1. Namespaces

2. Purpose Namespaces were added late to the XML specification
They serve two purposes
To distinguish between elements and attributes of different vocabularies
To group all related elements and attributes from an XML application so a software application can easily recognize them

3. Namespace Functions c:address c:customerid e:dept e:salary e:hiredate
xmlns:e=“
xmlns:c=”
c:address
c:customerid
e:name
c:name
c:phone
e:phone
e:dept
e:salary
e:hiredate
Group related objects
Distinguish vocabularies

4. Default Namespace
You can use the xmlns attribute to declare a default namespace
<elementname xmlns=“URI”>
The URI (universal Resource Identifier) can be a name or address that identifies a resource.
Typically the URI is a web address, however this address does not need to point to any actual document

5. Default Namespace Example
<?xml version=“1.0” encoding=“UTF-8” ?>
<employees xmlns=“
. . .
</employees>

6. Namespaces with Prefixes
You can assign a prefix to a namespace
<emp:employees xmlns:emp=“
<emp:employee>
<emp:firstname>Alice</emp:firstname>
. . .
</emp:employee>
</emp:employees>

7. Using Multiple Namespaces
A single XML document can contain multiple namespaces
You can nest default namespaces or differentiate them by prefixes

8. Nesting Namespaces
<employees xmlns=“
<employee>
<firstname>Alice</firstname>
<lastname>Smith</lastname>
<payroll xmlns=“
<status>Full time</status>
<paytype>Salary</paytype>
<paystep>5</paystep>
</payroll>
<dept>IT</dept>
</employee>
</employees>

9. Attributes The default namespace does not include the attributes
Attributes can include a namespace prefix
By default the attribute belongs to the element’s private namespace

10. Namespaces Best Practices
Use the default namespace on the root element
Use one default namespace at most
Declare prefixed namespaces as soon as possible
Do not use the same prefix for different name spaces
Use one prefix for each namespace