I had a need recently to access the Windows event logs. Reading the Event Log is useful when you want to be notified when a program fails. You read the Events and if there is a fatal error, do something like send an email the owner of the process. This is helpful if you have a console application that runs all the time unattended.

The .Net Framework offers the System.Diagnostics.EventLog class. This class gives you the power to interact with the Windows event logs.

Below is a C# program that accesses the Windows event logs.

using System;
using System.Text;
using System.Diagnostics;

class Program
{
    static void Main(string[] args)
    {
        StringBuilder sb = new StringBuilder();
        EventLog log = new
        EventLog("Application");

        DateTime dt = DateTime.Now.AddHours(-1.00);
        Console.WriteLine(dt.ToString());

        foreach (EventLogEntry entry in log.Entries)
        {
            if (entry.TimeGenerated > dt)
            {
                Console.WriteLine(entry.Source);
                Console.WriteLine(entry.EntryType);
                Console.WriteLine(entry.Message);
                Console.WriteLine("--------");
            }
        }

        Console.WriteLine("Done");
        Console.ReadLine();
    }
}

Below is the result of executing the code above. As you can see I had a crash in my Windows Live Writer Application.

Below is the Event Viewer and you can see there as well where there was an issue with the WLW application.

I can see where this class can be very helpful and plan on doing more research into what it can do as far as reading as well as writing operations.

Related Information

• EventLog Class Definition and Specifications on MSDN
• Beginning System.Diagnostics on CodeProject

In this presentation he talked about the importance of constant learning and refactoring.

Below are some of the high points I picked up.

1. The Goal

• Build the right thing and build it well
• Technical Debt – Shipping the right thing even though it is not perfect
• Do the simplest thing that can possibly work
• Enable change

Build architectural seams or fault lines into your code, so if need be, it can be picked up and “stitched in” somewhere else

*ilities

• Agility
• Testability
• Readability
• Reversability
• Changeability
• Flexibility
• Maintainability

Domain Driven Design

2. The Guidelines

Don’t Repeat Yourself (DRY) and Separation of Concerns are the yin and yang of Software Development

Examples of Separation of Concerns are MVC, MVP, HTML, CSS, JavaScript, (UI+Service+DAL).

SOLID Principals

• Single Responsibility Principle
• Open Closed Principle
• Liskov Substitution Principle
• Interface Segregation Principle
• Dependancy Inversion Principle

3. The Practice

A feedback loop is needed (code reviews, pair programming)

Test Driven Development

Yield keyword

–

Additional Information

• QConn Conferences
• Virtual Brown Bag – Weekly meetings held on Thursdays.
• Time Snapper – Automatic screen shot journal
• XUNIT.NET – Testing framework

–

I needed to find out which column in the DataSet was causing the error, so a co-worker suggested I create a temporary data adapter/set, so I can examine the GetErrors() method.

/*
*/
//-- Table Adaptor and DataSet with issue

spRoxStaffImportTableAdapter roxStaffImportTA =
    new spRoxStaffImportTableAdapter();

RoxStaffImport.Data.StaffImport.spRoxStaffImportDataTable importdt =
    roxStaffImportTA.spRoxStaffImport();

//-- Table Adaptor and DataSet with my temporary TA and DS

spRoxStaffImportTableAdapter roxStaffImportTA =
    new spRoxStaffImportTableAdapter();

//added for debugging
RoxStaffImport.Data.StaffImport myDS =
    new RoxStaffImport.Data.StaffImport(); 

//added for debugging
roxStaffImportTA.spRoxStaffImportfl(myDS.spRoxStaffImport);

//changed for debugging
RoxStaffImport.Data.StaffImport.spRoxStaffImportDataTable importdt =
    myDS.spRoxStaffImport; //roxStaffImportTA.spRoxStaffImport();

C# Listing on GitHub

Once the exception occurs, access the GetErrors() property using the Watch window. This will tell you exactly what your issue is.

Once the issue is fixed, you can remove the temporary data adapter/set.

With reflection we can dynamically create an instance of a type, bind the type to an existing object, or get the type from an existing object and invoke its methods or access its fields and properties. If Attributes (C#) are used in application, then with help of reflection we can access these attributes. It can be even used to emit Intermediate Language code dynamically so that the generated code can be executed directly.

I have been doing some research and test apps using the GetProperties method. GetProperties basically returns array of PropertyInfo objects.

–

Sample Program

using System;
using System.Reflection;

class Program
{
    static void Main(string[] args)
    {
        var person = new Person
        {
            Name = "Rhonda",
            FaveShow = "Fringe, Lost",
            FaveMovie = "Star Trek",
            FaveSong = "Contagious"
        };

        var type = typeof(Person);
        var properties = type.GetProperties();

        foreach (PropertyInfo property in properties)
        {
            Console.WriteLine("{0} : {1}",
                             property.Name, property.GetValue(person, null));
        }

        Console.Read();
    }
}

public class Person
{
    public string Name { get; set; }
    public string FaveShow { get; set; }
    public string FaveMovie { get; set; }
    public string FaveSong { get; set; }
}

C# Listing on GitHub 

As you can see below there are several other methods available as well as GetProperties.

Output

Additional Information

• Get Property Names using Reflection [C#]
• C# Tutorial – Using Reflection to Get Object Information

–

^..^

Announcements
Some people from TechSmith will be here for next month’s meeting
Meeting #100 is coming up quick. There will possibly be big prizes

Main Presentation
Markus Egger from EPS Software did a great presentation on C# 4.0 focusing mainly on the Dynamic aspects.

Types of .NET Lanuages

• Traditional – C#, VB.NET
• Functional – F# — Book recommendation: Expert F#
• Dynamic – IronPython, IronRuby

Dynamic (Python, Ruby, JavaScript) – Advantages

• Simple
• Implicitly typed
• No compilation

One of the main disadvantages of dynamic languages is the lack of Intellisense support.

Static (C#, VB.NET) languages – Advantages

• Performant
• Intelligent tools
• Better scaling

DLR – Dynamic Language Runtime

DynamicObject class

REST

Named and Optional Parameters

Improved COM Support

–

Markus Egger’s Information

• Presentation and Demos for C# 4.0 Dynamic Programming
• Email – MEgger@eps-software.com
• Twitter – @MarkusEgger
• Blog – http://www.MarkusEgger.com/blog

–

–

^..^

Silverlight

Ken defined Silverlight as a programmable browser plugin that supports animations, vector graphics and videos.

Some features include –

• Works on Mac/Linux/Windows
• Client-side technologies
• Uses XAML for declarative design
• Expression Blend – best software to use for Silverlight/XAML design
• Visual Studio 2010 includes the components needed to build Silverlight apps out of the box

The following site allows you to verify if your pc is able to run Silverlight applications http://www.microsoft.com/silverlight/get-started/install/default.aspx

Silverlight is basically an HTML page with an <object> tag.

–

LINQ to Objects

There are several LINQ providers –

• Objects
• SQL
• DataSets
• XML
• Entities

Example Usage

string[] geeks = { “Sheldon”, “Leonard”, “Howard”, “Raj”};

var myQuery = from g in geeks
              orderby g
              select g;

Console.WriteLine(“My Favorite Geeks”);

foreach (var x in myQuery)
{
    Console.WriteLine(x);
}

Ken provided a very informative presentation on LINQ to Objects and I am glad I was able to catch it.

Ken’s LINQ demo code

–

^..^

I posted this inquiry to the ALT.NET Google Group and received the following responses:  

Ben Scheirman 

Windows Forms timers are more to update things on the UI.

System.Threading.Timer is for performing timed actions in any .NET code.
For example, say you want to execute a function, but at a later time…
like “Call this method in 10 seconds”.  You can also set it up to execute
some code at a regular interval.

The short answer, use WinForms timer when you’re working on a WinForm, and
use Threading.Timer everywhere else.

Mohammad Azam suggested a great article that goes into great detail by Comparing the Timer Classes in the .NET Framework Class Library.

High point quotes from the article:

[Talking about Windows.Forms.Timer] Just like the rest of the code in a typical Windows Forms application, any code that resides inside a timer event handler (for this type of timer class) is executed using the application’s UI thread. During idle time, the UI thread is also responsible for processing all messages in the application’s Windows message queue.

The System.Timers.Timer class will, by default, call your timer event handler on a worker thread obtained from the common language runtime (CLR) thread pool. This means that the code inside your Elapsed event handler must conform to a golden rule of Win32 programming: an instance of a control should never be accessed from any thread other than the thread that was used to instantiate it.

[Talking about System.Threading.Timer] Instances of this class are not inherently thread safe, given that it resides in the System.Threading namespace. (Obviously, this doesn’t mean it can’t be used in a thread-safe manner.) The programmatic interface of this class is not consistent with the other two timer classes and it’s also a bit more cumbersome.

From reading this article and the replies to my inquiry on the ALT.NET Google Group, it sounds like if your needing a timer for the UI, use System.Windows.Forms.Timer; otherwise, the System.Threading.Timer is the way to go.

–

^..^

Good examples of Method Overloading in the .NET Framework include (but are not limited to) the Console.WriteLine() and Substring() methods.  You can pass different types to the Console.WriteLine() method and it will work because there are variations of the methods that will accept the different types.

–

C# Program

using System;
namespace MethodOverloading
{
  class Program
  {
     static void Main(string[] args)
     {
         MethodOverloadPlay(10, 3);
         Console.WriteLine("+++++");
         MethodOverloadPlay(5, 5, 6);
         Console.WriteLine("+++++");
         MethodOverloadPlay("SP");
         Console.ReadLine();
     }

     static void MethodOverloadPlay(int number1, int number2)
     {
         int result = number1 + number2;
         Console.WriteLine(result);
     }

     static void MethodOverloadPlay(int number1, int number2, int number3)
     {
         int result = number1 + number2 + number3;
         Console.WriteLine(result);
     }

     static void MethodOverloadPlay(string string1)
     {
         Console.WriteLine("Breaking Benjamin & Sick Puppies Rock!");
     }
  }
}

C# Listing on GitHub 

–

Result

–

The main advantage of Method Overloading is code readability. Programming languages that do not allow Method Overloading require the developer to create totally separate methods for each variation of the input.  Blackwasp Consulting states the following example: in the ANSI C programming language to truncate a value you would use trunc, truncf or truncl according to the data type being rounded.  In C#, method overloading allows you to always call Math.Truncate.

–

Additional Information

• C# Method Overloading – BlackWasp Consulting
• Guidelines for Method Overloading – Dave Donaldson
• Method overloading – CSharp .Net-tutorials
• Method overloading in C# .Net – Coder Source

–

^..^

The three types of timers are explained below.

1 – System.Timers.Timer

The System.Timers.Timer class timer is considered a server-based timer that was designed and optimized for use in multithreaded environments. It can be accessed safely from multiple threads.

C# Program

using System;
using System.Timers;

public class Program
{
  private static System.Timers.Timer testTimer;

  public static void Main(string[] args)
  {
    testTimer = new System.Timers.Timer(5000); // 5 seconds
    testTimer.Elapsed += new ElapsedEventHandler(OnTimerElapsed);

    testTimer.Interval = 5000;
    testTimer.Enabled = true;

    Console.WriteLine("Press the enter key to stop the timer");
    Console.ReadLine();

  }

  private static void OnTimerElapsed(object source, ElapsedEventArgs e)
  {
    Console.WriteLine("Timer elapsed at {0}", e.SignalTime);
  }
}

C# Listing on GitHub 

Output

–

2 – System.Threading.Timer

The System.Threading.Timer class timer uses a TimerCallBack Delegate to specify the associated methods. The methods do not execute in the thread that created the timer; they execute in a separate thread that is automatically allocated by the system.

C# Program

using System;
using System.Threading;

class Program
{
  static void Main()
  {
     AutoResetEvent reset = new AutoResetEvent(false);
     StatusChecker status = new StatusChecker(5);

     // Invoke methods for the timer via a Delegate
     TimerCallback timerDelegate = new TimerCallback(status.CheckStatus);

     // Create a timer that signals the delegate to invoke
     // Check status after one second, and then every 1/4 second
     Console.WriteLine("{0} Creating the timer.\n",
         DateTime.Now.ToString("h:mm:ss.fff"));

     Timer stateTimer = new Timer(timerDelegate, reset, 1000, 250);

     // When the auto reset executes, change to every 1/2 second
     reset.WaitOne(5000, false);
     stateTimer.Change(0, 500);
     Console.WriteLine("\nChanging the timer period.\n");

     reset.WaitOne(5000, false);
     stateTimer.Dispose();
     Console.WriteLine("\nDestroying the timer.");
  }
}

class StatusChecker
{
  int invokeCount, maxCount;

  public StatusChecker(int count)
  {
     invokeCount = 0;
     maxCount = count;
  }

    // This method is called by the timer delegate.
  public void CheckStatus(Object stateInfo)
  {
     AutoResetEvent autoEvent = (AutoResetEvent)stateInfo;
     Console.WriteLine("{0} Checking status {1,2}.",
         DateTime.Now.ToString("h:mm:ss.fff"),
         (++invokeCount).ToString());

     if (invokeCount == maxCount)
     {
         // Reset the counter and signal Main.
         invokeCount = 0;
         autoEvent.Set();
     }
  }
}

Output

–

3 – Windows.Forms.Timer

The Windows.Forms.Timer class works synchronously with the Windows Form, so that it will not interrupt any operations. It initializes on the UI thread.

C# Program

using System;
using System.Windows.Forms;

namespace WindowsFormsTimer
{
  public class Class1
  {
     static System.Windows.Forms.Timer theTimer =
         new System.Windows.Forms.Timer();

     static int alarmCounter = 1;
     static bool exitFlag = false;

      // Timer raised method
      private static void TimerEventProcessor(Object myObject,
          EventArgs myEventArgs)
      {
         theTimer.Stop();

         // Displays a message box asking whether to continue to run the timer
         if (MessageBox.Show("Continue running?", "Count is " +
             alarmCounter, MessageBoxButtons.YesNo) == DialogResult.Yes)
         {
             // Restarts the timer and increments the counter
             alarmCounter += 1;
             theTimer.Enabled = true;
         }
         else
         {
             // Stops the timer
             exitFlag = true;
         }
     }

     public static int Main()
     {
         //Adds the event and the event handler for the method that will
         //process the timer event to the timer
         theTimer.Tick += new EventHandler(TimerEventProcessor);

         // Sets the timer interval to 5 seconds
         theTimer.Interval = 2000;
         theTimer.Start();

         // Runs the timer, and raises the event
         while (exitFlag == false)
         {
             // Processes all the events in the queue
             Application.DoEvents();
         }
         return 0;
     }
  }
}

C# Listing on GitHub  

Output

–

There are three choices for timers in .NET.  It just depends on what you want to do.

–

More Information

• Comparing the Timer Classes in the .NET Framework Class Library
• System.Timers.Timer vs System.Threading.Timer
• Working with Timer Control in VB.NET

–

Until next time…

^..^

Announcements -

• Next month Zain Naboulsi will be presenting on Windows 7 for developers
• There is an upcoming ASP.NET User Group that will likely be on the 4th Tuesday of each month – no dates set yet

Main topic -

Claudio Lassala gave a great talk titled Be a Professional Developer and Write Clean Code. Below are some of the points covered.

• What is clean code? Elegant and efficient, can be read and enhanced, simple and direct, etc…
• Computers do not care what your code looks like
• Name variables so that you don’t need comments

          Instead of –

     //Setting employee’s first name
     string field1 = “Rhonda” ;

          Use this –

     string employeeFirstName = “Rhonda”;

• If you have source control, there is no reason to keep code commented
• NDepend – a good tool that provides metrics for your code
• Functions should do one thing and do it well
• Vertical Distance – Declare variables close to where they are used. There is no need to declare all variables at the top of the program.

Presentation Materials for Be a Professional Developer and Write Clean Code

There were a lot more great points, but I had to leave before Claudio was finished. He did a great job of explaining how bad code should be rewritten.

Looking for a user group meeting to attend? Check out my Houston Tech Groups and Events page.

–

Until next time…

^..^