Gegevensbanken laatste les: XML...

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Gegevensbanken“Laatse Les”

Prof. Erik Duval2009 - 2010

Sunday 30 May 2010

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http

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http://www.slideshare.net/erik.duval

http://www.slideshare.net/erik.duval

• NoSQL (Met dank aan Steven Noels)

• XML (met dank aan prof. Olivié!)

• over het examen...

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http://en.wikipedia.org/wiki/Extensible_Markup_Language

http://en.wikipedia.org/wiki/Extensible_Markup_Language

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http://www.itjobboard.be/ICT-banen/xml/Belgie/alle/0/relevantie/nl/


6 http://www.khbo.be/12385

Sunday 30 May 2010

http://www.khbo.be/12385

http://www.khbo.be/12385

http://www.w3.org/XML7

Sunday 30 May 2010

http://www.w3.org/XML

http://www.w3.org/XML

8 http://www.w3c.it/talks/2005/openCulture/slide7-0.html

Sunday 30 May 2010

http://www.w3c.it/talks/2005/openCulture/slide7-0.html

http://www.w3c.it/talks/2005/openCulture/slide7-0.html

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XML is not ...• Extension of HTML

• XHTML is XML-compliant, and extensible

• Just for Web pages

• Useful when data are stored or exchanged

• Concerned with semantics

• XML does not define semantics, just syntax

• Innovative new technology

• Standard, building on existing technology

• Only a hype

• Though also 10

Sunday 30 May 2010

XML is ...• Endorsed by W3C and major companies

• Extensible

• No tag name limitations

• No language limitations

• Human software developer-readable

• Can be processed with basic text tools

• Open standard

• no vendor lock-in (in theory...)

• Easy to implement

• powerful, cheap (free), off-the-shelf XML tools11

Sunday 30 May 2010

• 1969: SGML (Standard Generalized Markup Language)

• Meta-language: describe other languages

• Powerful, but rather complicated

• 1986: ISO standard

• 1992: HTML (HyperText Markup Language)

• Based on SGML

• Simple, but limited

• 1996: Start design of XML

• By World Wide Web Consortium (W3C)

• 1998: Publication of XML 1.012

Sunday 30 May 2010

Design Goals

• Easy to use over the Internet

• Power of SGML

• Simplicity of HTML

• Human-legible

• Easy to create

• Compactness is not an issue

• “The ASCII of the Web”13

Sunday 30 May 2010

XML Basics<Person>

<Name>

<First>Thomas</First>

<Last>Atkinson</Last>

</Name>

<Age>30</Age>

</Person>

• Self-defined, meaningful tags

• Separate data and its representation14

Sunday 30 May 2010

• Language for defining syntax

• Records and fields have explicit boundaries

• parse-able without knowing structure (self-descriptive)

• Unicode support (UTF-8, UTF-16, ...)

• Web-aware

• DTD, ENTITY and Schema can be loaded through URL

• Strictly parsed: no ambiguity (case sensitive!)

• Extensible: namespaces

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<?xml version="1.0” encoding=“UTF-8”?> <!DOCTYPE addressbook SYSTEM "http://www/~koenh/ddml/addressbook.dtd”>  <addressbook>  <person first-name="John" family-name="Doe” employee-number="1234"> <contact-info> <email address="[email protected]"/> </contact-info> <address street="Celestijnenlaan” number="200A"/> </person></addressbook>

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<H1 align=”center” > a Heading </H1>

attribute

openingtag

openingtag

openingtag

content closing tag

elementelementelementelementelement

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• Cfr. HTML markup tags

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attribute

openingtag

openingtag

openingtag

content closing tag


Sunday 30 May 2010

• Cfr. HTML markup tags

• Major differences:

• Case sensitive

• Proper nesting: No <A> … <B> … </A> … </B>

• Unicode instead of ASCII17


attribute

openingtag

openingtag

openingtag

content closing tag


Sunday 30 May 2010

Vocabularies

• Agreed-upon XML tag sets for specific domain

• Examples

• Chemical Markup Language (CML)

• Business: ebXML, RosettaNet, BizTalk

• Mathematics: MathML

• Multimedia: Synchronized Multimedia Integration Language (SMIL)

• Etc.

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• well-formed: follows XML syntax

• Proper tag and attribute names

• Tags properly closed

• Attributes and text between tags do not contain ‘<‘ (escape with <)

• valid: well-formed and vocabulary

• All elements and their attributes declared in DTD

• Attribute values follow DTD type declarations

• CDATA, ID, IDREF, IDREFS, NMTOKEN, NMTOKENS, enumerated

• Nesting and sequencing of elements follows DTD19

Sunday 30 May 2010

Elements• XML’s container for

• Attributes

• Character data

• Other elements (“child” elements)

• Delimited by opening and closing tags

• Non-empty element: <name>..</name>

• Empty element: <name/>

• Form a simple hierarchic tree

• Root = “document element”20

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Attributes and Strings

• Attributes

• Name-value pairs: name=value

• Only strings as value!

• Strings

• Enclosed by ‘...’ or “...”→ replace with ' or "

• Character data

• Any text that is not markup

• ‘&’, ‘<’ and ‘>’ are markup → replace with & < and >

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Sunday 30 May 2010

Document structure

• Prolog (optional)• <?xml version="1.0” encoding=“UTF-8”?>

• version="number" (compulsory)

• encoding="character encoding" (optional)

• Document type declaration• <!DOCTYPE document_element ... >

• Body–The document element

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Another example<?xml version="1.0" standalone="no"?>

<!DOCTYPE BankAccounts ...>



<BankAccounts>

<Account accountNr="123-456789-01" use="personal">

<Owners> <Person ID="1258-a8d72-98"> <Name>John Smith</Name></Person>

<Person ID="5842-df5ef-e9"> <Name>Claudia Scott</Name></Person>

</Owners>

<CreditCards><CreditCard number="12345"/></CreditCards>

<Balance Currency="EUR">50000</Balance>

</Account>

...

</BankAccounts> 23

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Document Type Definition

<!ELEMENT address EMPTY> 

<!ATTLIST address city CDATA #REQUIRED  

state NMTOKEN #REQUIRED 

number CDATA #REQUIRED street CDATA #REQUIRED>

<!ELEMENT addressbook (person+)> 

<!ELEMENT contact-info (home-phone|mobile-phone|email)*>  

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Document Type Definition<!ELEMENT email EMPTY><!ATTLIST email address CDATA #REQUIRED>

<!ELEMENT home-phone EMPTY><!ATTLIST home-phone number CDATA #REQUIRED>

<!ELEMENT job-info EMPTY><!ATTLIST job-info is-manager (yes|no) 'no’ 

emp-type (FullTime|PartTime) 'FullTime’ job-description CDATA #REQUIRED>

<!ELEMENT misc-info (#PCDATA)> 

<!ELEMENT mobile-phone EMPTY><!ATTLIST mobile-phone number CDATA #REQUIRED>25

Sunday 30 May 2010

Document Type Definition

<!ELEMENT manager EMPTY><!ATTLIST manager empnumber IDREF #REQUIRED> 

<!ELEMENT person (contact-info,address, job-info?,manager?,misc-info?)>  

<!ATTLIST person first-name CDATA #REQUIRED middle-initial CDATA #IMPLIED 

employee-number ID #REQUIRED 

family-name CDATA #REQUIRED>

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Sunday 30 May 2010

namespaces: problem

<widget type="gadget">

<head size="medium"/>

<big><subwidget ref="gizmo"/></big>

<info>

<head><title>Gadget</title></head>

<body><h1>Gadget</h1>

A gadget contains a big gizmo

</body>

</info>

</widget>

Name collision!

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namespaces: approach

• A collection of names, identified by a URI reference, which are used in XML documents as element types and attribute names

•xmlns:prefix="URI"

• URI used only as identifier

• does not need to point to anything

• applies to all nested elements and attributes

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namespaces: example<widget xmlns="http://www.widget.org"

xmlns:xhtml="http://www.w3.org/TR/xhtml1"

type="gadget">

<head size="medium"/>

<big><subwidget ref="gizmo"/></big>

<info><xhtml:head><xhtml:title>Gadget

</xhtml:title></xhtml:head>

<xhtml:body><xhtml:h1>Gadget

</xhtml:h1>A gadget contains...

</xhtml:body></info>

</widget> 29

Sunday 30 May 2010

Another example

<Address><Street>Celestijnenlaan</Street>

<Nr>200A</Nr> <City>Heverlee-Leuven</City> <Country>Belgium</Country></Address>

<Server><Name>www</Name><Address> 134.58.43.1 </Address>

</Server>

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Sunday 30 May 2010

Another example (2)

<Address xmlns="www.all.edu/departments"> <Street>Celestijnenlaan</Street> <Nr>200A</Nr> <City>Heverlee-Leuven</City> <Country>Belgium</Country></Address>

<Server xmlns="www.dns.net/servers"> <Name>www</Name> <Address> 134.58.43.1 </Address></Server>

<Department xmlns:edu="www.all.edu/departments" xmlns:dns="www.dns.net/servers"> <edu:Address> <Street>Celestijnenlaan</Street> ... </edu:Address> <dns:Name>www</dns:Name> <dns:Address>134.58.43.1</dns:Address></Department>

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Sunday 30 May 2010

Accessing XML documents

• Manual text file manipulation

• Cumbersome & Error-prone

• Parser

• Simplifies document manipulation

• Ensures proper grammar, well-formedness

• Abstracts content from grammar

• Accessed through standard API

• Document Object Model (DOM)

• Simple API for XML (SAX)32

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• DOM parser

• create DOM object tree

• SAX parser

• generates events when elements encountered

• one-pass translation

• no need to keep whole document tree in memory

• Both can be validating or non-validating

• Many available(most freeware, open source)

• ibm xml4j, apache xerces, sun parser, microsoft, datachannel, oracle, ...

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DOM approach

http://java.sun.com/xml/jaxp/dist/1.1/docs/tutorial/overview/3_apis.html#JAXP34

Sunday 30 May 2010

DOM Node Tree

<?xml version="1.0"?>

<BankAccounts> <Account accountNr="123-456789-01“> <Owner ID="1258-a8d72-98"> John Smith </Owner> <Balance Currency="EUR"> 50000 </Balance> </Account> <Account ...> ...</BankAccounts>

Doc

Com An example XML document

El BankAccounts

El Account

Att accountNr = “123-456789-01”

El Owner = “John Smith”

Att ID = “1258-a8d72-98”

El Balance = “50000”

Att Currency = “Eur”

El Account...

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parsing: DOM

public void print(Node node) {

...

NodeList nlist=node.getChildNodes();

if (nlist != null) {

int l = nlist.getLength();

for (int i=0; i<l; i++) {

print(nlist.item(i));

...

}...}...}36

Sunday 30 May 2010

Dom Benefits & Drawbacks

• Benefits

• W3C Recommendation

• Language- and platform-independent

• Random access

• Intuitive

• Drawback

• Entire object tree in memory37

Sunday 30 May 2010

Simple API for XML (SAX)

• Not an official standard

• Ad-hoc product by XML developers

• Primarily Java API

• Event-based mechanism

• Don’t call the parser, the parser calls you

• No object model in memory

• Programmer must keep state information

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SAX approachht

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SAX parsing modelApplication

Parser

ContentHandlernew ContentHandler()

new Parser()

setContentHandler()

parse()

startDocument()

startElement()

characters()

endElement()

endDocument()

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parsing: SAX$xml_parser = xml_parser_create();

xml_set_element_handler($xml_parser,

"startQuestion","endQuestion");

...

xml_parse($xml_parser,$data,feof($fp))

...

function startQuestion($parser,$name,$attrs) {

...if ($name == "QUESTION")

...new Question($attrs["QTEXT"]);

... 41

Sunday 30 May 2010

• Start and end of document

–startDocument()

–endDocument()

• Start and end of element

–startElement(namespace, name, qname, attlist)

–endElement(namespace, name, qname)

• Character data

–characters(char[] ch, int start, int length)

• Processing Instruction

–processingInstruction(target, data)

• No event for comments!42

Sunday 30 May 2010

Another SAX example<?xml version="1.0" standalone="no"?>

<!DOCTYPE BankAccounts ...>



<BankAccounts>

<Account accountNr="123-456789-01" use="personal">

<Owners>

<Person ID="1258-a8d72-98"><Name>John Smith</Name></Person>

<Person ID="5842-df5ef-e9"><Name>Claudia Scott</Name></Person>

</Owners>

<CreditCards><CreditCard number="12345"/></CreditCards>

<Balance Currency="EUR">50000</Balance>

</Account>

...

</BankAccounts> 43

Sunday 30 May 2010

public class AvgBalanceCalculator extends DefaultHandler {private double total = 0.0; private int count = 0; private boolean isBalance = false;

public void startElement(String uri, String name, String qname, Attributes atts) {if (name.equals(“Balance")) { isBalance = true; count++; }}

public void characters(char[] ch, int start, int len) throws SaxException {if (isBalance) { String help = new String(ch, start, len); double balance = (new double(help)).doubleValue(); total = total + balance; isBalance = false; }}

public void endDocument() {if (count != 0)

System.out.println(“Average balance is ”+(total/count)); }}

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SAX Benefits & Drawbacks• Benefits

• Suitable when

• parsing large documents

• constructing proprietary object structures

• only small subset of information is needed

• Simple and fast

• Drawbacks

• Read-only

• No random access

• Complex searches messy to program45

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beperkingen van DTDs

• geen typering van tekst elementen en attributen

• alle waarden zijn strings, geen integers, reals, enz.

• ongeordende verzameling van subelementen moeilijk te definiëren

• orde is meestal irrelevant in gegevensbanken

• IDs en IDREFs zijn niet getypeerd

• het DNO attribuut van een EMPLOYEE kan een referentie bevatten aan een andere EMPLOYEE, wat zinloos isvb. <EMPLOYEE SSN="_888665555 " SEX="M" DNO="_888665555 ">

• het DNO attribuut zou als beperking moeten hebben dat het slechts aan een DEPARTMENT kan refereren

Sunday 30 May 2010

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XML Schema

• typering van waarden

• vb. integer, string, enz.

• ook beperkingen op min/max waarden

• types door gebruiker gedefinieerd

• is gespecificeerd in XML syntax,

• meer gestandaardiseerde voorstelling

• is geïntegreerd met namespaces

• en nog andere mogelijkheden

• lijst types, uniciteitsbeperking op sleutels, verwijssleutelbeperkingen, overerving,…

Sunday 30 May 2010

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XSDL

• XML Schema Definition Language

• documenten met suffix .xsd

Sunday 30 May 2010

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XML Schema: voorbeeldXML schema

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">....<xsd:element name="PWORKER" minOccurs="0" maxOccurs="unbounded"> <xsd:complexType> <xsd:sequence> <xsd:element name="HOURS" type="xsd:float"/> </xsd:sequence> <xsd:attribute name="SSN" type="xsd:IDREF" use="required"/> </xsd:complexType></xsd:element>....</xsd:schema>

XML instantie

<PWORKER SSN="_123456789"> <HOURS>7.5</HOURS> </PWORKER>

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XML: eenvoudige types– ingebouwde eenvoudige types

• string, integer, decimal, float, boolean, date, time,…

• <xsd:element name=“gebdat” type=“xsd:date” />

– door gebruiker gedefinieerde eenvoudige types

• gedefinieerd met simpleType element

• restriction element geeft het basistype waarop gesteund is

• <xsd:simpleType name=“salaryRange”> <xsd:restriction base=“xsd:integer”> <xsd:minInclusive value=“25000” /> <xsd:maxInclusive value=“100000” /> </xsd:restriction></xsd:simpleType>

Sunday 30 May 2010

XML: eenvoudige types<xsd:simpleType name=“studentClassificatie”> <xsd:restriction base=“xsd:string”> <xsd:enumeration value=“bachelorstudent” /> <xsd:enumeration value=“masterstudent” /> <xsd:enumeration value=“doctorstudent” /> </xsd:restriction></xsd:simpleType>

<xsd:simpleType name=“deptType”> <xsd:restriction base=“xsd:string”> <xsd:length value=“3” /> </xsd:restriction></xsd:simpleType>

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XPath (example)/COMPANY/EMPLOYEE

ROOT

COMPANY

EMPLOYEE

SSN

_333445555

EMPLOYEE

SSN

_123456789

EMPLOYEE

SSN

_999887777

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/COMPANY/EMPLOYEE

ROOT

COMPANY

EMPLOYEE

SSN

_333445555

EMPLOYEE

SSN

_123456789

EMPLOYEE

SSN

_999887777

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/COMPANY/EMPLOYEE

ROOT

COMPANY

EMPLOYEE

SSN

_333445555

EMPLOYEE

SSN

_123456789

EMPLOYEE

SSN

_999887777

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/COMPANY/EMPLOYEE

ROOT

COMPANY

EMPLOYEE

SSN

_333445555

EMPLOYEE

SSN

_123456789

EMPLOYEE

SSN

_999887777

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/COMPANY/EMPLOYEE

ROOT

COMPANY

EMPLOYEE

SSN

_333445555

EMPLOYEE

SSN

_123456789

EMPLOYEE

SSN

_999887777

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XPath/COMPANY/EMPLOYEE

ROOT

COMPANY

EMPLOYEE

SSN

_333445555

EMPLOYEE

SSN

_123456789

EMPLOYEE

SSN

_999887777

<EMPLOYEE SSN="_123456789" SEX="M“ SUPERSSN="_333445555" DNO="_5">

<FNAME>John</FNAME> <MINIT>B</MINIT>

....</EMPLOYEE>

<EMPLOYEE SSN="_333445555" SEX="M“ SUPERSSN="_888665555" DNO="_5">

<FNAME>Franklin</FNAME> <MINIT>T</MINIT>

<LNAME>Wong</LNAME> <BDATE>08-DEC-45</BDATE>

</EMPLOYEE><EMPLOYEE SSN="_999887777" SEX="F“ SUPERSSN="_987654321" DNO="_4">

<FNAME>Alicia</FNAME>

.....

Sunday 30 May 2010

XML family of technologies

• Xlink: hypertext

• XSL: Extensible Style Sheet Language

• XSL-T Transformation

• Formatting Objects

• Xschema: additional constraints on attribute types

• and more...

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Sunday 30 May 2010

XML applications

• RDF: Resource Description Framework

• infra

• XHTML: eXtensible HTML en HTML5

• XML compliant HTML

• MathML

• SMILE: synchronized multimedia presentation

• Many others

• Chemical Markup Language, Vector Graphics Markup Language, Open Software Description Format, Weather observation, astronomical data, financial data, electronic components, workflow, business cards, real estate, newspaper, classifieds, javadoc, human resource, advertising, architecture ….

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Sunday 30 May 2010

XML Working Groups• XML Coordination

• XML Core

• XSL (XSLT, XSL/FO) -> W3C architecture

• Efficient XML Interchange

• XML Processing Model

• XML Query (XQuery, XPath)

• XML Schema

• Service Modeling Language (SML)64

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More XPath Features• Operator “|” used to implement union

• E.g. //EMPLOYEE[count(DEPENDENT) = 1] | //EMPLOYEE[not(DEPENDENT)]

• gives employees with either 0 or 1 dependents

• “//” can be used to skip multiple levels of nodes

• E.g. /COMPANY//FNAME

• finds any FNAME element anywhere under the /COMPANY element, regardless of the element in which it is contained.

• A step in the path can go to:

parents, siblings, ancestors and descendants

of the nodes generated by the previous step, not just to the children

• “//”, described above, is a short from for specifying “all descendants”

• “..” specifies the parent.

• e.g. : /COMPANY//FNAME/../BDATESunday 30 May 2010

• laat toe om meer algemene queries te formuleren dan XPath

• algemene vorm: FLWOR uitdrukking

FOR < for-variabele > IN < in-uitdrukking >

LET < let-variabele > := < let-uitdrukking >

[ WHERE < filter-uitdrukking > ]

[ ORDER BY < orde-specificatie > ]

RETURN < uitdrukking >

• opm: FOR en LET kunnen alleen of samen voorkomen66

XQuery

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• Q1: voornaam en familienaam van alle werknemers die meer dan 70000 verdienen

• FOR $x IN doc(www.company.com/info.xml)// employee [employeeSalary > 70000] / employeeNameRETURN < res > $x / firstName, $x / lastName </ res >

• alternatief:FOR $x IN doc(www.company.com/info.xml)company / employeeWHERE $x / employeeSalary > 70000RETURN < res > $x / employeeName / firstName, $x / employeeName / lastName </ res >

Sunday 30 May 2010

http://www.company.com/info.xml




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• Q3: voornaam en familienaam van alle werknemers die meer dan 20 uur op project nummer 5 werken, met dat aantal uren

• FOR $x IN doc(www.company.com/info.xml)/ company / project [projectNumber = 5] / projectWorker ,$y IN doc(www.company.com/info.xml) / company / employeeWHERE $x/hours > 20.0 AND $y.ssn = $x.ssnRETURN < res > $y / employeeName / firstName, $y / employeeName / lastName,$x / hours </ res >

Sunday 30 May 2010

http://www.company.com/info.xml)/company%20/






The End...

Bedankt!Vragen...?

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NoSQL

• non-relational

• distributed

• open source

• horizontally scalable

• “web scale”

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Sunday 30 May 2010

NoSQL

• non-relational

• distributed

• open source

• horizontally scalable

• “web scale”

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• schema free

• easy replication

• simple API

• BASE (not ACID)

Sunday 30 May 2010

Systems

• Core: Hadoop, HBase, Cassandra, Hypertable, ...

• Docs: CouchDB, MongoDB, Riak, Terrastore, ...

• Key-Value, tuple: Amazon SimpleDB, Azure, ...

• Graph: Neo4J, Bigdata, InfoGrid, HyperGraph, ...

• Object: Versant, Perst, ZODB, ...

• Grid: GigaSpaces, Hazelcast, ...

• XML: Tamino, eXist, Mark Logic, Xindice, ...

• ...71 http://nosql-databases.org/

Sunday 30 May 2010

http://nosql-databases.org

http://nosql-databases.org

nosql

• Google BigTable

• Amazon Dynamo

• Open source: HBase

• Cassandra: last.fm, FaceBook

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nosql: why

• big data sets:

• Digg green badge: 3 TB

• Facebook inbox: 50 TB

• eBay overall data: 2 PB

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http://about.digg.com/blog/looking-future-cassandra

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14 seconds

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75http://about.digg.com/blog/looking-future-cassandra

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Text

http://www.slideshare.net/oemebamo/database-sharding-at-netlog-presentation

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no attempt to ACID

• Atomicity

• Consistency

• Isolation

• Durability

• trade ACID off in favor of high availability

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query

• associative array, key-value pair

• XQuery

• SPARQL

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Vragen...?

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Gegevensbanken laatste les: XML...

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