WCF 第十三章 可编程站点 RSS与ATOM内容聚合

RSS和ATOM是网站内容的聚合形式。这些形式为所有类型的内容聚合所使用，比如新闻，视频以及博客。到目前为止这些格式最广泛的应用就是博客。因为它早期的流行，RSS和ATOM已经被每个主要站点所使用。WCF提供很多架构来与RSS和ATOM聚合种子一起使用。一个新的叫做System.ServiceModel.Syndication的命名空间包含了创建，使用以及格式化基于RSS和ATOM聚合种子的类。创建以及使用内容聚合种子的核心类是SyndicationFeed类。列表13.16显示了使用这个类来暴露RSS和ATOM的示例程序。这个应用列举了一个音乐集合并使用一个聚合种子暴露信息。

列表13.16 Zune 音乐聚合

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;
using System.ServiceModel.Syndication;
using System.IO;

namespace EssentialWCF.ZuneMusicSyndication
{
public class ZuneFeedService
{
private static Uri LiveSearchBaseUri = new Uri("http://search.live.com");
private static UriTemplate LiveSearchTemplate = new UriTemplate(@"/result.aspx?q={terms}");

private string MusicPath
{
get
{
return @"C:\Users\lenovo\Music\Zune";
}
}

private SyndicationFeed ZuneFeed
{
get
{
SyndicationFeed feed = new SyndicationFeed()
{
Title = new TextSyndicationContent("My Zune Music Library"),
Description = new TextSyndicationContent("My Zune Music Library")
};

DirectoryInfo di = new DirectoryInfo(MusicPath);
DirectoryInfo[] artists = di.GetDirectories();

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

foreach (DirectoryInfo artist in artists)
{
SyndicationItem item = new SyndicationItem()
{
Title = new TextSyndicationContent(string.Format("Artist: {0}", artist.Name)),
Summary = new TextSyndicationContent(artist.FullName),
PublishDate = DateTime.Now,
LastUpdatedTime = artist.LastAccessTime,
Copyright = new TextSyndicationContent(@"Zune Library (c)")
};

Uri searchUri = LiveSearchTemplate.BindByPosition(LiveSearchBaseUri, artist.Name);
item.Links.Add(new SyndicationLink(searchUri));
items.Add(item);
}
feed.Items = items;
return feed;
}
}

[OperationContract]
[WebGet]
[ServiceKnownType(typeof(Atom10FeedFormatter))]
[ServiceKnownType(typeof(Rss20FeedFormatter))]
public SyndicationFeedFormatter GetMusic(string format)
{
SyndicationFeedFormatter output;
if (format == "rss")
{
output = new Rss20FeedFormatter(ZuneFeed);
}
else
{
output = new Atom10FeedFormatter(ZuneFeed);
}
return output;
}
}
}

列表13.17 显示了寄宿聚合服务的代码。这个应用程序使用WebServiceHost类进行自我寄宿。它然后调用这个服务并向显示器输出种子。

列表13.17 Zune音乐种子控制台应用程序

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;
using EssentialWCF.ZuneMusicSyndication;
using System.ServiceModel.Description;
using System.ServiceModel.Syndication;
using System.Xml;

namespace EssentialWCF.ZuneFeed
{
class Program
{
static void Main(string[] args)
{
ServiceHost host = new ServiceHost(typeof(ZuneFeedService),
new Uri("http://localhost:8000/zune"));

ServiceEndpoint atomEndpoint = host.AddServiceEndpoint(typeof(ZuneFeedService),
new WebHttpBinding(), "feed");
atomEndpoint.Behaviors.Add(new WebHttpBehavior());

host.Open();

Console.WriteLine("Service host open");

SyndicationFeed feed = SyndicationFeed.Load(XmlReader.Create("http://localhost:8000/zune/feed/?format=rss"));

foreach (SyndicationItem item in feed.Items)
{
Console.WriteLine("Artist: " + item.Title.Text);
Console.WriteLine("Summary: " + item.Summary.Text);
};
Console.WriteLine("Service host open");
Console.ReadLine();
}
}
}