static void Main(string[] args)
{
//Set the default values
string SQLConnectionString = "Server = <server_name>; Database = <database_name> UID = <user_name>; Pwd = <password>"; // Connection string for the SQL Edge Instance.
string SourceTableName = "<table_name>"; //Source Table Name
string EventHubConnectionString = ""; // Connection String to the Event Hub
string EventHubName = ""; // Name of the Event hub
int ReadWriteFrequency = 1; /// Read/Write interval in minutes.
// Read Environment Variables.
if (Environment.GetEnvironmentVariable("SQLConnectionString") != null)
{
SQLConnectionString = Environment.GetEnvironmentVariable("SQLConnectionString").Trim('"');
}
if (Environment.GetEnvironmentVariable("SourceTableName") != null)
{
SourceTableName = Environment.GetEnvironmentVariable("SourceTableName").Trim('"');
}
if (Environment.GetEnvironmentVariable("EventHubConnectionString") != null)
{
EventHubConnectionString = Environment.GetEnvironmentVariable("EventHubConnectionString");
}
if (Environment.GetEnvironmentVariable("EventHubName") != null)
{
EventHubName = Environment.GetEnvironmentVariable("EventHubName");
}
if (Environment.GetEnvironmentVariable("ReadWriteFrequencyInMiutes") != null)
{
ReadWriteFrequency = Convert.ToInt32(Environment.GetEnvironmentVariable("ReadWriteFrequencyInMiutes"));
}
//Initializing the SQLLite Database. If it exists, reload it.
SQLiteDatabaseOperations.CreateDatabaseAndTable();
var tasks = new List <Task>(3);
///Get the Changed data from SQL Edge
///
//await Miscellaneouss.ReadDataSQLEdge(appsettings.SQLEdgeConnectionString, appsettings.TableName, Convert.ToInt32(appsettings.ReadWriteFrequencyInMs));
tasks.Add(Task.Factory.StartNew(() => Miscellaneouss.ReadDataSQLEdge(SQLConnectionString, SourceTableName, Convert.ToInt32(ReadWriteFrequency))));
///Send the data to Event Hub
///
tasks.Add(Task.Factory.StartNew(() => Miscellaneouss.WriteEventHub(EventHubConnectionString, EventHubName, Convert.ToInt32(ReadWriteFrequency))));
//await Miscellaneouss.WriteEventHub(appsettings.TargetConnectionString, appsettings.EventHubName, Convert.ToInt32(appsettings.ReadWriteFrequencyInMs));
/// Load the File Deletion Thread
///
tasks.Add(Task.Factory.StartNew(() => Miscellaneouss.DeleteOldUploadedFiles()));
Task.WaitAll(tasks.ToArray());
}
public static void DeleteOldUploadedFiles()
{
//Get the list of files to delete from the SQLite Database.
while (true)
{
string[] filelist = SQLiteDatabaseOperations.GetFilesToDelete();
foreach (string filename in filelist)
{
if (File.Exists(filename))
{
try
{
File.Delete(filename);
SQLiteDatabaseOperations.DeleteEntryFromDatabase(filename);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
}
Thread.Sleep(new TimeSpan(2, 0, 0));
}
}
//Read Data from SQL and Generate an JSON for the Rows.
// For the purpose of this demo, we are using Change Tracking feature in SQL
// The function reads the net changes from the underlying table.
public static Task ReadDataSQLEdge(string connectionString, string tablename, int ReadInterval)
{
// Check if the connection string is a valid connection string or not.
DataSet ds = new DataSet();
string json;
while (true)
{
if (connectionString != "" || tablename != "")
{
long min_version = GetMinValidCTVersionsFromSQL(connectionString, tablename);
if (min_version != -1)
{
long last_sync_version = SQLiteDatabaseOperations.SelectLastSyncVersion();
try
{
try
{
try
{
using (SqlConnection connection = new SqlConnection(connectionString))
{
/// Check the table is present in the database or not
/// If present, check if Change tracking is enabled on the Table or not.
///
string query = "Select count(*) as TableCount from sys.change_tracking_tables where object_id = object_id(N'" + tablename + "')";
SqlCommand sql_cmnd1 = new SqlCommand(query, connection);
connection.Open();
int result = (Int32)sql_cmnd1.ExecuteScalar();
connection.Close();
if (result == 1)
{
Console.WriteLine($"The specified Table [{tablename}] is enabled for change tracking.");
//Read Data from SQL Edge using the Predefined Stored Procedure.
/// This example used a SP, to minimize the usage of T-SQL constructs in the code.
///
SqlCommand sql_cmnd = new SqlCommand("GetChangesFromTable", connection);
sql_cmnd.CommandType = CommandType.StoredProcedure;
sql_cmnd.Parameters.AddWithValue("@TableName", SqlDbType.VarChar).Value = tablename;
sql_cmnd.Parameters.AddWithValue("@last_sync_version", SqlDbType.BigInt).Value = last_sync_version;
connection.Open();
SqlDataAdapter da = new SqlDataAdapter(sql_cmnd);
da.Fill(ds);
da.Dispose();
/// Convert this Database to a Json Object.
/// This JSON will be used to sync data to the targets
///
connection.Close();
}
else
{
Console.WriteLine("The specified table is not enabled for Changed Tracking");
}
}
}
catch (SqlException e)
{
Console.WriteLine(e.Message);
}
catch (System.ArgumentException ae)
{
Console.WriteLine($"Error Establishing connection to SQL to read the data. Reason: {ae.Message}");
}
long currnet_version = (Int64)ds.Tables[0].Rows[0]["Current_Sync_Version"];
//Console.WriteLine($"Current Version from Database -> {currnet_version}");
// get the Current Sync Version from the record set.
//System.Text.Json.JsonSerializer serializer = new JsonSerializer();
List <Dictionary <string, object> > rows = new List <Dictionary <string, object> >();
Dictionary <string, object> row;
foreach (DataRow dr in ds.Tables[1].Rows)
{
row = new Dictionary <string, object>();
foreach (DataColumn col in ds.Tables[1].Columns)
{
row.Add(col.ColumnName, dr[col]);
}
rows.Add(row);
}
ds.Clear();
ds.Dispose();
json = "";
json = System.Text.Json.JsonSerializer.Serialize(rows);
///create the json file for interim storage
///
string filename = "ChangeTrackingData_" + Convert.ToString(last_sync_version)
+ "_" + DateTime.UtcNow.ToString(new CultureInfo("en-us")).Replace("/", " ").Replace(":", " ").Replace(" ", "_") + ".json";
File.WriteAllText(filename, json);
///Write the last synchronization details to the datastore.json file.
///
//WriteLastSyncVersion(currnet_version, filename, "Created");
SQLiteDatabaseOperations.InsertRecords(currnet_version, filename);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
else
{
Console.WriteLine("There was either an error reading the MIN VALID LSN or the value returned was NULL");
}
}
else
{
Console.WriteLine("The Connection String to SQL Edge or the Source Table name is incorrect");
}
Thread.Sleep(new TimeSpan(0, ReadInterval, 0));
}
}
public static async Task WriteEventHub(string eventhubconn, string eventhubname, int WriteInterval)
{
//using EventDataBatch eventBatch = await producerClient.CreateBatchAsync();
while (true)
{
if (eventhubconn == "")
{
Console.WriteLine("Exception - Event Hub Connection string is not Valid. ");
break;
}
// this function will read the datastore.json file to first file (status = Created) which has not yet been Sent to the EventHub.
// We will first read the json file and then convert it into a byte stream
// which will then be used to send the events to the event hub.
string filename = "";
filename = SQLiteDatabaseOperations.SelectNextUploadedFile();
if (filename != "" && File.Exists(filename))
{
bool isConnected = CheckNetworkConnectivity();
if (isConnected)
{
Console.WriteLine("Network Connectivity Exists!! Proceeding with Data Sync");
await using (var producerClient = new EventHubProducerClient(eventhubconn, eventhubname))
{
using EventDataBatch eventBatch = await producerClient.CreateBatchAsync();
// Add events to the batch. An event is a represented by a collection of bytes and metadata.
try
{
string json = (new StreamReader(new FileStream(filename, FileMode.Open))).ReadToEnd();
if (json.Length >= 1048576)
{
//The json file is too big to send to event hub. The Limit on Standard Event Hub is 1 MB
// breakdown the JSON File and construct smaller json files.
List <object> items = JsonSerializer.Deserialize <List <object> >(json);
Console.WriteLine($"List contains {items.Count} elements");
int copyrange = 0;
for (int j = 0; j < items.Count; j += 2500)
{
string json2 = "";
if (items.Count - j > 2500)
{
copyrange = 2500;
}
else
{
copyrange = items.Count - j - 1;
}
object[] array = new object[copyrange];
Console.WriteLine($"Array Length {array.Length}, Value of J - {j}");
items.CopyTo(j, array, 0, copyrange);
//Console.WriteLine($"List contains {array.Length} elements");
json2 = JsonSerializer.Serialize(array);
//Console.WriteLine($"Length of the new json file is -> {json2.Length}");
EventData d2 = new EventData(Encoding.UTF8.GetBytes(json2));
eventBatch.TryAdd(d2);
try
{
await producerClient.SendAsync(eventBatch);
Console.WriteLine("Sent 1 JSON file with multiple records to the Event Hub");
}
catch (Exception e)
{
Console.WriteLine(e.Message);
continue;
}
}
SQLiteDatabaseOperations.UpdateRecords(filename);
// Also rename the file on the disk
try
{
//File.Move(filename, filename + "_processed");
}
catch
{
Console.WriteLine($"File {filename} cannot be renamed.");
}
}
else
{
EventData d = new EventData(Encoding.UTF8.GetBytes(json));
eventBatch.TryAdd(d);
try
{
await producerClient.SendAsync(eventBatch);
SQLiteDatabaseOperations.UpdateRecords(filename);
Console.WriteLine("Sent 1 JSON file with multiple records to the Event Hub");
try
{
//File.Move(filename, filename + "_processed");
}
catch
{
Console.WriteLine($"File {filename} cannot be renamed.");
}
}
catch (Exception e)
{
Console.WriteLine(e.Message);
continue;
}
}
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
}
}
Thread.Sleep(new TimeSpan(0, WriteInterval, 0));
}
}
