Document Object Model in XML

1. CIS-189

2.  DOM stands for Document Object Model
 Provides tools for working with XML
document in memory
◦ Tools include navigating and editing document
◦ “Interface” refers to how you interact with an object
 What is accessible outside of object?

3.  XML document in memory called XML
Information Set or Infoset
 DOM is a logical model
◦ How represented in memory may be different from
how document exists on disk
◦ Uses Nodes to represent XML Tree and contents

4.  Moving data from active memory to disk
 Serialization moves data from objects in
memory to disk
 Deserialization moves data from disk to
objects in memory

5.  Defines what interfaces (tools) will be
provided
◦ Focus is on results
◦ Doesn’t specify how a tool will work
 Software providers can provide additional
tools
◦ IE might process instructions that Firefox can’t

6.  Node represents the basic object in a
document
◦ Different kinds of nodes represent different
purposes and values
◦ All types of nodes inherit same initial definition
 One node can “own” another node
◦ Function similar to Windows tree-view of file
system
◦ Type of node can affect how object responds to
code

8.  Document
 Document Type
 Document
Fragment
 Element
 Entity Reference
 Entity
 Attribute
 Processing
Instruction
 Comment
 CDATA
 Text
 Notation

9.  Different types of nodes can have different
types of child nodes, or no child nodes
 Document node represents highest level
◦ Document node can have Element, Document type,
Processing Instruction, Comment nodes
◦ Document type, Processing instruction, Comment
nodes cannot have child nodes

10. Document
Element
Element
Comment
Document
Type
Document
Type
Processing
Instruction
Cannot have
child nodes

11.  Can have as child nodes: Element, Comment,
Processing instruction, Text, CDATA, Entity
reference
 Attributes of an element exist in Attribute
nodes
◦ Attribute nodes are not considered child and are
not part of DOM tree

12. Document
Element
(root)
Element
Element Comment
Comment Element
Attribute

13.  Portion of an XML document
 Has same “ownership” possibilities as an
Element
 Does NOT have to be well-formed
 Isn’t a complete XML document