c# - 使用反射的 Wcf 动态托管

我的目标是创建一个能够解析多个程序集、检测契约(Contract)和托管服务的宿主应用程序。

为了加载服务，我们通常需要对 servicehost 实例化进行硬编码。尽管不是我正在寻找的行为，但以下代码仍在工作。

ServiceHost wService1Host = new ServiceHost(typeof(Service1));
wService1Host.Open();

ServiceHost wService2Host = new ServiceHost(typeof(Service2));
wService2Host.Open();

然而，这意味着我提前知道服务是什么。
我不介意引用包含服务的程序集。我只是想让主机不知道程序集中包含哪些服务。例如，如果我向其中一个程序集添加新服务，则主机端不需要任何更改。

这与 question 非常相似，但由于上述原因增加了复杂性。

这是我到目前为止提供的主机代码。我现在不介意管理服务，我只是希望它们被正确加载。

class Program
  {
    static void Main(string[] args)
    {

      // find currently executing assembly
      Assembly curr = Assembly.GetExecutingAssembly();

      // get the directory where this app is running in
      string currentLocation = Path.GetDirectoryName(curr.Location);

      // find all assemblies inside that directory
      string[] assemblies = Directory.GetFiles(currentLocation, "*.dll");

      // enumerate over those assemblies
      foreach (string assemblyName in assemblies)
      {
        // load assembly just for inspection
        Assembly assemblyToInspect = Assembly.ReflectionOnlyLoadFrom(assemblyName);

        // I've hardcoded the name of the assembly containing the services only to ease debugging
        if (assemblyToInspect != null && assemblyToInspect.GetName().Name == "WcfServices")
        {
          // find all types
          Type[] types = assemblyToInspect.GetTypes();

          // enumerate types and determine if this assembly contains any types of interest
          // you could e.g. put a "marker" interface on those (service implementation)
          // types of interest, or you could use a specific naming convention (all types
          // like "SomeThingOrAnotherService" - ending in "Service" - are your services)
          // or some kind of a lookup table (e.g. the list of types you need to find from
          // parsing the app.config file)
          foreach (Type ty in types)
          {
            Assembly implementationAssembly = Assembly.GetAssembly(ty);
            // When loading the type for the service, load it from the implementing assembly.
            Type implementation = implementationAssembly.GetType(ty.FullName);

            ServiceHost wServiceHost = new ServiceHost(implementation); // FAIL
            wServiceHost.Open();
          }
        }
      }
      Console.WriteLine("Service are up and running.");
      Console.WriteLine("Press <Enter> to stop services...");
      Console.ReadLine();
    }
  }

尝试创建 serviceHost 时出现以下错误:

"It is illegal to reflect on the custom attributes of a Type loaded via ReflectionOnlyGetType (see Assembly.ReflectionOnly) -- use CustomAttributeData instead."

在上面给出的链接中，这个人似乎已经使用 typeof 解决了它的问题，因为他事先知道他想要公开什么服务。不幸的是，这不是我的情况。

注意:对于托管部分，我实际上有 3 个项目。第一个是宿主应用程序(见上文)，第二个是包含我所有服务契约(接口(interface))的程序集，最后一个程序集包含服务实现。

这是我实际用于托管服务的 app.config。包含实现的程序集命名为“WcfServices”并包含 2 个服务。一种是公开回调，另一种是公开基本服务。

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior name="metadataBehavior">
          <serviceMetadata httpGetEnabled="true"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <services>
      <service name="WcfServices.Service1"
               behaviorConfiguration="metadataBehavior">

        <endpoint address="Service1Service"
                  binding="basicHttpBinding"
                  contract="WcfServices.IService1"
                  name="basicHttp"/>

        <endpoint binding="mexHttpBinding"
                  contract="IMetadataExchange"
                  name="metadataExchange"/>

        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:8000/Service1"/>
          </baseAddresses>
        </host>
      </service>

      <service name="WcfServices.Service2"
               behaviorConfiguration="metadataBehavior">

        <endpoint address="Service2Service"
                  binding="wsDualHttpBinding"
                  contract="WcfServices.IService2"/>

        <endpoint address="mex"
                  binding="mexHttpBinding"
                  contract="IMetadataExchange"/>

        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:8000/Service2"/>
          </baseAddresses>
        </host>
      </service>

    </services>
  </system.serviceModel>
</configuration>

所以，要清楚，这就是我要找的:
1.在当前应用程序目录中加载程序集
2.看里面有没有契约实现
3. 如果有，实例化这些服务(暂时使用 app.config)

首先，这甚至可能吗？ (我的猜测是因为名为 wcfstorm 的应用程序似乎已经这样做了)
显然，我怎样才能使上面的代码有效？

谢谢!

最佳答案

这是我最终做的:

private static void LoadServices()
{
  // find currently executing assembly
  Assembly Wcurr = Assembly.GetExecutingAssembly();

  // get the directory where this app is running in
  string wCurrentLocation = Path.GetDirectoryName(Wcurr.Location);

  // enumerate over those assemblies
  foreach (string wAssemblyName in mAssemblies)
  {
    // load assembly just for inspection
    Assembly wAssemblyToInspect = null;
    try
    {
      wAssemblyToInspect = Assembly.LoadFrom(wCurrentLocation + "\\" + wAssemblyName);
    }
    catch (System.Exception ex)
    {
      Console.WriteLine("Unable to load assembly : {0}", wAssemblyName);
    }


    if (wAssemblyToInspect != null)
    {
      // find all types with the HostService attribute
      IEnumerable<Type> wTypes = wAssemblyToInspect.GetTypes().Where(t => Attribute.IsDefined(t, typeof(HostService), false));

      foreach (Type wType in wTypes)
      {
        ServiceHost wServiceHost = new ServiceHost(wType);
        wServiceHost.Open();
        mServices.Add(wServiceHost);
        Console.WriteLine("New Service Hosted : {0}", wType.Name);
      }
    }
  }

  Console.WriteLine("Services are up and running.");
}

注意:此方法要求“宿主”项目引用程序集。

注2:为了加速程序集解析，我硬编码了要在“mAssemblies”中加载的程序集。

关于c# - 使用反射的 Wcf 动态托管，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/13034546/