Built-in Types¶

Type usage examples for the high-level O6 library.

This example shows how to use the various OPC UA types provided by the o6 package: scalar wrappers live at the top level (o6.NodeId, o6.Int32, ...), while NS0 struct and enum types live under o6.ns.ns0.datatypes.

1. NodeId creation¶

o6.NodeId(...) parses the standard OPC UA string notation: ns=<namespace-index>;s=<string-id> or ns=<namespace-index>;i=<numeric-id>. Omitting ns= targets namespace 0.

print("--- 1. NodeId Creation ---")

node1 = o6.NodeId("ns=1;s=Temperature")
print(f"String NodeId: {node1}")

node2 = o6.NodeId("ns=2;i=1234")
print(f"Numeric NodeId: {node2}")

2. Scalar type wrappers¶

Every OPC UA built-in scalar type has a matching wrapper at the top level of o6 — o6.Int32, o6.Double, o6.String, o6.Boolean, o6.UInt32, o6.Float, and so on. Wrapping a value in one of these pins its wire type explicitly, which matters wherever the target type can't be inferred from a plain Python value — method arguments, DataValue.value, and anywhere overload resolution would otherwise be ambiguous (e.g. int could mean Int32, Int64, UInt32, ...).

print("\n--- 2. Scalar Type Wrappers ---")

var1 = o6.Int32(42)
print(f"Int32: {var1}")

var2 = o6.Double(3.14159)
print(f"Double: {var2}")

var3 = o6.String("Hello World")
print(f"String: {var3}")

var4 = o6.Boolean(True)
print(f"Boolean: {var4}")

var5 = o6.UInt32(42)
print(f"UInt32: {var5}")

var6 = o6.Float(3.14)
print(f"Float: {var6}")

3. DataValue¶

A DataValue wraps a value together with its status code and timestamps — it's what Read/Write service calls carry on the wire. Assigning to .value accepts any scalar wrapper.

print("\n--- 3. DataValue Creation ---")

dv1 = o6.DataValue()
dv1.value = o6.Double(25.5)
print(f"DataValue: {dv1}")
print(f"  value: {dv1.value}")

4. LocalizedText¶

A LocalizedText pairs a display string with an optional locale code. Omitting the locale leaves it unset; servers commonly use this for DisplayName/Description attributes that ship translations.

print("\n--- 4. Localized Text ---")

lt1 = o6.LocalizedText("Hello World")
print(f"LocalizedText: {lt1}")

lt2 = o6.LocalizedText("Hallo Welt", "de")
print(f"German locale: {lt2}")

lt3 = o6.LocalizedText("Bonjour le monde", "fr")
print(f"French locale: {lt3}")

5. QualifiedName¶

A QualifiedName is a BrowseName: a namespace index plus a name, written as <index>:<name>. It's what browse() results and node BrowseName attributes are made of — distinct from a NodeId, which identifies the node itself rather than its name within its parent.

print("\n--- 5. Qualified Name ---")

qn1 = o6.QualifiedName("0:MyVariable")
print(f"Default namespace: {qn1}")

qn2 = o6.QualifiedName("1:Temperature")
print(f"Namespace 1: {qn2}")

6. Struct types¶

Standard-defined structs (everything OPC UA calls a DataType with fields) live under ns0.datatypes, not at the o6 top level. Fields are set by attribute after construction; enum-typed fields (like applicationType below) take a member of the matching ns0.datatypes enum.

print("\n--- 6. OPC UA Struct Types ---")

app_desc = ns0.datatypes.ApplicationDescription()
app_desc.applicationUri = "urn:example:app"
app_desc.applicationName = o6.LocalizedText("My Application")
app_desc.applicationType = ns0.datatypes.ApplicationType.CLIENT
app_desc.productUri = "urn:example:product"
print(f"ApplicationDescription: {app_desc}")
print(f"  application_uri: {app_desc.applicationUri}")
print(f"  application_name: {app_desc.applicationName}")
print(f"  application_type: {app_desc.applicationType}")

read_val_id = ns0.datatypes.ReadValueId()
read_val_id.nodeId = o6.NodeId("ns=1;s=Temperature")
read_val_id.attributeId = o6.UInt32(13)  # Value attribute
print(f"\nReadValueId: {read_val_id}")

7. Discovering available types¶

dir(ns0.datatypes) lists every struct and enum type generated from the OPC UA namespace-0 nodeset — useful for finding the exact name of a type without leaving the Python shell.

    print("\n--- 7. Available Struct/Enum Types ---")

    type_names = sorted(
        [name for name in dir(ns0.datatypes) if not name.startswith("_") and name[0].isupper()]
    )
    print(f"Total available types: {len(type_names)}")
    print(f"First 20: {type_names[:20]}")

    print("\n=== Example completed ===")


if __name__ == "__main__":
    main()

Source Code¶

Download T02_types.py to run it locally.