OPC UA PubSub DataSetMetaDataType Structure|OPC UA Standard|Forum|OPC Foundation

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OPC UA PubSub DataSetMetaDataType Structure
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Jothi Sankarraj
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08/02/2019 - 01:10
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I'm now in the process of parsing the DataSetMetaDataType and in Part 14 of the Spec on page number 25, Chapter 6.2.2.1.2, Table 3 where it describes the DataSetMetaDataType structure, the first field in the table is the DataSetMetaDataType where the type is defined as "Structure".

Table 3 – DataSetMetaDataType Structure
Name
Type
Description
DataSetMetaDataType
Structure
 
name
String
Name of the DataSet.
description
LocalizedText
Description of the DataSet.
The default value is a null LocalizedText.
fields
FieldMetaData[]
The metadata for the fields in the DataSet.
The FieldMetaData DataType is defined in 6.2.2.1.3.
dataSetClassId
Guid
This field provides the globally unique identifier of the class of DataSet if the DataSet is based on a DataSetClass. In this case, this field shall match the DataSetClassId of the concrete DataSet configuration.
If the DataSets are not created from a class, this field is null.
configurationVersion
Configuration VersionDataType
The configuration version for the current configuration of the DataSet.

What does this mean when parsing the bytes? Should I ignore this Type and start parsing from the name field which is of Type String?

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Randy Armstrong
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08/02/2019 - 07:45
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The tables use indentation to indicate containers.

So the name through configurationVersion fields are indented which means they are components of the DataSetMetaDataType.

The Structure type is an abstract type with no fields. The table defines the fields that this particular Structure has.

This means the encoded form of the structure will start with a string representing the name.

Note that Structure are often serialized inside an ExtensionObject which adds an envelope with the DataType EncodingId.

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