DTDL Parser extensions

The DTDL dotnet parser provides and object model to inspect DTDL elements: Telemetry, Properties, Commands, Components and Relationships.

All of these are represented as DTEntityInfo elements that must be used with the appropriate DT* types using casting.

To make it easier the navigation through those types, and by using some C# goodness, I've created this DTDL parser C# extensions:

	namespace dtdl_dotnet
	{
	using Microsoft.Azure.DigitalTwins.Parser;
	using Microsoft.Azure.DigitalTwins.Parser.Models;
	public static class DtmiExtensions
	{
	public static string ToPath(this Dtmi dtmi) => $"{dtmi.ToString().ToLowerInvariant().Replace(":", "/").Replace(";", "-")}.json";
	}
	public static class ModelParserExtensions
	{
	public class InterfaceInfo
	{
	public IReadOnlyDictionary<Dtmi, DTEntityInfo> ObjectModel;
	DTEntityInfo root;
	public InterfaceInfo(IReadOnlyDictionary<Dtmi, DTEntityInfo> m)
	{
	ObjectModel = m;
	root = m.Values.Where(v => v.EntityKind == DTEntityKind.Interface).First(e => e.ChildOf == null);
	}
	public string Id => root.Id.ToString();
	public IEnumerable<DTTelemetryInfo> Telemetries =>
	((DTInterfaceInfo)root).Contents
	.Where(c => c.Value.EntityKind == DTEntityKind.Telemetry)
	.Select(t => (DTTelemetryInfo)t.Value);
	public IEnumerable<DTPropertyInfo> Properties =>
	((DTInterfaceInfo)root).Contents
	.Where(c => c.Value.EntityKind == DTEntityKind.Property)
	.Select(p => (DTPropertyInfo)p.Value);
	public IEnumerable<DTCommandInfo> Commands =>
	((DTInterfaceInfo)root).Contents
	.Where(c => c.Value.EntityKind == DTEntityKind.Command)
	.Select(c => (DTCommandInfo)c.Value);
	public IEnumerable<DTComponentInfo> Components =>
	((DTInterfaceInfo)root).Contents
	.Where(c => c.Value.EntityKind == DTEntityKind.Component)
	.Select(c => (DTComponentInfo)c.Value);
	public IEnumerable<DTRelationshipInfo> Relationships =>
	((DTInterfaceInfo)root).Contents
	.Where(c => c.Value.EntityKind == DTEntityKind.Relationship)
	.Select(r => (DTRelationshipInfo)r.Value);
	}
	public static async Task<InterfaceInfo> ParseAsync(this ModelParser parser, string jsonContent)
	=> new InterfaceInfo(await parser.ParseAsync(new string[] { jsonContent }));
	}
	}

view raw DTDLParserExtensions.cs hosted with ❤ by GitHub

That can be used as

var model = await new ModelParser().ParseAsync(ReadFile("dtmi/samples/aninterface-1.json"));

Console.WriteLine(model.Id);

foreach (var t in model.Telemetries)
{
    Console.WriteLine($" [T] {t.Name} {t.Schema.Id}");
}

foreach (var p in model.Properties)
{
    Console.WriteLine($" [P] {p.Name} {p.Schema.Id}");
}

foreach (var c in model.Commands)
{
    Console.WriteLine($" [C] {c.Name} {c.Request.Id} {c.Response.Id}");
}

Comments

[Andy Piper]

Interesting. What’s the MQTT element here?

[Andy Piper]

I'm going to remove the tag, as there is no clear relationship between the post and the MQTT topic.