the Web as a big (virtual) book

• Unique Resource Locator= machine name + page name [page is the only addressable item]

• Resource Language: HTML– for displaying pages– for linking pages in a web topology

• Resource Language Interpreter: WWW browser

• Protocol: HTTP– Simple communication language

See Weaving the Web by Tim Berners-Lee

10

Definitions - a starting point

• A web is an information resource network which – exchanges a single type of resource described in a

single language between computer processes, and – provides for arbitrarily linking these resources.

• An information resource network is a set of distributed computer processes which transfer information resources over packet sessions.

11

Some True Statements• A computer contains at least one process

• An information resource is exchanged between processes

• An information resource is carried in packets

• Packets travel in a session

• A session is established between processes

Translates to UML...

• • •

12

Computer contains processSentence:

Computer

Process

contains

Class

Association

Class

Note: “contains” is one of many types of this “whole-part” associationrepresented by the symbol at right.See Haim Kilov’s book for a hierarchical breakdown of subtypes.

Noun Verb Noun

13

Computer contains processSentence:

content

container Role

Role

Computer has role of container of process.Process has role of content of computer.

0..*

1..*

MultiplicityConstraints

A computer must contain one or more processes.A process can be the content of zero or more computers.

Computer

Process

14

A Process ID uniquely identifies a process in a computer.

A process has control logic which governs the execution of sentences which operate on local resources (resources within its address space).

Process

Process IDSentencesControl LogicLocal Resources

15

Continuing to translate from English to UML

in this fashion yields a general data model

(graphic representation of a web of sentences)for

Information Resource Networks

and Webs ...

16Information Resource NetworkComputer

Process


initiator

grantor

container

contentssupplier

user

Resource Exchange

Session

Session ID ASession ID B

Packet

Sequence No.convoy

vehicle

Resource

Content

vehicle

load

0..*1..*

Protocol

enactment

rules

content

format

expression

language

0..*1..*

17Generalized Web of Information ResourcesComputer

Process


interpreter

source

initiator

grantor

container

contents

Session


Protocol

enactment

rules

Packet

Sequence No.convoy vehicle

content

format

Resource Language

ConceptsNotationSyntaxLink Mechanism

Univ. Res. Exchange Universal Resource

U.R. Locator IDContent

vehicle

loadexpression

means

0..* 10..* 1

18

Computer

Process


interpreter

source

initiator

grantor

container

contents

Session


Protocol

enactment

rules

Packet

Sequence No.convoy vehicle

content

format

Resource Language

ConceptsNotationSyntaxLink Mechanism

Univ. Res. Exchange Universal Resource

U.R. Locator IDContent

vehicle

loadexpression

means

0..* 10..* 1

Generalized Web - distinguishing features

19


• Resource: Internet Name Information in DNS– UR Locator: [email protected]

– Resource Language: Schema of DNS protocol• Resource linkage topology: none

– Interpreter: DNS client interprets DNS protocol

– Protocol: DNS

• Resource: Email Message over SMTP– UR Locator: none (message ID is not a Locator)

– Resource Language: 822 & MIME for describing email parts• linkage topology: none (no locator)

– Interpreter: Mail client interprets 822 & MIME

– Protocol: SMTP & POP; 822 & MIME

20


• Resource: File on FTP Server– UR Locator: ftp://machine/directory path

– Resource Language: Schema of FTP Protocol• Linkage topology: directory tree structure

– Interpreter: FTP client (part of WWW browser)

– Protocol: FTP

• Resource: Entry in LDAP Directory– UR Locator: ldap://host/object

– Resource Language: Schema of LDAP Protocol• Linkage topology: tree structure (can use aliases for web structure)

– Interpreter: LDAP client (new part of WWW browsers)

– Protocol: LDAP

21

Information Resource Networks(summary)

• Page WWW file web

• File FTP file tree

• Name Information DNS database none

• Email message SMTP database none• Directory Entry LDAP database tree

(web?)

• Component DCOM or CORBA either web

• Database Entry SQL & RPC database none

ResourceResource Link

TopologyContext

UsualStorage

Type

Every resource could be converted to webto achieve a new dimension of power...

22

Web of Semantics web of database entries

Database Entry:•Schema•Data Item

Note: corresponds to the 2 parts of SQL: DDL = Data Definition LanguageDML = Data Manipulation Language

23

Web of Semantics-a web of database entries

• Types of Resource in web: model & data schema = model = metadata = data about data

• Universal Resource Locator= machine name + page name + tag name

• Resource Language: XML & DTD

– (extends & coexists with HTML) – link topology: web

• Interpreter: XML application on WWW browser

• Protocol: HTTP

24

Extend WWW Infrastructure• Models & Data Items on web page

• XML (eXtensible Markup Language) – describes data items in the terms of the model– locates each data item

• Absolute address

• Relative address in sequence of data items

– provides parsing instructions

• DTD (Document Type Definition)– describes the model of the data– locates each model element– provides processing instructions for XML statements

25

Selling Your Car on Your WebFirst Attempt: HTML

<HTML><BODY> Car For Sale. Chevy 1965 Impala $5000 email me at [email protected]</BODY></HTML>

How will search engines classify this page?How will people find it?

26

Selling Your Car on Your WebUse “well-known” XML tags ???

<Car> <Make> Chevrolet </Make> <Year> 1965 </Year> <Model> Impala </Model> <Price> 5000 </Price> <Email> [email protected] </Email></Car>

27

Posting a Model

DTD Sentence

<!ELEMENT Car (Make, Year, Model, Price, Email) >

Note: there are other key parameters of !Element which control how the XML tag data are processed.

28

DTD LanguageDocument Type Definition

• <!ELEMENT ElementName (content-model) >– defines an element and what it may contain

• <!ATTLIST ElementName AttribName AttribValueInfo >– Defines one or more attributes for the given element, including

the kind of content that the attribute value may take and default specifications to use in the event no value is provided by the author

• <!ENTITY % EntName parmlist >– Defines macro like things for use in XML or DTD

• <!NOTATION NotationName SYSTEM ProgramURL >– Defines a notation and the location of an external program which

can handle content of this media type

29

Essence of DTD

A language for writing your own XML markup language

A Modeling Language

30

•USE XMI :•a language that can model them both•allows mapping common elements

•The model is called the MOF Model•The facility is called MOF (Meta Object Facility)

DTD Elements Can Be Mapped to UML Elements

So, you can make your models in UML… and translate them into DTD

31

Managing the DTD’sthrough Meta-Model Consortiums

• Trust

• Repositories

• Registries

• Software Assets

• Data Warehouses

• Development Tools

• Electronic Commerce

• Data Elements – ISO Metadata Standards

32

Progress & Participation

• XMI Concept to Standard to Implementation – 7/98 Initial submissions– 11/98 XMI Interoperability Demo– 1/99 OMG technology adoption begins– 3/9 Initial implementations arrive– 3/23 Collaboration begun between OMG & MDC

• ISO Metadata Standards– Principles for managing shareable data– ANSI’s X3.285 has UML model which was

successfully translated by XMI MOF into DTD

33

Suggestions

• Do Conceptual Modeling of you business terms– The natural language model before the database

model

• Implement X3.285 (based on ISO 11179 principles)

– Managing your metadata

In another presentation, I’ll discuss the critical incompletenessof XML/DTD and how ISO 11179 can addresses it.

34

References, organizations• OMG = Object Management Group

– http://www.omg.org/

• MDC = MetaData Coalition– http://www.mdcinfo.com/

• ISO/IEC JTC1 SC32 WG2 (Metadata Committee) with ANSI NCITS/L8 as the US tech. Advisory– http://pueblo.lbl.gov/~olken/X3L8/

• THE ISO/IEC 11179 METADATA REGISTRY IMPLEMENTATION COALITION– http://www.sdct.itl.nist.gov/~ftp/l8/other/coalition/Coalition.htm

35

References, books• Just XML by John E. Simpson, Prentice Hall, 1999

– Entertaining but verbose.

• SQL : The Complete Reference by James R. Groff & Paul N. Weinberg, McGraw-Hill, 1999– Complete coverage of MS SQL Server 7, Oracle8,

IMB DB2, Informix, Sybase with all of their software on CD

• Internetworking with TCP/IP Vol. I: Principles, Protocols and Architecture by Douglas Comer, 3rd ed., Prentice Hall, 1995– clear, readable, good coverage

36

References, books

• Knowledge Representation: Logical, Philosophical, and Computational Foundations, by John Sowa, Brooks/Cole Pub. Co., 1999– Well structured presentation of the key components of

knowledge representation, from Aristotle through contemporary thinkers in artificial intelligence.

The Ultimate Web: Preparing for the Next Generation of the WWW

Documents

Transcript of The Ultimate Web: Preparing for the Next Generation of the WWW