XmlMessageFormatter.TargetTypes Property

Definition

Namespace:

System.Messaging

Assembly:

System.Messaging.dll

Specifies the set of possible types that will be deserialized by the formatter from the message provided.

C#

[System.ComponentModel.Browsable(false)]
[System.Messaging.MessagingDescription("XmlMsgTargetTypes")]
public Type[] TargetTypes { get; set; }

Property Value

Type[]

An array of type Type that specifies the types of objects to deserialize from the message body when reading the message.

Attributes

BrowsableAttribute MessagingDescriptionAttribute

Exceptions

ArgumentNullException

The TargetTypes property is null.

Examples

The following code example sends and receives a message that contains an order to and from a queue.

C#

using System;
using System.Messaging;
using System.Drawing;
using System.IO;

namespace MyProject
{

    // The following example
    // sends to a queue and receives from a queue.
    public class Order
    {
        public int orderId;
        public DateTime orderTime;
    };	

    /// <summary>
    /// Provides a container class for the example.
    /// </summary>
    public class MyNewQueue
    {

        //**************************************************
        // Provides an entry point into the application.
        //		
        // This example sends and receives a message from
        // a queue.
        //**************************************************

        public static void Main()
        {
            // Create a new instance of the class.
            MyNewQueue myNewQueue = new MyNewQueue();

            // Create a queue on the local computer.
            CreateQueue(".\\myQueue");
            
            // Send a message to a queue.
            myNewQueue.SendMessage();

            // Receive a message from a queue.
            myNewQueue.ReceiveMessage();

            return;
        }

        //**************************************************
        // Creates a new queue.
        //**************************************************

        public static void CreateQueue(string queuePath)
        {
            try	
            {
                if(!MessageQueue.Exists(queuePath))
                {
                    MessageQueue.Create(queuePath);
                }
                else
                {
                    Console.WriteLine(queuePath + " already exists.");
                }
            }
            catch (MessageQueueException e)
            {
                Console.WriteLine(e.Message);
            }
        }

        //**************************************************
        // Sends an Order to a queue.
        //**************************************************
        
        public void SendMessage()
        {
            try
            {

                // Create a new order and set values.
                Order sentOrder = new Order();
                sentOrder.orderId = 3;
                sentOrder.orderTime = DateTime.Now;

                // Connect to a queue on the local computer.
                MessageQueue myQueue = new MessageQueue(".\\myQueue");

                // Create the new order.
                Message myMessage = new Message(sentOrder);

                // Send the order to the queue.
                myQueue.Send(myMessage);
            }
            catch(ArgumentException e)
            {
                Console.WriteLine(e.Message);
            }

            return;
        }

        //**************************************************
        // Receives a message containing an order.
        //**************************************************
        
        public  void ReceiveMessage()
        {
            // Connect to the a queue on the local computer.
            MessageQueue myQueue = new MessageQueue(".\\myQueue");

            // Set the formatter to indicate body contains an Order.
            myQueue.Formatter = new XmlMessageFormatter(new Type[]
                {typeof(MyProject.Order)});
            
            try
            {
                // Receive and format the message.
                Message myMessage =	myQueue.Receive();
                Order myOrder = (Order)myMessage.Body;

                // Display message information.
                Console.WriteLine("Order ID: " +
                    myOrder.orderId.ToString());
                Console.WriteLine("Sent: " +
                    myOrder.orderTime.ToString());
            }
            
            catch (MessageQueueException)
            {
                // Handle Message Queuing exceptions.
            }

                // Handle invalid serialization format.
            catch (InvalidOperationException e)
            {
                Console.WriteLine(e.Message);
            }
            
            // Catch other exceptions as necessary.

            return;
        }
    }
}

Remarks

Both the TargetTypeNames and TargetTypes properties tell the formatter what schemas to attempt to match when deserializing a message. This allows the formatter to interpret the message body.

The instance serialized in the message body must comply with one of the schemas represented in the type array. When you read the message using the Receive method, the method creates an object of the type that corresponds to the schema identified and reads the message body into it.

Only one of the two properties needs to be set when reading from the queue, but you can set both. The set of types is the combined set from the two properties. The decision of which property to use is specific to your application. If the message body contains a type whose schema does not match any of the types in the array for either property, an exception will be thrown when the message is read.

The target types are only required when reading from the queue. The TargetTypeNames and TargetTypes properties do not need to be set to write to the queue.

When specifying TargetTypes rather than TargetTypeNames, type existence is checked at compile time rather than read time, reducing possibility for error.

When using TargetTypes, you can add each object (for example, MyClass) to the list in a way demonstrated by the C# code TargetTypes = new Type[]{typeof(MyClass), typeof (MyOtherClass)};.

Applies to

See also

• TargetTypeNames
• CanRead(Message)
• XmlMessageFormatter()