Creación de una fuente RSS básica

Windows Communication Foundation (WCF) le permite crear un servicio que exponga una fuente de distribución. En este tema se discute cómo crear un servicio de distribución que exponga una fuente de distribución RSS.

Creación de un servicio de distribución básico

1. Defina un contrato de servicios utilizando una interfaz marcada con el atributo WebGetAttribute. Cada operación que se expone como una fuente de distribución debería devolver un objeto Rss20FeedFormatter.

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

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

   Nota:
   Todas las operaciones de servicio que apliquen el atributo WebGetAttribute se asignan a solicitudes GET de HTTP. Para asignar su operación a un método HTTP diferente, utilice en su lugar WebInvokeAttribute. Para obtener más información, vea Cómo: Crear un servicio básico web HTTP de WCF.

2. Implemente el contrato de servicios.

   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("https://localhost/Content/One"), _
               "ItemOneID", _
               DateTime.Now)
   
           Dim item2 As SyndicationItem = New SyndicationItem( _
               "Item Two", _
               "This is the content for item two", _
               New Uri("https://localhost/Content/Two"), _
               "ItemTwoID", _
               DateTime.Now)
   
           Dim item3 As SyndicationItem = New SyndicationItem( _
               "Item Three", _
               "This is the content for item three", _
               New Uri("https://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
   

   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("https://localhost/Content/One"),
               "ItemOneID",
               DateTime.Now);
   
           SyndicationItem item2 = new SyndicationItem(
               "Item Two",
               "This is the content for item two",
               new Uri("https://localhost/Content/Two"),
               "ItemTwoID",
               DateTime.Now);
   
           SyndicationItem item3 = new SyndicationItem(
               "Item Three",
               "This is the content for item three",
               new Uri("https://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);
       }
   }
   

3. Cree un objeto SyndicationFeed y agregue un autor, categoría y descripción.

   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")
   

   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");
   

4. Cree varios objetos SyndicationItem.

   Dim item1 As SyndicationItem = New SyndicationItem( _
       "Item One", _
       "This is the content for item one", _
       New Uri("https://localhost/Content/One"), _
       "ItemOneID", _
       DateTime.Now)
   
   Dim item2 As SyndicationItem = New SyndicationItem( _
       "Item Two", _
       "This is the content for item two", _
       New Uri("https://localhost/Content/Two"), _
       "ItemTwoID", _
       DateTime.Now)
   
   Dim item3 As SyndicationItem = New SyndicationItem( _
       "Item Three", _
       "This is the content for item three", _
       New Uri("https://localhost/Content/three"), _
       "ItemThreeID", _
       DateTime.Now)
   

   SyndicationItem item1 = new SyndicationItem(
       "Item One",
       "This is the content for item one",
       new Uri("https://localhost/Content/One"),
       "ItemOneID",
       DateTime.Now);
   
   SyndicationItem item2 = new SyndicationItem(
       "Item Two",
       "This is the content for item two",
       new Uri("https://localhost/Content/Two"),
       "ItemTwoID",
       DateTime.Now);
   
   SyndicationItem item3 = new SyndicationItem(
       "Item Three",
       "This is the content for item three",
       new Uri("https://localhost/Content/three"),
       "ItemThreeID",
       DateTime.Now);
   

5. Agregue el SyndicationItem a la fuente.

   Dim items As New List(Of SyndicationItem)()
   
   items.Add(item1)
   items.Add(item2)
   items.Add(item3)
   
   feed.Items = items
   

   List<SyndicationItem> items = new List<SyndicationItem>();
   
   items.Add(item1);
   items.Add(item2);
   items.Add(item3);
   
   feed.Items = items;
   

6. Devuelva la fuente.

   Return New Rss20FeedFormatter(feed)
   

   return new Rss20FeedFormatter(feed);
   

Hospedaje de un servicio

1. Cree un objeto WebServiceHost.

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

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

2. Abra el host del servicio y espere hasta que el usuario presione Entrar.

   svcHost.Open()
   Console.WriteLine("Service is running")
   
   Dim reader As XmlReader = XmlReader.Create("https://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()
   

   svcHost.Open();
   Console.WriteLine("Service is running");
   
   XmlReader reader = XmlReader.Create("https://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();
   

Realización de llamadas a GetBlog() mediante HTTP GET

1. Abra Internet Explorer, escriba la siguiente URL y presione Entrar: https://localhost:8000/BlogService/GetBlog La URL contiene la dirección base del servicio (https://localhost:8000/BlogService), la dirección relativa del extremo y la operación del servicio que se va a llamar.

Llamar a GetBlog() mediante código

1. Cree un XmlReader con la dirección base y el método al que está llamando.

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

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

2. Llame al método estático Load, pasando el XmlReader que acaba de crear.

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

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

   Esto invoca la operación de servicio y rellena una nueva SyndicationFeed con el formateador devuelto desde la operación del servicio.

3. Obtenga acceso al objeto de fuente.

   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(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);
   }
   

Ejemplo

A continuación, se muestra una lista de código completa en este ejemplo.

Imports System
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("https://localhost/Content/One"), _
            "ItemOneID", _
            DateTime.Now)

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

        Dim item3 As SyndicationItem = New SyndicationItem( _
            "Item Three", _
            "This is the content for item three", _
            New Uri("https://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("https://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("https://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

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("https://localhost/Content/One"),
                "ItemOneID",
                DateTime.Now);

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

            SyndicationItem item3 = new SyndicationItem(
                "Item Three",
                "This is the content for item three",
                new Uri("https://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("https://localhost:8000/BlogService");
            WebServiceHost svcHost = new WebServiceHost(typeof(BlogService), baseAddress);

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

                XmlReader reader = XmlReader.Create("https://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();
            }
        }
    }
}

Compilar el código

Al compilar el código anterior, haga referencia a System.ServiceModel.dll y System.ServiceModel.Web.dll.

Vea también

Referencia

WebHttpBinding
WebGetAttribute