.Net Batch Job Template

Over the years I've had to write enough batch jobs that I've come up with a template. Most batch jobs have a number of common elements. When the job runs, you want it to record in a log the time when it ran, what tasks it performed and the time when it finished. If the batch job runs into problems, you want it to record the problem to the log and then exit with an error code. Most batch jobs also need to connect to a database.

Writing all the code to create a log, get a database connection string and connect to the database is time consuming. It's best to build something reusable. So without further ado, here is the template I use. Comments and explanation are at the end.

using System;
using System.Collections.Generic;
using System.Configuration;
using System.IO
using System.Text;

namespace ConsoleTemplate
{
    class BatchTemplate
    {
        public static StreamWriter LogWriter = null;

        static int Main(string[] args)
        {
            OpenLog();

            db = DatabaseFactory.CreateDatabase("MyDatabase");
            DbCommand cmd = db.GetStoredProcCommand("MyStoredProcedure");

            WriteToLog( "Hello world!");
            CloseLog();
            return 0;
        }

        static private void OpenLog()
        {
            // Create log folder if it doesn't exist
            string folderPath = Path.Combine(Environment.CurrentDirectory, "Log Files");
            DirectoryInfo logFolder = new DirectoryInfo(folderPath);

            if (!logFolder.Exists)
                logFolder.Create();

            // Clear out old logs
            string appSetting = ConfigurationManager.AppSettings["DaysToStoreLogFiles"];
            int days = int.Parse(appSetting);
            TimeSpan span = new TimeSpan(days, 0, 0, 0);

            foreach(FileInfo logFile in logFolder.GetFiles())
            {
                if (logFile.CreationTime < DateTime.Now - span)
                    logFile.Delete();
            }

            // Create new log file
            string filePath = Path.Combine(folderPath, DateTime.Now.ToString("yyyy-MM-dd-hhmmss"));

            if (File.Exists(filePath + ".txt"))
            {
                bool exitApplication = true;
                for (int x = 1; x <= 10; x++)
                {
                    string newPath = filePath + "(" + x.ToString() + ")";

                    if (!File.Exists(newPath + ".txt"))
                    {
                        filePath = newPath;
                        exitApplication = false;
                        break;
                    }
                }

                // If someone has really launched the batch job more than 10 times in
                // a single second, something is wrong.
                if (exitApplication)
                    Environment.Exit(1);
            }


            LogWriter = File.CreateText(filePath + ".txt");
            WriteToLog("Begin processing:  " + DateTime.Now.ToString("yyyy-MM-dd-hh:mm:ss"));
            WriteToLog("-----------------------------------------------------------");
            WriteToLog("");
        }

        static private void CloseLog()
        {
            WriteToLog("");
            WriteToLog("------------------------------------------------------------");
            WriteToLog("Finish processing:  " + DateTime.Now.ToString("yyyy-MM-dd-hh:mm:ss"));

            LogWriter.Close();
        }

        static private void WriteToLog(string logEntry)
        {
            LogWriter.WriteLine(logEntry);
        }
    }
}

The App.Config file:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="dataConfiguration"     
             type="Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings,
           Microsoft.Practices.EnterpriseLibrary.Data,
                   Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
  </configSections> 
  <connectionStrings>
    <add name="MyDatabase"
         connectionString="Data Source=MYDATABASE;Initial Catalog=DEV;User ID=XYZ;Password=12345"
         providerName="System.Data.SqlClient" />
  </connectionStrings>
  <appSettings>
    <add key="DaysToStoreLogFiles" value="60"/>
  </appSettings> 
</configuration>

Notes:

Every time the batch job runs, the first thing it does is call OpenLog( ).  This method performs a number of tasks.  The first thing it does is look for a folder called Log Files.  This folder should be in the same place as the batch job executable.  If it isn't there, it gets created.  All the batch job log files will be stored here.

The next task OpenLog( ) performs is to clear out old log files.  In the app.config file there is a setting which says log files should be stored for sixty days. Log files older than sixty days are deleted.   

Now OpenLog( ) creates a new log file named [year-month-day-hour-minute-second].txt.  If there is already a file with this name (because the batch job was launched twice in the same second), the second file will have a "(2)" added to the end of the file name.  

Now that we have a folder to hold log files and we've created a new log file for this run, OpenLog( ) records the time when processing began.

CloseLog( ) records the time when processing is complete and then closes the log file.

WriteToLog( ) writes a string into the log file.  Each string thus written goes on its own line in the log.  

The .config file also contains the entries for the Microsoft Enterprise Library data access block and a connection string.  With these in place, the batch job is ready to connect to a database, as shown in the Main( ) function.

After a successful run, the batch job exits with a return code of 0.  If it fails while creating the log, it exits with a return code of 1.

The batch job shown above creates a log file name 2009-11-28-110817.txt that looks like this:

Begin processing: 2009-11-28-09:08:17 ----------------------------------------------------------- Hello world! ------------------------------------------------------------ Finish processing: 2009-11-28-09:08:18

 

When you make your own batch job, the first thing you do is call OpenLog().  The last thing you do when you're done is call CloseLog().  In between, you can write to the log using the WriteToLog(string) method.  All that's left for you to do is add your own code.

Enjoy.