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();

        }

    }

}