An Application Insights telemetry processor that updates the Name of a DependencyTelemetry with the value of a property found in its Properties. Useful for making it easy to distinguish calls to SOAP web services, such as EWS.

SetDependencyNameProcessor.cs

// ---------------------------------------------------------------------------
// <copyright file="SetDependencyNameProcessor.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
// ---------------------------------------------------------------------------

namespace AppInsightsComponents
{
    using System.Diagnostics;

    using Microsoft.ApplicationInsights.Channel;
    using Microsoft.ApplicationInsights.DataContracts;
    using Microsoft.ApplicationInsights.Extensibility;

    /// <summary>
    /// A telemetry processor that updates the <see cref="DependencyTelemetry.Name"/> 
    /// of a <see cref="DependencyTelemetry"/> item with the value of a property 
    /// found in its <see cref="DependencyTelemetry.Properties"/>.
    /// </summary>
    /// <remarks>
    /// <para>
    /// This general purpose processor helps with visualization of 
    /// web service dependencies (such as EWS) in the Azure Portal,
    /// by allowing items to display the name of the web method called,
    /// or some other property, instead of the web service URL.
    /// </para>
    /// <para>
    /// In order to trigger this behavior, include an instance of this
    /// processor in the list of telemetry processors, giving it the key 
    /// to a property which will contain the web method name.
    /// Next, wrap HTTP calls with an <see cref="System.Diagnostics.Activity"/>
    /// and add the desired method name as <see cref="System.Diagnostics.Activity.Baggage"/> 
    /// using the same key given to the processor. Start and Stop the 
    /// <see cref="System.Diagnostics.Activity"/> as appropriate.
    /// </para>
    /// <para>
    /// Baggage propagates to child activities, in particular, the
    /// one created by the framework (System.Net.Http.Desktop.HttpRequestOut)
    /// when it is sending HTTP requests. When Application Insights is 
    /// handling the event that indicates that an HTTP request is being 
    /// sent (see ClientServerDependencyTracker.BeginTracking) 
    /// it will detect the 'HttpRequestOut' activity and will copy its baggage
    /// to a new DependencyTelemetry item. Initializers run as well, but 
    /// ClientServerDependencyTracker.OnBegin overrides any name they
    /// might have set (at least in 2.4.0), which is why we need to modify 
    /// the dependency's name in a processor.
    /// </para>
    /// <para>
    /// Eventually this item comes to our processor, and at this point
    /// we can look for the property given by the key. If we find it, 
    /// we update the <see cref="DependencyTelemetry.Name"/> and remove 
    /// it from <see cref="DependencyTelemetry.Properties"/>.
    /// </para>
    /// </remarks>
    public class SetDependencyNameProcessor : ITelemetryProcessor
    {
        private readonly ITelemetryProcessor next;

        /// <summary>
        /// Initializes a new instance of the <see cref="SetDependencyNameProcessor"/> class.
        /// </summary>
        /// <param name="next">The next processor.</param>
        /// <param name="key">The key of the property that contains the name of the dependency.</param>
        public SetDependencyNameProcessor(ITelemetryProcessor next, string key)
        {
            Debug.Assert(next != null);
            Debug.Assert(!string.IsNullOrWhiteSpace(key));
            this.next = next;
            this.Key = key;
        }

        public string Key
        {
            get;
        }

        public void Process(ITelemetry item)
        {
            if (item is DependencyTelemetry dependencyTelemetry)
            {
                if (dependencyTelemetry.Properties.TryGetValue(this.Key, out var name))
                {
                    dependencyTelemetry.Name = name;
                }
            }

            this.next.Process(item);
        }
    }
}

Usage.cs

// Initialize the processor in your application startup and give it the key to the property that will have the web method name:
            var activeConfiguration = TelemetryConfiguration.Active;
            var telemetryProcessorChainBuilder = activeConfiguration.TelemetryProcessorChainBuilder;
            telemetryProcessorChainBuilder.Use(next => new SetDependencyNameProcessor(next, "WebMethodName"));
            telemetryProcessorChainBuilder.Build();

// In code that invokes the web service or any other HTTP request, wrap the call with an Activity
// and add baggage, with the same key with which you initialize the telemetry processor:

            var activity = new Activity(methodName)
                .AddBaggage("WebMethodName", methodName)
                .Start();
            try
            {
                await this.httpClient.GetStringAsync(...);
            }
            finally
            {
                activity.Stop();
            }


// If you are using a proxy derived from SoapHttpClientProtocol (wsdl.exe),
// you can "override" BeginInvoke/EndInvoke so you have the activity for all methods automatically.
// Note that BeginInvoke/EndInvoke are not virtual, so we need a 'new' method; that works because 
// the generated proxy will have code that calls into "this.BeginInvoke(...)", so we can hijack it.
// (This is assuming you are calling the async versions of the methods; you can do the same with Invoke.)

        /// <inheritdoc />
        /// <remarks>
        /// We start a diagnostic activity and add the name of the method being invoked as baggage, so it flows to Application Insights.
        /// </remarks>
        protected new IAsyncResult BeginInvoke(string methodName, object[] parameters, AsyncCallback callback, object asyncState)
        {
            // I never call these methods with a state; if I did, I would need to wrap them.
            Debug.Assert(asyncState == null);
            var activity = new Activity(methodName)
                .AddBaggage("WebMethodName", methodName)
                .Start();
            return base.BeginInvoke(methodName, parameters, callback, activity);
        }

        /// <inheritdoc />
        /// <remarks>
        /// Stop the diagnostic activity as we get out of the web method call.
        /// </remarks>
        protected new object[] EndInvoke(IAsyncResult asyncResult)
        {
            var activity = asyncResult.AsyncState as Activity;
            activity?.Stop();
            return base.EndInvoke(asyncResult);
        }

In Application Insights we are using tags: https://github.com/Microsoft/ApplicationInsights-dotnet/blob/151509eac5e23fcbd09f3a8989a35d1099703957/src/Core/Managed/Shared/ActivityExtensions.cs#L38