Mirror, Mirror on the Wall, What is the Best Database Solution of All? Akmal B Chaudhri Senior...

Mirror, Mirror on the Wall, What is the Best <XML> Database Solution of All?

Akmal B ChaudhriSenior ArchitectInformix Labs

Copyright © 2001 Informix 2

Disclaimer Any opinions expressed are mine and not

necessarily those of my employer


Acknowledgements All trademarks are acknowledged Various people at Informix for some of

the presentation material Robert Sutor, Lee Kheng Joo and Eve

Maler


Abstract Managing XML documents is problematic

when document collections grow. How do we successfully store and query document collections? One solution is a database. We will discuss the problem of integrating XML with databases and examine choices, such as relational databases, object databases, object-relational databases and native XML servers


Speaker Biography The speaker has been working in the

area of Object Databases for 10 years He has previously worked for Reuters,

Logica and Computer Associates as well as OODB research at City University

?


Life at Informix Labs I build linear accelerators! Technology Evangelist Technology Pragmatist

C:\Program Files\shockwave.com\Shockmachine\Shockmachine.exe


Agenda The Importance of XML Architectural View of XML Demonstrations

XML to ORDB using “roll-your-own”XML to ORDB using Mapping Tool

The Importance of XML


Waves of Technology

Mainframes

Departmental Servers

Client Server

Internet Web Computing

eCommerce


The Importance of XML

By 2003, more than 75% of ebusiness applications will include XML, regardless of which language the application has been written-in.

By 2003, more than 75% of ebusiness applications will include XML, regardless of which language the application has been written-in.


Tasks/Roles Assumed by XML

0 10 20 30 40 50 60

Other

As a centralized database

As a document repository, possiblyreplacing SGML repositories

As middleware between an RDBMS andan e-commerce front end

Data transfer between applications andsystems

%

Source: [Walker00]


Vendor Market Share 1999Vendor Product Revenue

US$ Million

Market Share %

Sterling/CA

Vision 3 26.8

SAG Tamino 2.4 21.4

Poet CMS 2.1 18.8

eXcelon eXcelon 1.5 13.4

All Others 2.2 19.6Source: [IDC00]


XML DBs Predicted Growth

0

100

200

300

400

500

600

700

800

1999 2000 2001 2002 2003 2004

US

$ M

illi

on

Source: [IDC00]

Architectural View of XML


Jump Gate Ready …


XML Persistence Options Indexed File System Database System

RelationalObjectNative

Dynamic Hashing Libraries Hybrid

Source: [Edwards01]


XML Database ProductsType Data-

CentricDocument-

Centric

Middleware XML-Enabled DBs Native XML DBs XML Servers XML App Servers CMS Persistent DOM

Source: [Bourret00]


Data-Centric Fine-grained data Order of elements not significant Examples

Sales OrderFlight ScheduleRestaurant Menu…

Machine consumption

Source: [Bourret00]


Document-Centric Large-grained data Order of elements is significant Examples

BookEmailAdvertisement…

Human consumption

Source: [Bourret00]


Three Types of XML DBs XML Generating Database XML Document Database XML Component Database

Source: [Chelsom00]


XML Generating Database XML is generated from the database

XMLDocument

XMLDocument

XMLFor-

matter


XML Document Database Database stores complete XML

documents or document fragments

XMLDocument

XMLDocument XML

DocumentXMLDocumentXML

Document


XML Component Database Full XML awareness

XMLDocument

XMLDocument <A>

...</A>

<A>...</A>

<A>...</A>


XML Persistence Options Database System



Object Databases

World Wide Web

Java Language

Enterprise Java Beans

eXtensible Markup Language


IEEE Computer, August 2000


Cattell vs. Stonebraker Cattell

Stonebraker

Source: [Leavitt00]

ODBMSs occupy a small niche market that has no broad appeal. The technology is in semi-rigor mortis, …

ODBMSs occupy a small niche market that has no broad appeal. The technology is in semi-rigor mortis, …

Object-oriented databases are doing just fine, and the news of their demise is highly exaggerated.

Object-oriented databases are doing just fine, and the news of their demise is highly exaggerated.


DB Sales Revenue

1999

US$

2001*

US$

RDB/ORDB 11.1 Billion 15.6 Billion

OODB 211 Million 265 Million

Source: [IDC00]*Predicted


XML and OO XML is not OO

No inheritanceNo encapsulationNo behaviour...

OODB is overkill for structured text Some Content Management Systems are

built on top of OODBs





Native Databases Many vendors developing “Native” XML

databases Documents needed in original form

Structural information is maintainedStorage, query and retrieval of structure and

content Good for point solutions Support for non-XML data?





Relational Databases RDB products scale well Traditional and semi-structured data can

co-exist and be used by multiple applications

RDBs can process complex XML queries on large databases within seconds

Source: [Florescu99]


Three Things We Need To Do Get XML into Database (storage) Get XML out of Database (retrieval) Query XML (processing)


XML Storage

purchase_order

customer items

Multiple RelationalTable Mapping

1.0ORDERid, date

1.1PERSONgender,age

1.2ITEM

id

1.3ITEM

id

1.1.1NAME

1.1.1.1FAMILY

1.1.1.2GIVEN

1.1.2ADDRESS

XML DataPortHierarchical

Storage

BLOB/CLOB Storage

<?xml version='1.0'?><ORDER id="abc123" date="27 Oct 1999"> <PERSON age="50" gender="Male"> <NAME> <FAMILY>Doe</FAMILY> <GIVEN>John</GIVEN> </NAME> <ADDRESS> ... </ADDRESS> </PERSON> <ITEM id="s1">Shirt</ITEM> <ITEM id="j2">Jacket</ITEM></ORDER>


Choosing RDB Storage Model If Relational schema already exists

Consider mapping to multiple tables

If no Relational schema exists Consider BLOB/CLOB model

If documents needed in original form Consider hierarchical model Structural information is maintained Storage, query and retrieval of structure and content


XML Processing XML is SGML derivative HTML is SGML derivative Therefore …

Tools used for HTML can be reworked for XML

DTDs/XML SchemaSELECT query results formatted as XML


XML Storage/Retrieval Multiple Relational Tables

Roll-your-ownMapping ToolJDBC

BLOB/CLOBVerity/Excalibur

Hierarchical Storage


BLOB/CLOB BLOB storage for semi-structured data

This is the usual approach Indexing is key to efficient query

processingFull-text indexing for semi-structured dataAdvanced indexing for path queries


BLOB/CLOB

XMLDocument

XMLDocument


Indexing Example

create table docs (id serial, xml_doc clob);

insert into docs values (0,FileToClob('d:\xml\order_abc123.xml', 'server'));

create index idx1 on docs (xml_doc vts_clob_ops)using vts in sbspace;

select * from docswhere vts_contains(xml_doc, '(John) <IN> GIVEN');

create table docs (id serial, xml_doc clob);

insert into docs values (0,FileToClob('d:\xml\order_abc123.xml', 'server'));

create index idx1 on docs (xml_doc vts_clob_ops)using vts in sbspace;

select * from docswhere vts_contains(xml_doc, '(John) <IN> GIVEN');

















JAXP Overview Java API for XML Parsing (JAXP) is

currently available for programmatically accessing XML documents

JAXP can be divided into three setsSimple API for XML (SAX)Document Object Model (DOM)Plugability Layer


JAXP Glossary SAX - event-driven protocol, with the

programmer providing callback methods that the parser invokes when parsing a document

DOM - random-access protocol, which converts an XML document into a collection of in-memory objects

Plugability Layer - standardizes access to SAX/DOM by providing “Factory” methods for creating and configuring SAX parsers and creating DOM objects (type “Document”)


XML in JDBC 2.20 We would like to support users who use JAXP

in their JDBC applications without putting code that is specifically related to JDBC in the driver

New static methods to facilitate storage and retrieval of XML data in database columns

These methods not only support users of XML but also provide flexibility regarding which JAXP package the user is using


Storing XML Data The methods used during data storage

will assist inParsing the XML dataVerify that well-formed and/or valid XML

data are storedInvalid XML data are rejected


XMLtoString() Example

-- Example of inserting an XML file into an lvarchar columncreate table tab1 (col1 lvarchar);

try { String cmd = "insert into tab1 values(?)"; PreparedStatement pstmt = conn.prepareStatement(cmd); pstmt.setString(1, UtilXML.XMLtoString("/tmp/x.xml")); pstmt.execute(); pstmt.close();} catch (SQLException e) { ... }

-- Example of inserting an XML file into an lvarchar columncreate table tab1 (col1 lvarchar);

try { String cmd = "insert into tab1 values(?)"; PreparedStatement pstmt = conn.prepareStatement(cmd); pstmt.setString(1, UtilXML.XMLtoString("/tmp/x.xml")); pstmt.execute(); pstmt.close();} catch (SQLException e) { ... }


Retrieving XML Data The methods used during data retrieval

will assist in convertingXML data to type “InputSource” which is the

standard input type for both SAX and DOM methods

XML data to DOM


getInputSource() Example (1)

-- Fetch XML data from an lvarchar column into an InputSource -- for (SAX) parsing

try { String sql = "select col1 from tab1"; Statement stmt = conn.createStatement(); ResultSet r = stmt.executeQuery(sql);

// Other SAX parsers can go here if desired

Parser p = ParserFactory.makeParser("com.sun.xml.parser.Parser"); p.setDocumentHandler(new myHandler()); p.setErrorHandler(new errHandler());

-- Fetch XML data from an lvarchar column into an InputSource -- for (SAX) parsing

try { String sql = "select col1 from tab1"; Statement stmt = conn.createStatement(); ResultSet r = stmt.executeQuery(sql);

// Other SAX parsers can go here if desired

Parser p = ParserFactory.makeParser("com.sun.xml.parser.Parser"); p.setDocumentHandler(new myHandler()); p.setErrorHandler(new errHandler());


getInputSource() Example (2)

while(r.next()) { InputSource i = UtilXML.getInputSource(r.getString(1)); p.parse(i); } r.close();} catch (SQLException e) { ... }

while(r.next()) { InputSource i = UtilXML.getInputSource(r.getString(1)); p.parse(i); } r.close();} catch (SQLException e) { ... }


DOM Support The DOM specification does not provide

a standard way to create a DOM object JAXP provides factory methods that

provide a standard way of creating DOM objects


InputStreamtoDOM() Example

-- Fetch XML data from a text column into a DOM objectcreate table tab2 (col1 text);

try { String sql = "select col1 from tab2"; Statement stmt = conn.createStatement(); ResultSet r = stmt.executeQuery(sql); while(r.next()) { Document doc = UtilXML.InputStreamtoDOM(r.getAsciiStream(1)); } r.close();} catch (SQLException e) { ... }

-- Fetch XML data from a text column into a DOM objectcreate table tab2 (col1 text);

try { String sql = "select col1 from tab2"; Statement stmt = conn.createStatement(); ResultSet r = stmt.executeQuery(sql); while(r.next()) { Document doc = UtilXML.InputStreamtoDOM(r.getAsciiStream(1)); } r.close();} catch (SQLException e) { ... }


XML Parser JDBC driver uses Sun’s JAXP API and

by default a non-validating XML Parser The default can be changed in two ways

where <new parser> is the alternative parser% java -Dorg.xml.sax.parser=<new parser>System.setProperty("org.xml.sax.parser",

"<new parser>");


JAXP Summary JDBC 2.20 XML support makes it easy to

store/retrieve XML documents to/from an Informix Database using Sun’s JAXP 1.0 API

Ensures valid or well-formed XML document during insertion because of XML parsing using the SAX protocol

Sun’s non-validation parser is used by default, but the ability to specify and use any parser is provided

Demonstrations


Architecture for Demos

Source:Derived from [Plummer99]


Cloudscape Cloudscape can store Java objects in

table columnsNot just blobs – objects have structure

Java code can accept different data and store as XML

Embed XML formatter into CloudscapeExtend server


Cloudscape Demo: Tables

create table xml_objects (dtd_name char(20),constraint dtd_name_primary_key primary key,xml serialize(xmlobject));

create table dtd_nodes (nodename char(20),constraint nodename_primary_key primary key,contains_elements varchar(20),node_root boolean,contains_attributes varchar(20),attribute_required boolean,contains_data boolean,data_required boolean);

create table xml_objects (dtd_name char(20),constraint dtd_name_primary_key primary key,xml serialize(xmlobject));

create table dtd_nodes (nodename char(20),constraint nodename_primary_key primary key,contains_elements varchar(20),node_root boolean,contains_attributes varchar(20),attribute_required boolean,contains_data boolean,data_required boolean);


Cloudscape Demo: Java (1)

import ...

public class XMLObject implements Serializable {

public Vector elementNames; public Vector elementValues; public String rtnString;

public void XMLObject(Vector names, Vector values) { this.elementNames = names; this.elementValues = values; }...

import ...

public class XMLObject implements Serializable {

public Vector elementNames; public Vector elementValues; public String rtnString;

public void XMLObject(Vector names, Vector values) { this.elementNames = names; this.elementValues = values; }...


Cloudscape Demo: Java (2)

...

public String returnXMLFormat(String DTD) {

genFromDTD dtd = new genFromDTD(); // XML Formatter

rtnString = genFromDTD.returnXMLFormat(this, DTD);

return rtnString;

}

public String toString() {

return "XMLObject Class";

}

}

...

public String returnXMLFormat(String DTD) {

genFromDTD dtd = new genFromDTD(); // XML Formatter

rtnString = genFromDTD.returnXMLFormat(this, DTD);

return rtnString;

}

public String toString() {

return "XMLObject Class";

}

}


Cloudscape Demo: SQL

select xml.returnXMLFormat('BOOKS')from xml_objectswhere dtd_name = 'BOOKS';

select xml.returnXMLFormat('BOOKS')from xml_objectswhere dtd_name = 'BOOKS';


Cloudscape XML Demo

1.Start Cloudview

4.Start Cloudview

5.Start Web Server

6.Start Browser

7.Stop Web Server

2.View XML

3.Compile Java Files

C:\WINNT\system32\isjelchr.exe C:\Program Files\Cloudscape_3.5_Shortcuts\cloudview.ini


C:\WINNT\system32\CMD.EXE

http://localhost:8080/examples/servlets/XMLDemo.htm


C:\jakarta-tomcat-3.2.1\webapps\ROOT\test.xml



Object Translator Provides an object view of a database

Supports Java™/EJB (and VB/MTS)

Builds an object model from a relational schema DBA can focus on the schema, developers focus on

Java

Outputs components Supports Cloudscape, Informix and other

JDBC sources


Mapping/Modelling Process

OR MapsOR Maps

Data ModelData Model

Compile-timeSQL

Compile-timeSQL

Runtime DatabaseAccess

Runtime DatabaseAccess

Reverse Engineer

Object ModelObject Model

UMLUML

Forward Engineer

Object Translator Solution


Object Translator 1.1 Developer maps XML documents to map

objects Generated Java objects become XML

document handlersStore and restore the XML document data in

the database XML markup is not stored or restored

Allows applications to use existing schemas for incoming XML documents


Object Translator XML Demo Use an existing XML document Create links between elements of XML

document and attributes of map object Generate Java files and servlet from map

object Compile and run


Object Translator XML Demo

1.Start Cloudview

4.Copy Files

5.Start Web Server

6.Start Browser

7.Stop Web Server

2.View XML

3.Start OT




http://localhost:8080/examples/servlets/CustomersXMLCS.html


C:\jakarta-tomcat-3.2.1\webapps\ROOT\acustomer.xml

C:\Program Files\Informix\Object Translator\OrMapper.exe


What about Performance? A couple of independent benchmarks are

being developedXMach-1XML Store...


Example Performance Results

We conclude DTD approach is the best strategy among the six approaches we studied and there is no clear need to build an “XML-specific” database system.

We conclude DTD approach is the best strategy among the six approaches we studied and there is no clear need to build an “XML-specific” database system.

Source: [Tian]


Final Thoughts ... Technology is moving fast Vendor marketing ahead of product

capabilities Many “Beta” products available

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Software Downloads Cloudscape

http://www.cloudscape.com/ Object Translator

http://www.informix.com/idn-secure/webtools/ot/


Resources http://www.oasis-open.org/cover/

xmlAndDatabases.html http://www.rpbourret.com/xml/ http://www.sees.bangor.ac.uk/~rich/

research.html http://www.xml-und-datenbanken.de/ http://www.soi.city.ac.uk/~akmal/

html.dir/benchmarks.html

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