Directory listing of http: uap.unnes.ac.id ebook biblebook XML Bible
XM L Bible
™
Elliotte Rusty Harold
IDG Bo o ks Wo rldwide, Inc .
An Internatio nal Data Gro up Co mpany
Fo ster City, CA ✦ Chic ago , IL ✦ Indianapo lis, IN ✦ New Yo rk, NY
XML™ Bible
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Library o f Co ngress Catalo ging-in-Public atio n Data
Haro ld, Ellio te Rusty.
XML bible / Ellio te Rusty Haro ld.
p.
c m.
ISBN 0-7645-3236-7 (alk. paper)
1. XML (Do c ument markup language) I. Title.
QA76.76.H94H34
005.7’2--dc 21
1999
99-31021
CIP
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About the Author
Ellio tte Rusty Haro ld is an internatio nally respec ted writer, pro grammer, and
educ ato r bo th o n the Internet and o ff. He go t his start by writing FAQ lists fo r the
Mac into sh newsgro ups o n Usenet, and has sinc e branc hed o ut into bo o ks, Web
sites, and newsletters. He lec tures abo ut Java and o bjec t-o riented pro gramming
at Po lytec hnic University in Bro o klyn. His Cafe c o n Lec he Web site at http://
metalab.unc.edu/xml/ has bec o me o ne o f the mo st po pular independent XML
sites o n the Internet.
Ellio tte is o riginally fro m New Orleans where he returns perio dic ally in searc h o f
a dec ent bo wl o f gumbo . Ho wever, he c urrently resides in the Pro spec t Heights
neighbo rho o d o f Bro o klyn with his wife Beth and c ats Charm (named after the
quark) and Marjo rie (named after his mo ther-in-law). When no t writing bo o ks, he
enjo ys wo rking o n genealo gy, mathematic s, and quantum mec hanic s. His previo us
bo o ks inc lude The Java De ve lo pe r’s Re so urce , Java Ne two rk Pro gramming, Java
Se cre ts, JavaBe ans, XML: Exte nsible Markup Language , and Java I/O .
Fo r Ma, a gre at grandmo the r
Preface
Welc o me to the XML Bible . After reading this bo o k I ho pe yo u’ll agree with me that
XML is the mo st exc iting develo pment o n the Internet sinc e Java, and that it makes
Web site develo pment easier, mo re pro duc tive, and mo re fun.
This bo o k is yo ur intro duc tio n to the exc iting and fast gro wing wo rld o f XML. In this
bo o k, yo u’ll learn ho w to write do c uments in XML and ho w to use style sheets to
c o nvert tho se do c uments into HTML so legac y bro wsers c an read them. Yo u’ll
also learn ho w to use do c ument type definitio ns (DTDs) to desc ribe and validate
do c uments. This will bec o me inc reasingly impo rtant as mo re and mo re bro wsers like
Mo zilla and Internet Explo rer 5.0 pro vide native suppo rt fo r XML.
About You the Reader
Unlike mo st o ther XML bo o ks o n the market, the XML Bible c o vers XML no t fro m
the perspec tive o f a so ftware develo per, but rather that o f a Web-page autho r. I
do n’t spend a lo t o f time disc ussing BNF grammars o r parsing element trees.
Instead, I sho w yo u ho w yo u c an use XML and existing to o ls to day to mo re
effic iently pro duc e attrac tive, exc iting, easy-to -use, easy-to -maintain Web sites
that keep yo ur readers c o ming bac k fo r mo re.
This bo o k is aimed direc tly at Web-site develo pers. I assume yo u want to use XML
to pro duc e Web sites that are diffic ult to impo ssible to c reate with raw HTML. Yo u’ll
be amazed to disc o ver that in c o njunc tio n with style sheets and a few free to o ls,
XML enables yo u to do things that previo usly required either c usto m so ftware
c o sting hundreds to tho usands o f do llars per develo per, o r extensive kno wledge
o f pro gramming languages like Perl. No ne o f the so ftware in this bo o k will c o st
yo u mo re than a few minutes o f do wnlo ad time. No ne o f the tric ks require any
pro gramming.
What You Need to Know
XML do es build o n HTML and the underlying infrastruc ture o f the Internet. To that
end, I will assume yo u kno w ho w to use ftp files, send email, and lo ad URLs in yo ur
Web bro wser o f c ho ic e. I will also assume yo u have a reaso nable kno wledge o f
HTML at abo ut the level suppo rted by Netsc ape 1.1. On the o ther hand, when I
disc uss newer aspec ts o f HTML that are no t yet in widespread use like c asc ading
style sheets, I will c o ver them in depth.
x
Preface
To be mo re spec ific , in this bo o k I assume that yo u c an:
✦ Write a basic HTML page inc luding links, images, and text using a text edito r.
✦ Plac e that page o n a Web server.
On the o ther hand, I do no t assume that yo u:
✦ Kno w SGML. In fac t, this prefac e is almo st the o nly plac e in the entire bo o k
yo u’ll see the wo rd SGML used. XML is suppo sed to be simpler and mo re
widespread than SGML. It c an’t be that if yo u have to learn SGML first.
✦ Are a pro grammer, whether o f Java, Perl, C, o r so me o ther language, XML is
a markup language, no t a pro gramming language. Yo u do n’t need to be a
pro grammer to write XML do c uments.
What You’ll Learn
This bo o k has o ne primary go al; to teac h yo u to write XML do c uments fo r the Web.
Fo rtunately, XML has a dec idedly flat learning c urve, muc h like HTML (and unlike
SGML). As yo u learn a little yo u c an do a little. As yo u learn a little mo re, yo u c an do
a little mo re. Thus the c hapters in this bo o k build steadily o n eac h o ther. They are
meant to be read in sequenc e. Alo ng the way yo u’ll learn:
✦ Ho w an XML do c ument is c reated and delivered to readers.
✦ Ho w semantic tagging makes XML do c uments easier to maintain and develo p
than their HTML equivalents.
✦ Ho w to po st XML do c uments o n Web servers in a fo rm everyo ne c an read.
✦ Ho w to make sure yo ur XML is well-fo rmed.
✦ Ho w to use internatio nal c harac ters like _ and _ in yo ur do c uments.
✦ Ho w to validate do c uments with DTDs.
✦ Ho w to use entities to build large do c uments fro m smaller parts.
✦ Ho w attributes desc ribe data.
✦ Ho w to wo rk with no n-XML data.
✦ Ho w to fo rmat yo ur do c uments with CSS and XSL style sheets.
✦ Ho w to c o nnec t do c uments with XLinks and Xpo inters.
✦ Ho w to merge different XML vo c abularies with namespac es.
✦ Ho w to write metadata fo r Web pages using RDF.
Preface
In the final sec tio n o f this bo o k, yo u’ll see several prac tic al examples o f XML being
used fo r real-wo rld applic atio ns inc luding:
✦ Web Site Design
✦ Push
✦ Vec to r Graphic s
✦ Genealo gy
How the Book Is Organized
This bo o k is divided into five parts and inc ludes three appendixes:
I.
Intro duc ing XML
II.
Do c ument Type Definitio ns
III.
Style Languages
IV.
Supplemental Tec hno lo gies
V.
XML Applic atio ns
By the time yo u’re finished reading this bo o k, yo u’ll be ready to use XML to c reate
c o mpelling Web pages. The five parts and the appendixes are desc ribed belo w.
Part I: Introducing XM L
Part I c o nsists o f Chapters 1 thro ugh 7. It begins with the histo ry and theo ry behind
XML, the go als XML is trying to ac hieve, and sho ws yo u ho w the different piec es o f
the XML equatio n fit to gether to c reate and deliver do c uments to readers. Yo u’ll see
several c o mpelling examples o f XML applic atio ns to give yo u so me idea o f the wide
applic ability o f XML, inc luding the Vec to r Markup Language (VML), the Reso urc e
Desc riptio n Framewo rk (RDF), the Mathematic al Markup Language (MathML), the
Extensible Fo rms Desc riptio n Language (XFDL), and many o thers. Then yo u’ll learn
by example ho w to write XML do c uments with tags yo u define that make sense fo r
yo ur do c ument. Yo u’ll see ho w to edit them in a text edito r, attac h style sheets to
them, and lo ad them into a Web bro wser like Internet Explo rer 5.0 o r Mo zilla. Yo u’ll
even learn ho w yo u c an write XML do c uments in languages o ther than English,
even languages that aren’t written remo tely like English, suc h as Chinese, Hebrew,
and Russian.
xi
xii
Preface
Part II: Document Type Definitions
Part II c o nsists o f Chapters 8 thro ugh 11, all o f whic h fo c us o n do c ument type
definitio ns (DTDs). An XML do c ument may o ptio nally c o ntain a DTD that spec ifies
whic h elements are and are no t allo wed in an XML do c ument. The DTD spec ifies
the exac t c o ntext and struc ture o f tho se elements. A validating parser c an read a
do c ument and c o mpare it to its DTD, and repo rt any mistakes it finds. This enables
do c ument autho rs to make sure that their wo rk meets any nec essary c riteria.
In Part II, yo u’ll learn ho w to attac h a DTD to a do c ument, ho w to validate yo ur
do c uments against their DTDs, and ho w to write yo ur o wn DTDs that so lve yo ur
o wn pro blems. Yo u’l learn the syntax fo r dec laring elements, attributes, entities,
and no tatio ns. Yo u’ll see ho w yo u c an use entity dec laratio ns and entity referenc es
to build bo th a do c ument and its DTD fro m multiple, independent piec es. This
allo ws yo u to make lo ng, hard-to -fo llo w do c uments muc h simpler by separating
them into related mo dules and c o mpo nents. And yo u’ll learn ho w to integrate o ther
fo rms o f data like raw text and GIF image files in yo ur XML do c ument.
Part III: Style Languages
Part III c o nsists o f Chapters 12 thro ugh 15. XML markup o nly spec ifies what’s in a
do c ument. Unlike HTML, it do es no t say anything abo ut what that c o ntent sho uld
lo o k like. Info rmatio n abo ut an XML do c ument’s appearanc e when printed, viewed
in a Web bro wser, o r o therwise displayed is sto red in a style sheet. Different style
sheets c an be used fo r the same do c ument. Yo u might, fo r instanc e, want to use a
style sheet that spec ifies small fo nts fo r printing, ano ther o ne that uses larger fo nts
fo r o n-sc reen use, and a third with abso lutely humo ngo us fo nts to pro jec t the
do c ument o n a wall at a seminar. Yo u c an c hange the appearanc e o f an XML do c ument by c ho o sing a different style sheet witho ut to uc hing the do c ument itself.
Part III desc ribes in detail the two style sheet languanges in bro adest use o n the
Web, Casc ading Style Sheets (CSS) and the Extensible Style Language (XSL).
CSS is a simple style-sheet language o riginally designed fo r use with HTML. CSS
exists in two versio ns: CSS Level 1 and CSS Level 2. CSS Level 1 pro vides basic
info rmatio n abo ut fo nts, c o lo r, po sitio ning, and text pro perties, and is reaso nably
well suppo rted by c urrent Web bro wsers fo r HTML and XML. CSS Level 2 is a mo re
rec ent standard that adds suppo rt fo r aural style sheets, user interfac e styles,
internatio nal and bi-direc tio nal text, and mo re. CSS is a relatively simple standard
that spplies fixed style rules to the c o ntents o f partic ular elements.
XSL, by c o ntrast, is a mo re c o mplic ated and mo re po werful style language that c anno t
o nly apply styles to the c o ntents o f elements but c an also rearrange elements, add
bo ilerplate text, and transfo rm do c uments in almo st arbitrary ways. XSL is divided
into two parts: a transfo rmatio n language fo r c o nverting XML trees to alternative
trees, and a fo rmatting language fo r spec ifying the appearanc e o f the elements o f an
XML tree. Currently, the transfo rmatio n language is better suppo rted by mo st to o ls
Preface
than the fo rmatting language. No netheless, it is beginning to firm up, and is suppo rted
by Mic ro so ft Internet Explo rer 5.0 and so me third-party fo rmatting engines.
Part IV: Supplemental Technologies
Part IV c o nsists o f Chapters 16 thro ugh 19. It intro duc es so me XML-based languages
and syntaxes that layer o n to p o f basic XML. XLinks pro vides multi-direc tio nal
hypertext links that are far mo re po werful than the simple HTML tag. XPo inters
intro duc e a new syntax yo u c an attac h to the end o f URLs to link no t o nly to partic ular do c uments, but to partic ular parts o f partic ular do c uments. Namespac es use
prefixes and URLs to disambiguate c o nflic ting XML markup languages. The Reso urc e
Desc riptio n Framewo rk (RDF) is an XML applic atio n used to embed meta-data in
XML and HTML do c uments. Meta-data is info rmatio n abo ut a do c ument, suc h as the
autho r, date, and title o f a wo rk, rather than the wo rk itself. All o f these c an be added
to yo ur o wn XML-based markup languages to extend their po wer and utility.
Part V: XM L Applications
Part V, whic h c o nsists o f Chapters 20–23, sho ws yo u fo ur prac tic al uses o f XML in
different do mains. XHTML is a refo rmulatio n o f HTML 4.0 as valid XML. Mic ro so ft’s
Channel Definitio n Fo rmat (CDF), is an XML-based markup language fo r defining
c hannels that c an push updated Web site c o ntent to subsc ribers. The Vec to r
Markup Language (VML) is an XML applic atio n fo r sc alable graphic s used by Mic ro so ft Offic e 2000 and Internet Explo rer 5.0. Finally, a c o mpletely new applic atio n is
develo ped fo r genealo gic al data to sho w yo u no t just ho w to use XML tags, but why
and when to c ho o se them.
Appendixes
This bo o k has two appendixes, whic h fo c us o n the fo rmal spec ific atio ns fo r XML, as
o ppo sed to the mo re info rmal desc riptio n o f it used thro ugho ut the rest o f the
bo o k. Appendix A pro vides detailed explanatio ns o f three individual parts o f the
XML 1.0 spec ific atio n: XML BNF grammar, well-fo rmedness c o nstraints, and the
validity c o nstraints. Appendix B c o ntains the o ffic ial W3C XML 1.0 spec ific atio n
published by the W3C. The bo o k also has a third appendix, Appendix C, whic h
desc ribes the c o ntents o f the CD-ROM that ac c o mpanies this bo o k.
What You Need
To make the best use o f this bo o k and XML, yo u need:
✦ A PC running Windo ws 95, Windo ws 98, o r Windo ws NT
✦ Internet Explo rer 5.0
✦ A Java 1.1 o r later virtual mac hine
xiii
xiv
Preface
Any system that c an run Windo ws will suffic e. In this bo o k, I mo stly assume yo u’re
using Windo ws 95 o r NT 4.0 o r later. As a lo ngtime Mac and Unix user, I so mewhat
regret this. Like Java, XML is suppo sed to be platfo rm independent. Also like Java,
the reality is so mewhat sho rt o f the hype. Altho ugh XML c o de is pure text that c an
be written with any edito r, many o f the to o ls are c urrently o nly available o n
Windo ws.
Ho wever, altho ugh there aren’t many Unix o r Mac into sh native XML pro grams,
there are an inc reasing number o f XML pro grams written in Java. If yo u have a Java
1.1 o r later virtual mac hine o n yo ur platfo rm o f c ho ic e, yo u sho uld be able to make
do . Even if yo u c an’t lo ad yo ur XML do c uments direc tly into a Web bro wser, yo u
c an still c o nvert them to XML do c uments and view tho se. When Mo zilla is released,
it sho uld pro vide the best XML bro wser yet ac ro ss multiple platfo rms.
How to Use This Book
This bo o k is designed to be read mo re o r less c o ver to c o ver. Eac h c hapter builds
o n the material in the previo us c hapters in a fairly predic table fashio n. Of c o urse,
yo u’re always welc o me to skim o ver material that’s already familiar to yo u. I also
ho pe yo u’ll sto p alo ng the way to try o ut so me o f the examples and to write so me
XML do c uments o f yo ur o wn. It’s impo rtant to learn no t just by reading, but also by
do ing. Befo re yo u get started, I’d like to make a c o uple o f no tes abo ut grammatic al
c o nventio ns used in this bo o k.
Unlike HTML, XML is c ase sensitive. is no t the same as o r
. The father element is no t the same as the Father element o r the
FATHER element. Unfo rtunately, c ase-sensitive markup languages have an anno ying
habit o f c o nflic ting with standard English usage. On rare o c c asio n this means
that yo u may enc o unter sentenc es that do n’t begin with a c apital letter. Mo re
c o mmo nly, yo u’ll see c apitalizatio n used in the middle o f a sentenc e where yo u
wo uldn’t no rmally expec t it. Please do n’t get to o bo thered by this. All XML and
HTML c o de used in this bo o k is plac ed in a mo no spac ed fo nt, so mo st o f the time
it will be o bvio us fro m the c o ntext what is meant.
I have also ado pted the British c o nventio n o f o nly plac ing punc tuatio n inside quo te
marks when it belo ngs with the material quo ted. Frankly, altho ugh I learned to write
in the Americ an educ atio nal system, I find the British system is far mo re lo gic al,
espec ially when dealing with so urc e c o de where the differenc e between a c o mma
o r a perio d and no punc tuatio n at all c an make the differenc e between perfec tly
c o rrec t and perfec tly inc o rrec t c o de.
Preface
What the Icons M ean
Thro ugho ut the bo o k, I’ve used ico ns in the left margin to c all yo ur attentio n to
po ints that are partic ularly impo rtant.
Note
Note icons provide supplem ental inform ation about the subject at hand, but generally som ething that isn’t quite the m ain idea. Notes are often used to elaborate
on a detailed technical point.
Tip
Tip icons indicate a m ore efficient w ay of doing som ething, or a technique that
m ay not be obvious.
On the
CD-ROM
CD-ROM icons tell you that softw are discussed in the book is available on the
com panion CD-ROM. This icon also tells you if a longer exam ple, discussed but
not included in its entirety in the book, is on the CD-ROM.
Caution icons w arn you of a com m on m isconception or that a procedure doesn’t
alw ays w ork quite like it’s supposed to. The m ost com m on purpose of a Caution
icon in this book is to point out the difference betw een w hat a specification says
should happen, and w hat actually does.
Caution
CrossReference
The Cross Reference icon refers you to other chapters that have m ore to say about
a particular subject.
About the Companion CD-ROM
The inside bac k c o ver o f this bo o k c o ntains a CD-ROM that ho lds all numbered
c o de listings that yo u’ll find in the text. It also inc ludes many lo nger examples that
c o uldn’t fit into this bo o k. The CD-ROM also c o ntains the c o mplete text o f vario us
XML spec ific atio ns in HTML. (So me o f the spec ific atio ns will be in o ther fo rmats as
well.) Finally, yo u will find an asso rtment o f useful so ftware fo r wo rking with XML
do c uments. Many (tho ugh no t all) o f these pro grams are written in Java, so they’ll
run o n any system with a reaso nably c o mpatible Java 1.1 o r later virtual mac hine.
Mo st o f the pro grams that aren’t written in Java are designed fo r Windo ws 95, 98,
and NT.
Fo r a c o mplete desc riptio n o f the CD-ROM c o ntents, yo u c an read Appendix C. In
additio n, to get a c o mplete desc riptio n o f what is o n the CD-ROM, yo u c an lo ad the
file index.html o nto yo ur Web bro wser. The files o n the c o mpanio n CD-ROM are no t
c o mpressed, so yo u c an ac c ess them direc tly fro m the CD.
xv
xvi
Preface
Reach Out
The publisher and I want yo ur feedbac k. After yo u have had a c hanc e to use this
bo o k, please take a mo ment to c o mplete the IDG Bo o ks Wo rldwide Registratio n
Card (in the bac k o f the bo o k). Please be ho nest in yo ur evaluatio n. If yo u tho ught a
partic ular c hapter didn’t tell yo u eno ugh, let me kno w. Of c o urse, I wo uld prefer to
rec eive c o mments like: “This is the best bo o k I’ve ever read”, “Thanks to this bo o k,
my Web site wo n Co o l Site o f the Year”, o r “When I was reading this bo o k o n the
beac h, I was besieged by mo dels who tho ught I was super c o o l”, but I’ll take any
c o mments I c an get :-).
Feel free to send me spec ific questio ns regarding the material in this bo o k. I’ll do
my best to help yo u o ut and answer yo ur questio ns, but I c an’t guarantee a reply.
The best way to reac h me is by email:
[email protected]
Also , I invite yo u to visit my Cafe c o n Lec he Web site at http://metalab.unc.
edu/xml/, whic h c o ntains a lo t o f XML-related material and is updated almo st
daily. Despite my persistent effo rts to make this bo o k perfec t, so me erro rs have
do ubtless slipped by. Even mo re c ertainly, so me o f the material disc ussed here
will c hange o ver time. I’ll po st any nec essary updates and errata o n my Web site at
http://metalab.unc.edu/xml/books/bible/. Please let me kno w via email o f
any erro rs that yo u find that aren’t already listed.
Ellio tte Rusty Haro ld
[email protected]
http://metalab.unc.edu/xml/
New Yo rk City, June 1999
Acknowledgments
The fo lks at IDG have all been great. The ac quisitio ns edito r, Jo hn Osbo rn, deserves
spec ial thanks fo r arranging the unusual sc heduling this bo o k required to hit the
mo ving target XML presents. Terri Varveris shepherded this bo o k thro ugh the
develo pment pro c ess. With po ise and grac e, she managed the c o nstantly shifting
o utline and sc hedule that a bo o k based o n unstable spec ific atio ns and so ftware
requires. Amy Eo ff c o rrec ted many o f my grammatic al sho rtc o mings. Susan Parini
and Ritc hie Durdin, the pro duc tio n c o o rdinato rs, also deserve spec ial thanks fo r
managing the pro duc tio n o f this bo o k and fo r dealing with last-minute figure
c hanges.
Steven Champeo n bro ught his SGML experienc e to the bo o k, and pro vided many
insightful c o mments o n the text. My bro ther Tho mas Haro ld put his c o mmand
o f c hemistry at my dispo sal when I was trying to grasp the Chemic al Markup
Language. Carro ll Bellau pro vided me with parts o f my family tree, whic h yo u’ll
find in Chapter 17.
I also greatly apprec iate all the c o mments, questio ns, and c o rrec tio ns sent in by
readers o f my previo us bo o k, XML: Exte nsible Markup Language . I ho pe that I’ve
managed to address mo st o f tho se c o mments in this bo o k. They’ve definitely
helped make XML Bible a better bo o k. Partic ular thanks are due to Alan Esenther
and Do nald Lanc o n Jr. fo r their espec ially detailed c o mments.
WandaJane Phillips wro te the o riginal versio n o f Chapter 21 o n CDF that is adapted
here. Heather Williamso n, in additio n to perfo rming yeo man-like servic e as tec hnic al
edito r, wro te Chapter 13, CSS Le ve l 2, and parts o f Chapters 18, 19, and 22. Her help
was instrumental in helping me almo st meet my deadline. (Blame fo r this almo st
rests o n my sho ulders, no t theirs.) Also , I wo uld like to thank Piro z Mo hseni, who
also served as a tec hnic al edito r fo r this bo o k.
The agenting talents o f David and Sherry Ro gelberg o f the Studio B Literary Agenc y
( http://www.studiob.com/) have made it po ssible fo r me to write mo re o r less
full-time. I rec o mmend them highly to anyo ne thinking abo ut writing c o mputer
bo o ks. And as always, thanks go to my wife Beth fo r her endless lo ve and
understanding.
Contents at a Glance
Prefac e ................................................................................................................................ix
Ac kno wledgments ..........................................................................................................xvii
Part I: Introducing XM L ......................................................................................1
Chapter 1: An Eagle’s Eye View o f XML ..........................................................................3
Chapter 2: An Intro duc tio n to XML Applic atio ns ........................................................17
Chapter 3: Yo ur First XML Do c ument ..........................................................................49
Chapter 4: Struc turing Data ............................................................................................59
Chapter 5: Attributes, Empty Tags, and XSL ................................................................95
Chapter 6: Well-Fo rmed XML Do c uments
Chapter 7: Fo reign Languages and No n-Ro man Text ................................................161
Part II: Document Type Definitions ............................................................189
Chapter 8: Do c ument Type Definitio ns and Validity ................................................191
Chapter 9: Entities and External DTD Subsets ..........................................................247
Chapter 10: Attribute Dec laratio ns in DTDs ..............................................................283
Chapter 11: Embedding No n-XML Data ......................................................................307
Part III: Style Languages................................................................................321
Chapter 12: Casc ading Style Sheets Level 1 ..............................................................323
Chapter 13: Casc ading Style Sheets Level 2 ..............................................................389
Chapter 14: XSL Transfo rmatio ns ................................................................................433
Chapter 15: XSL Fo rmatting Objec ts ..........................................................................513
Part IV: Supplemental Technologies ..........................................................569
Chapter 16: XLinks ........................................................................................................571
Chapter 17: XPo inters ..................................................................................................591
Chapter 18: Namespac es ..............................................................................................617
Chapter 19: The Reso urc e Desc riptio n Framewo rk ..................................................631
PartV: XM L Applications ................................................................................655
Chapter 20: Reading Do c ument Type Definitio ns ......................................................657
Chapter 21: Pushing Web Sites with CDF ....................................................................775
Chapter 22: The Vec to r Markup Language ................................................................805
Chapter 23: Designing a New XML Applic atio n ..........................................................833
xx
Contents at a Glance
Appendix A: XML Referenc e Material ........................................................................863
Appendix B: The XML 1.0 Spec ific atio n ......................................................................921
Appendix C: What’s o n the CD-ROM ............................................................................971
Index ................................................................................................................................975
End-User Lic ense Agreement ......................................................................................1018
CD-ROM Installatio n Instruc tio ns ..............................................................................1022
Contents
Prefac e ................................................................................................................................ix
Ac kno wledgments ..........................................................................................................xvii
Part I: Introducing XM L
1
Chapter 1: An Eagle’s Eye View of XM L ........................................................3
What Is XML? ............................................................................................................3
XML Is a Meta-Markup Language .................................................................3
XML Desc ribes Struc ture and Semantic s, No t Fo rmatting ........................4
Why Are Develo pers Exc ited abo ut XML? ............................................................6
Design o f Do main-Spec ific Markup Languages ...........................................6
Self-Desc ribing Data .......................................................................................6
Interc hange o f Data Amo ng Applic atio ns ....................................................7
Struc tured and Integrated Data ....................................................................8
The Life o f an XML Do c ument ................................................................................8
Edito rs .............................................................................................................9
Parsers and Pro c esso rs .................................................................................9
Bro wsers and Other To o ls ............................................................................9
The Pro c ess Summarized ............................................................................10
Related Tec hno lo gies ............................................................................................10
Hypertext Markup Language ......................................................................10
Casc ading Style Sheets ................................................................................11
Extensible Style Language ...........................................................................12
URLs and URIs ..............................................................................................12
XLinks and XPo inters ...................................................................................13
The Unic o de Charac ter Set .........................................................................14
Ho w the Tec hno lo gies Fit To gether ...........................................................14
Chapter 2: An Introduction to XM L Applications ......................................17
What Is an XML Applic atio n? ................................................................................17
Chemic al Markup Language ........................................................................18
Mathematic al Markup Language ................................................................19
Channel Definitio n Fo rmat ..........................................................................22
Classic Literature .........................................................................................22
Sync hro nized Multimedia Integratio n Language ......................................24
HTML+TIME ..................................................................................................25
Open So ftware Desc riptio n .........................................................................26
Sc alable Vec to r Graphic s ............................................................................27
Vec to r Markup Language .............................................................................29
Music ML ........................................................................................................30
Vo xML ............................................................................................................32
xxii
Contents
Open Financ ial Exc hange ............................................................................34
Extensible Fo rms Desc riptio n Language ...................................................36
Human Reso urc es Markup Language ........................................................38
Reso urc e Desc riptio n Framewo rk ..............................................................40
XML fo r XML ...........................................................................................................42
XSL .................................................................................................................42
XLL .................................................................................................................43
DCD ................................................................................................................43
Behind-the-Sc ene Uses o f XML .............................................................................44
Chapter 3: Your First XM L Document ..........................................................49
Hello XML ................................................................................................................49
Creating a Simple XML Do c ument ..............................................................50
Saving the XML File ......................................................................................50
Lo ading the XML File into a Web Bro wser ................................................51
Explo ring the Simple XML Do c ument ..................................................................52
Assigning Meaning to XML Tags ...........................................................................54
Writing a Style Sheet fo r an XML Do c ument .......................................................55
Attac hing a Style Sheet to an XML Do c ument ....................................................56
Chapter 4: Structuring Data ..........................................................................59
Examining the Data ................................................................................................59
Batters ...........................................................................................................60
Pitc hers ..........................................................................................................62
Organizatio n o f the XML Data .....................................................................62
XMLizing the Data ..................................................................................................65
Starting the Do c ument: XML Dec laratio n and Ro o t Element .................65
XMLizing League, Divisio n, and Team Data ..............................................67
XMLizing Player Data ...................................................................................69
XMLizing Player Statistic s ...........................................................................70
Putting the XML Do c ument Bac k To gether Again ....................................72
The Advantages o f the XML Fo rmat ...................................................................80
Preparing a Style Sheet fo r Do c ument Display ...................................................81
Linking to a Style Sheet ...............................................................................82
Assigning Style Rules to the Ro o t Element ...............................................84
Assigning Style Rules to Titles ....................................................................85
Assigning Style Rules to Player
and Statistic s Elements ...........................................................................88
Summing Up ..................................................................................................89
Chapter 5: Attributes, Empty Tags, and XSL ..............................................95
Attributes ................................................................................................................95
Attributes versus Elements ................................................................................101
Struc tured Meta-data .................................................................................102
Meta-Meta-Data ...........................................................................................105
What’s Yo ur Meta-data Is So meo ne Else’s Data ......................................106
Elements Are Mo re Extensible ..................................................................106
Go o d Times to Use Attributes ..................................................................107
Contents
Empty Tags ............................................................................................................108
XSL .........................................................................................................................109
XSL Style Sheet Templates ........................................................................110
The Bo dy o f the Do c ument .......................................................................111
The Title ......................................................................................................113
Leagues, Divisio ns, and Teams .................................................................115
Players .........................................................................................................120
Separatio n o f Pitc hers and Batters ..........................................................122
CSS o r XSL? .................................................................................................130
Chapter 6: Well-Formed XM L Documents ................................................133
#1: The XML dec laratio n must begin the do c ument ..............................144
#2: Use Bo th Start and End Tags in No n-Empty Tags .............................144
Chapter 7: Foreign Languages and Non-Roman Text ............................161
No n-Ro man Sc ripts o n the Web .........................................................................161
Sc ripts, Charac ter Sets, Fo nts, and Glyphs ......................................................166
A Charac ter Set fo r the Sc ript ...................................................................166
A Fo nt fo r the Charac ter Set .....................................................................167
An Input Metho d fo r the Charac ter Set ...................................................167
Operating System and Applic atio n So ftware ..........................................168
Legac y Charac ter Sets .........................................................................................169
The ASCII Charac ter Set ............................................................................169
The ISO Charac ter Sets ..............................................................................172
The Mac Ro man Charac ter Set ..................................................................175
The Windo ws ANSI Charac ter Set ............................................................176
The Unic o de Charac ter Set .................................................................................177
UTF 8 ............................................................................................................182
The Universal Charac ter System ..............................................................182
Ho w to Write XML in Unic o de ............................................................................183
Inserting Charac ters in XML Files with Charac ter Referenc es .............183
Co nverting to and fro m Unic o de ..............................................................184
Ho w to Write XML in Other Charac ter Sets ............................................185
Part II: Document Type Definitions
189
Chapter 8: Document Type Definitions and Validity ..............................191
Do c ument Type Definitio ns ................................................................................191
Do c ument Type Dec laratio ns .............................................................................192
Validating Against a DTD .....................................................................................195
Listing the Elements ............................................................................................201
Element Dec laratio ns ...........................................................................................208
ANY ..............................................................................................................209
#PCDATA ......................................................................................................209
Child Lists ....................................................................................................212
Sequenc es ...................................................................................................214
One o r Mo re Children ................................................................................215
xxiii
™
Elliotte Rusty Harold
IDG Bo o ks Wo rldwide, Inc .
An Internatio nal Data Gro up Co mpany
Fo ster City, CA ✦ Chic ago , IL ✦ Indianapo lis, IN ✦ New Yo rk, NY
XML™ Bible
Published by
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Library o f Co ngress Catalo ging-in-Public atio n Data
Haro ld, Ellio te Rusty.
XML bible / Ellio te Rusty Haro ld.
p.
c m.
ISBN 0-7645-3236-7 (alk. paper)
1. XML (Do c ument markup language) I. Title.
QA76.76.H94H34
005.7’2--dc 21
1999
99-31021
CIP
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1/24/99
Credits
Acquisitions Editor
Copy Editors
Jo hn Osbo rn
Terri Varveris
Amy Eo ff
Amanda Kaufman
Nic o le LeClerc
Vic to ria Lee
Contributing Writer
Production
Heather Williamso n
IDG Bo o ks Wo rldwide Pro duc tio n
Technical Editor
Proofreading and Indexing
Greg Guntle
Yo rk Pro duc tio n Servic es
Development Editor
About the Author
Ellio tte Rusty Haro ld is an internatio nally respec ted writer, pro grammer, and
educ ato r bo th o n the Internet and o ff. He go t his start by writing FAQ lists fo r the
Mac into sh newsgro ups o n Usenet, and has sinc e branc hed o ut into bo o ks, Web
sites, and newsletters. He lec tures abo ut Java and o bjec t-o riented pro gramming
at Po lytec hnic University in Bro o klyn. His Cafe c o n Lec he Web site at http://
metalab.unc.edu/xml/ has bec o me o ne o f the mo st po pular independent XML
sites o n the Internet.
Ellio tte is o riginally fro m New Orleans where he returns perio dic ally in searc h o f
a dec ent bo wl o f gumbo . Ho wever, he c urrently resides in the Pro spec t Heights
neighbo rho o d o f Bro o klyn with his wife Beth and c ats Charm (named after the
quark) and Marjo rie (named after his mo ther-in-law). When no t writing bo o ks, he
enjo ys wo rking o n genealo gy, mathematic s, and quantum mec hanic s. His previo us
bo o ks inc lude The Java De ve lo pe r’s Re so urce , Java Ne two rk Pro gramming, Java
Se cre ts, JavaBe ans, XML: Exte nsible Markup Language , and Java I/O .
Fo r Ma, a gre at grandmo the r
Preface
Welc o me to the XML Bible . After reading this bo o k I ho pe yo u’ll agree with me that
XML is the mo st exc iting develo pment o n the Internet sinc e Java, and that it makes
Web site develo pment easier, mo re pro duc tive, and mo re fun.
This bo o k is yo ur intro duc tio n to the exc iting and fast gro wing wo rld o f XML. In this
bo o k, yo u’ll learn ho w to write do c uments in XML and ho w to use style sheets to
c o nvert tho se do c uments into HTML so legac y bro wsers c an read them. Yo u’ll
also learn ho w to use do c ument type definitio ns (DTDs) to desc ribe and validate
do c uments. This will bec o me inc reasingly impo rtant as mo re and mo re bro wsers like
Mo zilla and Internet Explo rer 5.0 pro vide native suppo rt fo r XML.
About You the Reader
Unlike mo st o ther XML bo o ks o n the market, the XML Bible c o vers XML no t fro m
the perspec tive o f a so ftware develo per, but rather that o f a Web-page autho r. I
do n’t spend a lo t o f time disc ussing BNF grammars o r parsing element trees.
Instead, I sho w yo u ho w yo u c an use XML and existing to o ls to day to mo re
effic iently pro duc e attrac tive, exc iting, easy-to -use, easy-to -maintain Web sites
that keep yo ur readers c o ming bac k fo r mo re.
This bo o k is aimed direc tly at Web-site develo pers. I assume yo u want to use XML
to pro duc e Web sites that are diffic ult to impo ssible to c reate with raw HTML. Yo u’ll
be amazed to disc o ver that in c o njunc tio n with style sheets and a few free to o ls,
XML enables yo u to do things that previo usly required either c usto m so ftware
c o sting hundreds to tho usands o f do llars per develo per, o r extensive kno wledge
o f pro gramming languages like Perl. No ne o f the so ftware in this bo o k will c o st
yo u mo re than a few minutes o f do wnlo ad time. No ne o f the tric ks require any
pro gramming.
What You Need to Know
XML do es build o n HTML and the underlying infrastruc ture o f the Internet. To that
end, I will assume yo u kno w ho w to use ftp files, send email, and lo ad URLs in yo ur
Web bro wser o f c ho ic e. I will also assume yo u have a reaso nable kno wledge o f
HTML at abo ut the level suppo rted by Netsc ape 1.1. On the o ther hand, when I
disc uss newer aspec ts o f HTML that are no t yet in widespread use like c asc ading
style sheets, I will c o ver them in depth.
x
Preface
To be mo re spec ific , in this bo o k I assume that yo u c an:
✦ Write a basic HTML page inc luding links, images, and text using a text edito r.
✦ Plac e that page o n a Web server.
On the o ther hand, I do no t assume that yo u:
✦ Kno w SGML. In fac t, this prefac e is almo st the o nly plac e in the entire bo o k
yo u’ll see the wo rd SGML used. XML is suppo sed to be simpler and mo re
widespread than SGML. It c an’t be that if yo u have to learn SGML first.
✦ Are a pro grammer, whether o f Java, Perl, C, o r so me o ther language, XML is
a markup language, no t a pro gramming language. Yo u do n’t need to be a
pro grammer to write XML do c uments.
What You’ll Learn
This bo o k has o ne primary go al; to teac h yo u to write XML do c uments fo r the Web.
Fo rtunately, XML has a dec idedly flat learning c urve, muc h like HTML (and unlike
SGML). As yo u learn a little yo u c an do a little. As yo u learn a little mo re, yo u c an do
a little mo re. Thus the c hapters in this bo o k build steadily o n eac h o ther. They are
meant to be read in sequenc e. Alo ng the way yo u’ll learn:
✦ Ho w an XML do c ument is c reated and delivered to readers.
✦ Ho w semantic tagging makes XML do c uments easier to maintain and develo p
than their HTML equivalents.
✦ Ho w to po st XML do c uments o n Web servers in a fo rm everyo ne c an read.
✦ Ho w to make sure yo ur XML is well-fo rmed.
✦ Ho w to use internatio nal c harac ters like _ and _ in yo ur do c uments.
✦ Ho w to validate do c uments with DTDs.
✦ Ho w to use entities to build large do c uments fro m smaller parts.
✦ Ho w attributes desc ribe data.
✦ Ho w to wo rk with no n-XML data.
✦ Ho w to fo rmat yo ur do c uments with CSS and XSL style sheets.
✦ Ho w to c o nnec t do c uments with XLinks and Xpo inters.
✦ Ho w to merge different XML vo c abularies with namespac es.
✦ Ho w to write metadata fo r Web pages using RDF.
Preface
In the final sec tio n o f this bo o k, yo u’ll see several prac tic al examples o f XML being
used fo r real-wo rld applic atio ns inc luding:
✦ Web Site Design
✦ Push
✦ Vec to r Graphic s
✦ Genealo gy
How the Book Is Organized
This bo o k is divided into five parts and inc ludes three appendixes:
I.
Intro duc ing XML
II.
Do c ument Type Definitio ns
III.
Style Languages
IV.
Supplemental Tec hno lo gies
V.
XML Applic atio ns
By the time yo u’re finished reading this bo o k, yo u’ll be ready to use XML to c reate
c o mpelling Web pages. The five parts and the appendixes are desc ribed belo w.
Part I: Introducing XM L
Part I c o nsists o f Chapters 1 thro ugh 7. It begins with the histo ry and theo ry behind
XML, the go als XML is trying to ac hieve, and sho ws yo u ho w the different piec es o f
the XML equatio n fit to gether to c reate and deliver do c uments to readers. Yo u’ll see
several c o mpelling examples o f XML applic atio ns to give yo u so me idea o f the wide
applic ability o f XML, inc luding the Vec to r Markup Language (VML), the Reso urc e
Desc riptio n Framewo rk (RDF), the Mathematic al Markup Language (MathML), the
Extensible Fo rms Desc riptio n Language (XFDL), and many o thers. Then yo u’ll learn
by example ho w to write XML do c uments with tags yo u define that make sense fo r
yo ur do c ument. Yo u’ll see ho w to edit them in a text edito r, attac h style sheets to
them, and lo ad them into a Web bro wser like Internet Explo rer 5.0 o r Mo zilla. Yo u’ll
even learn ho w yo u c an write XML do c uments in languages o ther than English,
even languages that aren’t written remo tely like English, suc h as Chinese, Hebrew,
and Russian.
xi
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Preface
Part II: Document Type Definitions
Part II c o nsists o f Chapters 8 thro ugh 11, all o f whic h fo c us o n do c ument type
definitio ns (DTDs). An XML do c ument may o ptio nally c o ntain a DTD that spec ifies
whic h elements are and are no t allo wed in an XML do c ument. The DTD spec ifies
the exac t c o ntext and struc ture o f tho se elements. A validating parser c an read a
do c ument and c o mpare it to its DTD, and repo rt any mistakes it finds. This enables
do c ument autho rs to make sure that their wo rk meets any nec essary c riteria.
In Part II, yo u’ll learn ho w to attac h a DTD to a do c ument, ho w to validate yo ur
do c uments against their DTDs, and ho w to write yo ur o wn DTDs that so lve yo ur
o wn pro blems. Yo u’l learn the syntax fo r dec laring elements, attributes, entities,
and no tatio ns. Yo u’ll see ho w yo u c an use entity dec laratio ns and entity referenc es
to build bo th a do c ument and its DTD fro m multiple, independent piec es. This
allo ws yo u to make lo ng, hard-to -fo llo w do c uments muc h simpler by separating
them into related mo dules and c o mpo nents. And yo u’ll learn ho w to integrate o ther
fo rms o f data like raw text and GIF image files in yo ur XML do c ument.
Part III: Style Languages
Part III c o nsists o f Chapters 12 thro ugh 15. XML markup o nly spec ifies what’s in a
do c ument. Unlike HTML, it do es no t say anything abo ut what that c o ntent sho uld
lo o k like. Info rmatio n abo ut an XML do c ument’s appearanc e when printed, viewed
in a Web bro wser, o r o therwise displayed is sto red in a style sheet. Different style
sheets c an be used fo r the same do c ument. Yo u might, fo r instanc e, want to use a
style sheet that spec ifies small fo nts fo r printing, ano ther o ne that uses larger fo nts
fo r o n-sc reen use, and a third with abso lutely humo ngo us fo nts to pro jec t the
do c ument o n a wall at a seminar. Yo u c an c hange the appearanc e o f an XML do c ument by c ho o sing a different style sheet witho ut to uc hing the do c ument itself.
Part III desc ribes in detail the two style sheet languanges in bro adest use o n the
Web, Casc ading Style Sheets (CSS) and the Extensible Style Language (XSL).
CSS is a simple style-sheet language o riginally designed fo r use with HTML. CSS
exists in two versio ns: CSS Level 1 and CSS Level 2. CSS Level 1 pro vides basic
info rmatio n abo ut fo nts, c o lo r, po sitio ning, and text pro perties, and is reaso nably
well suppo rted by c urrent Web bro wsers fo r HTML and XML. CSS Level 2 is a mo re
rec ent standard that adds suppo rt fo r aural style sheets, user interfac e styles,
internatio nal and bi-direc tio nal text, and mo re. CSS is a relatively simple standard
that spplies fixed style rules to the c o ntents o f partic ular elements.
XSL, by c o ntrast, is a mo re c o mplic ated and mo re po werful style language that c anno t
o nly apply styles to the c o ntents o f elements but c an also rearrange elements, add
bo ilerplate text, and transfo rm do c uments in almo st arbitrary ways. XSL is divided
into two parts: a transfo rmatio n language fo r c o nverting XML trees to alternative
trees, and a fo rmatting language fo r spec ifying the appearanc e o f the elements o f an
XML tree. Currently, the transfo rmatio n language is better suppo rted by mo st to o ls
Preface
than the fo rmatting language. No netheless, it is beginning to firm up, and is suppo rted
by Mic ro so ft Internet Explo rer 5.0 and so me third-party fo rmatting engines.
Part IV: Supplemental Technologies
Part IV c o nsists o f Chapters 16 thro ugh 19. It intro duc es so me XML-based languages
and syntaxes that layer o n to p o f basic XML. XLinks pro vides multi-direc tio nal
hypertext links that are far mo re po werful than the simple HTML tag. XPo inters
intro duc e a new syntax yo u c an attac h to the end o f URLs to link no t o nly to partic ular do c uments, but to partic ular parts o f partic ular do c uments. Namespac es use
prefixes and URLs to disambiguate c o nflic ting XML markup languages. The Reso urc e
Desc riptio n Framewo rk (RDF) is an XML applic atio n used to embed meta-data in
XML and HTML do c uments. Meta-data is info rmatio n abo ut a do c ument, suc h as the
autho r, date, and title o f a wo rk, rather than the wo rk itself. All o f these c an be added
to yo ur o wn XML-based markup languages to extend their po wer and utility.
Part V: XM L Applications
Part V, whic h c o nsists o f Chapters 20–23, sho ws yo u fo ur prac tic al uses o f XML in
different do mains. XHTML is a refo rmulatio n o f HTML 4.0 as valid XML. Mic ro so ft’s
Channel Definitio n Fo rmat (CDF), is an XML-based markup language fo r defining
c hannels that c an push updated Web site c o ntent to subsc ribers. The Vec to r
Markup Language (VML) is an XML applic atio n fo r sc alable graphic s used by Mic ro so ft Offic e 2000 and Internet Explo rer 5.0. Finally, a c o mpletely new applic atio n is
develo ped fo r genealo gic al data to sho w yo u no t just ho w to use XML tags, but why
and when to c ho o se them.
Appendixes
This bo o k has two appendixes, whic h fo c us o n the fo rmal spec ific atio ns fo r XML, as
o ppo sed to the mo re info rmal desc riptio n o f it used thro ugho ut the rest o f the
bo o k. Appendix A pro vides detailed explanatio ns o f three individual parts o f the
XML 1.0 spec ific atio n: XML BNF grammar, well-fo rmedness c o nstraints, and the
validity c o nstraints. Appendix B c o ntains the o ffic ial W3C XML 1.0 spec ific atio n
published by the W3C. The bo o k also has a third appendix, Appendix C, whic h
desc ribes the c o ntents o f the CD-ROM that ac c o mpanies this bo o k.
What You Need
To make the best use o f this bo o k and XML, yo u need:
✦ A PC running Windo ws 95, Windo ws 98, o r Windo ws NT
✦ Internet Explo rer 5.0
✦ A Java 1.1 o r later virtual mac hine
xiii
xiv
Preface
Any system that c an run Windo ws will suffic e. In this bo o k, I mo stly assume yo u’re
using Windo ws 95 o r NT 4.0 o r later. As a lo ngtime Mac and Unix user, I so mewhat
regret this. Like Java, XML is suppo sed to be platfo rm independent. Also like Java,
the reality is so mewhat sho rt o f the hype. Altho ugh XML c o de is pure text that c an
be written with any edito r, many o f the to o ls are c urrently o nly available o n
Windo ws.
Ho wever, altho ugh there aren’t many Unix o r Mac into sh native XML pro grams,
there are an inc reasing number o f XML pro grams written in Java. If yo u have a Java
1.1 o r later virtual mac hine o n yo ur platfo rm o f c ho ic e, yo u sho uld be able to make
do . Even if yo u c an’t lo ad yo ur XML do c uments direc tly into a Web bro wser, yo u
c an still c o nvert them to XML do c uments and view tho se. When Mo zilla is released,
it sho uld pro vide the best XML bro wser yet ac ro ss multiple platfo rms.
How to Use This Book
This bo o k is designed to be read mo re o r less c o ver to c o ver. Eac h c hapter builds
o n the material in the previo us c hapters in a fairly predic table fashio n. Of c o urse,
yo u’re always welc o me to skim o ver material that’s already familiar to yo u. I also
ho pe yo u’ll sto p alo ng the way to try o ut so me o f the examples and to write so me
XML do c uments o f yo ur o wn. It’s impo rtant to learn no t just by reading, but also by
do ing. Befo re yo u get started, I’d like to make a c o uple o f no tes abo ut grammatic al
c o nventio ns used in this bo o k.
Unlike HTML, XML is c ase sensitive. is no t the same as o r
. The father element is no t the same as the Father element o r the
FATHER element. Unfo rtunately, c ase-sensitive markup languages have an anno ying
habit o f c o nflic ting with standard English usage. On rare o c c asio n this means
that yo u may enc o unter sentenc es that do n’t begin with a c apital letter. Mo re
c o mmo nly, yo u’ll see c apitalizatio n used in the middle o f a sentenc e where yo u
wo uldn’t no rmally expec t it. Please do n’t get to o bo thered by this. All XML and
HTML c o de used in this bo o k is plac ed in a mo no spac ed fo nt, so mo st o f the time
it will be o bvio us fro m the c o ntext what is meant.
I have also ado pted the British c o nventio n o f o nly plac ing punc tuatio n inside quo te
marks when it belo ngs with the material quo ted. Frankly, altho ugh I learned to write
in the Americ an educ atio nal system, I find the British system is far mo re lo gic al,
espec ially when dealing with so urc e c o de where the differenc e between a c o mma
o r a perio d and no punc tuatio n at all c an make the differenc e between perfec tly
c o rrec t and perfec tly inc o rrec t c o de.
Preface
What the Icons M ean
Thro ugho ut the bo o k, I’ve used ico ns in the left margin to c all yo ur attentio n to
po ints that are partic ularly impo rtant.
Note
Note icons provide supplem ental inform ation about the subject at hand, but generally som ething that isn’t quite the m ain idea. Notes are often used to elaborate
on a detailed technical point.
Tip
Tip icons indicate a m ore efficient w ay of doing som ething, or a technique that
m ay not be obvious.
On the
CD-ROM
CD-ROM icons tell you that softw are discussed in the book is available on the
com panion CD-ROM. This icon also tells you if a longer exam ple, discussed but
not included in its entirety in the book, is on the CD-ROM.
Caution icons w arn you of a com m on m isconception or that a procedure doesn’t
alw ays w ork quite like it’s supposed to. The m ost com m on purpose of a Caution
icon in this book is to point out the difference betw een w hat a specification says
should happen, and w hat actually does.
Caution
CrossReference
The Cross Reference icon refers you to other chapters that have m ore to say about
a particular subject.
About the Companion CD-ROM
The inside bac k c o ver o f this bo o k c o ntains a CD-ROM that ho lds all numbered
c o de listings that yo u’ll find in the text. It also inc ludes many lo nger examples that
c o uldn’t fit into this bo o k. The CD-ROM also c o ntains the c o mplete text o f vario us
XML spec ific atio ns in HTML. (So me o f the spec ific atio ns will be in o ther fo rmats as
well.) Finally, yo u will find an asso rtment o f useful so ftware fo r wo rking with XML
do c uments. Many (tho ugh no t all) o f these pro grams are written in Java, so they’ll
run o n any system with a reaso nably c o mpatible Java 1.1 o r later virtual mac hine.
Mo st o f the pro grams that aren’t written in Java are designed fo r Windo ws 95, 98,
and NT.
Fo r a c o mplete desc riptio n o f the CD-ROM c o ntents, yo u c an read Appendix C. In
additio n, to get a c o mplete desc riptio n o f what is o n the CD-ROM, yo u c an lo ad the
file index.html o nto yo ur Web bro wser. The files o n the c o mpanio n CD-ROM are no t
c o mpressed, so yo u c an ac c ess them direc tly fro m the CD.
xv
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Preface
Reach Out
The publisher and I want yo ur feedbac k. After yo u have had a c hanc e to use this
bo o k, please take a mo ment to c o mplete the IDG Bo o ks Wo rldwide Registratio n
Card (in the bac k o f the bo o k). Please be ho nest in yo ur evaluatio n. If yo u tho ught a
partic ular c hapter didn’t tell yo u eno ugh, let me kno w. Of c o urse, I wo uld prefer to
rec eive c o mments like: “This is the best bo o k I’ve ever read”, “Thanks to this bo o k,
my Web site wo n Co o l Site o f the Year”, o r “When I was reading this bo o k o n the
beac h, I was besieged by mo dels who tho ught I was super c o o l”, but I’ll take any
c o mments I c an get :-).
Feel free to send me spec ific questio ns regarding the material in this bo o k. I’ll do
my best to help yo u o ut and answer yo ur questio ns, but I c an’t guarantee a reply.
The best way to reac h me is by email:
[email protected]
Also , I invite yo u to visit my Cafe c o n Lec he Web site at http://metalab.unc.
edu/xml/, whic h c o ntains a lo t o f XML-related material and is updated almo st
daily. Despite my persistent effo rts to make this bo o k perfec t, so me erro rs have
do ubtless slipped by. Even mo re c ertainly, so me o f the material disc ussed here
will c hange o ver time. I’ll po st any nec essary updates and errata o n my Web site at
http://metalab.unc.edu/xml/books/bible/. Please let me kno w via email o f
any erro rs that yo u find that aren’t already listed.
Ellio tte Rusty Haro ld
[email protected]
http://metalab.unc.edu/xml/
New Yo rk City, June 1999
Acknowledgments
The fo lks at IDG have all been great. The ac quisitio ns edito r, Jo hn Osbo rn, deserves
spec ial thanks fo r arranging the unusual sc heduling this bo o k required to hit the
mo ving target XML presents. Terri Varveris shepherded this bo o k thro ugh the
develo pment pro c ess. With po ise and grac e, she managed the c o nstantly shifting
o utline and sc hedule that a bo o k based o n unstable spec ific atio ns and so ftware
requires. Amy Eo ff c o rrec ted many o f my grammatic al sho rtc o mings. Susan Parini
and Ritc hie Durdin, the pro duc tio n c o o rdinato rs, also deserve spec ial thanks fo r
managing the pro duc tio n o f this bo o k and fo r dealing with last-minute figure
c hanges.
Steven Champeo n bro ught his SGML experienc e to the bo o k, and pro vided many
insightful c o mments o n the text. My bro ther Tho mas Haro ld put his c o mmand
o f c hemistry at my dispo sal when I was trying to grasp the Chemic al Markup
Language. Carro ll Bellau pro vided me with parts o f my family tree, whic h yo u’ll
find in Chapter 17.
I also greatly apprec iate all the c o mments, questio ns, and c o rrec tio ns sent in by
readers o f my previo us bo o k, XML: Exte nsible Markup Language . I ho pe that I’ve
managed to address mo st o f tho se c o mments in this bo o k. They’ve definitely
helped make XML Bible a better bo o k. Partic ular thanks are due to Alan Esenther
and Do nald Lanc o n Jr. fo r their espec ially detailed c o mments.
WandaJane Phillips wro te the o riginal versio n o f Chapter 21 o n CDF that is adapted
here. Heather Williamso n, in additio n to perfo rming yeo man-like servic e as tec hnic al
edito r, wro te Chapter 13, CSS Le ve l 2, and parts o f Chapters 18, 19, and 22. Her help
was instrumental in helping me almo st meet my deadline. (Blame fo r this almo st
rests o n my sho ulders, no t theirs.) Also , I wo uld like to thank Piro z Mo hseni, who
also served as a tec hnic al edito r fo r this bo o k.
The agenting talents o f David and Sherry Ro gelberg o f the Studio B Literary Agenc y
( http://www.studiob.com/) have made it po ssible fo r me to write mo re o r less
full-time. I rec o mmend them highly to anyo ne thinking abo ut writing c o mputer
bo o ks. And as always, thanks go to my wife Beth fo r her endless lo ve and
understanding.
Contents at a Glance
Prefac e ................................................................................................................................ix
Ac kno wledgments ..........................................................................................................xvii
Part I: Introducing XM L ......................................................................................1
Chapter 1: An Eagle’s Eye View o f XML ..........................................................................3
Chapter 2: An Intro duc tio n to XML Applic atio ns ........................................................17
Chapter 3: Yo ur First XML Do c ument ..........................................................................49
Chapter 4: Struc turing Data ............................................................................................59
Chapter 5: Attributes, Empty Tags, and XSL ................................................................95
Chapter 6: Well-Fo rmed XML Do c uments
Chapter 7: Fo reign Languages and No n-Ro man Text ................................................161
Part II: Document Type Definitions ............................................................189
Chapter 8: Do c ument Type Definitio ns and Validity ................................................191
Chapter 9: Entities and External DTD Subsets ..........................................................247
Chapter 10: Attribute Dec laratio ns in DTDs ..............................................................283
Chapter 11: Embedding No n-XML Data ......................................................................307
Part III: Style Languages................................................................................321
Chapter 12: Casc ading Style Sheets Level 1 ..............................................................323
Chapter 13: Casc ading Style Sheets Level 2 ..............................................................389
Chapter 14: XSL Transfo rmatio ns ................................................................................433
Chapter 15: XSL Fo rmatting Objec ts ..........................................................................513
Part IV: Supplemental Technologies ..........................................................569
Chapter 16: XLinks ........................................................................................................571
Chapter 17: XPo inters ..................................................................................................591
Chapter 18: Namespac es ..............................................................................................617
Chapter 19: The Reso urc e Desc riptio n Framewo rk ..................................................631
PartV: XM L Applications ................................................................................655
Chapter 20: Reading Do c ument Type Definitio ns ......................................................657
Chapter 21: Pushing Web Sites with CDF ....................................................................775
Chapter 22: The Vec to r Markup Language ................................................................805
Chapter 23: Designing a New XML Applic atio n ..........................................................833
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Contents at a Glance
Appendix A: XML Referenc e Material ........................................................................863
Appendix B: The XML 1.0 Spec ific atio n ......................................................................921
Appendix C: What’s o n the CD-ROM ............................................................................971
Index ................................................................................................................................975
End-User Lic ense Agreement ......................................................................................1018
CD-ROM Installatio n Instruc tio ns ..............................................................................1022
Contents
Prefac e ................................................................................................................................ix
Ac kno wledgments ..........................................................................................................xvii
Part I: Introducing XM L
1
Chapter 1: An Eagle’s Eye View of XM L ........................................................3
What Is XML? ............................................................................................................3
XML Is a Meta-Markup Language .................................................................3
XML Desc ribes Struc ture and Semantic s, No t Fo rmatting ........................4
Why Are Develo pers Exc ited abo ut XML? ............................................................6
Design o f Do main-Spec ific Markup Languages ...........................................6
Self-Desc ribing Data .......................................................................................6
Interc hange o f Data Amo ng Applic atio ns ....................................................7
Struc tured and Integrated Data ....................................................................8
The Life o f an XML Do c ument ................................................................................8
Edito rs .............................................................................................................9
Parsers and Pro c esso rs .................................................................................9
Bro wsers and Other To o ls ............................................................................9
The Pro c ess Summarized ............................................................................10
Related Tec hno lo gies ............................................................................................10
Hypertext Markup Language ......................................................................10
Casc ading Style Sheets ................................................................................11
Extensible Style Language ...........................................................................12
URLs and URIs ..............................................................................................12
XLinks and XPo inters ...................................................................................13
The Unic o de Charac ter Set .........................................................................14
Ho w the Tec hno lo gies Fit To gether ...........................................................14
Chapter 2: An Introduction to XM L Applications ......................................17
What Is an XML Applic atio n? ................................................................................17
Chemic al Markup Language ........................................................................18
Mathematic al Markup Language ................................................................19
Channel Definitio n Fo rmat ..........................................................................22
Classic Literature .........................................................................................22
Sync hro nized Multimedia Integratio n Language ......................................24
HTML+TIME ..................................................................................................25
Open So ftware Desc riptio n .........................................................................26
Sc alable Vec to r Graphic s ............................................................................27
Vec to r Markup Language .............................................................................29
Music ML ........................................................................................................30
Vo xML ............................................................................................................32
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Contents
Open Financ ial Exc hange ............................................................................34
Extensible Fo rms Desc riptio n Language ...................................................36
Human Reso urc es Markup Language ........................................................38
Reso urc e Desc riptio n Framewo rk ..............................................................40
XML fo r XML ...........................................................................................................42
XSL .................................................................................................................42
XLL .................................................................................................................43
DCD ................................................................................................................43
Behind-the-Sc ene Uses o f XML .............................................................................44
Chapter 3: Your First XM L Document ..........................................................49
Hello XML ................................................................................................................49
Creating a Simple XML Do c ument ..............................................................50
Saving the XML File ......................................................................................50
Lo ading the XML File into a Web Bro wser ................................................51
Explo ring the Simple XML Do c ument ..................................................................52
Assigning Meaning to XML Tags ...........................................................................54
Writing a Style Sheet fo r an XML Do c ument .......................................................55
Attac hing a Style Sheet to an XML Do c ument ....................................................56
Chapter 4: Structuring Data ..........................................................................59
Examining the Data ................................................................................................59
Batters ...........................................................................................................60
Pitc hers ..........................................................................................................62
Organizatio n o f the XML Data .....................................................................62
XMLizing the Data ..................................................................................................65
Starting the Do c ument: XML Dec laratio n and Ro o t Element .................65
XMLizing League, Divisio n, and Team Data ..............................................67
XMLizing Player Data ...................................................................................69
XMLizing Player Statistic s ...........................................................................70
Putting the XML Do c ument Bac k To gether Again ....................................72
The Advantages o f the XML Fo rmat ...................................................................80
Preparing a Style Sheet fo r Do c ument Display ...................................................81
Linking to a Style Sheet ...............................................................................82
Assigning Style Rules to the Ro o t Element ...............................................84
Assigning Style Rules to Titles ....................................................................85
Assigning Style Rules to Player
and Statistic s Elements ...........................................................................88
Summing Up ..................................................................................................89
Chapter 5: Attributes, Empty Tags, and XSL ..............................................95
Attributes ................................................................................................................95
Attributes versus Elements ................................................................................101
Struc tured Meta-data .................................................................................102
Meta-Meta-Data ...........................................................................................105
What’s Yo ur Meta-data Is So meo ne Else’s Data ......................................106
Elements Are Mo re Extensible ..................................................................106
Go o d Times to Use Attributes ..................................................................107
Contents
Empty Tags ............................................................................................................108
XSL .........................................................................................................................109
XSL Style Sheet Templates ........................................................................110
The Bo dy o f the Do c ument .......................................................................111
The Title ......................................................................................................113
Leagues, Divisio ns, and Teams .................................................................115
Players .........................................................................................................120
Separatio n o f Pitc hers and Batters ..........................................................122
CSS o r XSL? .................................................................................................130
Chapter 6: Well-Formed XM L Documents ................................................133
#1: The XML dec laratio n must begin the do c ument ..............................144
#2: Use Bo th Start and End Tags in No n-Empty Tags .............................144
Chapter 7: Foreign Languages and Non-Roman Text ............................161
No n-Ro man Sc ripts o n the Web .........................................................................161
Sc ripts, Charac ter Sets, Fo nts, and Glyphs ......................................................166
A Charac ter Set fo r the Sc ript ...................................................................166
A Fo nt fo r the Charac ter Set .....................................................................167
An Input Metho d fo r the Charac ter Set ...................................................167
Operating System and Applic atio n So ftware ..........................................168
Legac y Charac ter Sets .........................................................................................169
The ASCII Charac ter Set ............................................................................169
The ISO Charac ter Sets ..............................................................................172
The Mac Ro man Charac ter Set ..................................................................175
The Windo ws ANSI Charac ter Set ............................................................176
The Unic o de Charac ter Set .................................................................................177
UTF 8 ............................................................................................................182
The Universal Charac ter System ..............................................................182
Ho w to Write XML in Unic o de ............................................................................183
Inserting Charac ters in XML Files with Charac ter Referenc es .............183
Co nverting to and fro m Unic o de ..............................................................184
Ho w to Write XML in Other Charac ter Sets ............................................185
Part II: Document Type Definitions
189
Chapter 8: Document Type Definitions and Validity ..............................191
Do c ument Type Definitio ns ................................................................................191
Do c ument Type Dec laratio ns .............................................................................192
Validating Against a DTD .....................................................................................195
Listing the Elements ............................................................................................201
Element Dec laratio ns ...........................................................................................208
ANY ..............................................................................................................209
#PCDATA ......................................................................................................209
Child Lists ....................................................................................................212
Sequenc es ...................................................................................................214
One o r Mo re Children ................................................................................215
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