How to do the most basic listing of variables and simple reads on an existing OPC server with this crate as client

[kwinz]

Hi!

Sorry for the beginner question. How do I list all Nodes, DataNodes and Variables of an endpoint on a server with this crate as client?

I found Session's browse function but I am not sure what to use as node_id if I just want to list everything.

let browse_description = [BrowseDescription {
    node_id: NodeId::new(2, 2), // ????
    browse_direction: BrowseDirection::Forward,
    reference_type_id: ReferenceTypeId::Organizes.into(), // ????
    include_subtypes: true,
    node_class_mask: NodeClassMask::all().bits(),  // ????
    result_mask: BrowseDescriptionResultMask::all().bits(),  // ????
}];

let browse_results = session.browse(&browse_description).unwrap().unwrap();

println!("BrowseResults {:?}", browse_results);

If that helps my endpoint looks like this:

EndpointDescription {
endpoint_url: UAString { value: Some("opc.tcp://hostname:4845") },
server: ApplicationDescription { application_uri: UAString { value: Some("urn:Siemens.Automation.SimaticNET.S7:{removed_GUID}") }, 
product_uri: UAString { value: Some("Siemens/SimaticNet/OpcUaServer/S7") },
application_name: LocalizedText { locale: UAString { value: Some("en") }, text: UAString { value: Some("OPC.SimaticNET.S7") } },
application_type: Server, gateway_server_uri: UAString { value: None }, discovery_profile_uri: UAString { value: None },
discovery_urls: Some([UAString { value: Some("opc.tcp://hostname:4845") }]) }

PS: Maybe additionally to the simple-client example which shows how to start subscriptions for known variables we can also add some extremely-simple-client example code documentation for users like me who don't even know how to query the variable names.
That sample code could show how to do very basic variable listing and polling reading and writing.

[kwinz]

A did some further research and found a Python implementation FreeOpcUa/python-opcua#863 They have a client.get_root_node() and node.get_children(). Do we have something similar in this crate that allows me to list all OPC UA variable names as a client?