Address Space Overview

Namespaces

The server exposes 5 namespaces:

Index	URI	Description
`ns=0`	`http://opcfoundation.org/UA/`	OPC UA standard namespace
`ns=1`	`urn:opcua:testserver:nodes`	All custom test nodes
`ns=2`	`http://opcfoundation.org/UA/DI/`	Device Integration namespace
`ns=3`	`urn:opcua:test-server:custom-types`	Extension object types and encodings
`ns=4`	`http://opcfoundation.org/UA/Diagnostics`	Diagnostics namespace

All test variables, methods, events, and alarms use ns=1. Extension object type definitions and encoding nodes use ns=3.

NodeId format: Auto-generated numeric (ns=1;i=XXXX). Use BrowsePaths for stable navigation.

ApplicationUri: urn:opcua:testserver:nodes (same for all server instances)

Root Structure

All test nodes are organized under a single root folder:

Objects (ns=0)
└── TestServer (ns=1)
    ├── DataTypes        -> 85 variables: scalars, arrays, matrices, analog items
    ├── Methods          -> 12 callable methods
    ├── Dynamic          -> 13 time-varying variables
    ├── Events           -> Event emitter + custom event types
    ├── Alarms           -> 3 alarms + 2 source variables
    ├── Historical       -> 4 variables with history
    ├── Structures       -> Nested objects, collections, deep nesting
    ├── ExtensionObjects -> Custom structured types (PointValue, RangeValue)
    └── AccessControl    -> 50 variables with different access levels

Views are under the standard Views folder:

Views (ns=0)
├── OperatorView     -> Dynamic, Methods, Alarms
├── EngineeringView  -> Everything (TestServer root)
├── HistoricalView   -> Historical
└── DataView         -> DataTypes, Structures

Browsing

Start from Objects (NodeId ns=0;i=85), then browse to TestServer. From there, each sub-folder groups related nodes.

Example browse path from root:

Objects -> TestServer -> DataTypes -> Scalar -> BooleanValue

Access Level Legend

Throughout the documentation, these abbreviations are used:

Abbreviation	Meaning	OPC UA Access Level Flags
`R`	Read only	CurrentRead
`W`	Write only	CurrentWrite
`RW`	Read and write	CurrentRead + CurrentWrite
`WO`	Write only (user level)	userAccessLevel = CurrentWrite only
`HR`	History read	HistoryRead
`R+HR`	Read + history	CurrentRead + HistoryRead
`RW+HR`	Read, write, history	CurrentRead + CurrentWrite + HistoryRead

Feature Toggles

Each address space section can be independently enabled/disabled via environment variables. When disabled, the corresponding folder and its nodes are not created.

Section	Env Variable	Default
DataTypes	(always enabled)	--
Methods	`OPCUA_ENABLE_METHODS`	`true`
Dynamic	`OPCUA_ENABLE_DYNAMIC`	`true`
Events & Alarms	`OPCUA_ENABLE_EVENTS`	`true`
Historical	`OPCUA_ENABLE_HISTORICAL`	`true`
Structures	`OPCUA_ENABLE_STRUCTURES`	`true`
ExtensionObjects	(always enabled)	--
Views	`OPCUA_ENABLE_VIEWS`	`true`
AccessControl	(always enabled)	--

For detailed node listings, see the individual documentation pages for each section.