Adding EventSource to NetFx

doc/samples/SqlClientEventSource_EventLogger.cs

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+using System;
+using System.Data;
+using System.Diagnostics.Tracing;
+using Microsoft.Data.SqlClient;
+
+// <Snippet1>
+class Program
+{
+    static void Main()
+    {
+        static void Main(string[] args)
+        {
+            using (var listener = new SampleEventListener())
+            {
+                //This Enables events for Keywords.Tracing
+                //We also can select EventKeywords.All to get all possible available events.
+                listener.EnableEvents(SqlClientEventSource.Log, EventLevel.Informational, SqlClientEventSource.Keywords.Trace);
+                using (SqlConnection connection = new SqlConnection("Data Source=tcp:localhost;Database=Northwind;Integrated Security=SSIP;"))
+                {
+                    connection.Open();
+                    using (SqlCommand command = new SqlCommand("SELECT * From [Customers]", connection))
+                    {
+                        command.ExecuteNonQuery();
+                    }
+                }
+            }
+        }
+    }
+}
+
+public class SampleEventListener : EventListener
+{
+    static TextWriter Out = Console.Out;
+
+    /// <summary>
+    /// We override this method to get a callback on every event.
+    /// </summary>
+    /// <param name="eventData"></param>
+    protected override void OnEventWritten(EventWrittenEventArgs eventData)
+    {
+        // report all event information
+        Out.Write("  Event {0} ", eventData.EventName);
+
+        // Events can have formatting strings 'the Message property on the 'Event' attribute.  
+        // If the event has a formatted message, print that, otherwise print out argument values.  
+        if (eventData.Message != null)
+            Out.WriteLine(eventData.Message, eventData.Payload.ToArray());
+        else
+        {
+            string[] sargs = eventData.Payload != null ? eventData.Payload.Select(o => o.ToString()).ToArray() : null;
+            Out.WriteLine("({0}).", sargs != null ? string.Join(", ", sargs) : "");
+        }
+    }
+}
+// </Snippet1>