Postupy: Zveřejnění informačního kanálu ve formátu Atom i RSS

Článek
03/02/2024

Windows Communication Foundation (WCF) umožňuje vytvořit službu, která zveřejňuje kanál syndikace. Toto téma popisuje, jak vytvořit službu syndikace, která zveřejňuje kanál syndikace pomocí Atomu 1.0 i RSS 2.0. Tato služba zveřejňuje jeden koncový bod, který může vrátit jeden formát syndikace. Pro zjednodušení je služba použitá v této ukázce hostovaná sama. V produkčním prostředí by služba tohoto typu byla hostována ve službě IIS nebo WAS. Další informace o různých možnostech hostování WCF naleznete v tématu Hostování.

Vytvoření základní služby syndikace

Definujte kontrakt služby pomocí rozhraní označeného atributem WebGetAttribute . Každá operace, která je vystavena jako kanál syndikace, vrátí SyndicationFeedFormatter objekt. Poznamenejte si parametry pro .WebGetAttribute UriTemplate určuje adresu URL použitou k vyvolání této operace služby. Řetězec pro tento parametr obsahuje literály a proměnnou ve složených závorkách ({format}). Tato proměnná odpovídá parametru format operace služby. Další informace najdete na webu UriTemplate. BodyStyle ovlivňuje způsob zápisu zpráv, které tato operace služby odesílá a přijímá. Bare určuje, že data odesílaná do a z této operace služby nejsou zabalena elementy XML definovanými infrastrukturou. Další informace najdete na webu WebMessageBodyStyle.
```
[ServiceContract]
[ServiceKnownType(typeof(Atom10FeedFormatter))]
[ServiceKnownType(typeof(Rss20FeedFormatter))]
public interface IBlog
{
    [OperationContract]
    [WebGet(UriTemplate = "GetBlog?format={format}")]
    SyndicationFeedFormatter GetBlog(string format);
}
```
```
<ServiceContract()> _
<ServiceKnownType(GetType(Atom10FeedFormatter))> _
<ServiceKnownType(GetType(Rss20FeedFormatter))> _
Public Interface IBlog
    <OperationContract()> _
    <WebGet(UriTemplate:="GetBlog?format={format}")> _
    Function GetBlog(ByVal format As String) As SyndicationFeedFormatter
End Interface
```
Poznámka:

ServiceKnownTypeAttribute Slouží k určení typů vrácených operacemi služby v tomto rozhraní.

Implementujte kontrakt služby.

public class BlogService : IBlog
{
    public SyndicationFeedFormatter GetBlog(string format)
    {
        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 sample that demonstrates how to expose a feed through RSS and Atom 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;

        if (format == "rss")
            return new Rss20FeedFormatter(feed);
        else if (format == "atom")
            return new Atom10FeedFormatter(feed);
        else return null;
    }
}

Public Class BlogService
    implements IBlog

    Public Function GetBlog(ByVal format As String) As SyndicationFeedFormatter Implements IBlog.GetBlog
        Dim feed As 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 sample that demonstrates how to expose a feed through RSS and Atom with WCF")
        Dim item1 As New SyndicationItem( _
            "Item One", _
            "This is the content for item one", _
            New Uri("http://localhost/Content/One"), _
            "ItemOneID", _
            DateTime.Now)

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

        Dim item3 As 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

        If (format = "rss") Then
            Return New Rss20FeedFormatter(feed)
        Else
            Return New Atom10FeedFormatter(feed)
        End If
    End Function
End Class

Vytvořte SyndicationFeed objekt a přidejte autora, kategorii a popis.

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 sample that demonstrates how to expose a feed through RSS and Atom with WCF");

Dim feed As 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 sample that demonstrates how to expose a feed through RSS and Atom with WCF")

Vytvořte několik SyndicationItem objektů.

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

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

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

SyndicationItem Přidejte objekty do informačního kanálu.

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

K vrácení požadovaného formátu použijte parametr formátu.

if (format == "rss")
    return new Rss20FeedFormatter(feed);
else if (format == "atom")
    return new Atom10FeedFormatter(feed);
else return null;

If (format = "rss") Then
    Return New Rss20FeedFormatter(feed)
Else
    Return New Atom10FeedFormatter(feed)
End If

Hostování služby

Vytvoření objektu WebServiceHost Třída WebServiceHost automaticky přidá koncový bod na základní adresu služby, pokud není zadán v kódu nebo konfiguraci. V této ukázce nejsou zadány žádné koncové body, takže se zobrazí výchozí koncový bod.

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

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

Otevřete hostitele služby, načtěte informační kanál ze služby, zobrazte informační kanál a počkejte, až uživatel stiskne klávesu ENTER.

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

Console.WriteLine("Loading feed in Atom 1.0 format.");
XmlReader atomReader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog?format=atom");
SyndicationFeed atomFeed = SyndicationFeed.Load(atomReader);
Console.WriteLine(atomFeed.Title.Text);
Console.WriteLine("Items:");
foreach (SyndicationItem item in atomFeed.Items)
{
    Console.WriteLine("Title: {0}", item.Title.Text);
    Console.WriteLine("Content: {0}", ((TextSyndicationContent)item.Content).Text);
}

Console.WriteLine("Loading feed in RSS 2.0 format.");
XmlReader rssReader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog?format=rss");
SyndicationFeed rssFeed = SyndicationFeed.Load(rssReader);
Console.WriteLine(rssFeed.Title.Text);
Console.WriteLine("Items:");
foreach (SyndicationItem item in rssFeed.Items)
{
    Console.WriteLine("Title: {0}", item.Title.Text);
    // Notice we are using item.Summary here instead of item.Content. This is because
    // of the differences between Atom 1.0 and RSS 2.0 specs.
    Console.WriteLine("Content: {0}", ((TextSyndicationContent)item.Summary).Text);
}

Console.WriteLine("Press <ENTER> to quit...");
Console.ReadLine();
svcHost.Close();

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

Console.WriteLine("Loading feed in Atom 1.0 format.")
Dim atomReader As XmlReader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog?format=atom")
Dim atomFeed As SyndicationFeed = SyndicationFeed.Load(atomReader)
Console.WriteLine(atomFeed.Title.Text)
Console.WriteLine("Items:")
For Each item As SyndicationItem In atomFeed.Items
    Console.WriteLine("Title: {0}", item.Title.Text)
    Console.WriteLine("Content: {0}", CType(item.Content, TextSyndicationContent).Text)
Next

Console.WriteLine("Loading feed in RSS 2.0 format.")
Dim rssReader As XmlReader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog?format=rss")
Dim rssFeed As SyndicationFeed = SyndicationFeed.Load(rssReader)
Console.WriteLine(rssFeed.Title.Text)
Console.WriteLine("Items:")
For Each item As SyndicationItem In rssFeed.Items
    Console.WriteLine("Title: {0}", item.Title.Text)
    Console.WriteLine("Content: {0}", CType(item.Content, TextSyndicationContent).Text)
Next


Console.WriteLine("Press <ENTER> to quit...")
Console.ReadLine()
svcHost.Close()

Volání GetBlogu pomocí HTTP GET

Otevřete prohlížeč, zadejte následující adresu URL a stiskněte Enter: http://localhost:8000/BlogService/GetBlog.

Adresa URL obsahuje základní adresu služby (http://localhost:8000/BlogService), relativní adresu koncového bodu a operaci služby, která se má volat.

Volání Metody GetBlog() z kódu

Vytvořte základní XmlReader adresu a metodu, kterou voláte.

XmlReader reader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog?format=atom");

Dim atomReader As XmlReader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog?format=atom")

Zavolejte statickou Load(XmlReader) metodu a předejte právě vytvořenou metodu XmlReader .
```
SyndicationFeed feed = SyndicationFeed.Load(reader);
```
```
Dim feed As SyndicationFeed = SyndicationFeed.Load(atomReader)
```
Tím se vyvolá operace služby a naplní se nový SyndicationFeed formátovacím modulem vráceným z operace služby.

Přístup k objektu informačního kanálu

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

Příklad

Následuje úplný výpis kódu pro tento příklad.

using System;
using System.Xml;
using System.Collections.Generic;
using System.ServiceModel;
using System.ServiceModel.Description;
using System.ServiceModel.Syndication;
using System.ServiceModel.Web;
namespace Service
{
    [ServiceContract]
    [ServiceKnownType(typeof(Atom10FeedFormatter))]
    [ServiceKnownType(typeof(Rss20FeedFormatter))]
    public interface IBlog
    {
        [OperationContract]
        [WebGet(UriTemplate = "GetBlog?format={format}")]
        SyndicationFeedFormatter GetBlog(string format);
    }

    public class BlogService : IBlog
    {
        public SyndicationFeedFormatter GetBlog(string format)
        {
            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 sample that demonstrates how to expose a feed through RSS and Atom 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;

            if (format == "rss")
                return new Rss20FeedFormatter(feed);
            else if (format == "atom")
                return new Atom10FeedFormatter(feed);
            else return null;
        }
    }

    public class Host
    {
        static void Main(string[] args)
        {
            Uri address = new Uri("http://localhost:8000/BlogService/");
            WebServiceHost svcHost = new WebServiceHost(typeof(BlogService), address);
            try
            {
                svcHost.Open();
                Console.WriteLine("Service is running");

                Console.WriteLine("Loading feed in Atom 1.0 format.");
                XmlReader atomReader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog?format=atom");
                SyndicationFeed atomFeed = SyndicationFeed.Load(atomReader);
                Console.WriteLine(atomFeed.Title.Text);
                Console.WriteLine("Items:");
                foreach (SyndicationItem item in atomFeed.Items)
                {
                    Console.WriteLine("Title: {0}", item.Title.Text);
                    Console.WriteLine("Content: {0}", ((TextSyndicationContent)item.Content).Text);
                }

                Console.WriteLine("Loading feed in RSS 2.0 format.");
                XmlReader rssReader = XmlReader.Create("http://localhost:8000/BlogService/GetBlog?format=rss");
                SyndicationFeed rssFeed = SyndicationFeed.Load(rssReader);
                Console.WriteLine(rssFeed.Title.Text);
                Console.WriteLine("Items:");
                foreach (SyndicationItem item in rssFeed.Items)
                {
                    Console.WriteLine("Title: {0}", item.Title.Text);
                    // Notice we are using item.Summary here instead of item.Content. This is because
                    // of the differences between Atom 1.0 and RSS 2.0 specs.
                    Console.WriteLine("Content: {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();
            }
        }
    }
}

Probíhá kompilace kódu

Při kompilaci předchozího kódu System.ServiceModel.dll a System.ServiceModel.Web.dll.

Sdílet prostřednictvím