Paul blog

How can we get the first IP4 Address of the local machine in c#?

When we write client server or peer to peer application, a frequent task is to find the first IP4 address of local machine. A machine has multiple types of addresses besides IP4 and IP6. For this reason, we will first get the address list of the machine then will loop through all the addresses to check whether there is an IP4 address. If found then we will return the first address. Otherwise will  return null.

Now the question is how we will detect IP4 address Type. There is an Enumeration named AddressFamily under System.Net.Sockets namespace which specifies the addressing type. The members of AddressFamily Enumeration are in the following:

(The table is stolen from MSDN website)

 The member InterNetwork  of AddressFamily Enumeration indicates Address for IP version 4.Here the member InterNetwork  of AddressFamily Enumeration  is used to check whether this is a IP4 address or not. The routine to find the first IP4 Address of the Host (local) machine is in the following:

   1: private static IPAddress ReturnMachineIP()

   2:    {

   3:        String hostName = Dns.GetHostName();

   4:        IPHostEntry ipEntry = Dns.GetHostEntry(hostName);

   5:        IPAddress[] addr = ipEntry.AddressList;

   6:        IPAddress ipV4 = null;

   7:        foreach (IPAddress item in addr)

   8:        {

   9:            if (item.AddressFamily == AddressFamily.InterNetwork)

  10:            {

  11:                ipV4 = item;

  12:                break;

  13:            }

  14:  

  15:        }

  16:        if (ipV4 == null)

  17:        {

  18:            throw new ApplicationException("You have no IP of Version 4.Server can not run witout it");

  19:        }

  20:        return ipV4;

  21:    }

   Hope this will save some of your time.

How can we make a deep copy of a WPF object?

We can make a deep copy of  a WPF object using XamlWriter and XamlReader. Here the XamlWriter.Save is used to serialize the contents of a WPF object into xaml string.  XamlReader.Load is used to parse XAML string into a WPF object. To make deep copy of an wpf UIelement , you can use the following method.

   1: public UIElement DeepCopy(UIElement element)

   2:    {

   3:        string shapestring = XamlWriter.Save(element);

   4:        StringReader stringReader = new StringReader(shapestring);

   5:        XmlTextReader xmlTextReader = new XmlTextReader(stringReader);

   6:        UIElement DeepCopyobject = (UIElement)XamlReader.Load(xmlTextReader);

   7:        return DeepCopyobject;

   8:    }

If you would like to make deep copy of  WPF  objects without XamlWriter, you have to use reflection .For that you have to navigate recursively inside the type to get all Dependency Properties and Dependency Objects as well as plain .net properties.

Remora Pattern by Ben Constable

According to Ben Constable, Remora Pattern allows you to attach a chunk of logic to any existing element that you have. This pattern can be implemented using an Attached Dependency Property in WPF. Here an Attached Dependency Property is attached with an object. When the object is initiated, it goes to set the value of the Attached Dependency Property, which results in calling an Attached Dependency Property Change event. In the event handler, you can add your intended functionality, which is the additional functionality of the object.

You can get more info about this pattern  in Ben Constable's blog. You can take a look at it here. I have written an article using Remora Pattern to implement a Touch Screen Keyboard. You can take a look at it here (no advertisement intended).

Why should we use Channel factory instead of proxy generation to construct communication channel between client and server in WCF?

If we use proxy class to construct communication channel between server and client , then when we will change data contract, Service contract, callback contract we need to regenerate the proxy for client. If we use channel factory to construct the channel we do not need to change channel factory code when there is a change in data contract, service contract and callback contract. To use Channel Factory to construct channel between server and client , all the contracts must be kept in a separate DLL that must be shared by server and client. But if you do not know, who are your service clients or any third party can consume your service, then by default we have to depend on proxy generation.