1. Extensible Markup Language(XML)

2. What is a Markup Language • A syntax and procedure for embedding in text documents tags that control formatting when the documents are viewed by a special application. <b> Hi </b> • a set of codes or tags that surrounds content and tells a person or program what that content is (its structure) and/or what it should look like (its format). Markup tags have a distinct syntax that sets them apart from the content that they surround.

3. History of Markup Languages • 1967: GenCode • 1970s, 1980s :Tex • 1980s: Scribe • Early 80s: SGML • 1991: HTML • Late 90s: XML`

5. Motivation For XML. • XML is an attempt to package up the important virtues and most-used features of SGML in a compact, easily-implemented package that is optimized for delivery on the WWW. (Bray) • XML is started as a simplified subset of the Standard Generalized Markup Language (SGML), and is designed to be relatively human-legible. By adding semantic constraints, application languages can be implemented in XML. • Data Storage in an organized way. • Fast and easy exchange of Data.

6. XML Syntax • Header <?xml version="1.0" encoding="utf-8"?> • Comments:- <!-- This is a comment --> • Nesting:- <a> <b> </b> </a> <!-- OK --> • Empty elements:- <a value="123"></a> <a value="123"/> • One root element!

7. Some Standards that use XML • SVG • MathML • HL7 V. 3.0 and Medical Markup Language (MML)

8. XML Example <?xml version="1.0" encoding="ISO-8859-1"?> <?xml-stylesheet type="text/xsl" href="book.xsl"?> <dblp> <book mdate="2004-03-08" key="books/acm/Kim95"> <editor>Won Kim</editor> <title>Modern Database Systems: The Object Model, Interoperability, and Beyond.</title> <booktitle>Modern Database Systems</booktitle> <publisher>ACM Press and Addison-Wesley</publisher> <year>1995</year> <isbn>0-201-59098-0</isbn> <url>db/books/collections/kim95.html</url> </book> <book mdate="2002-01-03" key="books/aw/AbiteboulHV95"> <author>Serge Abiteboul</author> <author>Richard Hull</author> <author>Victor Vianu</author> <title>Foundations of Databases.</title> <publisher>Addison-Wesley</publisher> <year>1995</year> <isbn>0-201-53771-0</isbn> <url>db/books/dbtext/abiteboul95.html</url> </book> </dblp>

9. Defining an XML Language i.e. which <tags> in which order • Not strictly necessary • you can parse/produce XML without formally defining the structure of the language • This is called a Well-formed document • DTDs (“Document Type Definitions”) • Simple, limited • This is called a valid document • XML-Schema • (too?) complex and expressive (includes inheritance, restricted datatypes, ranges) • Data binding • Define (e.g.) java classes + mapping from object tree to XML Document • JAXB, Castor, JSX, NeuroML

10. DTD <!ELEMENT dblp (article|inproceedings|proceedings|book|incollection| phdthesis|mastersthesis|www)*> <!ENTITY % field "author|editor|title|booktitle|pages|year|address|journal|volume|number|month|url|ee|cdrom|cite|publisher|note|crossref|isbn|series|school|chapter"> ………………….. <!ELEMENT book (%field;)*> <!ATTLIST book key CDATA #REQUIRED mdate CDATA #IMPLIED ………………………. <!ELEMENT author (#PCDATA)> <!ELEMENT editor (#PCDATA)> <!ELEMENT address (#PCDATA)> <!ENTITY % titlecontents "#PCDATA|sub|sup|i|tt|ref"> <!ELEMENT title (%titlecontents;)*> <!ELEMENT booktitle (#PCDATA)>

11. Databases Overview Data RelationalData XML Secondary Storage Main Memory • RDBMS as • - MySQL • MS SQL Server • Oracle • DB2 Tools as - SAX - DOM - LINQ DBMS as - Sedna

12. Tools to read/write an XML file • SAX • DOM • LINQ Why we need such tools??? • To make sure that the file is either valid or • well-formed. • To read document in term of entities or • attributes.

13. SAX (Simple API for XML) • Event based. • … you provide a startElement(), characters() endElement() methods. • You have to keep track of where you are in the tree/document. • Fast, but a bit painful to code. • Mainly adopted in Java.

14. DOM (Document Object Model) • You get a tree of objects of type “Element” and “Attribute” + methods to navigate the tree. • Contents are all strings, so you have to do data conversion yourself to set ints, floats, your Object types. • Mainly adopted in MS .NET.

15. LINQ (Language Integrated Query) • Microsoft Property and innovation. • Introduced in Nov 2007 as a library in .NET Framework 3.5. • Very fast and efficient library to query Relational Databases, XML Files or even arrays. • We write SQL like Query to get the information.

16. How to Query These Data???

17. Querying Data Data Translator RelationalData XML Secondary Storage Main Memory Standard Query Language (SQL) XQuery

18. XQUERY • An XML Query Language • W3C Recommendation since 23 January 2007 • e.g: “/dblp/book[author=“John Smith”]” • Return of Query is XML Elements

19. Query Data (Once Again) Data Translator RelationalData XML Secondary Storage Main Memory Standard Query Language (SQL) Translator XQuery

20. Related Technologies • XPath • XSLT

21. XPATH • XPath: a way to refer to specific subset of elements / atributes in a document • Method to navigate in file not to query. • "/dblp" -- the root element • "/dblp/book[1]" -- first book element • "//book" -- all <book> elements • "//@title" -- all title= attributes ... used in XSLT for pattern matching

22. How to Display These Data in user friendly way ???

23. XSLT (Extensible Stylesheet Language Transformations) <html> <body> <h2>Currently Incollection</h2> <table border="1"> <trbgcolor="#9acd32"> <th align="left">Title</th> <th align="left">Book Title</th> <th align="left">Author</th> <th align="left">Pages</th> <th align="left">Year</th> </tr> <xsl:for-each select="dblp/incollection"> <tr> </body> </html>

24. XSLT (continued) • Add this line to original file <?xml-stylesheet type="text/xsl" href="book.xsl"?>

25. Questions