在工作階段中群組佇列訊息

發行項
05/22/2023

Windows Communication Foundation (WCF) 提供工作階段，可讓您將一組相關的訊息分組，以透過單一接收應用程式進行處理。本身是工作階段一部分的訊息，也必須是屬於相同的異動。由於所有訊息都屬於相同的異動，所以如果有任何一個訊息無法進行處理，就會回復整個工作階段。工作階段對於寄不出的信件佇列與有害佇列，會採取類似行為。針對工作階段在佇列繫結上設定的存留時間 (TTL) 屬性會完整地套用到工作階段。如果工作階段中只有部分訊息在 TTL 到期之前傳送出去，則整個工作階段將置於寄不出的信件佇列中。同樣地，當工作階段中的訊息無法從應用程式佇列傳送到應用程式的話，則整個工作階段將置於有害佇列 (如果有的話)。

訊息群組範例

舉例來說，當您將訂單處理應用程式實作為 WCF 服務時，會發現將訊息分組非常實用。例如，用戶端將訂單提交給包含一些項目的應用程式。接著，用戶端針對每個項目向服務進行呼叫，以便分別傳送每個訊息。情況可能變成：伺服器 A 收到第一個項目，而伺服器 B 則收到第二個項目。每次新增一個項目時，負責處理該項目的伺服器就必須找到適當的順序，並將該項目附加上去，如此一來就會變得很沒效率。就算只有一部伺服器在處理所有要求，效率仍舊可能不彰，因為伺服器必須追蹤目前正在處理的所有訂單，並判斷新增的項目歸屬哪個訂單。將單一訂單上的所有要求加以群組可大幅簡化此類應用程式的實作。用戶端應用程式將單一訂單的所有項目傳送到工作階段，這樣一來，當服務處理訂單時，就會立即處理整個工作階段。 \

程序

若要設定服務合約使用工作階段

定義需要工作階段的服務合約。若要這麼做，使用 ServiceContractAttribute 屬性並指定：
```
SessionMode=SessionMode.Required  
```
將合約中的作業標示為單向，因為這些方法無法傳回任何東西。若要這麼做，使用 OperationContractAttribute 屬性並指定：
```
[OperationContract(IsOneWay = true)]  
```
實作服務合約並指定 InstanceContextMode 的 InstanceContextMode.PerSession。這樣只會針對每個工作階段產生服務一次。
```
[ServiceBehavior(InstanceContextMode=InstanceContextMode.PerSession)]  
```
每個服務作業都需要一筆異動。請使用 OperationBehaviorAttribute 屬性來加以指定。完成異動的作業應該同時將 TransactionAutoComplete 設為 true。
```
[OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = true)]
```
設定使用系統提供之 NetMsmqBinding 繫結的端點。
使用 System.Messaging 來建立交易式佇列。您也可以使用訊息佇列 (MSMQ) 或 MMC 來建立佇列。如果您要這麼做，請建立異動式佇列。
請使用 ServiceHost 來建立服務的服務主機。
開啟服務主機來提供服務。
關閉服務主機。

若要設定用戶端

建立異動範圍以寫入異動式佇列。
使用 ServiceModel 中繼資料公用程式工具 (Svcutil.exe) 來建立 WCF 用戶端。
下訂單。
關閉 WCF 用戶端。

範例

描述

下列範例提供 IProcessOrder 服務以及使用此服務之用戶端的程式碼。其說明 WCF 如何使用佇列工作階段來提供分組行為。

服務的程式碼

// Service Code:

using System;

using System.ServiceModel.Channels;
using System.Configuration;
using System.Messaging;
using System.ServiceModel;
using System.Transactions;
using System.Text;
using System.Collections.Generic;

namespace Microsoft.ServiceModel.Samples
{
    // Define a service contract.
    [ServiceContract(Namespace = "http://Microsoft.ServiceModel.Samples", SessionMode=SessionMode.Required)]
    public interface IOrderTaker
    {
        [OperationContract(IsOneWay = true)]
        void OpenPurchaseOrder(string customerId);

        [OperationContract(IsOneWay = true)]
        void AddProductLineItem(string productId, int quantity);

        [OperationContract(IsOneWay = true)]
        void EndPurchaseOrder();
    }

    // Define the Purchase Order Line Item
    public class PurchaseOrderLineItem
    {
        static Random r = new Random(137);

        string ProductId;
        float UnitCost;
        int Quantity;

        public PurchaseOrderLineItem(string productId, int quantity)
        {
            this.ProductId = productId;
            this.Quantity = quantity;
            this.UnitCost = r.Next(10000);
        }

        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 Purchase Order
    public class PurchaseOrder
    {
        string PONumber;
        string CustomerId;
        LinkedList<PurchaseOrderLineItem> orderLineItems = new LinkedList<PurchaseOrderLineItem>();

        public PurchaseOrder(string customerId)
        {
            this.CustomerId = customerId;
            this.PONumber = Guid.NewGuid().ToString();
        }

        public void AddProductLineItem(string productId, int quantity)
        {
            orderLineItems.AddLast(new PurchaseOrderLineItem(productId, quantity));
        }

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

        public string Status
        {
            get
            {
                return "Pending";
            }
        }

        public override string ToString()
        {
            StringBuilder strbuf = new 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();
        }
    }

    // Service class which implements the service contract.
    // Added code to write output to the console window
    [ServiceBehavior(InstanceContextMode=InstanceContextMode.PerSession)]
    public class OrderTakerService : IOrderTaker
    {
        PurchaseOrder po;

        [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = false)]
        public void OpenPurchaseOrder(string customerId)
        {
            Console.WriteLine("Creating purchase order");
            po = new PurchaseOrder(customerId);
        }

        [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = false)]
        public void AddProductLineItem(string productId, int quantity)
        {
            po.AddProductLineItem(productId, quantity);
            Console.WriteLine("Product " + productId + " quantity " + quantity + " added to purchase order");
        }

        [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = true)]
        public void EndPurchaseOrder()
        {
            Console.WriteLine("Purchase Order Completed");
            Console.WriteLine();
            Console.WriteLine(po.ToString());
        }

        // Host the service within this EXE console application.
        public static void Main()
        {
            // Get MSMQ queue name from app settings in configuration
            string queueName = ConfigurationManager.AppSettings["queueName"];

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

            // Get the base address that is used to listen for WS-MetaDataExchange requests
            string baseAddress = ConfigurationManager.AppSettings["baseAddress"];

            // Create a ServiceHost for the OrderTakerService type.
            using (ServiceHost serviceHost = new ServiceHost(typeof(OrderTakerService), new Uri(baseAddress)))
            {
                // Open the ServiceHostBase 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 ServiceHostBase to shutdown the service.
                serviceHost.Close();
            }
        }
    }
}

' Service Code:

Imports System.ServiceModel.Channels
Imports System.Configuration
Imports System.Messaging
Imports System.ServiceModel
Imports System.Transactions
Imports System.Text
Imports System.Collections.Generic

Namespace Microsoft.ServiceModel.Samples
    ' Define a service contract. 
    <ServiceContract(Namespace:="http://Microsoft.ServiceModel.Samples", SessionMode:=SessionMode.Required)> _
    Public Interface IOrderTaker
        <OperationContract(IsOneWay:=True)> _
        Sub OpenPurchaseOrder(ByVal customerId As String)

        <OperationContract(IsOneWay:=True)> _
        Sub AddProductLineItem(ByVal productId As String, ByVal quantity As Integer)

        <OperationContract(IsOneWay:=True)> _
        Sub EndPurchaseOrder()
    End Interface

    ' Define the Purchase Order Line Item
    Public Class PurchaseOrderLineItem
        Private Shared r As New Random(137)

        Private ProductId As String
        Private UnitCost As Single
        Private Quantity As Integer

        Public Sub New(ByVal productId As String, ByVal quantity As Integer)
            Me.ProductId = productId
            Me.Quantity = quantity
            Me.UnitCost = r.Next(10000)
        End Sub

        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 Purchase Order
    Public Class PurchaseOrder
        Private PONumber As String
        Private CustomerId As String
        Private orderLineItems As New LinkedList(Of PurchaseOrderLineItem)()

        Public Sub New(ByVal customerId As String)
            Me.CustomerId = customerId
            Me.PONumber = Guid.NewGuid().ToString()
        End Sub

        Public Sub AddProductLineItem(ByVal productId As String, ByVal quantity As Integer)
            orderLineItems.AddLast(New PurchaseOrderLineItem(productId, quantity))
        End Sub

        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 "Pending"
            End Get
        End Property

        Public Overrides Function ToString() As String
            Dim strbuf As New 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


    ' Service class which implements the service contract.
    ' Added code to write output to the console window
    <ServiceBehavior(InstanceContextMode:=InstanceContextMode.PerSession)> _
    Public Class OrderTakerService
        Implements IOrderTaker
        Private po As PurchaseOrder

        <OperationBehavior(TransactionScopeRequired:=True, TransactionAutoComplete:=False)> _
        Public Sub OpenPurchaseOrder(ByVal customerId As String) Implements IOrderTaker.OpenPurchaseOrder
            Console.WriteLine("Creating purchase order")
            po = New PurchaseOrder(customerId)
        End Sub

        <OperationBehavior(TransactionScopeRequired:=True, TransactionAutoComplete:=False)> _
        Public Sub AddProductLineItem(ByVal productId As String, ByVal quantity As Integer) Implements IOrderTaker.AddProductLineItem
            po.AddProductLineItem(productId, quantity)
            Console.WriteLine("Product " & productId & " quantity " & quantity & " added to purchase order")
        End Sub

        <OperationBehavior(TransactionScopeRequired:=True, TransactionAutoComplete:=True)> _
        Public Sub EndPurchaseOrder() Implements IOrderTaker.EndPurchaseOrder
            Console.WriteLine("Purchase Order Completed")
            Console.WriteLine()
            Console.WriteLine(po.ToString())
        End Sub


        ' Host the service within this EXE console application.
        Public Shared Sub Main()
            ' Get MSMQ queue name from app settings 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


            ' Get the base address that is used to listen for WS-MetaDataExchange requests
            Dim baseAddress As String = ConfigurationManager.AppSettings("baseAddress")

            ' Create a ServiceHost for the OrderTakerService type.
            Using serviceHost As New ServiceHost(GetType(OrderTakerService), New Uri(baseAddress))
                ' Open the ServiceHostBase 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 ServiceHostBase to shutdown the service.
                serviceHost.Close()
            End Using
        End Sub
    End Class
End Namespace

用戶端的程式碼

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

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

    //Client implementation code.
    class Client
    {
        static void Main()
        {
            //Create a transaction scope.
            using (TransactionScope scope = new TransactionScope(TransactionScopeOption.Required))
            {
                // Create a proxy with given client endpoint configuration
                OrderTakerClient client = new OrderTakerClient("OrderTakerEndpoint");
                try
                {
                    // Open a purchase order
                    client.OpenPurchaseOrder("somecustomer.com");
                    Console.WriteLine("Purchase Order created");

                    // Add product line items
                    Console.WriteLine("Adding 10 quantities of blue widget");
                    client.AddProductLineItem("Blue Widget", 10);

                    Console.WriteLine("Adding 23 quantities of red widget");
                    client.AddProductLineItem("Red Widget", 23);

                    // Close the purchase order
                    Console.WriteLine("Closing the purchase order");
                    client.EndPurchaseOrder();
                    client.Close();
                }
                catch (CommunicationException ex)
                {
                    client.Abort();
                }
                // Complete the transaction.
                scope.Complete();
            }
            Console.WriteLine();
            Console.WriteLine("Press <ENTER> to terminate client.");
            Console.ReadLine();
        }
    }
}


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

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

    'Client implementation code.
    Friend Class Client
        Shared Sub Main()
            'Create a transaction scope.
            Using scope As New TransactionScope(TransactionScopeOption.Required)
                ' Create a proxy with given client endpoint configuration
                Dim client As New OrderTakerClient("OrderTakerEndpoint")
                Try
                    ' Open a purchase order
                    client.OpenPurchaseOrder("somecustomer.com")
                    Console.WriteLine("Purchase Order created")

                    ' Add product line items
                    Console.WriteLine("Adding 10 quantities of blue widget")
                    client.AddProductLineItem("Blue Widget", 10)

                    Console.WriteLine("Adding 23 quantities of red widget")
                    client.AddProductLineItem("Red Widget", 23)

                    ' Close the purchase order
                    Console.WriteLine("Closing the purchase order")
                    client.EndPurchaseOrder()
                    client.Close()
                Catch ex As CommunicationException
                    client.Abort()
                End Try
                ' Complete the transaction.
                scope.Complete()
            End Using
            Console.WriteLine()
            Console.WriteLine("Press <ENTER> to terminate client.")
            Console.ReadLine()
        End Sub
    End Class
End Namespace

共用方式為