Write: null Values and AccessLevel

[johannwesely]

Hello,
we are right now in the certification process of our milo server.
another Point that occured during the process is this:
"Write:
Attempting to write a null value returns Bad_TypeMissmatch. This occurs on variable nodes, that have been initialized with a null value.

Nodes with AccessLevel/UserAccessLevel as ReadOnly return Bad_UserAccessDenied instead of Bad_NotWritable"

Do you have a suggestion what could be wrong here?

[kevinherron]

Two separate issues here I think.

"Write:
Attempting to write a null value returns Bad_TypeMissmatch. This occurs on variable nodes, that have been initialized with a null value.

You must set "AllowNulls" Property of the VariableNode to true for the server to accept a null value. See

milo/opc-ua-sdk/sdk-server/src/main/java/org/eclipse/milo/opcua/sdk/server/nodes/UaVariableNode.java

Lines 580 to 590 in 253e115

	/**
	* Set the value of the AllowNulls Property.
	*
	* <p>A PropertyNode will be created if it does not already exist.
	*
	* @param allowNulls the value to set.
	* @see VariableNodeProperties#AllowNulls
	*/
	public void setAllowNulls(Boolean allowNulls) {
	setProperty(VariableNodeProperties.AllowNulls, allowNulls);
	}

https://reference.opcfoundation.org/Core/Part3/v104/docs/5.6.4#:~:text=The%20Property%20AllowNulls%20indicates%20if%20null%20values%20are%20allowed%20for%20the%20Value%20Attribute.

[kevinherron]

I can change the default used by UaVariableNode: #1581

You also have full control over this now by just setting a different value when you create a VariableNode.

[johannwesely]

Hello,
i think the problem is not the inital value you fixed in 1.0.6 Snapshot. I get Good when i try to read a null Value on a Value that has no allowNull property, but i expect Bad_NoValue as Error Message. Because the ctt reads the null and tries to write it on the same node and then gets the Bad_TypeMissmatch. Is it possible that i override the inital status when i parse the nodeset wit uanodeset from digitalpetri ?

[kevinherron]

Hmm, yes, that could be the issue.

It looks like NodeSetNodeLoader will need some changes as well.

[kevinherron]

Something like this: digitalpetri/uanodeset#7

[kevinherron]

I am at a conference for work this week so it's difficult to be responsive with changes here.

[kevinherron]

Nodes with AccessLevel/UserAccessLevel as ReadOnly return Bad_UserAccessDenied instead of Bad_NotWritable"

Checks for UserAccessLevel (and access restrictions and role permissions) are taking precedence over the check for regular AccessLevel. Can they point to something in the spec that requires otherwise?

[johannwesely]

You where right here they closed this point. ;-)