Chapter 15 PowerPoint Slides - Computer Information Systems

eCommerce and Database Systems
Chapter 15 - Objectives
 What eCommerce is.
 About general architecture of eCommerce
systems and where database systems fit in.
 About data management issues encountered
in interorganizational systems.
 About a general architecture for Web-database
 About some technologies for integrating Web
and databases .
 About XML.
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Distribution, buying, selling, and marketing of
physical and information goods and services
accomplished using computer networks such as
the Internet.
 Database systems play crucial role in eCommerce
systems by supporting functions such as catalog
search and browsing, order management,
payment systems, inventory management
systems, online marketing, CRM.
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 Business
according to individuals or organizations
participating in the transaction.
 ‘Business to Consumer’ or ‘B2C’.
 ‘Business to Business’ or‘B2B’.
 ‘Consumer to Consumer’ or ‘C2C’ or ‘P2P’ (eg.
 Governments have also entered this chain
lending a ‘G’ component to these combinations.
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eCommerce - Size
 According to (Burns 2006), online consumer
spending (B2C travel and all other B2C online
retail) grew from US$117.2 billion in 2004 to
US$143.2 billion in 2005 worldwide.
 Forrester Research and eMarketer indicate this
market segment will grow to US$316 billion by
 Forrester also reports B2B (including EDI) grew
from US$2.8 trillion in 2004 to US$4.1 trillion in
2005 and could grow to US$6.8 trillion by 2007.
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eCommerce Systems
 Also considered a type of interorganizational
I.S., as they link IT resources between
organizations, typically using network services
on the Internet.
 Student buying a textbook online is using IT
resources of the online book retailer by connecting
to retailer’s Web site from their desktop PC (B2C).
 Automobile manufacturer may send orders for parts
from their purchase order management DBMS to a
supplier’s customer order DBMS by way of EDI over
the Internet (B2B).
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eCommerce – B2C Site
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eCommerce – B2B Site
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eCommerce – G2C Site
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eCommerce – C2C Site
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General Architecture for eCommerce Systems
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General Architecture for eCommerce Systems
 Large
organization (colored box) maintains
systems such as
accounting, inventory
resources, payroll.
Each system contains applications and a
DBMS/database, and potentially each system may
be provided by a different vendor.
Systems may be tightly integrated where a suite of
applications shares the same database schema.
Or systems may be loosely coupled perhaps
installed at different points in time. In this case
data may be copied from one system to another.
Systems are used directly by users internal to the
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General Architecture for eCommerce Systems
 Next logical step is to allow customers to browse
products & services and to place orders via a Web
 Requires business to establish a Web server
system, an eCommerce system, and an online
payment system, such that:
 Web server interacts with Web browsers of the
external users.
 eCommerce system includes features to support
customer user registration, catalog searching and
browsing, product comparison, shopping cart, email list sign-up, and other typical eCommerce
 Online payment system acts as a gateway that sends
out credit verification requests.
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General Architecture for eCommerce Systems
 In B2C, products or services being sold may have a
small unit value (such as songs, images, articles, or
cell phone ringtones).
 Given that processing a credit card transaction costs
about $0.25, purchasing a $0.50 article would not be
commercially sensible.
 In P2P cases, a participant’s low volume of
transactions would preclude setting up a credit card
processing system altogether (eg., consider a seller
who wants to auction off an antique on eBay).
 Micropayment systems such as PayPal and
Peppercoin have been developed to address these
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General Architecture for eCommerce Systems
 Further step business could take would be to
partially integrate their internal systems with
those of other businesses such as key suppliers to
form a supply chain.
 A B2B gateway would be used to link supplier’s
order management system, accounts receivables,
and shipping systems with the businesses’
purchasing, accounts payable, and receiving
 Such supply chain management systems can then
be used to more accurately schedule orders and
deliveries of raw materials and components
required for production of the final product.
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Accessing eCommerce products and services
using mobile devices.
 Include services enabled and/or delivered to
mobile devices such as a cell phone, PDA,
smartphone, or digital music player.
 Take advantage of faster and more robust wireless
data networks to deliver services directly to the
mobile device.
 Now have cell phones that can play movies, PDAs
that can access maps & directions and, in some
countries, cell phones that can be used to pay for
items such as soft drinks, food, and magazines.
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 According to Jupiter Research the revenues for
downloadable ringtones market reached US$450
million in 2005 and expected to grow to US$700
million by 2009.
 ‘Location aware’ services (“show me the closest
Indian food restaurant”) are a fast growing
segment of mCommerce.
 These services use location of customer as an
input to tailor search results, products,
advertising, and services delivered to their mobile
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Critical Success Factors in eCommerce
 As ‘Dot-com bust’ of 2000/2001 proved, not all
eCommerce ventures survived.
 Of many lessons learned, developing robust
business models appears to be one of the main
success factors in any eCommerce venture.
 Needs to address market needs and competitive
risks, while remaining flexible and open to change
as technology and competition evolves in the
 Also, with competitors ‘just a click away’, having
robust and secure systems is a critical success
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Critical Success Factors in eCommerce
 eCommerce businesses that can harness Business
Intelligence and CRM systems and use them to
their advantage stand a much better chance of
attracting and retaining customers.
 While CRM systems support Customer side of B2C,
supply chain management systems support the
business side of B2B.
 Again, leveraging IT to effectively manage and
streamline the flow of materials can give
businesses a competitive advantage.
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Web-Database Integration
 Major task common to all eCommerce systems
centers on integration of organization’s Web site
with its internal database system(s).
 Consider different languages ‘spoken’ by the
respective components of such an integrated system
according to three-tier architecture.
 Web browser (such as IE or Firefox) makes its
requests to a Web server (such as Apache or IIS)
using HTTP.
 For example, if a user clicks on a link to display an
item from a catalog, HTTP request might look like:
GET /home/catalog/LOR3.html
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Web-Database Integration
 When Web server receives this request, it will look in
folder /home/catalog for file LOR3.html and send it
back to Web browser.
File would contain text marked up in HTML.
Small online stores may provide pre-written HTML
pages for each of their products (“static Web pages”).
For more than a few dozen items, managing HTML
pages will become difficult.
Integrating Web site with DBMS that stores products,
descriptions, pricing, and inventory status allows much
larger collection of products and services by turning
requests for Web pages into database queries.
Such pages are called dynamic Web pages, because the
content of the page is dynamically created upon
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Web-Database Integration
 If underlying DBMS is relational, Web server must express
query using SQL. In response, DBMS will either return a
set of records, an acknowledgement that the query was
successful, or an error message.
 Based on this response, Web server will generate an
appropriate Web page and send it back to the Web
 For example, suppose a user clicks on a link to display a
list of all DVDs in a particular genre. HTTP request might
appear as:
GET /home/dvd_list.asp?genre=Action
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Web-Database Integration
 In this case, Web server will invoke a small
program, called a script, written in ASP and pass
along the parameter “genre=Action”.
 At Web server, this request will need to be
unpacked, formed into a SQL query, and
submitted to DBMS on database server.
 In response, DBMS will return a set of records to
Web server, which then must apply appropriate
HTML tags to the records so that they display
properly in Web browser.
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Web-Database Integration – More Detail
Web browser packages up request and sends it via HTTP to
Web server.
Web server receives HTTP request and invokes appropriate
script (dvd_list.asp) on Web server passing along contents of
HTTP request using CGI standard.
Script on Web Server unpacks HTTP request, parses out
various parameters/values (genre=Action), and builds
appropriate SQL.
Script on Web server connects to DBMS on database server
and submits SQL.
DBMS executes SQL, packages up resulting records or
acknowledgement codes, and returns this to Web server.
Script on Web server receives results from database server and
formats results using HTML.
Finally, Web server sends HTML back to Web browser for
interpretation and display.
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Web-Database Integration Technologies
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Web-Database Integration Technologies
 Early approaches based on compiled languages such as C/C++,
plus scripting languages such as Perl, using steps described
Provided freedom to customize interaction, but also required
most programming effort.
Over time, specialized scripting languages such as ASP, JSP,
ColdFusion, and PHP emerged.
Deploying such applications on an enterprise scale requires
another layer of refinement as legacy systems integration,
transaction processing, session management, security, and ability
to serve applications to a variety of mobile devices became
common requirements for Internet applications.
Development platforms such as IBM WebSphere, WebLogic from
BEA Systems, and Microsoft .NET Framework provide pre-built
components that can be assembled into larger Internet
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Examples of Web-Database Integration
Technologies - HTML
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dvd_list.asp Script
<!-- dvd_list.asp -->
<HTML><BODY><H3>The results of your query are</H3>
<TR><TH>CatalogNo <TH> Title <TH> Genre <TH> Rating </TR>
‘ Create a SQL Query using the q_genre field from the query form
strSQL = "SELECT catalogNo, title, genre, rating FROM dvd WHERE genre =
‘” & Request.Form("q_genre") & “'"
‘ Create a connection object and open the connection to a Microsoft
Access database
Set cnn = Server.CreateObject("ADODB.Connection")
cnn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data
‘ Create a query result set object to hold the query results
Set rstQuery = Server.CreateObject("ADODB.Recordset")
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‘ Create a query result set object to hold the query results
Set rstQuery = Server.CreateObject("ADODB.Recordset")
‘ Execute the query in the database and store the results
rstQuery.Open strSQL, cnn
‘ Loop through the query results and for each record print out the
record data
Do Until rstQuery.EOF
Response.Write "<TR><TD>" & rstQuery("catalogNo")
Response.Write "<TD>" & rstQuery("title")
Response.Write "<TD>" & rstQuery("genre")
Response.Write "<TD>" & rstQuery("rating")
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Examples of Web-Database Integration
Technologies - PHP
 PHP Hypertext Processor is an open source
scripting language that was developed in the mid
 Intended to be embedded within HTML pages.
When a PHP page is served, the HTML portions
are sent directly back to the Web browser,
however any code contained within special PHP
tags <?php and ?> are executed by the PHP parser
and the results of the execution are returned to
the Web browser.
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Examples of Web-Database Integration
Technologies - ASP
 Active Server Pages (ASP) is a scripting language
developed by Microsoft that works within Microsoft’s IIS
Web server.
Latest version, ASP.NET, is incorporated into Microsoft’s
.NET framework.
As with other server-side scripting languages such as JSP
and PHP, an ASP page consists of HTML tags with
scripting code placed inside the special HTML tags <% and
When a request arrives for an ASP page, HTML portions
are returned to the Web browser directly while the ASP
code is executed on the server and the results returned to
the Web browser.
ASP code can be written in a number of different
languages including Microsoft’s VBScript and JScript.
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Examples of Web-Database Integration
Technologies - Coldfusion
 ColdFusion is an extension to HTML originally developed
by Allaire Software, later purchased by Macromedia and
who has recently been acquired by Adobe.
 ColdFusion Markup Language (CFML) consists of a
collection of special HTML tags (all start with <CF) that
are mixed within standard HTML to interact with the
ColdFusion Server to access databases and other server
 When Web server receives a request for a CFML page with
a ‘.cfm’ extension, ColdFusion Server handles request,
interprets the CFML tags within the document and
returns resulting HTML to the Web server for delivery to
the Web browser.
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Examples of Web-Database Integration
Technologies – Ruby on Rails
 Ruby is an OO programming language developed in
Japan in the early 1990’s.
Rails (often referred to as ‘Ruby on Rails’) is a
framework for creating database-driven Web and
interactive Web applications using the Ruby
In the Rails framework, objects are created
automatically for each database table along with a
collection of default methods for retrieving,
displaying, editing, and deleting database records.
These existing methods can be extended relatively
easily to perform custom operations on the data.
When establishing a new Rail application, the
database connection is specified once in a
configuration file named ‘database.yml’ so that all
parts of the application can work using the same
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A meta-language (a language for describing other
languages) that enables designers to create their
own customized tags to provide functionality not
available with HTML.
 Most documents on Web currently stored and
transmitted in HTML.
 One strength of HTML is its simplicity.
Simplicity may also be one of its weaknesses,
with users wanting tags to simplify some tasks
and make HTML documents more attractive and
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 To satisfy this demand, vendors introduced some
browser-specific HTML tags, making it difficult
to develop sophisticated, widely viewable Web
 W3C has produced XML, which could preserve
general application independence that makes
HTML portable and powerful.
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 XML is a restricted version of SGML, designed
especially for Web documents.
 SGML allows document to be logically separated into
two: one that defines the structure of the document
(DTD), other containing the text itself.
 By giving documents a separately defined structure,
and by giving authors ability to define custom
structures, SGML provides extremely powerful
document management system.
 However, SGML has not been widely adopted due to
its inherent complexity.
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 XML attempts to provide a similar function to
SGML, but is less complex and, at same time,
 XML retains key SGML advantages of
extensibility, structure, and validation.
 Since XML is a restricted form of SGML, any fully
compliant SGML system will be able to read XML
documents (although the opposite is not true).
 XML is not intended as a replacement for SGML
or HTML.
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Advantages of XML
 Simplicity
 Open standard and platform/vendor-independent
 Extensibility
 Reuse
 Separation of content and presentation
 Improved load balancing
 Support for the integration of data from multiple vendors
 Ability to describe data from a wide variety of applications
 More advanced search engines
 New opportunities.
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Potential Weaknesses of XML
 Requires new software tools and training
 Size and complexity of syntax
 Limited data types in native XML
 Storing
XML documents
OODBMS can be difficult.
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XML - Example
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XML - Elements
 Elements, or tags, are most common form of
 First element must be a root element, which can
contain other (sub)elements.
 XML document must have one root element
(<STAFFLIST>. Element begins with start-tag
(<STAFF>) and ends with end-tag (</STAFF>).
 XML elements are case sensitive
 An element can be empty, in which case it can be
abbreviated to <EMPTYELEMENT/>.
 Elements must be properly nested.
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XML - Attributes
 Attributes are name-value pairs that contain
descriptive information about an element.
 Attribute is placed inside start-tag after
corresponding element name with the attribute
value enclosed in quotes.
<STAFF branchNo = “S1500”>
 Could
also have represented branch as
subelement of STAFF.
 A given attribute may only occur once within a
tag, while subelements with same tag may be
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XML – Other Sections
 XML declaration: optional at start of XML
 Entity references: serve various purposes, such as
shortcuts to often repeated text or to distinguish
reserved characters from content.
 Comments: enclosed in <!– and --> tags.
 CDATA sections: instructs XML processor to
ignore markup characters and pass enclosed text
directly to application.
 Processing instructions: can also be used to
provide information to application.
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Document Type Definitions (DTDs)
Defines the valid syntax of an XML document.
 Lists element names that can occur in document,
which elements can appear in combination with
which other ones, how elements can be nested,
what attributes are available for each element
type, and so on.
 Term vocabulary sometimes used to refer to the
elements used in a particular application.
 Note: Grammar not specified using XML.
 Although optional, DTD is recommended for
document conformity.
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Document Type Definitions (DTDs)
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Document Type Definitions (DTDs)
 Identify the rules for elements that can occur in
the XML document. Options for repetition are:
 * indicates zero or more occurrences for an element;
 + indicates one or more occurrences for an element;
 ? indicates either zero occurrences or exactly one
occurrence for an element.
 Name with no qualifying punctuation must occur
exactly once.
 Commas between element names indicate they
must occur in succession; if commas omitted,
elements can occur in any order.
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Document Type Definitions (DTDs)
 Identify which elements may have attributes,
what attributes they may have, what values
attributes may hold, plus optional defaults.
Some types:
 CDATA: character data, containing any text.
 ID: used to identify individual elements in
document (ID is an element name).
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Document Type Definitions (DTDs)
 Two levels of document processing: well-formed
and valid.
 Non-validating processor ensures an XML
document is well-formed before passing
information on to application.
 XML document that conforms to structural and
notational rules of XML is considered wellformed; e.g.:
 document must start with <?xml version “1.1”>;
 all elements must be within one root element;
 elements must be nested in a tree structure without any
 Validating processor will not only check that an XML
document is well-formed but that it also conforms to
a DTD, in which case XML document is considered
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XML Schema
 DTDs have number of limitations:
 it is written in a different (non-XML) syntax;
 it has no support for namespaces;
 it only offers extremely limited data typing.
 XML Schema is more comprehensive method of
defining content model of an XML document.
 Additional expressiveness will allow Web
applications to exchange XML data more
robustly without relying on ad hoc validation
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XML Schema – Major Features
 complexType: named element that can contain other elements
or other complexTypes.
sequence: named element that contains an ordered set of
simpleType: named element with a simple data type (such as
boolean, string, date, or decimal).
Cardinality: element can be specified with minOccurs and
maxOccurs indicating minimum and maximum occurrences
References: such as <xs:element ref = “STAFFNO”/>, can be used
to refer to other elements defined elsewhere in same XML
Defining new data types.
Defining groups of elements and attributes.
Constraints on elements and attributes including uniqueness of
values among a set of elements or attributes, as well as key
constraints that require a non-null, as well as unique value.
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XML Schema - Example
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XSL (eXtensible Stylesheet Language)
 In HTML, default styling is built into browsers as
tag set for HTML is predefined and fixed.
 Cascading
provides alternative rendering for tags. Can also
be used to render XML in a browser but cannot
make structural alterations to a document.
 XSL created to define how XML data is rendered
and to define how one XML document can be
transformed into another document.
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XSLT (XSL Transformations)
 Subset of XSL, XSLT is a language in both markup
and programming sense, providing a mechanism
to transform XML structure into either another
XML structure, HTML, or any number of other
text-based formats (such as SQL).
 XSLT’s main ability is to change the underlying
structures rather than simply the media
representations of those structures, as with CSS.
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XSLT (XSL Transformations)
is important because it provides a
mechanism for dynamically changing the view of
a document and for filtering data.
 Also robust enough to encode business rules and
it can generate graphics (not just documents)
from data.
 Can even handle communicating with servers
(scripting modules can be integrated into XSLT)
and can generate the appropriate messages
within body of XSLT itself.
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 Reformulation of HTML 4.01 in XML 1.0 and is
intended to be next generation of HTML.
 Basically a stricter and cleaner version of HTML;
 tags and attributes must be in lowercase;
 all XHTML elements must be have an end-tag;
 attribute values must be quoted and minimization
is not allowed;
 ID attribute replaces the name attribute;
 documents must conform to XML rules.
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 XQuery derived from XML query language called
Quilt, which has borrowed features from XPath,
XML-QL, SQL, OQL, Lorel, XQL, and YATL.
 Like OQL, XQuery is a functional language in
which a query is represented as an expression.
 XQuery supports several kinds of expression,
which can be nested (supporting notion of a
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XQuery Path Expressions
 Uses syntax of XPath.
 In XQuery, result of a path expression is ordered
list of nodes representing data.
 Result of path expression may contain duplicate
 Can begin with the function document(string),
which refers to a named XML document.
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XQuery Path Expressions - Examples
Find staff number of first member of staff in our
XML document.
 Three steps:
 first opens staff_list.xml and returns its document
 second locates first STAFF element that is child of
root element;
 Third
finds STAFFNO elements occurring
anywhere within this STAFF element.
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XQuery Path Expressions - Examples
Find staff numbers of first two members of staff.
doc(“staff_list.xml”)/STAFF[1 TO 2]/STAFFNO
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XQuery Path Expressions - Examples
Find names of staff at distribution center D001.
doc(“staff_list.xml”)/STAFF[DCENTERNO =“D001”]/NAME
 Four steps:
 first two as before;
 third consists of predicate that restricts STAFF
elements to those with DCENTERNO attribute =
 Fourth selects NAME element(s) occurring
anywhere within these elements.
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XQuery – FLWR Expressions
 FLWR (“flower”) expression is constructed from FOR,
FLWR expression starts with one or more FOR or LET
clauses in any order, followed by optional WHERE
clause, and required RETURN clause.
FOR clause is used to loop over collection of
elements so each element can be inspected
LET clause is used to reference a collection of
elements for purposes of summarizing the set of
WHERE clause filters elements in the XML document
according to some condition.
RETURN clause is similar to the SELECT clause of
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XQuery – FLWR Expressions
List staff at center D001 with salary > $15,000.
FOR $S IN document("staff_list.xml")//STAFF
 Note, predicate seems to compare an element
(SALARY) with a value (15000). In fact, ‘=’ operator
extracts typed value of element resulting in a
decimal value in this case, which is then compared
with 15000.
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XQuery – FLWR Expressions
List each center and average salary at the center.
LET $avgSalary := avg(doc(“staff_list.xml”)//
< DCENTERNO>{ $D/text() }</ DCENTERNO>,
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XQuery – FLWR Expressions
List centers that have more than 20 staff.
LET $S := doc(“staff_list.xml”)/STAFF/[DCENTERNO = $D]
WHERE count($S) > 20
<BRANCHNO>{ $B/text() }</BRANCHNO>
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 SQL:2003 has extensions to enable publication of
XML (commonly referred to as SQL/XML):
 new native XML data type, XML, which allows XML
documents to be treated as relational values in
columns of tables, attributes in user-defined
types, variables, and parameters to functions;
 set of operators for the type;
 implicit set of mappings from relational data to
 Standard does not define any rules for the inverse
process; i.e., shredding XML data into an SQL form,
with some minor exceptions.
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SQL/XML Functions
 XMLELEMENT(), creates an XML element from a
named column name. Works on one column at a
XMLATTRIBUTES(), creates an XML attribute from a
column value using the column name as the name of
the attribute. Works on one column at a time.
XMLFOREST(), creates a list of XML elements from a
set of column names.
XMLCONCAT(), concatenates two or more XML
values into one XML element.
XMLAGG(), aggregates a collection of values into one
XML element.
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Web Services
interoperable machine-to-machine interaction
over a network.
 Have recently been established as important paradigm in
building applications and processes for integration of
heterogeneous applications in the future.
 Based on open standards and focus on communication
and collaboration among people and applications.
 Unlike other Web-based applications, Web services have
no user interface and are not targeted for browsers.
Instead, they consist of reusable software components
designed to be consumed by other applications, such as
traditional client applications, Web-based applications, or
other Web services.
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Web Services
 Common example is a stock quote facility, which
receives request for current of a specified stock
and responds with the requested price.
 Second example, Microsoft has produced a
MapPoint Web service that allows high quality
maps, driving directions, and other location
information to be integrated into a user
application, business process, or Web site.
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Web Services
 Based on use of widely accepted technologies and
standards; eg:
 XML.
 SOAP (Simple Object Access Protocol) protocol,
based on XML, is used for communication over the
(Web Services Description Language)
protocol, again based on XML, is used to describe the
Web service. WSDL adds a layer of abstraction
between the interface and the implementation,
providing a loosely-coupled service for future
 UDDI (Universal Discovery, Description, and
Integration) protocol is used to register the Web
service for prospective users.
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Web Services
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 An XML-based messaging protocol that defines a
set of rules for structuring messages.
 Protocol can be used for simple one-way
messaging but also useful for performing RPCstyle request-response dialogues.
 Not tied to any particular operating system or
programming language nor any particular
transport protocol, although HTTP is popular.
 Important advantage of SOAP is that most
firewalls allow HTTP to pass right through,
facilitating point-to-point SOAP data exchanges.
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 SOAP message is an XML document containing:
 A required Envelope element that identifies the
XML document as a SOAP message.
 An optional Header element that contains
application specific information such as
authentication or payment information.
 A required Body Header element that contains call
and response information.
 An optional Fault element that provides
information about errors that occurred while
processing message.
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 XML-based protocol for defining a Web service.
 Specifies location of a service, operations service
exposes, SOAP messages involved, and comms
protocol used to talk to service.
 Notation that a WSDL file uses to describe
message formats is typically based on XML
 Published WSDL descriptions can be used to
obtain information about available Web services.
©Pearson Education 2009
Web Services - Examples
 Google Applications Programming interface, which
allows other programmers to access Google search
results by submitting Web services requests.
 Amazon Web Service (AWS) provides access to’s products catalog as well as a variety of
other services. For example, any retailer can publish
their products and make them available within
Amazon’s catalog for search, product comparison
and so on.
 OpenSearch, supported by an aggregate
search engine developed by, provides a
set of formats and Web services used for sharing
search results.
©Pearson Education 2009

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