Detailed Description

Data source base class for variable nodes.

The server redirects every read and write request to callback functions. Internally, the data source needs to implement its own memory management.

Definition at line 60 of file nodestore.hpp.

Public Member Functions
virtual StatusCode	read (Session &session, const NodeId &id, const NumericRange *range, DataValue &value, bool timestamp)=0

virtual StatusCode	write (Session &session, const NodeId &id, const NumericRange *range, const DataValue &value)=0

UA_DataSource	create (bool ownsAdapter) override

Public Member Functions inherited from opcua::PluginAdapter< UA_DataSource >
	PluginAdapter ()=default

	PluginAdapter (const PluginAdapter &)=default

	PluginAdapter (PluginAdapter &&) noexcept=default

virtual	~PluginAdapter ()=default

PluginAdapter &	operator= (const PluginAdapter &)=default

PluginAdapter &	operator= (PluginAdapter &&) noexcept=default

Additional Inherited Members
Public Types inherited from opcua::PluginAdapter< UA_DataSource >
using	PluginType

Member Function Documentation

virtual StatusCode opcua::DataSourceBase::read	(	Session &	session,
		const NodeId &	id,
		const NumericRange *	range,
		DataValue &	value,
		bool	timestamp )

pure virtual

Callback to set the read value, the result status and optionally a source timestamp.

Note: Zero-copy operations are possible. It is not required to return a copy of the actual content data. You can return a pointer to memory owned by the user. Memory can be reused between read callbacks of a data source, as the result is already encoded on the network buffer between each read operation. To use zero-copy reads, set the value of the Variant (DataValue::setValue) without copying, e.g. with Variant::assign.

Parameters

session	Current session
id	The identifier of the node being read from
range	If not `nullptr`, then the data source shall return only a selection of the (non-scalar) data. Set `UA_STATUSCODE_BADINDEXRANGEINVALID` in `value` if this does not apply.
value	The DataValue that is returned to the reader
timestamp	Set the source timestamp of `value` if `true`

virtual StatusCode opcua::DataSourceBase::write	(	Session &	session,
		const NodeId &	id,
		const NumericRange *	range,
		const DataValue &	value )

pure virtual

Callback to write the value into a data source.

Parameters

session	Current session
id	The identifier of the node being written to
range	If not `nullptr`, then only this selection of (non-scalar) data should be written into the data source.
value	The DataValue that has been written by the writer

UA_DataSource opcua::DataSourceBase::create ( bool ownsAdapter )

overridevirtual