Reading an Xml

1. Parsing the XML 1.0 byte stream

a. XmlTextReader : Parses the XML 1.0 Byte Stream and the complexities of the XML 1.0 syntax by serving up the document as a logical-tree structure through higher-level APIs.

- Performance - Memory - Traversal - Operation - XPath - XSLT

- Fastest - Most efficient as only one node needs to be in memory - Forward Only - Read Only - No - No

2. Processing the Logical Tree via XML APIs

i. Streaming

a. XmlReader

- Models read an Xml as a forward-only, linear stream of nodes.
- XmlReader allows the client to pull the nodes one at a time much like the firehose cursor model in data access technology.


ii. Traversal Oriented

a. XmlNode (XmlDocument)

- Built on top of XmlReader

- Performance - Memory - Traversal - Operation - XPath - XSLT

- 2 to 3x slower than XmlTextReader - Loads entire Xml/Tree Structure in Memory - Full Traversal - Read/Write - Yes - No

b. XPathNavigator

- Uses a cursor model, which gives the underlying implementation more options in terms of how the tree is actually stored.

- Performance - Memory - Traversal - Operation - XPath - XSLT

- Faster than XmlDocument - More efficient than XmlDocument - Full Traversal - Read Only - Yes - Yes

3. Choosing which class

• What kind of reader should I use?
  Use XmlTextReader if:
  * Performance is your highest priority and…
  * You don't need XSD/DTD validation and…
  * You don't need XSD type information at runtime and…
  * You don't need XPath/XSLT services
  
  Use XmlValidatingReader if:
  
  * You need XSD/DTD validation or…
  * You need XSD type information at runtime or…
• Should I load the tree into memory?
  
  Use the DOM if:
  
  * Productivity is your highest priority or…
  * You need XPath services or…
  * You need to update the document (read/write)
• XmlDocument or XPathDocument?
  * You need to execute an XSLT transformation or…
  * You want to leverage an implementation (like XPathDocument)