Extensibility

Contents

• Core Concepts
• Tree Creation
• Infrastructure As Code
• Migration
• Tree Manipulation
• Extensibility
  • Overview
  • C#
  • PowerShell

Overview

For scenarios in which you need to perform advanced manipulations/analytics, custom visitor types can be defined. PrtgAPI defines several base types you can leverage in designing your visitor:

Visitor	Result	Base	Description
PrtgNodeVisitor	void		Visits a single PrtgNode. Fully abstract class.
PrtgNodeVisitor<T>	T		Visits a single PrtgNode and returns a value of type T. Fully abstract class
PrtgNodeWalker	void	PrtgNodeVisitor	Traverses every node of a PrtgNode tree
PrtgNodeRewriter	PrtgNode	PrtgNodeVisitor<T>	Traverses every node of a PrtgNode tree, rewriting parent nodes when child nodes are changed
PrtgNodeDefaultVisitor	void	PrtgNodeVisitor	Visits a single PrtgNode and performs a common action for each node by default
PrtgNodeDefaultVisitor<T>	T	PrtgNodeVisitor<T>	Visits a single PrtgNode and performs a common action for each node that returns a value of type T by default

The following table outlines the scenarios each visitor should be used, and provides examples of where the visitor has been used within PrtgAPI for reference purposes.

I want to...	Recommended Visitor	Examples
Read all the nodes in a tree, performing a common action for most or all node types	PrtgNodeDefaultVisitor	PrtgNodePrettyTreeVisitor
Read all the nodes in a tree, performing a different action for each node type	PrtgNodeWalker
Modify the nodes of a tree	PrtgNodeRewriter	PrtgNodeListEditor, PrtgNodeRemover, PrtgNodeReplacer
Transform the nodes of a tree into completely unrelated types, performing a common transformation for each node type	PrtgNodeDefaultVisitor<T>	CompareTreeVisitor
Read a custom set of nodes from a tree, potentially performing a different transformation on each node type	PrtgNodeVisitor, PrtgNodeVisitor<T>

Generally speaking, PrtgNodeDefaultVisitor, PrtgNodeWalker and PrtgNodeRewriter are sufficient for most purposes. Even when the purpose of your visitor is to construct some value that should eventually be returned, it is often best to do so using an instance member, rather than returning this value over and over again as you would in visitors like PrtgNodeVisitor<T>.

C#

PowerShell