OPC UA JSON Encoding for Workstation.UaClient

This repository defines OPC UA JSON encoder and decoder classes for the Workstation.UaClient .NET OPC UA client library using System.Text.Json.

The encoder uses Utf8JsonWriter for maximum performance. The decoder uses JsonDocument to allow properties on OPC UA data types to be decoded from JSON in an order-agnostic way.

Getting Started

Install the Jaahas.OpcUa.JsonEncoding NuGet package.

The JsonEncoder and JsonDecoder classes implement the Workstation.UaClient IEncoder and IDecoder interfaces respectively. The JsonEncodingProvider class implements IEncodingProvider.

Example:

var provider = new JsonEncodingProvider(encoderOptions: new JsonEncoderOptions() {
    UseReversibleEncoding = false,
    WriteIndented = true
});

using var ms = new MemoryStream();

using (var encoder = provider.CreateEncoder(ms, context: null, keepStreamOpen: true)) {
    encoder.WriteRequest(new ReadRequest() { 
        MaxAge = 1000,
        NodesToRead = [
            new ReadValueId() {
                NodeId = NodeId.Parse("ns=2;s=Demo.Static.Scalar.UInt32"),
                AttributeId = AttributeIds.Value
            },
            new ReadValueId() {
                NodeId = NodeId.Parse("ns=2;s=Demo.Static.Scalar.String"),
                AttributeId = AttributeIds.Value
            }
        ],
        TimestampsToReturn = TimestampsToReturn.Both,
        RequestHeader = new RequestHeader() { 
            AuditEntryId = "Test",
            RequestHandle = 42
        }
    });
}

Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));

The above code produces the following output using the non-reversible form of the OPC UA JSON encoding:

{
  "RequestHeader": {
    "AuthenticationToken": null,
    "Timestamp": "0001-01-01T00:00:00",
    "RequestHandle": 42,
    "ReturnDiagnostics": 0,
    "AuditEntryId": "Test",
    "TimeoutHint": 0,
    "AdditionalHeader": null
  },
  "MaxAge": 1000,
  "TimestampsToReturn": "Both_2",
  "NodesToRead": [
    {
      "NodeId": {
        "IdType": 1,
        "Id": "Demo.Static.Scalar.UInt32",
        "Namespace": 2
      },
      "AttributeId": 13,
      "IndexRange": null,
      "DataEncoding": null
    },
    {
      "NodeId": {
        "IdType": 1,
        "Id": "Demo.Static.Scalar.String",
        "Namespace": 2
      },
      "AttributeId": 13,
      "IndexRange": null,
      "DataEncoding": null
    }
  ]
}

Building the Solution

The repository uses Cake for cross-platform build automation. The build script allows for metadata such as a build counter to be specified when called by a continuous integration system such as TeamCity.

A build can be run from the command line using the build.ps1 PowerShell script or the build.sh Bash script. For documentation about the available build script parameters, see build.cake.

Software Bill of Materials

To generate a Software Bill of Materials (SBOM) for the repository in CycloneDX XML format, run build.ps1 or build.sh with the --target BillOfMaterials parameter.

The resulting SBOM is written to the artifacts/bom folder.