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New Object "Aliases" in the Opc.Ua.NodeSet2.xml #54

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prrw opened this issue Feb 27, 2020 · 3 comments
Closed

New Object "Aliases" in the Opc.Ua.NodeSet2.xml #54

prrw opened this issue Feb 27, 2020 · 3 comments

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@prrw
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prrw commented Feb 27, 2020 •
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In the commit cc39b5e of the Schema/Opc.Ua.NodeSet2.xml, there is an inclusion of a new Object "Aliases". Why is it included or is it a bug ?

<UAObject NodeId="i=23470" BrowseName="Aliases" ReleaseStatus="Draft">
    <DisplayName>Aliases</DisplayName>
    <References>
      <Reference ReferenceType="HasComponent">i=23476</Reference>
      <Reference ReferenceType="Organizes" IsForward="false">i=85</Reference>
      <Reference ReferenceType="HasTypeDefinition">i=23456</Reference>
    </References>
  </UAObject>
  <UAMethod NodeId="i=23476" BrowseName="FindAlias" ReleaseStatus="Draft" ParentNodeId="i=23470" MethodDeclarationId="i=23462">
    <DisplayName>FindAlias</DisplayName>
    <References>
      <Reference ReferenceType="HasProperty">i=23477</Reference>
      <Reference ReferenceType="HasProperty">i=23478</Reference>
      <Reference ReferenceType="HasComponent" IsForward="false">i=23470</Reference>
    </References>
  </UAMethod>
  <UAVariable NodeId="i=23477" BrowseName="InputArguments" ReleaseStatus="Draft" ParentNodeId="i=23476" DataType="i=296" ValueRank="1" ArrayDimensions="0">
    <DisplayName>InputArguments</DisplayName>
    <References>
      <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
      <Reference ReferenceType="HasProperty" IsForward="false">i=23476</Reference>
    </References>
    <Value>
      <ListOfExtensionObject xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
        <ExtensionObject>
          <TypeId>
            <Identifier>i=297</Identifier>
          </TypeId>
          <Body>
            <Argument>
              <Name>AliasNameSearchPattern</Name>
              <DataType>
                <Identifier>i=12</Identifier>
              </DataType>
              <ValueRank>-1</ValueRank>
              <ArrayDimensions />
            </Argument>
          </Body>
        </ExtensionObject>
        <ExtensionObject>
          <TypeId>
            <Identifier>i=297</Identifier>
          </TypeId>
          <Body>
            <Argument>
              <Name>ReferenceTypeFilter</Name>
              <DataType>
                <Identifier>i=17</Identifier>
              </DataType>
              <ValueRank>-1</ValueRank>
              <ArrayDimensions />
            </Argument>
          </Body>
        </ExtensionObject>
      </ListOfExtensionObject>
    </Value>
  </UAVariable>
  <UAVariable NodeId="i=23478" BrowseName="OutputArguments" ReleaseStatus="Draft" ParentNodeId="i=23476" DataType="i=296" ValueRank="1" ArrayDimensions="0">
    <DisplayName>OutputArguments</DisplayName>
    <References>
      <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
      <Reference ReferenceType="HasProperty" IsForward="false">i=23476</Reference>
    </References>
    <Value>
      <ListOfExtensionObject xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
        <ExtensionObject>
          <TypeId>
            <Identifier>i=297</Identifier>
          </TypeId>
          <Body>
            <Argument>
              <Name>AliasNodeList</Name>
              <DataType>
                <Identifier>i=23468</Identifier>
              </DataType>
              <ValueRank>1</ValueRank>
              <ArrayDimensions>
                <UInt32>0</UInt32>
              </ArrayDimensions>
            </Argument>
          </Body>
        </ExtensionObject>
      </ListOfExtensionObject>
    </Value>
  </UAVariable>
  <UAObject NodeId="i=23479" BrowseName="Tags" ReleaseStatus="Draft">
    <DisplayName>Tags</DisplayName>
    <References>
      <Reference ReferenceType="HasComponent">i=23485</Reference>
      <Reference ReferenceType="Organizes" IsForward="false">i=23470</Reference>
      <Reference ReferenceType="HasTypeDefinition">i=23456</Reference>
    </References>
  </UAObject>
  <UAMethod NodeId="i=23485" BrowseName="FindAlias" ReleaseStatus="Draft" ParentNodeId="i=23479" MethodDeclarationId="i=23462">
    <DisplayName>FindAlias</DisplayName>
    <References>
      <Reference ReferenceType="HasProperty">i=23486</Reference>
      <Reference ReferenceType="HasProperty">i=23487</Reference>
      <Reference ReferenceType="HasComponent" IsForward="false">i=23479</Reference>
    </References>
  </UAMethod>
  <UAVariable NodeId="i=23486" BrowseName="InputArguments" ReleaseStatus="Draft" ParentNodeId="i=23485" DataType="i=296" ValueRank="1" ArrayDimensions="0">
    <DisplayName>InputArguments</DisplayName>
    <References>
      <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
      <Reference ReferenceType="HasProperty" IsForward="false">i=23485</Reference>
    </References>
    <Value>
      <ListOfExtensionObject xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
        <ExtensionObject>
          <TypeId>
            <Identifier>i=297</Identifier>
          </TypeId>
          <Body>
            <Argument>
              <Name>AliasNameSearchPattern</Name>
              <DataType>
                <Identifier>i=12</Identifier>
              </DataType>
              <ValueRank>-1</ValueRank>
              <ArrayDimensions />
            </Argument>
          </Body>
        </ExtensionObject>
        <ExtensionObject>
          <TypeId>
            <Identifier>i=297</Identifier>
          </TypeId>
          <Body>
            <Argument>
              <Name>ReferenceTypeFilter</Name>
              <DataType>
                <Identifier>i=17</Identifier>
              </DataType>
              <ValueRank>-1</ValueRank>
              <ArrayDimensions />
            </Argument>
          </Body>
        </ExtensionObject>
      </ListOfExtensionObject>
    </Value>
  </UAVariable>
  <UAVariable NodeId="i=23487" BrowseName="OutputArguments" ReleaseStatus="Draft" ParentNodeId="i=23485" DataType="i=296" ValueRank="1" ArrayDimensions="0">
    <DisplayName>OutputArguments</DisplayName>
    <References>
      <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
      <Reference ReferenceType="HasProperty" IsForward="false">i=23485</Reference>
    </References>
    <Value>
      <ListOfExtensionObject xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
        <ExtensionObject>
          <TypeId>
            <Identifier>i=297</Identifier>
          </TypeId>
          <Body>
            <Argument>
              <Name>AliasNodeList</Name>
              <DataType>
                <Identifier>i=23468</Identifier>
              </DataType>
              <ValueRank>1</ValueRank>
              <ArrayDimensions>
                <UInt32>0</UInt32>
              </ArrayDimensions>
            </Argument>
          </Body>
        </ExtensionObject>
      </ListOfExtensionObject>
    </Value>
  </UAVariable>
  <UAObject NodeId="i=23488" BrowseName="Topics" ReleaseStatus="Draft">
    <DisplayName>Topics</DisplayName>
    <References>
      <Reference ReferenceType="HasComponent">i=23494</Reference>
      <Reference ReferenceType="Organizes" IsForward="false">i=23470</Reference>
      <Reference ReferenceType="HasTypeDefinition">i=23456</Reference>
    </References>
  </UAObject>
  <UAMethod NodeId="i=23494" BrowseName="FindAlias" ReleaseStatus="Draft" ParentNodeId="i=23488" MethodDeclarationId="i=23462">
    <DisplayName>FindAlias</DisplayName>
    <References>
      <Reference ReferenceType="HasProperty">i=23495</Reference>
      <Reference ReferenceType="HasProperty">i=23496</Reference>
      <Reference ReferenceType="HasComponent" IsForward="false">i=23488</Reference>
    </References>
  </UAMethod>
  <UAVariable NodeId="i=23495" BrowseName="InputArguments" ReleaseStatus="Draft" ParentNodeId="i=23494" DataType="i=296" ValueRank="1" ArrayDimensions="0">
    <DisplayName>InputArguments</DisplayName>
    <References>
      <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
      <Reference ReferenceType="HasProperty" IsForward="false">i=23494</Reference>
    </References>
    <Value>
      <ListOfExtensionObject xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
        <ExtensionObject>
          <TypeId>
            <Identifier>i=297</Identifier>
          </TypeId>
          <Body>
            <Argument>
              <Name>AliasNameSearchPattern</Name>
              <DataType>
                <Identifier>i=12</Identifier>
              </DataType>
              <ValueRank>-1</ValueRank>
              <ArrayDimensions />
            </Argument>
          </Body>
        </ExtensionObject>
        <ExtensionObject>
          <TypeId>
            <Identifier>i=297</Identifier>
          </TypeId>
          <Body>
            <Argument>
              <Name>ReferenceTypeFilter</Name>
              <DataType>
                <Identifier>i=17</Identifier>
              </DataType>
              <ValueRank>-1</ValueRank>
              <ArrayDimensions />
            </Argument>
          </Body>
        </ExtensionObject>
      </ListOfExtensionObject>
    </Value>
  </UAVariable>
  <UAVariable NodeId="i=23496" BrowseName="OutputArguments" ReleaseStatus="Draft" ParentNodeId="i=23494" DataType="i=296" ValueRank="1" ArrayDimensions="0">
    <DisplayName>OutputArguments</DisplayName>
    <References>
      <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
      <Reference ReferenceType="HasProperty" IsForward="false">i=23494</Reference>
    </References>
    <Value>
      <ListOfExtensionObject xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
        <ExtensionObject>
          <TypeId>
            <Identifier>i=297</Identifier>
          </TypeId>
          <Body>
            <Argument>
              <Name>AliasNodeList</Name>
              <DataType>
                <Identifier>i=23468</Identifier>
              </DataType>
              <ValueRank>1</ValueRank>
              <ArrayDimensions>
                <UInt32>0</UInt32>
              </ArrayDimensions>
            </Argument>
          </Body>
        </ExtensionObject>
      </ListOfExtensionObject>
    </Value>
  </UAVariable>

It makes my server look this way.
grafik
@PaulHunkar
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The Aliases node is a new addition that is in part 17, I think it might be early, in that it is only an RC, but the definition appears to be correct and it should move to released some time fairly soon.

@prrw
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prrw commented Mar 2, 2020

Okay Thanks. I will check that out.

@prrw prrw closed this as completed Mar 2, 2020
@mpostol
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mpostol commented Mar 2, 2020

Hi @PaulHunkar,

My concern is that using the object-oriented approach we should use inheritance as the paradigm to expand the existing model. Adding, over and over new stuff makes the model unstable and inevitably causes versioning problems. As a consequence, this could put in danger the interoperability, which must be the main concern of the standardization process.

Partially I know the answer. @PaulHunkar let me recall our discussion many years ago about the fundamental difference between:

  • OPC UA Information Model definition - we can carve it in stone
  • OPC UA Address Space instance - we need the power supply to keep it alive

Between both there is the ModelCompiler tool. Inheritance makes sense only in the case of the Information Model - "one stone (derived) can refer to another one (base)", so there is no need to reshape the base one. Talking about NodeSet2 we are talking about a formal description of the Address Space instance.

What do you think about returning to this discussion to avoid problems like this in the future?

I am not sure what exactly means "I will check that out" (@prv), but I know many cases where this means I will keep it on hold for the next couple years :(.

The discussion is important for me because as a part of the lab: Programming Technologies - Mobile Devices we will try to use Blockchain as the repository of the custom OPC UA Information Model definitions.

Any comments are welcome.

Mariusz

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@mpostol @PaulHunkar @prrw