XML - What XML DOM Is

What XML DOM Is

  • The DOM = Document Object Model.

  • It is a tree-based representation of an XML document in memory.

  • Each XML element, attribute, text, and comment is treated as a node in this tree.

  • Using DOM, programs can create, read, modify, or delete XML content easily.

How It Works

When an XML document is loaded with a DOM parser:

  1. The entire document is read into memory.

  2. A tree structure is created.

  3. You can traverse the tree (parent → child → sibling) and manipulate nodes.

Example

XML:

<book>
  <title>XML Guide</title>
  <author>A. Smith</author>
</book>

DOM Tree Representation:

  • book (element node)

    • title (element node) → "XML Guide" (text node)

    • author (element node) → "A. Smith" (text node)

DOM API Operations

With DOM you can:

  • Traverse: Move through parent/child/sibling nodes.

  • Read: Get element text or attribute values.

  • Modify: Change node values.

  • Create/Delete: Add or remove nodes.

Advantages of DOM

  • Random access: You can go to any part of the XML tree.

  • Rich manipulation: You can modify, insert, or delete nodes.

  • Standardized: Works across many programming languages.

Disadvantages

  • Memory-intensive: Whole document must be loaded (not good for very large XML).

  • Slower than streaming parsers (SAX/StAX) for huge files.

In Short

  • DOM = loads entire XML into memory as a tree.

  • Best when you need to read and modify XML freely.

  • Not ideal for huge XML documents (use SAX or StAX instead).