Create ResilientDBApp.program

Author: danimir

samples/tutorials/c#/Windows/SqlMIResilientCloudApp/ResilientDBApp.program

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+using System;
+using System.Configuration; // use App.config file
+using System.Collections.Specialized;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Data.SqlClient; // use SQL client library
+using CG = System.Collections.Generic;
+using TD = System.Threading;
+using QC = System.Data.SqlClient;
+
+namespace ResilientDBApp
+{
+	public class Program
+	{
+		static void Main(string[] args)
+		{
+			// Query executions and waits
+			int executions = 100;				// how many executions
+			int sleeptime = 2;                              // wait time between executions (seconds)
+
+			// Connection parameters and resiliency options
+			string InstanceConnectionString = "ConnMI1";	// connection string to SQL MI
+			bool ResilientQuery = true;			// execute resilient, or non-resilient query to transient errors (retry logic true/false)
+
+			// Query text to execute
+			string SQLtext = "INSERT INTO timetable (datestamp) VALUES (CURRENT_TIMESTAMP);";
+			bool ReadBack = false;                          // read query response from SQL MI - if using SELECT statements
+
+			try
+			{
+				for (int i = 1; i <= executions; i++)
+				{
+					Console.Write("Execution # {0} ", i);
+					if (!ResilientQuery)
+                    {
+						Console.WriteLine ("(NON-RESILIENT)");
+						InsertNonResilient(SQLtext, InstanceConnectionString, ReadBack);	// execute NON-resilient DB query - NO retry logic
+					} else
+                    {
+						Console.WriteLine("(RESILIENT)");
+						InsertResilient(SQLtext, InstanceConnectionString, ReadBack);		// execute resilient DB query - HAS RETRY LOGIC
+					}
+					TD.Thread.Sleep(1000 * sleeptime); // wait between the queries
+				}
+			}
+			catch (Exception e)
+			{
+				Console.WriteLine("Error: " + e.Message); // throw error message if connection unsuccessul
+			}
+			Console.WriteLine("\nProgram terminated. Press any key to close the window...");
+			Console.ReadLine();
+		}
+
+		// Logic to execure NON-RESILIENT database query (no retry logic)
+		static public void InsertNonResilient(string SQLtext, string InstanceConnectionString, bool ReadBack)
+		{
+			AccessDatabase(SQLtext, InstanceConnectionString, ReadBack);
+			Console.WriteLine();
+		}
+
+		// Logic to execure RESILIENT database query
+		static public int InsertResilient(string SQLtext, string InstanceConnectionString, bool ReadBack)
+		{
+			bool succeeded = false;
+			int totalNumberOfTimesToTry = 4;	// how many times to retry
+			int retryIntervalSeconds = 10;		// after how many seconds
+
+			for (int tries = 1;
+			  tries <= totalNumberOfTimesToTry;
+			  tries++)
+			{
+				try
+				{
+					if (tries > 1)
+					{
+						Console.WriteLine
+						  ("Transient error encountered. Will begin attempt number {0} of {1} max...",
+						  tries, totalNumberOfTimesToTry
+						  );
+						TD.Thread.Sleep(1000 * retryIntervalSeconds);
+						retryIntervalSeconds = Convert.ToInt32
+						  (retryIntervalSeconds * 1.5);
+					}
+
+					AccessDatabase(SQLtext, InstanceConnectionString, ReadBack);
+					succeeded = true;
+					break;
+				}
+
+				catch (QC.SqlException sqlExc)
+				{
+					if (TransientErrorNumbers.Contains
+					  (sqlExc.Number) == true)
+					{
+						Console.WriteLine("{0}: transient error.", sqlExc.Number);
+						continue;
+					}
+					else
+					{
+						Console.WriteLine(sqlExc);
+						succeeded = false;
+						break;
+					}
+				}
+
+				catch (Exception Exc)
+				{
+					Console.WriteLine(Exc);
+					succeeded = false;
+					break;
+				}
+			}
+
+			if (succeeded == true)
+			{
+				Console.WriteLine("SUCCESS.\n");
+				return 0;
+			}
+			else
+			{
+				Console.WriteLine("ERROR: Unable to access the database.\n");
+				return 1;
+			}
+		}
+
+		// Connects to the database, executes query
+		static public void AccessDatabase(string sqltext, string instance, bool read)
+		{
+			//throw new TestSqlException(4060); //(7654321);  // Uncomment for testing.  
+
+			using (var sqlConnection = new QC.SqlConnection
+				(GetSqlConnectionString(instance)))
+			{
+				using (var dbCommand = sqlConnection.CreateCommand())
+				{
+					sqlConnection.Open();
+					dbCommand.CommandText = sqltext;
+					Console.WriteLine("Executing query: " + dbCommand.CommandText);
+
+					// are we reading from SQL Server, or only comitting
+					if (read == true) // execute SQL query and read reaspons
+					{
+						var dataReader = dbCommand.ExecuteReader();
+						while (dataReader.Read())
+						{
+							Console.WriteLine(dataReader.GetString(0));
+						}
+					} else // exectue SQL query and report rows affected
+                    {
+						int rowsAffected = dbCommand.ExecuteNonQuery(); //execute query and get row count
+						Console.WriteLine(rowsAffected + " row(s) updated");
+					}
+				}
+			}
+		}
+
+		// Build connection string to the server
+		// ADD your SQL MI server details into App.config,
+		// OR manuall edit the four string values - DataSource, InitialCatalog, UserID, Password with your SQL MI connection details
+		static private string GetSqlConnectionString(string instance)
+		{
+			// Prepare the connection string to Azure SQL Database.  
+			var sqlConnectionSB = new QC.SqlConnectionStringBuilder();
+
+			// Change these values to your values.  
+			sqlConnectionSB.DataSource = ConfigurationManager.AppSettings.Get(instance + ".server"); // Server  
+			sqlConnectionSB.InitialCatalog = ConfigurationManager.AppSettings.Get(instance + ".database"); // Database  
+			sqlConnectionSB.UserID = ConfigurationManager.AppSettings.Get(instance + ".username");
+			sqlConnectionSB.Password = ConfigurationManager.AppSettings.Get(instance + ".pass");
+			
+			// Adjust these values if you like. (ADO.NET 4.5.1 or later.)  
+			sqlConnectionSB.ConnectRetryCount = 3;
+			sqlConnectionSB.ConnectRetryInterval = 10;  // Seconds.  
+
+			// Leave these values as they are.  
+			sqlConnectionSB.IntegratedSecurity = false;
+			sqlConnectionSB.Encrypt = true;
+			sqlConnectionSB.ConnectTimeout = 30;
+
+			// Test the connection string configuration online
+			// Console.WriteLine(sqlConnectionSB);
+
+			return sqlConnectionSB.ToString();
+		}
+
+		// Error numbers for transient errors
+		static public CG.List<int> TransientErrorNumbers =
+		  new CG.List<int> { 4060, 40197, 40501, 40613, 49918, 49919, 49920, 11001 };
+	}
+
+}