Procedura: scambiare messaggi in coda con endpoint WCF

Le code garantiscono una messaggistica affidabile tra un client e un servizio WCF (Windows Communication Foundation), anche se il servizio non è disponibile al momento della comunicazione. Nelle procedure seguenti viene spiegato come assicurare una comunicazione durevole tra un client e un servizio usando il binding in coda standard in caso di implementazione del servizio WCF.

Questa sezione illustra come usare NetMsmqBinding per la comunicazione in coda tra un client WCF e un servizio WCF.

Per utilizzare l'accodamento in un servizio WCF

1. Definire un contratto di servizio utilizzando un'interfaccia contrassegnata con ServiceContractAttribute. Contrassegnare con OperationContractAttribute le operazioni che nell'interfaccia fanno parte del contratto di servizio e specificare che sono unidirezionali dal momento che non viene restituita alcuna risposta al metodo. Nel codice seguente sono contenuti un esempio di contratto di servizio semplice e la relativa definizione di operazione.

   [ServiceContract(Namespace="http://Microsoft.ServiceModel.Samples")]
   public interface IOrderProcessor
   {
       [OperationContract(IsOneWay = true)]
       void SubmitPurchaseOrder(PurchaseOrder po);
   }
   

   <ServiceContract(Namespace:="http://Microsoft.ServiceModel.Samples")> _
   Public Interface IOrderProcessor
       <OperationContract(IsOneWay:=True)> _
       Sub SubmitPurchaseOrder(ByVal po As PurchaseOrder)
   End Interface
   

2. Quando il contratto di servizio passa tipi definiti dall'utente, è necessario definire contratti dati per tali tipi. Nel codice seguente vengono illustrati due contratti dati, PurchaseOrder e PurchaseOrderLineItem. Questi due tipi definiscono i dati inviati al servizio. Si noti che le classi che definiscono questo contratto dati definiscono anche un certo numero di metodi. Questi non vengono considerati parte del contratto dati. Solo i membri che sono dichiarati con l'attributo DataMemberAttribute fanno parte del contratto dati.

   [DataContract(Namespace = "http://Microsoft.ServiceModel.Samples")]
   public class PurchaseOrder
   {
       static readonly string[] OrderStates = { "Pending", "Processed", "Shipped" };
       static Random statusIndexer = new Random(137);
   
       [DataMember]
       public string PONumber;
   
       [DataMember]
       public string CustomerId;
   
       [DataMember]
       public PurchaseOrderLineItem[] orderLineItems;
   
       public float TotalCost
       {
           get
           {
               float totalCost = 0;
               foreach (PurchaseOrderLineItem lineItem in orderLineItems)
                   totalCost += lineItem.TotalCost;
               return totalCost;
           }
       }
   
       public string Status
       {
           get
           {
               return OrderStates[statusIndexer.Next(3)];
           }
       }
   
       public override string ToString()
       {
           System.Text.StringBuilder strbuf = new System.Text.StringBuilder("Purchase Order: " + PONumber + "\n");
           strbuf.Append("\tCustomer: " + CustomerId + "\n");
           strbuf.Append("\tOrderDetails\n");
   
           foreach (PurchaseOrderLineItem lineItem in orderLineItems)
           {
               strbuf.Append("\t\t" + lineItem.ToString());
           }
   
           strbuf.Append("\tTotal cost of this order: $" + TotalCost + "\n");
           strbuf.Append("\tOrder status: " + Status + "\n");
           return strbuf.ToString();
       }
   }
   

   <DataContract(Namespace:="http://Microsoft.ServiceModel.Samples")> _
   Public Class PurchaseOrder
       Private Shared ReadOnly OrderStates() As String = {"Pending", "Processed", "Shipped"}
       Private Shared statusIndexer As New Random(137)
   
       <DataMember> _
       Public PONumber As String
   
       <DataMember> _
       Public CustomerId As String
   
       <DataMember> _
       Public orderLineItems() As PurchaseOrderLineItem
   
       Public ReadOnly Property TotalCost() As Single
           Get
               Dim totalCost_Renamed As Single = 0
               For Each lineItem In orderLineItems
                   totalCost_Renamed += lineItem.TotalCost
               Next lineItem
               Return totalCost_Renamed
           End Get
       End Property
   
       Public ReadOnly Property Status() As String
           Get
               Return OrderStates(statusIndexer.Next(3))
           End Get
       End Property
   
       Public Overrides Function ToString() As String
           Dim strbuf As New System.Text.StringBuilder("Purchase Order: " & PONumber & Constants.vbLf)
           strbuf.Append(Constants.vbTab & "Customer: " & CustomerId & Constants.vbLf)
           strbuf.Append(Constants.vbTab & "OrderDetails" & Constants.vbLf)
   
           For Each lineItem In orderLineItems
               strbuf.Append(Constants.vbTab + Constants.vbTab + lineItem.ToString())
           Next lineItem
   
           strbuf.Append(Constants.vbTab & "Total cost of this order: $" & TotalCost + Constants.vbLf)
           strbuf.Append(Constants.vbTab & "Order status: " & Status + Constants.vbLf)
           Return strbuf.ToString()
       End Function
   End Class
   

3. Implementare i metodi del contratto di servizio definiti nell'interfaccia in una classe.

   public class OrderProcessorService : IOrderProcessor
   {
       [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = true)]
       public void SubmitPurchaseOrder(PurchaseOrder po)
       {
           Orders.Add(po);
           Console.WriteLine("Processing {0} ", po);
       }
   }
   

   Public Class OrderProcessorService
       Implements IOrderProcessor
       <OperationBehavior(TransactionScopeRequired:=True, TransactionAutoComplete:=True)> _
       Public Sub SubmitPurchaseOrder(ByVal po As PurchaseOrder) Implements IOrderProcessor.SubmitPurchaseOrder
           Orders.Add(po)
           Console.WriteLine("Processing {0} ", po)
       End Sub
   End Class
   

   Si noti OperationBehaviorAttribute sul metodo SubmitPurchaseOrder. In tal modo viene specificato che questa operazione deve essere chiamata all'interno di una transazione e che la transazione viene completata automaticamente quando il metodo è stato completato.

4. Creare una coda transazionale utilizzando lo spazio dei nomi System.Messaging. È possibile scegliere di creare la coda mediante la console MMC (Microsoft Management Console) MSMQ. In tal caso, avere cura di creare una coda transazionale.

   // Create the transacted MSMQ queue if necessary.
   if (!MessageQueue.Exists(queueName))
       MessageQueue.Create(queueName, true);
   

   ' Create the transacted MSMQ queue if necessary.
   If (Not MessageQueue.Exists(queueName)) Then
       MessageQueue.Create(queueName, True)
   End If
   

5. Definire un oggetto ServiceEndpoint nella configurazione che specifichi l'indirizzo del servizio e utilizzi l'associazione NetMsmqBinding standard. Per altre informazioni sull'uso della configurazione WCF, vedere Configurazione dei servizi WCF.

6. Creare un host per il servizio OrderProcessing utilizzando l'elemento ServiceHost che legge i messaggi dalla coda e li elabora. Aprire l'host del servizio per rendere disponibile il servizio. Visualizzare un messaggio che indichi all'utente di premere un tasto qualsiasi per terminare il servizio. Chiamare ReadLine per attendere che il tasto venga premuto, quindi chiudere il servizio.

   // Create a ServiceHost for the OrderProcessorService type.
   using (ServiceHost serviceHost = new ServiceHost(typeof(OrderProcessorService)))
   {
       // Open the ServiceHost to create listeners and start listening for messages.
       serviceHost.Open();
   
       // The service can now be accessed.
       Console.WriteLine("The service is ready.");
       Console.WriteLine("Press <ENTER> to terminate service.");
       Console.WriteLine();
       Console.ReadLine();
   
       // Close the ServiceHostB to shutdown the service.
       serviceHost.Close();
   }
   

   ' Create a ServiceHost for the OrderProcessorService type.
   Using serviceHost As New ServiceHost(GetType(OrderProcessorService))
       ' Open the ServiceHost to create listeners and start listening for messages.
       serviceHost.Open()
   
       ' The service can now be accessed.
       Console.WriteLine("The service is ready.")
       Console.WriteLine("Press <ENTER> to terminate service.")
       Console.WriteLine()
       Console.ReadLine()
   
       ' Close the ServiceHostB to shutdown the service.
       serviceHost.Close()
   End Using
   

Per creare un client per il servizio in coda

1. Nell'esempio di codice riportato di seguito viene illustrato come eseguire l'applicazione host e usare lo strumento Svcutil.exe per creare il client WCF.

   svcutil http://localhost:8000/ServiceModelSamples/service  
   

2. Definire un ServiceEndpoint nella configurazione che specifichi l'indirizzo e utilizzi l'associazione NetMsmqBinding standard, come illustrato nell'esempio seguente.

3. Creare un ambito di transazione da scrivere nella coda transazionale, chiamare l'operazione SubmitPurchaseOrder e chiudere il client WCF, come illustrato nell'esempio seguente.

   //Create a transaction scope.
   using (TransactionScope scope = new TransactionScope(TransactionScopeOption.Required))
   {
       // Make a queued call to submit the purchase order.
       client.SubmitPurchaseOrder(po);
       // Complete the transaction.
       scope.Complete();
   }
   
   //Closing the client gracefully closes the connection and cleans up resources.
   client.Close();
   

   'Create a transaction scope.
   Using scope As New TransactionScope(TransactionScopeOption.Required)
       ' Make a queued call to submit the purchase order.
       client.SubmitPurchaseOrder(po)
       ' Complete the transaction.
       scope.Complete()
   End Using
   
   'Closing the client gracefully closes the connection and cleans up resources.
   client.Close()
   

Esempio

Negli esempi seguenti vengono illustrati il codice di servizio, l'applicazione host, il file App.config e il codice client inclusi per questo esempio.

// This is the service code
//  Copyright (c) Microsoft Corporation.  All Rights Reserved.

using System;
using System.ServiceModel.Channels;
using System.Configuration;
using System.Messaging;
using System.ServiceModel;
using System.Transactions;
using System.Runtime.Serialization;
using System.Collections.Generic;

namespace Microsoft.ServiceModel.Samples
{
    // Define the purchase order line item.
    [DataContract(Namespace = "http://Microsoft.ServiceModel.Samples")]
    public class PurchaseOrderLineItem
    {
        [DataMember]
        public string ProductId;

        [DataMember]
        public float UnitCost;

        [DataMember]
        public int Quantity;

        public override string ToString()
        {
            String displayString = "Order LineItem: " + Quantity + " of "  + ProductId + " @unit price: $" + UnitCost + "\n";
            return displayString;
        }

        public float TotalCost
        {
            get { return UnitCost * Quantity; }
        }
    }

    // Define the purchase order.
    [DataContract(Namespace = "http://Microsoft.ServiceModel.Samples")]
    public class PurchaseOrder
    {
        static readonly string[] OrderStates = { "Pending", "Processed", "Shipped" };
        static Random statusIndexer = new Random(137);

        [DataMember]
        public string PONumber;

        [DataMember]
        public string CustomerId;

        [DataMember]
        public PurchaseOrderLineItem[] orderLineItems;

        public float TotalCost
        {
            get
            {
                float totalCost = 0;
                foreach (PurchaseOrderLineItem lineItem in orderLineItems)
                    totalCost += lineItem.TotalCost;
                return totalCost;
            }
        }

        public string Status
        {
            get
            {
                return OrderStates[statusIndexer.Next(3)];
            }
        }

        public override string ToString()
        {
            System.Text.StringBuilder strbuf = new System.Text.StringBuilder("Purchase Order: " + PONumber + "\n");
            strbuf.Append("\tCustomer: " + CustomerId + "\n");
            strbuf.Append("\tOrderDetails\n");

            foreach (PurchaseOrderLineItem lineItem in orderLineItems)
            {
                strbuf.Append("\t\t" + lineItem.ToString());
            }

            strbuf.Append("\tTotal cost of this order: $" + TotalCost + "\n");
            strbuf.Append("\tOrder status: " + Status + "\n");
            return strbuf.ToString();
        }
    }

    // Order Processing Logic
    // Can replace with transaction-aware resource such as SQL or transacted hashtable to hold the purchase orders.
    // This example uses a non-transactional resource.
    public class Orders
    {
        static Dictionary<string, PurchaseOrder> purchaseOrders = new Dictionary<string, PurchaseOrder>();

        public static void Add(PurchaseOrder po)
        {
            purchaseOrders.Add(po.PONumber, po);
        }

        public static string GetOrderStatus(string poNumber)
        {
            PurchaseOrder po;
            if (purchaseOrders.TryGetValue(poNumber, out po))
                return po.Status;
            else
                return null;
        }

        public static void DeleteOrder(string poNumber)
        {
            if(purchaseOrders[poNumber] != null)
                purchaseOrders.Remove(poNumber);
        }
    }

    // Define a service contract.
    [ServiceContract(Namespace="http://Microsoft.ServiceModel.Samples")]
    public interface IOrderProcessor
    {
        [OperationContract(IsOneWay = true)]
        void SubmitPurchaseOrder(PurchaseOrder po);
    }

    // Service class that implements the service contract.
    // Added code to write output to the console window.
    public class OrderProcessorService : IOrderProcessor
    {
        [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = true)]
        public void SubmitPurchaseOrder(PurchaseOrder po)
        {
            Orders.Add(po);
            Console.WriteLine("Processing {0} ", po);
        }
    }
}

' This is the service code
'  Copyright (c) Microsoft Corporation.  All Rights Reserved.

Imports System.ServiceModel.Channels
Imports System.Configuration
Imports System.Messaging
Imports System.ServiceModel
Imports System.Transactions
Imports System.Runtime.Serialization
Imports System.Collections.Generic

Namespace Microsoft.ServiceModel.Samples
    ' Define the purchase order line item.
    <DataContract(Namespace:="http://Microsoft.ServiceModel.Samples")> _
    Public Class PurchaseOrderLineItem
        <DataMember> _
        Public ProductId As String

        <DataMember> _
        Public UnitCost As Single

        <DataMember> _
        Public Quantity As Integer

        Public Overrides Function ToString() As String
            Dim displayString As String = "Order LineItem: " & Quantity & " of " & ProductId & " @unit price: $" & UnitCost + Constants.vbLf
            Return displayString
        End Function

        Public ReadOnly Property TotalCost() As Single
            Get
                Return UnitCost * Quantity
            End Get
        End Property
    End Class

    ' Define the purchase order.
    <DataContract(Namespace:="http://Microsoft.ServiceModel.Samples")> _
    Public Class PurchaseOrder
        Private Shared ReadOnly OrderStates() As String = {"Pending", "Processed", "Shipped"}
        Private Shared statusIndexer As New Random(137)

        <DataMember> _
        Public PONumber As String

        <DataMember> _
        Public CustomerId As String

        <DataMember> _
        Public orderLineItems() As PurchaseOrderLineItem

        Public ReadOnly Property TotalCost() As Single
            Get
                Dim totalCost_Renamed As Single = 0
                For Each lineItem In orderLineItems
                    totalCost_Renamed += lineItem.TotalCost
                Next lineItem
                Return totalCost_Renamed
            End Get
        End Property

        Public ReadOnly Property Status() As String
            Get
                Return OrderStates(statusIndexer.Next(3))
            End Get
        End Property

        Public Overrides Function ToString() As String
            Dim strbuf As New System.Text.StringBuilder("Purchase Order: " & PONumber & Constants.vbLf)
            strbuf.Append(Constants.vbTab & "Customer: " & CustomerId & Constants.vbLf)
            strbuf.Append(Constants.vbTab & "OrderDetails" & Constants.vbLf)

            For Each lineItem In orderLineItems
                strbuf.Append(Constants.vbTab + Constants.vbTab + lineItem.ToString())
            Next lineItem

            strbuf.Append(Constants.vbTab & "Total cost of this order: $" & TotalCost + Constants.vbLf)
            strbuf.Append(Constants.vbTab & "Order status: " & Status + Constants.vbLf)
            Return strbuf.ToString()
        End Function
    End Class

    ' Order Processing Logic
    ' Can replace with transaction-aware resource such as SQL or transacted hashtable to hold the purchase orders.
    ' This example uses a non-transactional resource.
    Public Class Orders
        Private Shared purchaseOrders As New Dictionary(Of String, PurchaseOrder)()

        Public Shared Sub Add(ByVal po As PurchaseOrder)
            purchaseOrders.Add(po.PONumber, po)
        End Sub

        Public Shared Function GetOrderStatus(ByVal poNumber As String) As String
            Dim po As PurchaseOrder = Nothing
            If purchaseOrders.TryGetValue(poNumber, po) Then
                Return po.Status
            Else
                Return Nothing
            End If
        End Function

        Public Shared Sub DeleteOrder(ByVal poNumber As String)
            If purchaseOrders(poNumber) IsNot Nothing Then
                purchaseOrders.Remove(poNumber)
            End If
        End Sub
    End Class

    ' Define a service contract. 
    <ServiceContract(Namespace:="http://Microsoft.ServiceModel.Samples")> _
    Public Interface IOrderProcessor
        <OperationContract(IsOneWay:=True)> _
        Sub SubmitPurchaseOrder(ByVal po As PurchaseOrder)
    End Interface

    ' Service class that implements the service contract.
    ' Added code to write output to the console window.
    Public Class OrderProcessorService
        Implements IOrderProcessor
        <OperationBehavior(TransactionScopeRequired:=True, TransactionAutoComplete:=True)> _
        Public Sub SubmitPurchaseOrder(ByVal po As PurchaseOrder) Implements IOrderProcessor.SubmitPurchaseOrder
            Orders.Add(po)
            Console.WriteLine("Processing {0} ", po)
        End Sub
    End Class
End Namespace

// This is the hosting application.

using System;
using System.ServiceModel.Channels;
using System.Configuration;
using System.Messaging;
using System.ServiceModel;
using System.Transactions;
using System.Runtime.Serialization;
using System.Collections.Generic;

namespace Microsoft.ServiceModel.Samples
{
    class hostApp
    {
        // Host the service within this EXE console application.
        public static void Main()
        {
            // Get MSMQ queue name from appsettings in configuration.
            string queueName = ConfigurationManager.AppSettings["queueName"];

            // Create the transacted MSMQ queue if necessary.
            if (!MessageQueue.Exists(queueName))
                MessageQueue.Create(queueName, true);

            // Create a ServiceHost for the OrderProcessorService type.
            using (ServiceHost serviceHost = new ServiceHost(typeof(OrderProcessorService)))
            {
                // Open the ServiceHost to create listeners and start listening for messages.
                serviceHost.Open();

                // The service can now be accessed.
                Console.WriteLine("The service is ready.");
                Console.WriteLine("Press <ENTER> to terminate service.");
                Console.WriteLine();
                Console.ReadLine();

                // Close the ServiceHostB to shutdown the service.
                serviceHost.Close();
            }
        }
    }
}

' This is the hosting application.

Imports System.ServiceModel.Channels
Imports System.Configuration
Imports System.Messaging
Imports System.ServiceModel
Imports System.Transactions
Imports System.Runtime.Serialization
Imports System.Collections.Generic

Namespace Microsoft.ServiceModel.Samples
    Friend Class hostApp
        ' Host the service within this EXE console application.
        Public Shared Sub Main()
            ' Get MSMQ queue name from appsettings in configuration.
            Dim queueName As String = ConfigurationManager.AppSettings("queueName")

            ' Create the transacted MSMQ queue if necessary.
            If (Not MessageQueue.Exists(queueName)) Then
                MessageQueue.Create(queueName, True)
            End If

            ' Create a ServiceHost for the OrderProcessorService type.
            Using serviceHost As New ServiceHost(GetType(OrderProcessorService))
                ' Open the ServiceHost to create listeners and start listening for messages.
                serviceHost.Open()

                ' The service can now be accessed.
                Console.WriteLine("The service is ready.")
                Console.WriteLine("Press <ENTER> to terminate service.")
                Console.WriteLine()
                Console.ReadLine()

                ' Close the ServiceHostB to shutdown the service.
                serviceHost.Close()
            End Using
        End Sub
    End Class
End Namespace

// This is the client code.
//  Copyright (c) Microsoft Corporation.  All Rights Reserved.

using System;
using System.Configuration;
using System.Messaging;
using System.ServiceModel;
using System.Transactions;

namespace Microsoft.ServiceModel.Samples
{
    //The service contract is defined in generatedClient.cs, generated from the service by the svcutil tool.

    //Client implementation code.
    class Client
    {
        static void Main()
        {
            // Create a client.
            OrderProcessorClient client = new OrderProcessorClient();

            // Create the purchase order.
            PurchaseOrder po = new PurchaseOrder();
            po.CustomerId = "somecustomer.com";
            po.PONumber = Guid.NewGuid().ToString();

            PurchaseOrderLineItem lineItem1 = new PurchaseOrderLineItem();
            lineItem1.ProductId = "Blue Widget";
            lineItem1.Quantity = 54;
            lineItem1.UnitCost = 29.99F;

            PurchaseOrderLineItem lineItem2 = new PurchaseOrderLineItem();
            lineItem2.ProductId = "Red Widget";
            lineItem2.Quantity = 890;
            lineItem2.UnitCost = 45.89F;

            po.orderLineItems = new PurchaseOrderLineItem[2];
            po.orderLineItems[0] = lineItem1;
            po.orderLineItems[1] = lineItem2;

            //Create a transaction scope.
            using (TransactionScope scope = new TransactionScope(TransactionScopeOption.Required))
            {
                // Make a queued call to submit the purchase order.
                client.SubmitPurchaseOrder(po);
                // Complete the transaction.
                scope.Complete();
            }

            //Closing the client gracefully closes the connection and cleans up resources.
            client.Close();

            Console.WriteLine();
            Console.WriteLine("Press <ENTER> to terminate client.");
            Console.ReadLine();
        }
    }
}

' This is the client code.
'  Copyright (c) Microsoft Corporation.  All Rights Reserved.

Imports System.Configuration
Imports System.Messaging
Imports System.ServiceModel
Imports System.Transactions

Namespace Microsoft.ServiceModel.Samples
    'The service contract is defined in generatedClient.cs, generated from the service by the svcutil tool.

    'Client implementation code.
    Friend Class Client
        Shared Sub Main()
            ' Create a client.
            Dim client As New OrderProcessorClient()

            ' Create the purchase order.
            Dim po As New PurchaseOrder()
            po.CustomerId = "somecustomer.com"
            po.PONumber = Guid.NewGuid().ToString()

            Dim lineItem1 As New PurchaseOrderLineItem()
            lineItem1.ProductId = "Blue Widget"
            lineItem1.Quantity = 54
            lineItem1.UnitCost = 29.99F

            Dim lineItem2 As New PurchaseOrderLineItem()
            lineItem2.ProductId = "Red Widget"
            lineItem2.Quantity = 890
            lineItem2.UnitCost = 45.89F

            po.orderLineItems = New PurchaseOrderLineItem(1) {}
            po.orderLineItems(0) = lineItem1
            po.orderLineItems(1) = lineItem2

            'Create a transaction scope.
            Using scope As New TransactionScope(TransactionScopeOption.Required)
                ' Make a queued call to submit the purchase order.
                client.SubmitPurchaseOrder(po)
                ' Complete the transaction.
                scope.Complete()
            End Using

            'Closing the client gracefully closes the connection and cleans up resources.
            client.Close()

            Console.WriteLine()
            Console.WriteLine("Press <ENTER> to terminate client.")
            Console.ReadLine()
        End Sub
    End Class
End Namespace

Vedi anche

• NetMsmqBinding
• Associazioni MSMQ transazionali
• Accodamento in WCF
• Procedura: Scambiare messaggi con endpoint WCF e con applicazioni di accodamento messaggi
• Da Windows Communication Foundation a Accodamento messaggi
• Installazione accodamento messaggi (MSMQ)
• Accodamento messaggi in Windows Communication Foundation
• Sicurezza dei messaggi nell'accodamento messaggi