1. Chapter 1 XML Design for Data
Database Lab
석사1학기 강 나 영

2. XML for Text vs.XML for Data
If the markup were removed, the text of paragraph itself would still have the same meaning outside the XML document.
The order of the information is of critical importance to understanding its meaning.
XML for Data
Data can be represented in a number of different ways and still have the same functionality.

3. Representing Data in XML
Element Content Models
Element-only content
Mixed content
Text-only content
The EMPTY model
The Ant model
Using Attributes
Other Considerations
Audience
Performance
Data modeling vs. representation modeling

4. Element Content Models(1)
Element-only content
Elements may only contain other elements.
ex)
Mixed Content
Elements may contain zero or more instances of list of elements.
<!ELEMENT Invoice (Customer, LineItem+)>
<Invoice>
<Customer />
<LineItem />
</Invoice>
<!ELEMENT Invoice (#PCDATA | LineItem | Custome)*>
<Invoice>
This is the invoice for <Customer>Kevin Williams</Customer>
</Invoice>

5. Element Content Models(2)
Text-only Content
Elements may only contain text string.
ex)
One way to include data points in our documents.
EMPTY Content
An element cannot contain anything at all.
<!ELEMENT Customer (#PCDATA)>
<Customer>Kevin Williams</Customer>
<!ELEMENT Customer EMPTY>
<Customer />

6. Element Content Models(3)
ANY Content
Any element or text may appear inside the element. ex) or
※Mixed content model & ANY content model
; too permissive for data
<!ELEMENT Customer ANY>
<Customer>Kevin Williams</Customer>
<Customer>
<Customer>Kevin Williams</Customer>
</Customer>

7. Using Attributes The other way to represent data points. ex)
<!ELEMENT Customer EMPTY>
<!ATTLIST Customer
FirstName CDATA #REQUIRED
LastName CDATA #REQUIRED>
<Customer
FirstName=“Kevin”
LastName=“Williams”/>

8. Other Considerations(1)
Audience
Dose the document need to be human-readable?
Is the document intended primarily for display or for processing?
How many consumers will be processing the document?
Is the document intended to operate under a standard that constrains the allowable structure?
Performance
ex)
<Invoice
customerName=“Kevin Williams”>
<LineItem
productName=“Grommets (2 inch)”
quantity=“17”
price=“0.10” /></Invoice>
<I c=“c17”><L p=“p22” q=“17” pr=“.1” /></I>

9. Other Considerations(2)
Data Modeling vs. Representation Modeling
Representation Modeling
ex)
<Invoice>
Widgets, Inc.
Invoice
Customer: <customerName>Kevin Williams</customerName>
<orderAddress>742 Evergreen Terrace</orderAddress>
Ship to: <shipName>Kevin Williams</shipName>
<shipAddress>742 Evergreen Terrace</shipAddress>
Shipper: <shippingCompany>FedEx</shoppingCompany>
Item Code Description Quantity price Total
<LineItem>
<itemCode>1A2A3AB</itemCode>
<itemDescription>Widget(3 inch)</itemDescription>
<quantity>17</quantity>
<price>$0.10</price>
<linePrice>$1.70</linePrice>
</LineItem>
</Invoice>

10. Other Considerations(2)
Data Modeling vs. Representation Modeling
Data Modeling
ex)
<Invoice
customerName=“Kevin Williams”
<Address
addressType=“billing”
street=“742 Evergreen Terrace”/>
addressType=“shipping”
<LineItem
itemCode=“1A2A3AB”
itemDescription=“Widget(3 inch)”
quantity=“17”
price=“0.10”
currency=“USD”/>
</Invoice>

11. Mapping Between RDBMS and XML Structures(1)
When moving data between XML form and a relational database
a table ↔ an element with element-only content
ex)
Within <Customer> element, the details about the customer can be represented in one of two ways.
Using text-only elements.
Using attributes.
CREATE TABLE Customer (
firstName varchar(50),
lastName varchar(50),
mailingAddress varchar(50),
mailingCity varchar(60),
mailingState varchar(3))

12. Mapping Between RDBMS and XML Structures(2)
1) Elements
ex)
<!ELEMENT Customer (firstName, lastName, mailingAddress,
mailingCity, mailingState)>
<!ELEMENT firstName (#PCDATA)>
<!ELEMENT lastName (#PCDATA)>
<!ELEMENT mailingAddress (#PCDATA)> ‥‥
<Customer>
<firstName>Kevin</firstName>
<lastName>Williams</lastName>
<mailingAddress>742 Evergreen Terrace</mailingAddress> ‥‥
</Customer>
When representing data in an XML document, any element
that is defined as having text-only content using the #PCDATA
keyword will correspond to a column in a relational database.

13. Mapping Between RDBMS and XML Structures(3)
2) Attributes
Elements that represent tables have attributes associated with them that represent columns.
ex)
<!ELEMENT Customer EMPTY>
<!ATTRIST Customer
firstName CDATA #REQUIRED
lastName CDATA #REQUIRED
mailingAddress CDATA #REQUIRED ‥‥
<Customer
firstName=“Kevin”
lastName=“Williams”
mailingAddress=“742 Evergreen Terrace”
‥‥ />

14. Mapping Between RDBMS and XML Structures(4)
Data Points
There are two primary design strategies that may be used to represent column s as XML structures.
Elements, which are nested as children of the element that represents the grouping of information.
Attributes, which are added to the element that represents the grouping of information.
ex)
Widgets, Inc.
Invoice
Customer: Kevin Williams
742 Evergreen Terrace
Ship to: Kevin Williams
Shipper: FedEx
Item Code Description Quantity price Total
1A2A3AB Widget(3 inch) $ $1.70

15. Mapping Between RDBMS and XML Structures(5)
1) Our Invoice Using Elements
ex)
<!ELEMENT Invoice (customerName, billingAddress, billingCity,
billingState, ‥‥, LineItem+)>
<!ELEMENT customerName (#PCDAYA)>
<!ELEMENT billingAddress (#PCDATA)> ‥‥
<!ELEMENT LineItem (itemCode, itemDescription,quantity,price)>
<!ELEMENT itemCode (#PCDATA)>
<!ELEMENT itemDescription (#PCDATA)>
[Ch02_ex1.dtd]
<?xml version=“1.0” ?>
<!DOCTYPE Invoice SYSTEM
<Invoice>
<customerName>Kevin Williams</customerName> ‥‥
<LineItem>
<itemCode>1A2A3AB</itemCode>
[Ch02_ex1.xml]

16. Mapping Between RDBMS and XML Structures(6)
2) Our Invoice Using Attributes
ex)
<!ELEMENT Invoive (LineItem+)>
<!ATTRIST Invoice
customerName CDATA #REQUIRED
billingAddress CDATA #REQUIRED
‥‥ >
<!ELEMENT LineItem EMPTY>
<!ATTRIST Lineitem
itemCode CDATA #REQUIRED
itemDescription CDATA #REQUIRED
[Ch02_ex2.dtd]
<?xml version=“1.0” ?>
<!DOCTYPE Invoice SYSTEM
<Invoice
customerName=“Kevin Williams”
‥‥ />
<LineItem
itemCode=“1A2A3AB”
</Invoice>
[Ch02_ex2.xml]

17. Mapping Between RDBMS and XML Structures(7)
3) Comparing the two Approaches
Readability
Compatibility with database
Strong data typing
Programming complexity
DOM (Document object Model)
SAX (Simple API for XML)
Document size

18. Mapping Between RDBMS and XML Structures(8)
Relationships
ex)
Invoice
LineItem
CREATE TABLE Invoice (
invoiceID integer PRIMARY KEY,
customerID integer,
‥‥ )
CREATE TABLE LineItem (
lineItem integer,
invoiceID integer, ‥‥
CONSTAINT fk_LineItemInvoice
FOREIGN KEY (invoiceID)
REFERENCES Invoice (invoiceID))
invoiceID
customerID
orderDate
shipDate
lineItemID
invoiceID
productDescription
quantity
unitprice

19. Mapping Between RDBMS and XML Structures(9)
1) Containment
One-to-one and one-to-many relationships are best represented by containment
ex)
<!ELEMENT Invoive (LineItem+)>
<!ATTRIST Invoice
orderDate CDATA #REQUIRED
shipDate CDATA #REQUIRED>
<!ELEMENT LineItem EMPTY>
<!ATTRIST Lineitem
productDescription CDATA #REQUIRED
‥‥ >

20. Mapping Between RDBMS and XML Structures(10)
2) More Complex Relationships - Pointers
Invoice
invoiceID
customerID
orderDate
shipDate
LineItem
lineItemID
invoiceID
productID
quantity
unitprice
Product
productID
productShortName
productDescription

21. Mapping Between RDBMS and XML Structures(11)
2) More Complex Relationships - Pointers
ex) ch02_ex3.dtd
<!ELEMENT orderData (Invoice+, Product+)>
<!ELEMENT Invoive (LineItem+)>
<!ATTRIST Invoice
orderDate CDATA #REQUIRED
shipDate CDATA #REQUIRED>
<!ELEMENT LineItem EMPTY>
<!ATTRIST Lineitem
productIDREF IDREF #REQUIRED
‥‥ >
<!ELEMENT Product EMPTY>
<!ATTRIST Product
productID ID #REQUIRED

22. Mapping Between RDBMS and XML Structures(12)
ex) ch02_ex3.xml
<?xml version=“1.0” ?>
<!DOCTYPE Invoice SYSTEM
<orderData>
<Invoice
orderDate=“7/23/2000”
shipData=“7/28/2000”>
<LineItem
productIDREF=“prod1”
‥‥ />
/Invoice> ‥‥
<Product
productID=“prod1”
productShortName=“Widgets (3 inch)”
</orderData>

23. Mapping Between RDBMS and XML Structures(13)
3) More Complex Relationships - Contianments
ex) ch02_ex4.dtd
<!ELEMENT orderData (Invoice+)>
<!ELEMENT Invoive (LineItem+)>
<!ATTRIST Invoice
orderDate CDATA #REQUIRED
shipDate CDATA #REQUIRED>
<!ELEMENT LineItem (Product)>
<!ATTRIST Lineitem
quantity CDATA #REQUIRED
‥‥ >
<!ELEMENT Product EMPTY>
<!ATTRIST Product
productShortName CDATA #REQUIRED

24. Mapping Between RDBMS and XML Structures(14)
ex) ch02_ex4.xml
<?xml version=“1.0” ?>
<!DOCTYPE Invoice SYSTEM
<orderData>
<Invoice
orderDate=“7/23/2000”
shipData=“7/28/2000”>
<LineItem
quantity=“17”
uniPrice=“0.10”>
<Product
productShortName=“Widgets (3 inch)”
‥‥ />
</LineItem>
</Invoice> ‥‥
</orderData>