<?xml version="1.0" encoding="UTF-8"?>
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xmlns:xlink="http://www.w3.org/1999/xlink"
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<info>
<title>Lecture notes of Martin Goik</title>
<author>
<personname><firstname>Martin</firstname>
<surname>Goik</surname></personname>
<affiliation>
<orgname>https://www.hdm-stuttgart.de/mi</orgname>
</affiliation>
</author>
<legalnotice>
<para>Source code available at <uri
xlink:href="https://gitlab.mi.hdm-stuttgart.de/goik/GoikLectures.git">https://gitlab.mi.hdm-stuttgart.de/goik/GoikLectures.git</uri></para>
</legalnotice>
</info>
<part xml:id="sda1">
<title>Structured Data and Applications 1</title>
<chapter xml:id="basicXmlDataModels">
<title>Basic XML Schema</title>
<para>We would like to support a company's organization. We start
modeling employees. Each employee shall have the following
attributes:</para>
<figure xml:id="fig_ModelEmployee">
<title>Modelling employees</title>
<itemizedlist>
<listitem>
<para>Given name / surname, mandatory</para>
</listitem>
<listitem>
<para>birth date</para>
</listitem>
<listitem>
<para>sex (male/female), mandatory</para>
</listitem>
<listitem>
<para>email</para>
</listitem>
<listitem>
<para>phone</para>
</listitem>
</itemizedlist>
<para>In addition we want each dataset to receive a unique identity
attribute <code>id</code> <coref linkend="co_uniqueId"/> in order to
distinguish between employees having identical names by coincidence.
Regarding relational databases we may start with the following
implementation:</para>
</figure>
<figure xml:id="fig_SqlDdlEmployee">
<title>Relational database implementation of employees</title>
<programlisting language="sql">CREATE TABLE EMPLOYEE
(
ID BIGINT <co xml:id="co_uniqueId"/> NOT NULL PRIMARY KEY,
GIVENNAME CHAR(20) NOT NULL,
SURNAME CHAR(20) NOT NULL,
BIRTHDATE DATE,
SEX CHAR NOT NULL,
EMAIL CHAR(20),
PHONE CHAR(20)
);</programlisting>
</figure>
<qandaset defaultlabel="qanda"
xml:id="sda1QandaImplicitSchemaConstraints">
<title>Implicit model parameters</title>
<qandadiv>
<qandaentry xml:id="quandaentry_companyAddionIntegrity">
<question>
<para><xref linkend="fig_SqlDdlEmployee"/> shows an
implementation of <xref linkend="fig_ModelEmployee"/>. But it
does contain additional integrity constraints of two different
categories not being stated in <xref
linkend="fig_ModelEmployee"/>.</para>
</question>
<answer>
<itemizedlist>
<listitem>
<para>Each attribute is being typed. For example <code
language="sql">BIRTHDAY DATE</code> declares an attribute
<code language="sql">BIRTHDAY</code> of SQL type
<code>DATE</code>.</para>
</listitem>
<listitem>
<para>An attribute may or may not allow for <code
language="sql">NULL</code> values.</para>
</listitem>
</itemizedlist>
</answer>
</qandaentry>
</qandadiv>
</qandaset>
<para>We may as well represent our current physical <link
linkend="gloss_SQL">SQL</link> model graphically. The annotation
<quote>(<abbrev>NN</abbrev>)</quote> denotes <quote><code>not
nullable</code></quote>:</para>
<figure xml:id="fig_GraphModelEmployee">
<title>Graphical representation of employees' model.</title>
<mediaobject>
<imageobject>
<imagedata fileref="Ref/Fig/employee.png"/>
</imageobject>
</mediaobject>
</figure>
<para>We now turn to <link linkend="gloss_XML">XML</link> representation
of data. Completely disregarding integrity constraints we may use a so
called <emphasis>well formed</emphasis> XML file representation:</para>
<figure xml:id="fig_EmployeeWellformed">
<title>Representing an employee's data</title>
<programlisting language="xml"><?xml version="1.0" encoding="UTF-8"?>
<employee>
<id>21</id>
<givenName>Bob</givenName>
<surname>Hope</surname>
<birthday>1982-07-22</birthday>
<sex>m</sex>
<email>hope@exploitation.com</email>
<phone>1123-33244</phone>
</employee></programlisting>
</figure>
<para><link linkend="gloss_XML">XML</link> allows for multiple employees
as well:</para>
<programlisting language="xml"><?xml version="1.0" encoding="UTF-8"?>
<employeeList>
<employee>
<id>21</id>
<givenName>Bob</givenName>
<surname>Hope</surname>
<birthday>1982-07-22</birthday>
<sex>m</sex>
<email>hope@exploitation.com</email>
<phone>1123-33244</phone>
</employee>
<employee>
<id>22</id>
<givenName>Gill</givenName>
<surname>Evans</surname>
<birthday>1973-01-15</birthday>
<sex>f</sex>
<email>gill@flashmaster.com</email>
<phone>9771-43421</phone>
</employee>
</employeeList></programlisting>
<qandaset defaultlabel="qanda" xml:id="sda1QandaWellFormed">
<title>Well-formed XML data questions</title>
<qandadiv>
<qandaentry xml:id="quandaentry_prologueRequired">
<question>
<para>Is the prologue <emphasis role="bold"><code><?xml
version="1.0" encoding="UTF-8"?></code></emphasis> mandatory
for a file to become a well formed XML document? Find the
corresponding passage in the <link
xlink:href="https://www.w3.org/TR/2008/REC-xml-20081126">XML 1.0
standard reference document</link> and explain your
answer.</para>
</question>
<answer>
<para>The <link
xlink:href="https://www.w3.org/TR/2008/REC-xml-20081126/#sec-prolog-dtd">Prolog
and Document Type Declaration</link> section defines <emphasis
role="bold"><code><?xml version="1.0" ...
?></code></emphasis> defines this header as being optional
(<emphasis role="bold">should</emphasis>). In addition the <link
linkend="gloss_EBNF">EBNF</link> diagram
contains:<programlisting language="ebnf">22] prolog ::= XMLDecl<emphasis
role="bold">?</emphasis> <co xml:id="co_XmlDeclOptional"/>...</programlisting>The
<quote>?</quote> <coref linkend="co_XmlDeclOptional"/> tells us
that the header in question may appear once or may be
omitted.</para>
</answer>
</qandaentry>
<qandaentry xml:id="quandaentry_prologueVersionExplain">
<question>
<para>Explain the meaning of the <emphasis role="bold"><code
language="xml">version="1.0"</code></emphasis> prologue
attribute.</para>
</question>
<answer>
<para>The version attribute allows for an evolving XML standard.
This way XML parsers are able to parse XML documents adhering to
different XML standard versions.</para>
<para>For example XML documents adhering to the (unsuccessful)
<link xlink:href="https://www.w3.org/TR/xml11/#sec-xml11">XML
1.1</link> Standard may be analyzed by a parser accordingly by
reading the prologue to apply the respective rule set.</para>
</answer>
</qandaentry>
<qandaentry xml:id="quandaentry_prologueEncodingExplain">
<question>
<para>Explain the meaning of <emphasis role="bold"><code
language="xml">encoding="UTF-8"</code></emphasis> prologue
attribute. What about other values than <code>UTF-8</code>
?</para>
</question>
<answer>
<para>XML allows for choosing an encoding like <code
language="xml">encoding="US-ASCII"</code> or <code
language="xml">encoding="ISO-8859-1" for western European
countries</code>. So the XML standard supports
<trademark>Unicode</trademark> but may use different encodings
as well.</para>
</answer>
</qandaentry>
</qandadiv>
</qandaset>
<qandaset defaultlabel="qanda" xml:id="sda1QandaMediaStore">
<title>Building up a media store software</title>
<qandadiv>
<qandaentry xml:id="quandaentry_mediaformatSQL">
<question xml:id="quandaentry_mediaFormats">
<para>We do a step by step development of a media store in
parallel to the company example. This is an ongoing set of
exercises.</para>
<para>We start representing media formats like
<abbrev>Mp3</abbrev>, <abbrev>Flac</abbrev>,
<abbrev>Avi</abbrev> and so on. True media objects like album
tracks will later reference a given media format. So our format
descriptions are independent from the actual media
content:</para>
<informalfigure>
<mediaobject>
<imageobject>
<imagedata fileref="Ref/Fig/mediaFormat.png"/>
</imageobject>
</mediaobject>
</informalfigure>
<para>Implement the given entity as a relational table and
create a well-formed sample XML dataset. Explain the ratio
behind the seemingly redundant definition of a second <code
language="sql">UNIQUE</code> attribute <code>CODE</code> on top
of the primary key attribute <code>ID</code>.</para>
</question>
<answer>
<para>The following table may represent different formats and
codecs:</para>
<programlisting language="sql">CREATE TABLE MEDIAFORMAT (
ID BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
NAME CHAR(10) NOT NULL UNIQUE COMMENT 'mp3,flac,avi,...',
CODE INT NOT NULL UNIQUE COMMENT 'unique number representing a mediaformat'
);</programlisting>
<para>Having a second attribute CODE allows us to keep primary
key values immutable. Thus foreign key definitions referencing
<code>Mediaformat</code> datasets remain stable if we change
values of <code>CODE</code> attribute values. This way we avoid
<code language="sql">ON UPDATE CASCADE</code> clauses giving
rise to performance problems.</para>
<para>XML sample data may be represented as:</para>
<programlisting language="xml"><?xml version="1.0" encoding="UTF-8"?>
<formatlist>
<format>
<id>1</id>
<name>MP3</name>
<code>12</code>
</format>
<format>
<id>2</id>
<name>FLAC</name>
<code>7</code>
</format>
</formatlist></programlisting>
</answer>
</qandaentry>
</qandadiv>
</qandaset>
<section xml:id="xmlDataTypes">
<title>XML data typing</title>
<para>So far our database representation limits attribute values to
domains by imposing type restrictions. We recall <xref
linkend="fig_SqlDdlEmployee"/>. For example the following
<code>UPDATE</code> statement will fail:</para>
<programlisting language="sql"><emphasis role="bold">-- Subsequent UPDATE yields "Incorrect integer value: 'thousand' for column 'ID'" --</emphasis>
UPDATE EMPLOYEE
SET id = 'thousand'
WHERE ID=1</programlisting>
<para>On contrary XML data just being well formed imposes no
restrictions at all:</para>
<programlisting language="xml"><employee>
<id><emphasis role="bold">Thousand</emphasis></id>
<givenName>Bob</givenName>
</employee></programlisting>
<para>So apparently well formedness of XML data does not meet
programming standards for declarative specification of data integrity
constraints. For this purpose the following three standards are on
offer:</para>
<itemizedlist>
<listitem>
<para><link linkend="gloss_DTD">DTD</link> (old)</para>
</listitem>
<listitem>
<para><link linkend="gloss_RelaxNG">RelaxNG</link> (document
oriented)</para>
</listitem>
<listitem>
<para><link linkend="gloss_XmlSchema">XML Schema</link> (data
oriented)</para>
</listitem>
</itemizedlist>
<para>In this lecture only <link linkend="gloss_XmlSchema">XML
Schema</link> is being described. Regarding a database schema like
<xref linkend="fig_SqlDdlEmployee"/> the <link
linkend="gloss_XmlSchema">XML Schema</link> standard offers a
counterpart namely an <emphasis>XML Schema Definition</emphasis>
(<filename>.xsd</filename>). We consider the following file
<filename>employee.xsd</filename>:</para>
<figure xml:id="fig_XsdEmployee">
<title>A schema describing an employee's data structure</title>
<programlisting language="xml"><?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" >
<xs:element name="employee">
<xs:complexType>
<xs:sequence>
<xs:element name="id" type="xs:unsignedInt" <co
xml:id="co_IdNonNegative"/> />
<xs:element name="givenName" type="xs:string"/>
<xs:element name="surname" type="xs:string"/>
<xs:element name="birthday" type="xs:string"/>
<xs:element name="sex" type="xs:string"/>
<xs:element name="email" type="xs:string"/>
<xs:element name="phone" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema></programlisting>
</figure>
<para>Notice the subtle difference with respect to the id attribute
<coref linkend="co_IdNonNegative"/>: We expect this attribute to have
non-negative values. To ensure this integrity constraint the<link
linkend="gloss_XSD"> XSD</link> standard data type
<code>xs:unsignedInt</code> has been chosen in favour of
<code>xs:int</code>.</para>
<para>This XML schema definition acts like <code>CREATE TABLE</code>
statements with respect to relational databases. It adds a grammar to
our XML data thereby enabling validation:</para>
<programlisting language="xml"><?xml version="1.0" encoding="UTF-8"?>
<employee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="<emphasis role="bold">employee.xsd</emphasis>">
<id>21</id>
<givenName>Bob</givenName>
<surname>Hope</surname>
<birthday>1982-07-22</birthday>
<sex>m</sex>
<email>hope@exploitation.com</email>
<phone>1123-33244</phone>
</employee></programlisting>
<para>Having just one employee isn't very satisfying. We choose one of
different possibilities to allow for a sequence of employees:</para>
<figure xml:id="fig_ListOfEmployees">
<title>A list of employees</title>
<programlisting language="xml"><xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" >
<xs:element name="employee"> <co linkends="schemaElementReference-1"
xml:id="schemaElementReference-1-co"/>
<xs:complexType>
<xs:sequence>
<xs:element name="id" type="xs:unsignedInt"/>
<xs:element name="givenName" type="xs:string"/>
<xs:element name="surname" type="xs:string"/>
<xs:element name="birthday" type="xs:string"/>
<xs:element name="sex" type="xs:string"/>
<xs:element name="email" type="xs:string"/>
<xs:element name="phone" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="employeeList">
<xs:complexType>
<xs:sequence>
<xs:element ref="employee" <co
linkends="schemaElementReference-2"
xml:id="schemaElementReference-2-co"/>
minOccurs="0" <co linkends="schemaElementReference-3"
xml:id="schemaElementReference-3-co"/>
maxOccurs="unbounded"/> <co
linkends="schemaElementReference-3"
xml:id="schemaElementReference-4-co"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema></programlisting>
</figure>
<calloutlist>
<callout arearefs="schemaElementReference-1-co"
xml:id="schemaElementReference-1">
<para>Defining an employee's data structure like in <xref
linkend="fig_XsdEmployee"/>.</para>
</callout>
<callout arearefs="schemaElementReference-2-co"
xml:id="schemaElementReference-2">
<para>An element is being defined by referencing the definition in
<coref linkend="schemaElementReference-1-co"/>.</para>
</callout>
<callout arearefs="schemaElementReference-3-co schemaElementReference-4-co"
xml:id="schemaElementReference-3">
<para>We may have an arbitrary number of employee datasets
including none at all.</para>
</callout>
</calloutlist>
<para>This allows for an arbitrary number of employee data
sets:</para>
<programlisting language="xml"><employeeList xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="employee.xsd">
<employee>
<id>21</id>
<givenName>Bob</givenName>
<surname>Hope</surname>
<birthday>1982-07-22</birthday>
<sex>m</sex>
<email>hope@exploitation.com</email>
<phone>1123-33244</phone>
</employee>
<employee>
<id>22</id>
<givenName>Gill</givenName>
<surname>Evans</surname>
<birthday>1973-01-15</birthday>
<sex>f</sex>
<email>gill@flashmaster.com</email>
<phone>9771-43421</phone>
</employee>
</employeeList></programlisting>
<qandaset defaultlabel="qanda" xml:id="sda1QandaMediaFormatGrammar">
<title>Adding a grammar to <tag
class="starttag">mediaFormat</tag>.</title>
<qandadiv>
<qandaentry xml:id="quandaentry_Track">
<question>
<para>Consider the following example of an album consisting of
tracks:</para>
<table border="1" width="70%" xml:id="table_AlbumExample">
<caption>An example album</caption>
<colgroup width="10%"/>
<colgroup width="76%"/>
<colgroup width="14%"/>
<tr>
<th>Album:</th>
<td colspan="2">...Nothing Like the Sun</td>
</tr>
<tr>
<th>Artist:</th>
<td colspan="2">Sting</td>
</tr>
<tr>
<th colspan="3"/>
</tr>
<tr>
<th>Track number</th>
<th>track title</th>
<th>track time</th>
</tr>
<tr>
<td>1</td>
<td>The Lazarus Heart</td>
<td>4:34</td>
</tr>
<tr>
<td>2</td>
<td>Be Still My Beating Heart</td>
<td>5:32</td>
</tr>
<tr>
<td>3</td>
<td>Englishman in New York</td>
<td>4:25</td>
</tr>
<tr>
<th>...</th>
<th>...</th>
<th>...</th>
</tr>
</table>
<para>In the current exercise we'll only consider the tracks
themselves:</para>
<figure xml:id="fig_SingleMusicTrack">
<title>A single music track</title>
<mediaobject>
<imageobject>
<imagedata fileref="Ref/Fig/track.png"/>
</imageobject>
</mediaobject>
</figure>
<para>Though all tracks of a given album will typically share
a common media format like e.g. MP3 our model allows each
track having its own encoding. Create a well formed XML file
containing the three tracks from <xref
linkend="table_AlbumExample"/>.</para>
</question>
<answer>
<para>We omit the XML header for brevity in accordance with
the XML 1.0 specification:</para>
<programlisting language="xml"><trackList>
<track>
<id>231</id>
<album>...Nothing Like the Sun</album>
<number>1</number>
<name>The Lazarus Heart</name>
<duration>4:34</duration>
<mediaformat>MP3</mediaformat>
</track>
<track>
<id>232</id>
<album>...Nothing Like the Sun</album>
<number>2</number>
<name>Be Still My Beating Heart</name>
<duration>5:32</duration>
<mediaformat>MP3</mediaformat>
</track>
<track>
<id>233</id>
<album>Englishman in New York</album>
<number>3</number>
<name>Be Still My Beating Heart</name>
<duration>4:25</duration>
<mediaformat>MP3</mediaformat>
</track>
</trackList></programlisting>
</answer>
</qandaentry>
<qandaentry xml:id="quandaentry_TrackXmlSchema">
<question>
<para>Reconsider the current track model to create a suitable
XML schema <filename>track.xsd</filename> allowing for an
arbitrary number of tracks.</para>
<para>Hints: Regarding a track's time data type look for the
heading <quote><emphasis role="bold">Duration Data
Type</emphasis></quote> in <link
xlink:href="http://www.w3schools.com/xml/schema_dtypes_date.asp">http://www.w3schools.com/xml/schema_dtypes_date.asp</link>
and consider the corresponding reference definition in <link
xlink:href="https://www.w3.org/TR/xmlschema11-2/#duration">http://www.w3.org/TR/xmlschema11-2</link>.</para>
</question>
<answer>
<para>A single track may be modeled by
<filename>track.xsd</filename>:</para>
<programlisting language="xml"><xs:element name="track">
<xs:complexType>
<xs:sequence>
<xs:element name="id" type="xs:unsignedInt"/>
<xs:element name="album" type="xs:string"/>
<xs:element name="number" type="xs:unsignedInt"/>
<xs:element name="name" type="xs:string"/>
<emphasis role="bold"><xs:element name="duration" type="xs:duration"/></emphasis> <co
xml:id="co_DurationExample"/>
<xs:element name="mediaformat" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element></programlisting>
<para>The element duration <coref
linkend="co_DurationExample"/> offers a precise syntax <coref
linkend="co_DurationExampleValue"/> describing time
periods:</para>
<programlisting continuation="continues" language="xml"><track xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="track.xsd">
<id>231</id>
<album>...Nothing Like the Sun</album>
<number>1</number>
<name>The Lazarus Heart</name>
<emphasis role="bold"><duration>PT4M34S</duration></emphasis> <co
xml:id="co_DurationExampleValue"/>
<mediaformat>MP3</mediaformat>
</track></programlisting>
<para>Extending the current model to a set of tracks is
straightforward cf. <xref
linkend="fig_ListOfEmployees"/>:</para>
<programlisting language="xml"><xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
<xs:element name="trackList">
<xs:complexType>
<xs:sequence>
<xs:element ref="track"
minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="track">
<xs:complexType>
<xs:sequence>
<xs:element name="id" type="xs:unsignedInt"/>
<xs:element name="album" type="xs:string"/>
<xs:element name="number" type="xs:unsignedInt"/>
<xs:element name="name" type="xs:string"/>
<xs:element name="duration" type="xs:duration"/>
<xs:element name="mediaformat" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema></programlisting>
<para>This allows for an arbitrary number of tracks:</para>
<figure xml:id="fig_TwoTrackBasic">
<title>Two tracks belonging to the same album.</title>
<programlisting language="xml"><trackList xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="trackList.xsd">
<track>
<id>231</id>
<album>...Nothing Like the Sun</album>
<number>1</number>
<name>The Lazarus Heart</name>
<duration>PT4M34S</duration>
<mediaformat>mp3</mediaformat>
</track>
<track>
<id>232</id>
<album>...Nothing Like the Sun</album>
<number>2</number>
<name>Be Still My Beating Heart</name>
<duration>PT5M32S</duration>
<mediaformat>flac</mediaformat>
</track>
<!-- maybe more to come ... -->
</trackList></programlisting>
</figure>
</answer>
</qandaentry>
</qandadiv>
</qandaset>
</section>
<section xml:id="restrictDataTypes">
<title>User defined data types</title>
<para>Some SQL and XML Schema data types are quite appropriate.
Correct <code>BIRTHDAY</code> values are being well described by its
<link linkend="gloss_SQL">SQL</link> data type
<code>DATE</code>.</para>
<para>We may however want add further restrictions on existing types
to enhance data integrity. The attribute <code>SEX</code> for example
may be restricted to allow only male/'m' and female/'f' values. <link
linkend="gloss_SQL">SQL</link> enables us to do so by adding a
<code>CHECK</code> constraint <coref linkend="co_CheckSex"/>:</para>
<programlisting language="sql">CREATE TABLE EMPLOYEE
(
...
SEX CHAR NOT NULL,
...
<emphasis role="bold">CHECK(SEX in ('m', 'f'))</emphasis> <co
xml:id="co_CheckSex"/>
);</programlisting>
<para>This constraint effectively restricts the domain of arbitrary
character values to a set of just two values {'m', 'f'}.</para>
<para>XML Schema provides similar means to enforce data integrity.
Consider for example a rule enforcing id attribute values to a minimum
of 200. This rule may be implemented by restricting the domain of
unsigned integer values <coref linkend="co_RestrictInt"/> to numbers
starting from and including 200 <coref
linkend="co_RestrictInt200"/>:</para>
<programlisting language="xml"><xs:element name="employee">
<xs:annotation>
<emphasis role="bold"><xs:documentation>restricting possible values of id</xs:documentation></emphasis> <co
xml:id="co_CommentOnElement"/>
</xs:annotation>
<xs:complexType>
<xs:sequence>
<xs:element name="id">
<xs:simpleType>
<xs:restriction base="xs:unsignedInt"> <co
xml:id="co_RestrictInt"/>
<emphasis role="bold"><xs:minInclusive value="200"/></emphasis> <co
xml:id="co_RestrictInt200"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="givenName" type="xs:string"/>
...
</xs:sequence>
</xs:complexType>
</xs:element></programlisting>
<para>Notice the ability ox XML Schema to allow structured comments
<coref linkend="co_CommentOnElement"/>. The following document
instance violates the rule in question:</para>
<programlisting language="xml"><employee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="employee.xsd">
<id>21</id>
<givenName>Bob</givenName>
...
</employee></programlisting>
<para>A validating parser thus yields a corresponding error
message:</para>
<screen>cvc-minInclusive-valid: Value '21' is not facet-valid with respect to minInclusive '200'
for type <emphasis role="bold">'#AnonType_idemployee'</emphasis> <co
xml:id="co_ErrAnonTypeEmployee"/></screen>
<qandaset defaultlabel="qanda" xml:id="sda1QandamMessageErrorType">
<title>The type error message in detail</title>
<qandadiv>
<qandaentry xml:id="quandaentry_AnonTypeMsg">
<question>
<para>What does the somewhat strange value <emphasis
role="bold">#AnonType_idemployee</emphasis> in the error
message indicate? Hint: The parser chooses this value since
something optional is missing.</para>
</question>
<answer>
<para>To better understand the error message note that we have
defined a new type namely the subset of all
<code>xs:unsignedInt</code> values starting from 200. This
data type has not been given a name like
<code>integerLargerThan200</code>. Consequently we call this
an anonymous type.</para>
<para>The parser internally assigns the<code> synthetic name
</code><quote><code>#AnonType_idemployee</code></quote>
appearing in the error message .</para>
</answer>
</qandaentry>
</qandadiv>
</qandaset>
<para>Though we have implemented the desired restrictions two topics
may still be addressed:</para>
<itemizedlist>
<listitem>
<para>Our new data type <quote>integer values starting from
200</quote> might be used to restrict other elements as well. For
example <tag class="starttag">id</tag> elements typically appear
once per employee and other entities. We want to be able reusing
data type definitions in favour of "copy/paste". The following
code illustrates the problem of duplicated type
definitions:</para>
<figure xml:id="fig_AnonDuplicateTypeDef">
<title>Two identical and thus redundant anonymous type
definitions</title>
<programlisting language="xml">...
<emphasis role="bold"><xs:element name="employee"></emphasis>
<xs:complexType>
<xs:sequence>
<xs:element name="id">
<emphasis role="bold"><xs:simpleType>
<xs:restriction base="xs:integer">
<xs:minInclusive value="200"/>
</xs:restriction>
</xs:simpleType></emphasis>
</xs:element>
<xs:element name="givenName" type="xs:string"/>
...
</xs:sequence>
</xs:complexType>
</xs:element>
<emphasis role="bold"><xs:element name="department"></emphasis>
<xs:complexType>
<xs:sequence>
<xs:element name="id">
<emphasis role="bold"><!-- Duplicate type definition --></emphasis>
<emphasis role="bold"><xs:simpleType>
<xs:restriction base="xs:integer">
<xs:minInclusive value="200"/>
</xs:restriction>
</xs:simpleType></emphasis>
</xs:element>
...</programlisting>
</figure>
</listitem>
<listitem>
<para>User defined data types should have names rather than being
anonymous to provide better code understanding.</para>
</listitem>
</itemizedlist>
<para>The XML Schema standard supports named type definitions. <xref
linkend="fig_AnonDuplicateTypeDef"/> may be represented by:</para>
<figure xml:id="fig_CentralizedIdDefinition">
<title>Defining a separate non-anonymous identity data type</title>
<programlisting language="xml"><emphasis role="bold"><xs:simpleType name="NumericIdentity"></emphasis> <emphasis
role="bold"><!-- User defined type NumericIdentity --></emphasis>
<xs:restriction base="xs:unsignedInt">
<xs:minInclusive value="200"/>
</xs:restriction>
</xs:simpleType>
<xs:element name="employee">
<xs:complexType>
<xs:sequence>
<emphasis role="bold"><!-- type referral to previously defined type -->
<xs:element name="id" type="NumericIdentity"/></emphasis>
<xs:element name="givenName" type="xs:string"/>
<xs:element name="surname" type="xs:string"/>
<xs:element name="birthday" type="xs:string"/>
<xs:element name="sex" type="xs:string"/>
<xs:element name="email" type="xs:string"/>
<xs:element name="phone" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<emphasis role="bold"><xs:element name="department"></emphasis>
<xs:complexType>
<xs:sequence>
<emphasis role="bold"><!-- type referral to previously defined type NumericIdentity -->
</emphasis> <emphasis role="bold"><xs:element name="id" type="NumericIdentity"/></emphasis>
...</programlisting>
</figure>
<qandaset defaultlabel="qanda" xml:id="sda1QandaEncFormats">
<title>Predefined set of track encoding formats</title>
<qandadiv>
<qandaentry xml:id="quandaentry_XmlRestrictCodecs">
<question>
<para>Your current <filename><link
linkend="fig_TwoTrackBasic">track.xsd</link></filename> schema
allows for arbitrary encoding values like <tag
class="starttag">mediaformat</tag>mp3<tag
class="endtag">mediaformat</tag>. Restrict its values to the
set {<code>mp3</code>, <code>flac</code>,
<code>mp4</code>}.</para>
<para>Hint: Media encoding names disallow spaces and special
characters. In a nutshell allowed values syntactically
resemble typical naming conventions for tokens in programming
languages. So a token type may be restricted to the above set.
The corresponding chapter in <xref linkend="bib_Walmsley02"/>
dealing with data types provides a similar example.</para>
</question>
<answer>
<para>We may define a new type named
<code>TrackEncoding</code> allowing our three allowed
values:</para>
<programlisting language="xml"><emphasis role="bold"><xs:simpleType name="TrackEncoding"></emphasis>
<xs:restriction>
<xs:simpleType>
<xs:list itemType="xs:token"/>
</xs:simpleType>
<emphasis role="bold"><xs:enumeration value="mp3"/>
<xs:enumeration value="mp4"/>
<xs:enumeration value="flac"/></emphasis>
</xs:restriction>
</xs:simpleType></programlisting>
<para>This new type replaces our current
<code>xs:string</code> data type:</para>
<programlisting language="xml"><xs:element name="track">
<xs:complexType>
<xs:sequence>
...
<xs:element name="duration" type="xs:duration"/>
<emphasis role="bold"><xs:element name="mediaformat" type="TrackEncoding"/></emphasis>
</xs:sequence>
</xs:complexType>
</xs:element></programlisting>
</answer>
</qandaentry>
</qandadiv>
</qandaset>
</section>
<section xml:id="sect_OptionsAndChoices">
<title>Optional content and choices</title>
<para>Elements may be optional. We allow an element <tag
class="starttag">middleInitial</tag> in employee instances:</para>
<programlisting language="xml"><employee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="employee.xsd">
<id>21</id>
<givenName>John</givenName>
<emphasis role="bold"><middleInitial>Fitzgerald</middleInitial></emphasis>
<surname>Kennedy</surname>
...
</employee></programlisting>
<para>Since not every employee has a middle initial this element has
to be optional. This may be achieved by defining
<code>minOccurs="0"</code> and <code>maxOccurs="1"</code>:</para>
<programlisting language="xml"><xs:element name="employee">
<xs:complexType>
<xs:sequence>
<xs:element name="id" type="xs:unsignedInt"/>
<xs:element name="givenName" type="xs:string"/>
<emphasis role="bold"><xs:element name="middleInitial" type="xs:string" minOccurs="0" maxOccurs="1"/></emphasis>
<xs:element name="surname" type="xs:string"/>
...
</xs:sequence>
</xs:complexType>
</xs:element></programlisting>
<qandaset defaultlabel="qanda"
xml:id="sda1QandaMutualExclusiveElemens">
<title>Mutual exclusive elements</title>
<qandadiv>
<qandaentry xml:id="quandaentry_SchemaChoice">
<question>
<para>XML Schema does allow us to define an exclusive choice
between a given set of alternatives. Consider the following
example:</para>
<programlisting language="xml"><xs:element name="employee">
<xs:complexType>
<xs:sequence>
<xs:element name="id" type="xs:unsignedInt"/>
<xs:element name="givenName" type="xs:string"/>
<xs:element name="middleInitial" type="xs:string" minOccurs="0" maxOccurs="1"/>
<xs:element name="surname" type="xs:string"/>
<xs:element name="birthday" type="xs:string"/>
<xs:element name="sex" type="xs:string"/>
<xs:element name="email" type="RfcEmail" minOccurs="0" maxOccurs="1"/>
<xs:element name="phone" type="xs:string" minOccurs="0" maxOccurs="1"/>
<xs:element name="skype" type="xs:string" minOccurs="0" maxOccurs="1"/>
</xs:sequence>
</xs:complexType>
</xs:element></programlisting>
<para>This XML schema allows for eight (why?) different
classes with respect to the occurrence of <tag
class="starttag">email</tag>, <tag
class="starttag">phone</tag> or <tag
class="starttag">skype</tag> id. We show possible
examples:</para>
<glosslist>
<glossentry>
<glossterm>An employee having all three address attributes
<coref linkend="prog_PowerAllEmail"/>, <coref
linkend="prog_PowerAllPhone"/> and <coref
linkend="prog_PowerAllSkype"/>:</glossterm>
<glossdef>
<programlisting language="xml"><employee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="employee.xsd">
<id>25</id>
<givenName>Laura</givenName>
<surname>Anderson</surname>
<birthday>1956-41-02</birthday>
<sex>f</sex>
<email>anderson@corporate.com</email> <co
xml:id="prog_PowerAllEmail"/>
<phone>223-324323</phone> <co xml:id="prog_PowerAllPhone"/>
<skype>l.anderson</skype> <co xml:id="prog_PowerAllSkype"/>
</employee></programlisting>
</glossdef>
</glossentry>
<glossentry>
<glossterm>An employee having no address attribute at
all:</glossterm>
<glossdef>
<programlisting language="xml"><employee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
...
<surname>Anderson</surname>
<birthday>1956-41-02</birthday>
<sex>f</sex>
</employee></programlisting>
</glossdef>
</glossentry>
<glossentry>
<glossterm>An employee having <tag
class="starttag">email</tag> <coref
linkend="prog_PowerEmailSkype_Email"/> and <tag
class="starttag">skype</tag> id <coref
linkend="prog_PowerEmailSkype_Skype"/> but no <tag
class="starttag">phone</tag> number:</glossterm>
<glossdef>
<programlisting language="xml"><employee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
...
<surname>Anderson</surname>
<birthday>1956-41-02</birthday>
<sex>f</sex>
<email>anderson@corporate.com</email> <co
xml:id="prog_PowerEmailSkype_Email"/>
<skype>l.anderson</skype> <co
xml:id="prog_PowerEmailSkype_Skype"/>
</employee></programlisting>
</glossdef>
</glossentry>
</glosslist>
<para>We want to resole this ambiguity by restricting employee
data according to the following rule:</para>
<itemizedlist>
<listitem>
<para>Each employee shall have exactly one address either
being <tag class="starttag">email</tag>, <tag
class="starttag">phone</tag> or <tag
class="starttag">skype</tag> id.</para>
</listitem>
</itemizedlist>
<para>Create an appropriate XML Schema. <emphasis
role="bold">Hint:</emphasis> Read the documentation of the XML
Schema element <emphasis role="bold"><tag
class="starttag">xs:choice</tag></emphasis>.</para>
</question>
<answer>
<para>An <tag class="starttag">xs:choice</tag> element
implements the rule in question:</para>
<programlisting language="xml"><xs:element name="employee">
<xs:complexType>
<xs:sequence>
...
<xs:choice>
<xs:element name="email" type="RfcEmail"/>
<xs:element name="phone" type="xs:string"/>
<xs:element name="skype" type="xs:string"/>
</xs:choice>
</xs:sequence>
</xs:complexType>
</xs:element></programlisting>
<para>Now the following example will fail with the error
message <emphasis role="bold"><quote>Invalid content was found
starting with element 'phone'. No child element is expected at
this point</quote></emphasis>:</para>
<programlisting language="xml"><employee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="addressChoice.xsd">
<id>25</id>
<givenName>Laura</givenName>
<surname>Anderson</surname>
<birthday>1956-41-02</birthday>
<sex>f</sex>
<email>anderson@corporate.com</email>
<phone>223-324323</phone>
<skype>l.anderson</skype>
</employee></programlisting>
</answer>
</qandaentry>
</qandadiv>
</qandaset>
</section>
<section xml:id="xmlAttributes">
<title>XML Attributes</title>
<para>So far we used sub elements to represent data in XML. It is
possible to use attributes instead. The following example is
equivalent to <xref linkend="fig_EmployeeWellformed"/>:</para>
<programlisting language="xml"><employee id = "21" givenName = "Bob" surname = "Hope"
birthday = "1982-07-22" sex = "m"
email = "hope@exploitation.com" phone= "1123-33244"/></programlisting>
<para>XML Schema allows to impose data integrity constraints on
attributes equivalent to element definitions. Thus <xref
linkend="fig_XsdEmployee"/> may be replaced by <tag
class="emptytag">xs:attribute</tag> definitions:</para>
<programlisting language="xml"><xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" >
<xs:element name="employee">
<xs:complexType>
<xs:attribute name="id" type="xs:unsignedInt"/>
<xs:attribute name="givenName" type="xs:string"/>
<xs:attribute name="surname" type="xs:string"/>
<xs:attribute name="birthday" type="xs:string"/>
<xs:attribute name="sex" type="xs:string"/>
<xs:attribute name="email" type="xs:string"/>
<xs:attribute name="phone" type="xs:string"/>
</xs:complexType>
</xs:element>
</xs:schema></programlisting>
<para>We may reference the above schema constructing a valid XML
instance:</para>
<programlisting language="xml"><employee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="employeeAttrib.xsd"
id = "21"
givenName = "Bob"
surname = "Hope"
birthday = "1982-07-22"
sex = "m"
email = "hope@exploitation.com"
phone = "1123-33244"
/></programlisting>
<para>So you might have the impression about <tag
class="starttag">xs:element</tag> and <tag
class="starttag">xs:attribute</tag> being equivalent. Attributes
however do have limitations with respect to element
declarations:</para>
<orderedlist>
<listitem>
<para>XML attributes forbid multiple values whereas <tag
class="starttag">xs:element</tag> declarations may allow (via
<code>maxOccurs</code>) the repeated appearance of a given
element:</para>
<programlisting language="xml"><employee>
...
<email>gill@flashmaster.com</email>
<email>gilly@private.org</email>
<phone>9771-43421</phone>
</employee></programlisting>
<para>The following <quote>equivalent</quote> with duplicate
attribute names is off course wrong as it would also be in a
<trademark linkend="gloss_Java">Java</trademark> class
declaration:</para>
<programlisting language="xml"><employee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="employeeAttrib.xsd"
...
email = "gill@flashmaster.com"
email = "gilly@private.org"
phone ="9771-43421"
/></programlisting>
</listitem>
<listitem>
<para>During schema evolution elements sometimes require a more
complex structure. Consider an element representing phone
numbers:</para>
<programlisting language="xml"><employee>
...
<phone>9771-43421</phone>
</employee></programlisting>
<para>The transformation into an <tag
class="starttag">xs:attribute</tag> declaration is
straightforward. Beware however about a possible business
requirement for the representation of area codes:</para>
<programlisting language="xml"><employee>
...
<phone>
<area>9771</area>
<local>43421</local>
</phone>
</employee></programlisting>
<para>The transformation of <tag
class="starttag">xs:attribute</tag> based data and dependent
applications may be more difficult than having the schema based on
<tag class="starttag">xs:element</tag> in the first place.</para>
<remark>Rule of thumb: Whenever you do consider a value possibly
demanding an inner structure choose <xs:element> in favour
of <xs:attribute>.</remark>
</listitem>
</orderedlist>
<para><tag class="starttag">xs:attribute</tag> declarations offer an
optional attribute <code>use</code>:</para>
<programlisting language="xml"><xs:element name="employee">
<xs:complexType>
...
<xs:attribute name="email" type="xs:string" use="required"/>
<xs:attribute name="phone" type="xs:string" use="optional" default="12212-0"/>
</xs:complexType>
</xs:element></programlisting>
<qandaset defaultlabel="qanda" xml:id="sda1QandaAttDefaultChoices">
<title>Attribute default choices</title>
<qandadiv>
<qandaentry xml:id="qanda_RequiredDefault">
<question>
<para>How does a <code>default = "..."</code> definition
coexists with <code>use="required"</code>?</para>
</question>
<answer>
<para>In the presence of <code>use="required"</code> a
<code>default = "..."</code> declaration is being
ignored.</para>
</answer>
</qandaentry>
<qandaentry xml:id="qand_IdElementOrAttribute">
<question>
<para>Which is a natural choice to implement id-like values as
being given in <xref linkend="fig_XsdEmployee"/>? Would you
prefer <tag class="starttag">xs:element</tag> or <tag
class="starttag">xs:attribute</tag>? Give reasons to explain
your choice.</para>
</question>
<answer>
<para>Database id values are simply numbers. Many relational
databases offer IDENTITY declarations to define at maximum one
element per table to become a data identity attribute,
typically the primary key. So there is and never will be an
inner structure and the value is unique per dataset. Thus <tag
class="starttag">xs:attribute</tag> in conjunction with
<code>use="required"</code> is a natural choice.</para>
</answer>
</qandaentry>
</qandadiv>
</qandaset>
</section>
<section xml:id="sec_Keys">
<title>Unique values</title>
<para>So far we know about types to ensure data integrity regarding
individual datasets. This however still permits all kind of
oddities:</para>
<figure xml:id="fig_DuplicateEmployeeValue">
<title>Duplicate value <code>id=21</code> for different
employees</title>
<programlisting language="xml"><employeeList xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="employee.xsd">
<employee>
<id>21</id>
<givenName>Bob</givenName>
...
</employee>
<employee>
<id>21</id> <emphasis role="bold"><!-- Uups: id=21 again? --></emphasis>
<givenName>Gill</givenName>
...
</employee> ...</programlisting>
</figure>
<para>In analogy to<xref linkend="fig_SqlDdlEmployee"/> would like to
add the equivalent of a primary key to <xref
linkend="fig_ListOfEmployees"/>. XML Schema offers <tag
class="starttag">xs:key</tag> and <tag
class="starttag">xs:unique</tag> declarations for this purpose:</para>
<programlisting language="xml"><xs:element name="employee">
<xs:complexType>
<xs:sequence>
<xs:element name="id" type="xs:unsignedInt"/>
<xs:element name="givenName" type="xs:string"/>
...
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="employeeList">
<xs:complexType>
<xs:sequence>
<xs:element ref="employee" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<emphasis role="bold"><xs:key name="employeeId"></emphasis> <co
xml:id="co_Keydef"/>
<emphasis role="bold"><xs:selector xpath="employee"/>
<xs:field xpath="id"/>
</xs:key></emphasis>
</xs:element>
</programlisting>
<para/>
</section>
</chapter>
<chapter xml:id="basicXpathQuery">
<title>Basic XPath query elements</title>
<para>The <link linkend="gloss_XPath">XPath</link> <link
linkend="gloss_W3C">W3C</link> standard acts on XML document instances
like <link linkend="gloss_SQL">SQL</link> acts on relational data. We
consider an example:</para>
</chapter>
</part>
<appendix>
<title>Glossary</title>
<para/>
<glossary>
<glossentry xml:id="gloss_API">
<glossterm><abbrev xlink:href="https://en.wikipedia.org/wiki/Api"
xml:id="abbr_api">API</abbrev></glossterm>
<glossdef>
<para>Application programming interface</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_SqlDdl">
<glossterm><abbrev
xlink:href="https://en.wikipedia.org/wiki/Data_definition_language"
xml:id="abbr_Ddl">DDL</abbrev> <link
linkend="gloss_SQL">(SQL)</link></glossterm>
<glossdef>
<para>Data definition language. The subset of <link
linkend="gloss_SQL">SQL</link> dealing with the creation of tables,
views etc.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_DOM">
<glossterm><acronym xlink:href="https://www.w3.org/DOM"
xml:id="abbr_Dom">DOM</acronym></glossterm>
<glossdef>
<para>The <link linkend="gloss_W3C">W3C</link> <link
xlink:href="https://www.w3.org/DOM">Document Object Model</link>
standard</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_DTD">
<glossterm><abbrev
xlink:href="https://en.wikipedia.org/wiki/Document_Type_Declaration"
xml:id="abbr_Dtd">DTD</abbrev></glossterm>
<glossdef>
<para>Document Type Definition. An older standard with respect to
<link linkend="gloss_RelaxNG">RelaxNG</link> and <link
linkend="gloss_RelaxNG">XML schema</link> to define an XML documents
grammar.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_EBNF">
<glossterm><abbrev>EBNF</abbrev></glossterm>
<glossdef>
<para>Extended Backus-Naur form.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_ftp">
<glossterm><abbrev
xlink:href="https://en.wikipedia.org/wiki/File_Transfer_Protocol"
xml:id="abbr_Ftp">ftp</abbrev></glossterm>
<glossdef>
<para>File Transfer Protocol</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_FO">
<glossterm><abbrev
xlink:href="https://www.w3.org/TR/2001/REC-xsl-20011015/slice6.html#fo-section"
xml:id="abbr_Fo">FO</abbrev></glossterm>
<glossdef>
<para>The Formatting Objects Standard for printable output
generation</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_HDM">
<glossterm><orgname xlink:href="https://www.hdm-stuttgart.de"
xml:id="org_Hdm">Hdm</orgname></glossterm>
<glossdef>
<para xml:lang="de">Hochschule der Medien.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_Hql">
<glossterm><abbrev
xlink:href="https://docs.jboss.org/hibernate/orm/4.1/manual/en-US/html/ch16.html"
xml:id="abbr_Hql">HQL</abbrev></glossterm>
<glossdef>
<para>The <link
xlink:href="https://docs.jboss.org/hibernate/orm/3.3/reference/en/html/queryhql.html">Hibernate
Query Language</link>.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_http">
<glossterm><abbrev xlink:href="https://www.w3.org/Protocols"
xml:id="abbr_Http">http</abbrev></glossterm>
<glossdef>
<para>The Hypertext Transfer Protocol</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_IDE">
<glossterm><abbrev
xlink:href="https://en.wikipedia.org/wiki/Integrated_development_environment"
xml:id="abbr_Ide">IDE</abbrev></glossterm>
<glossdef>
<para>Integrated Development Environment</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_J2EE">
<glossterm><trademark
xlink:href="http://www.oracle.com/technetwork/java/javaee"
xml:id="tm_J2ee">J2EE</trademark></glossterm>
<glossdef>
<para>Java Platform, Enterprise Edition</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_Java">
<glossterm><trademark
xlink:href="http://www.oracle.com/us/legal/third-party-trademarks/index.html">Java</trademark></glossterm>
<glossdef>
<para>General purpose programming language with support for object
oriented concepts.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_Javadoc">
<glossterm><trademark
xlink:href="https://docs.oracle.com/javase/1.5.0/docs/guide/javadoc">Javadoc</trademark></glossterm>
<glossdef>
<para>Extracting documentation embedded in <link
linkend="gloss_Java"><trademark>Java</trademark></link> source
code.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_JDBC">
<glossterm><trademark
xlink:href="http://www.oracle.com/technetwork/java/javase/jdbc"
xml:id="tm_Jdbc">JDBC</trademark></glossterm>
<glossdef>
<para>XXX.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_JDK">
<glossterm><trademark
xlink:href="http://www.oracle.com/technetwork/java/javase"
xml:id="tm_Jdk">JDK</trademark></glossterm>
<glossdef>
<para>Java Development Kit.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_JPA">
<glossterm><abbrev
xlink:href="http://www.javaworld.com/javaworld/jw-01-2008/jw-01-jpa1.html"
xml:id="abbr_Jpa">JPA</abbrev></glossterm>
<glossdef>
<para><link
xlink:href="http://www.javaworld.com/javaworld/jw-01-2008/jw-01-jpa1.html">Java
Persistence Architecture</link></para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_JRE">
<glossterm><trademark
xlink:href="http://www.oracle.com/technetwork/java/javase"
xml:id="tm_Jre">JRE</trademark></glossterm>
<glossdef>
<para>Java Runtime Environment</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_MathML">
<glossterm><abbrev>MathML</abbrev></glossterm>
<glossdef>
<para><link xlink:href="https://www.w3.org/Math">Mathematical Markup
Language</link></para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_MIB">
<glossterm><orgname xlink:href="https://www.mi.hdm-stuttgart.de"
xml:id="org_Mib">MIB</orgname></glossterm>
<glossdef>
<para xml:lang="de">Bachelor Studiengang Medieninformatik</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_Mysql">
<glossterm><trademark
xlink:href="https://www.mysql.com/about/legal/trademark.html"
xml:id="tm_Mysql">Mysql</trademark></glossterm>
<glossdef>
<para>Open source Oracle database product</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_MP3">
<glossterm><abbrev>MP3</abbrev></glossterm>
<glossdef>
<para>Audio codec.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_ORM">
<glossterm><abbrev>ORM</abbrev></glossterm>
<glossdef>
<para>Object relational mapping.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_PHP">
<glossterm><abbrev
xlink:href="https://secure.php.net">PHP</abbrev></glossterm>
<glossdef>
<para>Hypertext preprocessor</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_RelaxNG">
<glossterm><acronym
xlink:href="http://relaxng.org">RelaxNG</acronym></glossterm>
<glossdef>
<para>An <link
xlink:href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c037605_ISO_IEC_19757-2_2003(E).zip">ISO</link>
standard to define the grammar of XML documents. Primary use for
document oriented applications.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_SAX">
<glossterm><acronym
xlink:href="http://www.saxproject.org">SAX</acronym></glossterm>
<glossdef>
<para><link xlink:href="http://www.saxproject.org">Simple API for
XML</link>.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_SQL">
<glossterm><acronym
xlink:href="https://en.wikipedia.org/wiki/Sql">SQL</acronym></glossterm>
<glossdef>
<para><link xlink:href="https://en.wikipedia.org/wiki/SQL">Structured
query language</link>.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_SVG">
<glossterm><abbrev>SVG</abbrev></glossterm>
<glossdef>
<para><link xlink:href="https://www.w3.org/Graphics/SVG">Scalable
Vector Graphics</link>.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_TCP">
<glossterm><acronym
xlink:href="https://en.wikipedia.org/wiki/Transmission_Control_Protocol"
xml:id="abbr_Tcp">TCP</acronym></glossterm>
<glossdef>
<para>Transmission Control Protocol</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_URL">
<glossterm><abbrev xlink:href="https://www.ietf.org/rfc/rfc1738.txt"
xml:id="abbr_Url">URL</abbrev></glossterm>
<glossdef>
<para>Uniform Resource Locator</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_W3C">
<glossterm><orgname
xlink:href="http://www.w3.org">W3C</orgname></glossterm>
<glossdef>
<para>World Wide Web Consortium</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_XHTML">
<glossterm><abbrev>XHTML</abbrev></glossterm>
<glossdef>
<para>Html as <link linkend="gloss_XML">XML</link> <link
xlink:href="https://www.w3.org/TR/xhtml11">standard</link>.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_XML">
<glossterm><abbrev
xlink:href="https://www.w3.org/XML">Xml</abbrev></glossterm>
<glossdef>
<para>The <link xlink:href="https://www.w3.org/XML">Extensible Markup
Language</link>.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_XmlSchema">
<glossterm>XML Schema</glossterm>
<glossdef>
<para>A W3C standard to define grammars for XML documents. Rich set
of features with respect to data modeling.</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_XPath">
<glossterm><acronym xlink:href="https://www.w3.org/TR/xpath"
xml:id="abbr_Xpath">XPath</acronym></glossterm>
<glossdef>
<para>XML Path Language</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_XSD">
<glossterm><abbrev
xlink:href="https://www.w3.org/Style/XSL">XSD</abbrev></glossterm>
<glossdef>
<para>XML Schema description Language</para>
</glossdef>
</glossentry>
<glossentry xml:id="gloss_XSL">
<glossterm><abbrev xlink:href="https://www.w3.org/Style/XSL"
xml:id="abbr_Xsl">XSL</abbrev></glossterm>
<glossdef>
<para>Extensible Stylesheet Language</para>
</glossdef>
</glossentry>
</glossary>
</appendix>
<xi:include href="../Common/bibliography.xml" xpointer="element(/1)"/>
</book>