作法：建立基本 RSS 摘要

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05/22/2023

Windows Communication Foundation (WCF) 可讓您建立會公開新聞訂閱摘要的服務。本主題討論如何建立可公開 RSS 新聞訂閱摘要的新聞訂閱服務。

若要建立基本新聞訂閱服務

使用以 WebGetAttribute 屬性標記的介面來定義服務合約。每個公開為新聞訂閱摘要的作業都應該傳回 Rss20FeedFormatter 物件。
```
[ServiceContract]
public interface IBlog
{
    [OperationContract]
    [WebGet]
    Rss20FeedFormatter GetBlog();
}
```
```
<ServiceContract()> _
Public Interface IBlog
    <OperationContract()> _
    <WebGet> _
    Function GetBlog() As Rss20FeedFormatter
End Interface
```
注意

所有套用 WebGetAttribute 屬性的服務作業都會對應至 HTTP GET 要求。若要將您的作業對應至不同的 HTTP 方法，請改用 WebInvokeAttribute。如需詳細資訊，請參閱如何：建立基本 WCF Web HTTP 服務。

實作服務合約。

public class BlogService : IBlog
{
    public Rss20FeedFormatter GetBlog()
    {
        SyndicationFeed feed = new SyndicationFeed("My Blog Feed", "This is a test feed", new Uri("http://SomeURI"));
        feed.Authors.Add(new SyndicationPerson("someone@microsoft.com"));
        feed.Categories.Add(new SyndicationCategory("How To Sample Code"));
        feed.Description = new TextSyndicationContent("This is a how to sample that demonstrates how to expose a feed using RSS with WCF");

        SyndicationItem item1 = new SyndicationItem(
            "Item One",
            "This is the content for item one",
            new Uri("http://localhost/Content/One"),
            "ItemOneID",
            DateTime.Now);

        SyndicationItem item2 = new SyndicationItem(
            "Item Two",
            "This is the content for item two",
            new Uri("http://localhost/Content/Two"),
            "ItemTwoID",
            DateTime.Now);

        SyndicationItem item3 = new SyndicationItem(
            "Item Three",
            "This is the content for item three",
            new Uri("http://localhost/Content/three"),
            "ItemThreeID",
            DateTime.Now);

        List<SyndicationItem> items = new List<SyndicationItem>();

        items.Add(item1);
        items.Add(item2);
        items.Add(item3);

        feed.Items = items;

        return new Rss20FeedFormatter(feed);
    }
}

Public Class BlogService
    Implements IBlog

    Public Function GetBlog() As Rss20FeedFormatter Implements IBlog.GetBlog
        Dim feed As SyndicationFeed = New SyndicationFeed("My Blog Feed", "This is a test feed", New Uri("http://SomeURI"))
        feed.Authors.Add(New SyndicationPerson("someone@microsoft.com"))
        feed.Categories.Add(New SyndicationCategory("How To Sample Code"))
        feed.Description = New TextSyndicationContent("This is a how to sample that demonstrates how to expose a feed using RSS with WCF")

        Dim item1 As SyndicationItem = New SyndicationItem( _
            "Item One", _
            "This is the content for item one", _
            New Uri("http://localhost/Content/One"), _
            "ItemOneID", _
            DateTime.Now)

        Dim item2 As SyndicationItem = New SyndicationItem( _
            "Item Two", _
            "This is the content for item two", _
            New Uri("http://localhost/Content/Two"), _
            "ItemTwoID", _
            DateTime.Now)

        Dim item3 As SyndicationItem = New SyndicationItem( _
            "Item Three", _
            "This is the content for item three", _
            New Uri("http://localhost/Content/three"), _
            "ItemThreeID", _
            DateTime.Now)

        Dim items As New List(Of SyndicationItem)()

        items.Add(item1)
        items.Add(item2)
        items.Add(item3)

        feed.Items = items

        Return New Rss20FeedFormatter(feed)
    End Function
End Class

建立 SyndicationFeed 物件並新增作者、分類和描述。

SyndicationFeed feed = new SyndicationFeed("My Blog Feed", "This is a test feed", new Uri("http://SomeURI"));
feed.Authors.Add(new SyndicationPerson("someone@microsoft.com"));
feed.Categories.Add(new SyndicationCategory("How To Sample Code"));
feed.Description = new TextSyndicationContent("This is a how to sample that demonstrates how to expose a feed using RSS with WCF");

Dim feed As SyndicationFeed = New SyndicationFeed("My Blog Feed", "This is a test feed", New Uri("http://SomeURI"))
feed.Authors.Add(New SyndicationPerson("someone@microsoft.com"))
feed.Categories.Add(New SyndicationCategory("How To Sample Code"))
feed.Description = New TextSyndicationContent("This is a how to sample that demonstrates how to expose a feed using RSS with WCF")

建立幾個 SyndicationItem 物件。

SyndicationItem item1 = new SyndicationItem(
    "Item One",
    "This is the content for item one",
    new Uri("http://localhost/Content/One"),
    "ItemOneID",
    DateTime.Now);

SyndicationItem item2 = new SyndicationItem(
    "Item Two",
    "This is the content for item two",
    new Uri("http://localhost/Content/Two"),
    "ItemTwoID",
    DateTime.Now);

SyndicationItem item3 = new SyndicationItem(
    "Item Three",
    "This is the content for item three",
    new Uri("http://localhost/Content/three"),
    "ItemThreeID",
    DateTime.Now);

Dim item1 As SyndicationItem = New SyndicationItem( _
    "Item One", _
    "This is the content for item one", _
    New Uri("http://localhost/Content/One"), _
    "ItemOneID", _
    DateTime.Now)

Dim item2 As SyndicationItem = New SyndicationItem( _
    "Item Two", _
    "This is the content for item two", _
    New Uri("http://localhost/Content/Two"), _
    "ItemTwoID", _
    DateTime.Now)

Dim item3 As SyndicationItem = New SyndicationItem( _
    "Item Three", _
    "This is the content for item three", _
    New Uri("http://localhost/Content/three"), _
    "ItemThreeID", _
    DateTime.Now)

將 SyndicationItem 加入至摘要。

List<SyndicationItem> items = new List<SyndicationItem>();

items.Add(item1);
items.Add(item2);
items.Add(item3);

feed.Items = items;

Dim items As New List(Of SyndicationItem)()

items.Add(item1)
items.Add(item2)
items.Add(item3)

feed.Items = items

傳回摘要。

return new Rss20FeedFormatter(feed);

Return New Rss20FeedFormatter(feed)

若要裝載服務

建立 WebServiceHost 物件。

Uri baseAddress = new Uri("http://localhost:8000/BlogService");
WebServiceHost svcHost = new WebServiceHost(typeof(BlogService), baseAddress);

Dim baseAddress As New Uri("http://localhost:8000/BlogService")
Dim svcHost As New WebServiceHost(GetType(BlogService), baseAddress)

開啟服務主機並等候使用者按下 ENTER。

svcHost.Open();
Console.WriteLine("Service is running");

XmlReader reader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog");
SyndicationFeed feed = SyndicationFeed.Load(reader);
Console.WriteLine(feed.Title.Text);
Console.WriteLine("Items:");
foreach (SyndicationItem item in feed.Items)
{
    Console.WriteLine("Title: {0}", item.Title.Text);
    Console.WriteLine("Summary: {0}", ((TextSyndicationContent)item.Summary).Text);
}
Console.WriteLine("Press <enter> to quit...");
Console.ReadLine();
svcHost.Close();

svcHost.Open()
Console.WriteLine("Service is running")

Dim reader As XmlReader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog")
Dim feed As SyndicationFeed = SyndicationFeed.Load(reader)
Console.WriteLine(feed.Title.Text)
Console.WriteLine("Items:")
For Each item As SyndicationItem In feed.Items
    Console.WriteLine("Title: {0}", item.Title.Text)
    Console.WriteLine("Summary: {0}", item.Summary.Text)
Next
Console.WriteLine("Press <enter> to quit...")
Console.ReadLine()
svcHost.Close()

若要使用 HTTP GET 呼叫 GetBlog()

在網頁瀏覽器中，瀏覽至下列 URL：http://localhost:8000/BlogService/GetBlog。 URL 包含服務的基底位址 (http://localhost:8000/BlogService)、端點的相對位址，以及要呼叫的服務作業。

若要從程式碼呼叫 GetBlog()

使用基底位址與您要呼叫的方法建立 XmlReader。

Uri serviceAddress = new Uri("http://localhost:8000/BlogService/GetBlog");

Dim serviceAddress As New Uri("http://localhost:8000/BlogService/GetBlog")

呼叫靜態 Load(XmlReader) 方法，傳入剛才建立的 XmlReader。

XmlReader reader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog");
SyndicationFeed feed = SyndicationFeed.Load(reader);

Dim reader As XmlReader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog")
Dim feed As SyndicationFeed = SyndicationFeed.Load(reader)

這會叫用服務作業，並在新的 SyndicationFeed 中填入服務作業所傳回的格式器。

存取摘要物件。

Console.WriteLine(feed.Title.Text);
Console.WriteLine("Items:");
foreach (SyndicationItem item in feed.Items)
{
    Console.WriteLine("Title: {0}", item.Title.Text);
    Console.WriteLine("Summary: {0}", ((TextSyndicationContent)item.Summary).Text);
}

Console.WriteLine(feed.Title.Text)
Console.WriteLine("Items:")
For Each item As SyndicationItem In feed.Items
    Console.WriteLine("Title:  {0}", item.Title.Text)
    Console.WriteLine("Summary:  {0}", item.Summary.Text)
Next

範例

以下是這個範例的完整程式碼清單。

using System;
using System.Xml;
using System.ServiceModel;
using System.ServiceModel.Description;
using System.ServiceModel.Syndication;
using System.ServiceModel.Web;
using System.Collections.ObjectModel;
using System.Collections.Generic;

namespace Service
{
    [ServiceContract]
    public interface IBlog
    {
        [OperationContract]
        [WebGet]
        Rss20FeedFormatter GetBlog();
    }

    public class BlogService : IBlog
    {
        public Rss20FeedFormatter GetBlog()
        {
            SyndicationFeed feed = new SyndicationFeed("My Blog Feed", "This is a test feed", new Uri("http://SomeURI"));
            feed.Authors.Add(new SyndicationPerson("someone@microsoft.com"));
            feed.Categories.Add(new SyndicationCategory("How To Sample Code"));
            feed.Description = new TextSyndicationContent("This is a how to sample that demonstrates how to expose a feed using RSS with WCF");

            SyndicationItem item1 = new SyndicationItem(
                "Item One",
                "This is the content for item one",
                new Uri("http://localhost/Content/One"),
                "ItemOneID",
                DateTime.Now);

            SyndicationItem item2 = new SyndicationItem(
                "Item Two",
                "This is the content for item two",
                new Uri("http://localhost/Content/Two"),
                "ItemTwoID",
                DateTime.Now);

            SyndicationItem item3 = new SyndicationItem(
                "Item Three",
                "This is the content for item three",
                new Uri("http://localhost/Content/three"),
                "ItemThreeID",
                DateTime.Now);

            List<SyndicationItem> items = new List<SyndicationItem>();

            items.Add(item1);
            items.Add(item2);
            items.Add(item3);

            feed.Items = items;

            return new Rss20FeedFormatter(feed);
        }
    }

    public class Host
    {
        static void Main(string[] args)
        {
            Uri baseAddress = new Uri("http://localhost:8000/BlogService");
            WebServiceHost svcHost = new WebServiceHost(typeof(BlogService), baseAddress);

            try
            {
                svcHost.Open();
                Console.WriteLine("Service is running");

                XmlReader reader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog");
                SyndicationFeed feed = SyndicationFeed.Load(reader);
                Console.WriteLine(feed.Title.Text);
                Console.WriteLine("Items:");
                foreach (SyndicationItem item in feed.Items)
                {
                    Console.WriteLine("Title: {0}", item.Title.Text);
                    Console.WriteLine("Summary: {0}", ((TextSyndicationContent)item.Summary).Text);
                }
                Console.WriteLine("Press <enter> to quit...");
                Console.ReadLine();
                svcHost.Close();
            }
            catch (CommunicationException ce)
            {
                Console.WriteLine("An exception occurred: {0}", ce.Message);
                svcHost.Abort();
            }
        }
    }
}

Imports System.Xml
Imports System.ServiceModel
Imports System.ServiceModel.Description
Imports System.ServiceModel.Syndication
Imports System.ServiceModel.Web
Imports System.Collections.ObjectModel
Imports System.Collections.Generic

<ServiceContract()> _
Public Interface IBlog
    <OperationContract()> _
    <WebGet> _
    Function GetBlog() As Rss20FeedFormatter
End Interface

Public Class BlogService
    Implements IBlog

    Public Function GetBlog() As Rss20FeedFormatter Implements IBlog.GetBlog
        Dim feed As SyndicationFeed = New SyndicationFeed("My Blog Feed", "This is a test feed", New Uri("http://SomeURI"))
        feed.Authors.Add(New SyndicationPerson("someone@microsoft.com"))
        feed.Categories.Add(New SyndicationCategory("How To Sample Code"))
        feed.Description = New TextSyndicationContent("This is a how to sample that demonstrates how to expose a feed using RSS with WCF")

        Dim item1 As SyndicationItem = New SyndicationItem( _
            "Item One", _
            "This is the content for item one", _
            New Uri("http://localhost/Content/One"), _
            "ItemOneID", _
            DateTime.Now)

        Dim item2 As SyndicationItem = New SyndicationItem( _
            "Item Two", _
            "This is the content for item two", _
            New Uri("http://localhost/Content/Two"), _
            "ItemTwoID", _
            DateTime.Now)

        Dim item3 As SyndicationItem = New SyndicationItem( _
            "Item Three", _
            "This is the content for item three", _
            New Uri("http://localhost/Content/three"), _
            "ItemThreeID", _
            DateTime.Now)

        Dim items As New List(Of SyndicationItem)()

        items.Add(item1)
        items.Add(item2)
        items.Add(item3)

        feed.Items = items

        Return New Rss20FeedFormatter(feed)
    End Function
End Class


Module Program

    Sub Main()
        Dim baseAddress As New Uri("http://localhost:8000/BlogService")
        Dim svcHost As New WebServiceHost(GetType(BlogService), baseAddress)

        Try
            svcHost.Open()
            Console.WriteLine("Service is running")

            Dim reader As XmlReader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog")
            Dim feed As SyndicationFeed = SyndicationFeed.Load(reader)
            Console.WriteLine(feed.Title.Text)
            Console.WriteLine("Items:")
            For Each item As SyndicationItem In feed.Items
                Console.WriteLine("Title: {0}", item.Title.Text)
                Console.WriteLine("Summary: {0}", item.Summary.Text)
            Next
            Console.WriteLine("Press <enter> to quit...")
            Console.ReadLine()
            svcHost.Close()
        Catch ce As CommunicationException
            Console.WriteLine("An exception occurred: {0}", ce.Message)
            svcHost.Abort()
        End Try
    End Sub
End Module

編譯程式碼

在編譯先前的程式碼時，請參考 System.ServiceModel.dll 和 System.ServiceModel.Web.dll。

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