AccessViolationException in ArcGIS.Core.Internal.IUtilityNetworkTracerIOP.UtilityNetworkTracer_Trace

Question

Working on a standalone ArcGIS Core Host application that is going to do downstream tracing from Transformers to Service Points on the utility network.  Admittedly, it's my first, and I am following pro snippet and concept documentation, and looking at the trace utility in ArcGIS Pro for a single transformer to see if I can at least get trace results in my standalone application.

Unfortunately, as soon as I hit the Trace(traceargument) call, I get  a System.AccessViolationException.  Any ideas would be greatly appreciated.

Aashis · Answer

What version of Pro and database are you using, @JimGrinwald ?

JimGrinwald · Answer

Hi @Aashis , thank you for getting back to me.  Interesting that you brought up the community example.  I took said example, and refactored the tracing logic out to a separate class and assembly for a proof of concept, such that the trace button click could instantiate that class in a QueuedTask.Run and pass simple information in, and get the same results out.  I verified that the Pro Add-In still worked, then created a separate Core host project to make the same instatntiation, and pass the same simple information in and get the same results out, and everything worked.

Then I used the same pattern to create a new trace class based on the tracing logic I needed for a simple downstream trace, except

* using an SDE connection instead of a local file GDB, and
* to get my starting point not from the UN_Temp_Starting_Points table, but from a named feature class and object Id, retrieving the information needed from said feature and feature class to create the starting point element.

Having done that, I tested the new tracer from a Pro AddIn button, and the Trace() call worked.  Then I tested the new tracer from the CoreHost console application, and I ran into the same exception that this post originated with.  I can tell you that  Resharper does allow me to drill down to the exact point (ArcGIS.Core.Internal.IUtilityNetworkTracerIOP.UtilityNetworkTracer_Trace) where the System.AccessViolationException exception gets thrown.  I get the impression that there is a COM Interop issue going on with this particular configuration. when trying to run as a standalone CoreHost console application, vs as a Pro AddIn.

Aashis · Answer

@JimGrinwald, I apologize for the delay. There are a couple of thoughts on the above snippet, but it is hard to pinpoint without looking at the data model. 1. The process of getting a trace manager and building a trace argument/configuration doesn't need to be in a loop (it should work fine but inefficient) 2. If associated is an edge feature, I'm not sure what line 7 is going to do 3. you probably should use var traceConfiguration = Tier.TraceConfiguration rather than creating a new trace configuration (2.9 and older) 4. I also recommend adding using statements to dispose objects properly ( should not be causing the crash though) Here is a sample trace snippet based on the community UN data: // Guid of a known medium voltagee Transformer to begin a trace Guid startingPointGuid = Guid.Parse("{5D6574D1-340A-43A8-8BEE-7A87914CE477}"); // Opens a file geodatabase that can be downloaded from community sample data using (Geodatabase geodatabase = new Geodatabase(new FileGeodatabaseConnectionPath(new Uri(@"C:\Data\UtilityNetwork\NapervilleElectricSDKData.gdb")))) { IReadOnlyList utilityNetworkDefinitions = geodatabase.GetDefinitions(); string unName = string.Empty; if(utilityNetworkDefinitions.Count < 0 ) { return; } // Get utility network from the dataset foreach (var definition in utilityNetworkDefinitions) { unName = definition.GetName(); Console.WriteLine(definition.GetName() + "=>" + definition.DatasetType); definition.Dispose(); } // Open utility network using (UtilityNetwork utilityNetwork = geodatabase.OpenDataset(unName)) using (UtilityNetworkDefinition utilityNetworkDefinition = utilityNetwork.GetDefinition()) { using (NetworkSource networkSource = utilityNetworkDefinition.GetNetworkSource("ElectricDevice")) using (AssetGroup assetGroup = networkSource.GetAssetGroup("Medium Voltage Transformer")) using(AssetType assetType = assetGroup.GetAssetType("Overhead Single Phase")) { Terminal terminal = null; if (assetType.IsTerminalConfigurationSupported()) { TerminalConfiguration terminalConfiguration = assetType.GetTerminalConfiguration(); IReadOnlyList terminals = terminalConfiguration.Terminals; terminal = terminals.First(t => !t.IsUpstreamTerminal); } DomainNetwork domainNetwork = utilityNetworkDefinition.GetDomainNetwork("Electric"); Tier sourceTier = domainNetwork.GetTier("Electric Distribution"); // TraceConfiguration traceConfiguration = sourceTier.GetTraceConfiguration(); // For 3.0 pre release TraceConfiguration traceConfiguration = sourceTier.TraceConfiguration; // For 2.9 // Create an element to begin a trace Element startingPointElement = utilityNetwork.CreateElement(assetType, startingPointGuid, terminal); List startingPoints = new List(); startingPoints.Add(startingPointElement); List barriers = new List(); using (TraceManager traceManager = utilityNetwork.GetTraceManager()) { TraceArgument traceArgument = new TraceArgument(startingPoints); traceArgument.Configuration = traceConfiguration; // Trace downstream Tracer tracer = traceManager.GetTracer(); IReadOnlyList traceResults = tracer.Trace(traceArgument); // Prints the results of trace in console foreach (Result result in traceResults) { if (result is ElementResult) { ElementResult elementResult = result as ElementResult; IReadOnlyList elements = elementResult.Elements; Console.WriteLine("Trace Elements"); foreach (Element element in elements) { Console.WriteLine($"{element.ObjectID}-{element.AssetType}"); } } else if (result is FunctionOutputResult) { FunctionOutputResult functionResult = result as FunctionOutputResult; IReadOnlyList functionOutputs = functionResult.FunctionOutputs; foreach (var functionOut in functionOutputs) { Console.WriteLine($"{functionOut.Value}-{functionOut.Function}"); } } else if (result is AggregatedGeometryResult) { AggregatedGeometryResult aggResults = result as AggregatedGeometryResult; Polyline aggregatedLine = aggResults.Line as Polyline; Multipoint aggregatedPoint = aggResults.Point as Multipoint; Polygon aggregatedPolygon = aggResults.Polygon as Polygon; } } } } } }