使用导数Darko 的动态 IIS 托管 WCF 服务 http://blog.micic.ch/net/dynamic-iis-hosted-wcf-service工作,你可以实现你想要的东西。让我们从我们可能想要托管的示例服务开始,我们将其称为IMessageBroker
,它的契约很简单:
[ServiceContract]
public interface IMessageBroker
{
[OperationContract]
string Send(string message);
}
我们将此合同用于服务和 MEF 出口/进口。我们还将定义一些附加元数据:
public interface IMessageBrokerMetadata
{
public string Name { get; }
public string Channel { get; }
}
由于这是一个简单的项目,我将作弊并使用一个简单的静态类来管理 MEFCompositionContainer
用于组成零件:
public static class MEF
{
private static CompositionContainer container;
private static bool initialised;
public static void Initialise()
{
var catalog = new DirectoryCatalog("bin");
container = new CompositionContainer(catalog);
initialised = true;
}
public static CompositionContainer Container
{
get
{
if (!initialised) Initialise();
return container;
}
}
}
为了能够动态生成 WCF 服务,我们需要创建一个 ServiceHostFactory ,它可以访问我们的组合容器来访问我们的类型,因此您可以执行以下操作:
public class MEFServiceHostFactory : ServiceHostFactory
{
public override ServiceHostBase CreateServiceHost(string constructorString, System.Uri[] baseAddresses)
{
var serviceType = MEF.Container
.GetExports<IMessageBroker, IMessageBrokerMetadata>()
.Where(l => l.Metadata.Name == constructorString)
.Select(l => l.Value.GetType())
.Single();
var host = new ServiceHost(serviceType, baseAddresses);
foreach (var contract in serviceType.GetInterfaces())
{
var attr = contract.GetCustomAttributes(typeof(ServiceContractAttribute), true).FirstOrDefault();
if (attr != null)
host.AddServiceEndpoint(contract, new BasicHttpBinding(), "");
}
var metadata = host.Description.Behaviors
.OfType<ServiceMetadataBehavior>()
.FirstOrDefault();
if (metadata == null)
{
metadata = new ServiceMetadataBehavior();
metadata.HttpGetEnabled = true;
host.Description.Behaviors.Add(metadata);
}
else
{
metadata.HttpGetEnabled = true;
}
return host;
}
}
本质上是constructorString
参数用于传入我们想要的特定服务的元数据名称。接下来,我们需要处理定位这些服务。我们现在需要的是一个VirtualPathProvider
我们可以使用它来动态创建实例,通过VirtualFile
。提供者看起来像:
public class ServiceVirtualPathProvider : VirtualPathProvider
{
private bool IsServiceCall(string virtualPath)
{
virtualPath = VirtualPathUtility.ToAppRelative(virtualPath);
return (virtualPath.ToLower().StartsWith("~/services/"));
}
public override VirtualFile GetFile(string virtualPath)
{
return IsServiceCall(virtualPath)
? new ServiceFile(virtualPath)
: Previous.GetFile(virtualPath);
}
public override bool FileExists(string virtualPath)
{
if (IsServiceCall(virtualPath))
return true;
return Previous.FileExists(virtualPath);
}
public override System.Web.Caching.CacheDependency GetCacheDependency(string virtualPath, System.Collections.IEnumerable virtualPathDependencies, DateTime utcStart)
{
return IsServiceCall(virtualPath)
? null
: Previous.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart);
}
}
我们正在做的是将任何调用映射到/Services/
到我们的 MEF 派生端点。该服务需要一个虚拟文件,这就是我们将它们连接在一起的地方:
public class ServiceFile : VirtualFile
{
public ServiceFile(string virtualPath) : base(virtualPath)
{
}
public string GetName(string virtualPath)
{
string filename = virtualPath.Substring(virtualPath.LastIndexOf("/") + 1);
filename = filename.Substring(0, filename.LastIndexOf("."));
return filename;
}
public override Stream Open()
{
var stream = new MemoryStream();
var writer = new StreamWriter(stream);
writer.Write("<%@ ServiceHost Language=\"C#\" Debug=\"true\" Service=\"" + GetName(VirtualPath) +
"\" Factory=\"Core.MEFServiceHostFactory, Core\" %>");
writer.Flush();
stream.Position = 0;
return stream;
}
}
虚拟文件将从虚拟路径中分离出元数据名称,其中/Services/SampleMessageBroker.svc
-> SampleMessageBroker
。然后我们生成一些标记,它代表一个标记.svc
文件与Service="SampleMessageBroker"
。该参数将被传递给MEFServiceHostFactory
我们可以在其中选择端点。因此,给定一个示例端点:
[Export(typeof(IMessageBroker)),
ExportMetadata("Name", "SampleMessageBroker"),
ExportMetadata("Channel", "Greetings")]
public class SampleMessageBroker : IMessagerBroker
{
public string Send(string message)
{
return "Hello! " + message;
}
}
我们现在可以动态访问它/Services/SampleMessageBroker.svc
。您可能想要做的是提供一个静态服务,该服务允许您查询可用的端点,并将其反馈给您的消费客户端。
哦,不要忘记连接您的虚拟路径提供程序:
HostingEnvironment.RegisterVirtualPathProvider(new ServiceVirtualPathProvider());