Web Information Systems
Universal Client Access
Prof. Beat Signer
Department of Computer Science
Vrije Universiteit Brussel
http://vub.academia.edu/BeatSigner
2 December 2005

Web Interfaces to Databases
 Universal client (front-end) for databases (back-end) that
are located anywhere around the world
 no application-specific software has to be installed on the client
side (e.g. just a browser)
 While early interfaces were mainly HTML-based, single
channel access is often no longer sufficient
 web technologies are nowadays used to deliver information to
a range of devices
 multi-channel access/interfaces
 how can multiple input/output channels be supported with minimal
effort?
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 2

Multi-Channel Access
 The idea is to reuse most of the application logic and
only adapt the final rendering step (visualisation)
 A possible solution is to use an intermediary and media
neutral format (e.g. XML)
 middle-tier retrieves information from databases or services
- either the information is already retrieved in XML or the middle-tier creates
new XML documents
 use XSLT to transform the intermediary XML format to the
appropriate output format
- type of client for example identified by the User-Agent HTTP header field
 Two types of user interfaces
 generic database interfaces
 application-specific interfaces
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 3

XML Storage
 Use file system to make XML documents persistent
 problems: document size, versioning, concurrency, security
 Use RDBMS to store XML documents
 XML-enabled databases
 e.g. Oracle 11g offers features to query XML documents that
have been stored in a field
 Use native XML database (NXD)
 e.g. Software AG's Tamino
 Dynamically generate the XML documents from the
database content rather than storing XML itself
 publishing of DB content to XML documents
 shredding of XML documents to store them in DB tables
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 4

XML Storage …
 Object Database Management Systems (ODBMS) offer
advantages when dealing with objects that have complex
relationships
 the OMS Java ODBMS will be used in some of the examples
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 5

XML for Data Interchange
 Standard representation to exchange information
between different systems
 General way to query data from different systems
 e.g. via the XML Query (XQuery) language
 Connect applications running on different operating
systems and computers with different architectures
 XML Remote Procedure Call (XML-RPC)
 Simple Object Access Protocol (SOAP) which is a successor
of XML-RPC and used for accessing Web Services
- discussed later in the course
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 6

XML-RPC
 XML-RPC specification released in April 1998
 Advantages
 XML-based Esperanto understood by different applications
 HTTP as carrier protocol
 not tied to any single object model (like CORBA etc.)
 easy to implement (based on HTTP and XML standards)
 light-weight protocol
 built-in error handling
 Disadvantages
 slower than specialised protocols used in closed networks
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 7

XML-RPC Request and Response
POST /RPC2 HTTP/1.0 HTTP/1.1 200 OK
User-Agent: Java1.2 Connection: close
Host: macrae.vub.ac.be Content-Length: 159
Content-Type: text/xml;charset=UTF-8 Content-Type: text/xml
Content-length: 245 Server: macbain.vub.ac.be
<?xml version="1.0" encoding="ISO-8859-1"?> <?xml version="1.0" encoding="ISO-8859-1"?>
<methodCall> <methodResponse>
<methodName>Math.multiply</methodName> <params>
<params> <param>
<param> <value><double>32768.0</double></value>
<value><double>128.0</double></value> </param>
</param> </params>
<param> </methodResponse>
<value><double>256.0</double></value>
</param>
</params>
</methodCall>
XML-RPC Request XML-RPC Response
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 8

XML-RPC Error Message
HTTP/1.1 200 OK
Connection: close
Content-Length: 159
Content-Type: text/xml
Server: macbain.vub.ac.be
<?xml version="1.0" encoding="ISO-8859-1"?>
<methodResponse>
<fault>
<value>
<struct>
<member>
<name>faultCode</name>
<value><int>873</int></value>
</member>
<member>
<name>faultString</name>
<value><string>Error message</string></value>
</member>
</struct>
</value>
</fault>
</methodResponse>
XML-RPC Response
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 9

XML-RPC Scalar Values
XML-Tag Type Corresponding Java Type
<i4> or <int> four-byte signed integer Integer
<boolean> 0 or 1 Boolean
<string> ASCII string String
<double> double-precision signed float Double
<dateTime.iso8601> date/time Date
<base64> base64-encoded binary byte[]
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 10

XML-RPC Composed Values
XML-Tag Type Corresponding Java Type
A structure contains
<member> elements and
<struct> each member contains a Hashtable
<name> and a <value>
element
An array contains a single
<data> element, which can
<array> Vector
contain any number of
<value> elements
 Complex data types can be represented by nested
<struct> and <array> structures
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 11

XML-RPC Example: GOMES
 Object-Oriented GUI for
the Object Model Multi-
User Extended Filesystem
 GOMES is implemented in
Java and uses XML-RPC
to communicate with the
Object Model Multi-user
Extended File System
(OMX-FS) which was XML-RPC
written in the Oberon
programming language
OMX-FS
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 12

Framework for Universal Client Access
 Generic database interface instead of developing a new
interface from scratch for each new device type
 use a technology which enables the separation of content from its
representation (XML)
 rendering based on the user agent type requesting the data (XSL)
 The presented eXtensible Information Management
Architecture (XIMA) is based on
 OMS Java object database
- application data
 Java Servlet Technology
 generic XML database interface
 XSLT
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 13

XIMA Architecture
HTML WML VXML
Browser Browser Browser
Main Entry Servlet
XML + XSLT
Delegation → Response
HTML Servlet WML Servlet VXML Servlet
Builds XML
based on JDOM
XML Server
OM Model
Collections, Associations,
multiple inheritance and
multiple instantiation
OMS Java API
OMS Java Workspace
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 14

Generic XIMA Interfaces
XHTML Interface WML Interface
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 15

Contextual Information about a Client
 The content of a response may be adapted based on
 type of client device
 browser version
 user
 user role
 user preferences
- language, colour, ...
 user access history
 location
 time
 ...
 XIMA currently uses the User-Agent HTTP header field
for identifying the type of client device
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 16

Composite Capability/Preference Profiles
 Composite Capabilities/Preference Profiles (CC/PP) is a
W3C specification for defining a client's preferences and
capabilities
 Client sends a request together with their CC/PP profile
 CC/PP profiles are decribed by using the Resource
Description Framework (RDF)
 <resource, property, value> triples
 RDF will be discussed later in the course
 A CC/PP profile defines a number of components
(e.g. hardware) together with their corresponing
attributes (e.g. screen resolution)
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 17

CC/PP Example
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:prf="http://www.w3.org/TR/WD-profile-vocabulary#">
<rdf:Description about="HardwarePlatform">
<prf:Defaults Vendor="Nokia" Model="2160" Keyboard="Yes" ... />
<prf:Modifications Memory="32mB" />
</rdf:Description>
<rdf:Description about="SoftwarePlatform">
<prf:Defaults OS="EPOC1.0" HTMLVersion="4.01" WAPVersion="1.1" ... />
<prf:Modifications Sound="Off" ... />
</rdf:Description>
<rdf:Description about="EpocEmail1.0">
<prf:Defaults HTMLVersion="4.01" />
</rdf:Description>
<rdf:Description about="UserPreferences">
<prf:Defaults Language="English"/>
</rdf:Description>
...
</rdf:RDF>
 Supports multiple vocabularies via namespaces
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 18

WML and WAP
 Wireless Markup Language (WML) is a markup language
for WAP browsers
 XML application based on a minimal set of tags
 pages are called decks (transfer unit) and they contain
cards (navigation unit)
 navigation based on tasks (buttons, …) and events (timers, …)
 Wireless Application Protocol (WAP) is the protocol used
for data exchange between mobile clients and a gateway
 handles protocol conversion between HTTP and WAP
 compiles WML source text into bytecode
 enables the use of established HTTP server technology
(Servlets, CGI, Perl Scripts, PHP, …) to serve WML content
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 19

WML and WAP …
Client WAP Gateway Web Server
WML Protocol Adapters Content
2 3
WMLScript WAP WMLScript Encoder HTTP CGI Scripts
6 5
WMLEncoder Java Servlets
1
WML Decks
7 4
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 20

WML Example
<?xml version="1.0"?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN"
"http://www.wapforum.org/DTD/wml_1.1.xml">
<wml>
<card id="sven" title="Sven">
<p><b>Sven Casteleyn</b>
<img src="/images/sven.wbmp" alt="picture sven" />
... Sven's friend <anchor>William<go href="#william"/></anchor> ...
</p>
</card>
<card id="william" title="William">
<p><b>William Van Woensel</b>
<img src="/images/william.wbmp" alt="picture william" />
...
</p>
</card>
...
</wml>
 Deck size limited to ~1.5 kB
 Only *.wbmp images supported
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 21

Other WML Tags
 <input>
 input fields
 <select> and <option>
 show list of choices
 <timer>
 automatically trigger the loading of new content
 ...
 Check the WML tutorial
 http://www.w3schools.com/wap/
 In the exercise you will have the chance to further
investigate WML
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 22

Implications for the XIMA WML Interface
 WAP limits the deck size to ~ 1.5 kB
 Large OMS Collections have to be transferred in several
pieces (sections)
 splitting is done by reducing the DOM tree after the WML
transformation (if result > 1.5 kB)
- retransform the reduced XML document
 section size is varied dynamically and memorised for each
membertype
 Large OMS Instances (too many attributes) also have to
be split
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 23

WAP 2.0
 Since WAP 2.0 the gateway is no longer required
 end-to-end HTTP communication
 gateway can still be used to add additional information (proxy)
 WML has been replaced by XHTML Mobile Profile
(XHTML MP)
 however WML is still widely used
 XHTML MP
 looks like a regular XHTML document with special functionality for
mobile devices
 sometimes XHTML MP may show different behaviour on different
devices (e.g. binding of keys etc.)
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 24

XHTML MP Example: Numbered Menu
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.0//EN"
"http://www.wapforum.org/DTD/xhtml-mobile10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<title>Contacts</title>
</head>
<body>
<p>
select a contact:
<ol>
<li><a href="contacts.php?id=12" accesskey="1">Sven</a></li>
<li><a href="contacts.php?id=76" accesskey="2">William</a></li>
<li><a href="contacts.php?id=16" accesskey="3">Olga</a></li>
<li><a href="contacts.php?id=31" accesskey="4">Wolf</a></li>
</ol>
</p>
</body>
</html>
 Entries can be selected by pressing the corresponding
number
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 25

Why Voice Interfaces?
 Trend for ubiquitous information services
 small screens, keyboards etc. often clumsy to use
 Sometimes it is necessary to have hand-free interfaces
 e.g. while driving or operating a machine
 Alternative input modality for visually impaired users
 Voice interfaces can be accessed by a regular phone
 no new device is required
 no installation effort
 Improvements in speech recognition and text-to-speech
synthesis make automatic voice interfaces more feasible
 e.g. for call centers
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 26

Why VoiceXML
 Application developers do not have to deal with the
complexity of speech processing
 can build the system using specific SDKs and IDEs
 only at the end the system has to be deployed to
a voice portal server
 Can develop more flexible and user friendly call services
 integrated with already existing interfaces for HTML and other
channels
 can share information infrastructure of other interfaces
 Based on web technologies (e.g. XML)
 Various VoiceXML outsourcers (voice portals)
 hosting of speech processing system and telephony equipment
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 27

VoiceXML Functionality
 Input
 recognition of spoken input
 recognition of DTMF (dual-tone multi-frequency) input
 recording of spoken input
 Output
 speech synthesis (TTS)
 recorded audio files
 Telephony features (e.g. call transfer, disconnect)
 Each dialogue has one or more speech or DTMF
grammars associated with it
 Events are thrown by the platform under a variety of
circumstances (e.g. timeout)
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 28

VoiceXML Architecture
Voice Input Voice Output
Speech Language Application Speech
Speech Text Meaning Text Speech
Recogniser Analyser Server Synthesiser
Converts voice Extracts meaning Gets data (text) Generates
input into text from text from database speech output
Application Pronounciation
Speech model Grammar
database rules
 Various solutions
 development: IBM WebSphere Voice Server SDK
 deployment: BeVocal Cafe Voice Portal
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 29

VoiceXML Architecture (for XIMA)
Websphere Voice BeVocal
Server SDK Voice Portal
Apache
Tomcat XIMA Framework
Web Server
OMS Java
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 30

Basic VoiceXML Concepts
 Dialogue
 conversational state
 each dialogue is either a form or a menu
 Form
 interaction that collects values for field item variables
 Menu
 presents user with a choice of options
 transition to next dialogue based on choice
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 31

VoiceXML Form Example
<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.w3.org/2001/vxml
http://www.w3.org/TR/voicexml20/vxml.xsd" version="2.0">
<form id="drinkForm">
<field name="drink">
<prompt>Would you like to order beer, wine, whisky, or nothing?</prompt>
<grammar src="drinks.grxml" type="application/srgs+xml"/>
</field>
<block>
<submit next="http://www.wise.vub.ac.be/drinks.php"/>
</block>
</form>
</vxml>
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 32

VoiceXML Menu Example
<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.w3.org/2001/vxml
http://www.w3.org/TR/voicexml20/vxml.xsd" version="2.0">
<menu id="mainMenu">
<prompt>
This is the main menu. What would you like to order? <enumerate/>
</prompt>
<choice next="#foodForm">food</choice>
<choice next="#drinkForm">drink</choice>
</menu>
...
</vxml>
 Check the VoiceXML specification
 http://www.w3.org/TR/voicexml20/
 In the exercise you will have the chance to further
investigate VoiceXML
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 33

Design Phase for XIMA Voice Interface
 Define the required functionality
 User analysis
 motivation, expertise
 High level decisions
 full-duplex (barge-in)
 simple grammars (dynamic)
 only synthesised speech (TTS)
- prerecorded audio make the system less flexible for changes
 Representation of base types
 Information flow
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 34

The database contains #Collections and #Associations
Would you like to go to the collections, to the associations,
directly to an object or back to the main menu?
collections associations objects
The database contains the The database contains the
The database contains #Objects
following # collections following # associations
Choose a collection Choose an association Choose an object or say back
Collection 'name' contains #M Association 'name' contains #A
Would you like to list the Would you like to list the
members or go back? members or go back?
Collection 'name' contains the Association 'name' contains the
following # members following # associations
Choose a 'domaintype' or
Choose one of the members
a 'rangetype' or say back
Object 'oID' is dressed with type 'type' and currently viewed as type 'type'. It contains #Attr, #Links, and #Methods
Would you like to hear the attributes, the links or
the methods or go back?
The object contains the You can choose among You can choose among You can view the object
following # attributes the following links the following methods as the following types
Choose a link Choose a method Choose one of the
or say back or say back types or say back
The result of the
method is Result
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 35

Comments to Design
 Reduce recognition problems
 elimination of similar sounding words from the grammar
 addition of optional (filling) words to the grammar (e.g. 'please')
 Provide sufficient help functionality
 consider introduction of prompt-specific help instead of always
active command list
 Provide immediate feedback after input has been
processed ('OK' prompt)
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 36

Define Flexible Grammars
 For example, a yes/no question may be answered by
 yes
 yeah
 sure
 yes, that's right
 yes it is
 no
 nope
 incorrect
 no way
 no it's not
 …
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 37

XIMA VoiceXML Grammar Example
<?xml version="1.0" encoding="UTF-8"?>
<vxml ... >
...
<grammar type="application/grammar+xml" root="toplevel2" mode="voice">
<rule id="toplevel2">
<one-of>
<item>
<token>Association</token>
</item>
<item>
<token>Associations</token>
</item>
<item>
<token>Association please</token>
</item>
<item>
<token>Associations please</token>
</item>
<item>
<token>Go to the Association</token>
</item>
...
</one-of>
</rule>
</grammar>
</vxml>
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 38

Example: Avalanche Forecasting System
Project to provide WAP
and voice access
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 39

Other XML Applications
 Synchronized Multimedia Integration Language (SMIL)
 animations (timing, transitions etc.)
 Mathematical Markup Language (MathML)
 mathematical notations (content and structure)
 Scalable Vector Graphics (SVG)
 two-dimensional vector graphics (static or dynamic)
 InkML
 digital ink representation (e.g. from electronic pen)
 Note that XML standards can also be combined
 e.g. XHTML+Voice Profile 1.0
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 40

Other XML Applications …
 Office Open XML (OOXML)
 file format (ZIP) for representing word processing documents,
presentations etc. (e.g. *.docx, *.pptx and *.xlsx)
- various XML files within these ZIP documents
- specific markup languages for different domains (wordprocessingML,
presentationML, spreadsheetML, …)
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<p:sld xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main"
xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"
xmlns:p="http://schemas.openxmlformats.org/presentationml/2006/main">
... <a:p>
<a:r><a:rPr lang="en-GB" dirty="0" smtClean="0" />
<a:t>Other XML</a:t>
</a:r>
<a:r><a:rPr lang="en-GB" dirty="0" smtClean="0" />
<a:t>Applications ...</a:t>
</a:r>
<a:endParaRPr lang="en-GB" dirty="0" />
</a:p> ...
</p:sld>
single slide from a pptx file
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 41

Exercise 4
 Hands-on experience with XML applications
 WML or XHTML MP user interface
 VoiceXML user interface
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 42

References
 XML-RPC Homepage
 http://www.xmlrpc.com
 WML Tutorial
 http://www.w3schools.com/wap/
 VoiceXML Version 2.0
 http://www.w3.org/TR/voicexml20/
 B. Signer et al., Aural Interfaces to Databases based on
VoiceXML, Proc. of VDB6, Brisbane, Australia, 2002
 http://www.inf.ethz.ch/~signer/publications/2002a-sngh-vdb.pdf
October 15, 2009 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 43

Next Week
Web 2.0 Basics
2 December 2005