我们将从运行时读取的元数据构建Web服务。我的意思是整个Web服务：签名，合同和实现。
我从这里看到两条主要路径。
第一个路径是您生成代码。您可以在字符串中生成C＃代码并在运行中进行编译或更优雅（并且更复杂），您可以发出MSIL代码。这样你就有了WCF代码，WCF将负责从中生成WSDL。
第二条路径是使用通用服务。具有接受所有内容的操作消息进程（消息）的服务。我们仍然希望将服务公开为“普通”服务，因此我需要在某处使用WSDL。我如何创建WSDL？我想到使用System.ServiceModel.Description，直到我意识到内部深处，这个API依赖于具体类型。使用这种方法，我们不会有任何数据协定类型，并且会动态处理XML，使用元数据来解释它。所以我们需要以某种方式生成WSDL。这是一个疯狂的想法吗？ WSDL有一个非常复杂的规范......
第三种选择是使用混合方法，发布类型只是为了创建签名，但使用非发射代码实现服务（反映发射的类型）。很奇怪，但可能比手工制作WSDL更简单......
建议？
这样做很痛苦，但可能会散发类型。创建.svc并将其指向您的自定义ServiceHostFactory：
<%@ ServiceHost Language="C#" Debug="true" Factory="Foo.FooServiceHostFactory" %>
[ServiceContract]
public class FooService { }
您的ServiceHostFactory是您生成操作合同，使用它的类型等的地方：
public class FooServiceHostFactory : ServiceHostFactory {
public override System.ServiceModel.ServiceHostBase CreateServiceHost(string constructorString, Uri[] baseAddresses) {
ServiceHost serviceHost = new FooServiceHost(baseAddresses);
serviceHost.AddDefaultEndpoints();
GenerateServiceOperations(serviceHost);
return serviceHost;
}
private void GenerateServiceOperations(ServiceHost serviceHost) {
var methodNames = new[] {
new { Name = "Add" },
new { Name = "Subtract" },
new { Name = "Multiply" }
};
foreach (var method in methodNames) {
foreach (var endpoint in serviceHost.Description.Endpoints) {
var contract = endpoint.Contract;
var operationDescription = new OperationDescription("Operation" + method.Name, contract);
var requestMessageDescription = new MessageDescription(string.Format("{0}{1}/Operation{2}", contract.Namespace, contract.Name, method.Name), MessageDirection.Input);
var responseMessageDescription = new MessageDescription(string.Format("{0}{1}/Operation{2}Response", contract.Namespace, contract.Name, method.Name), MessageDirection.Output);
var elements = new List<FooDataItem>();
elements.Add(new FooDataItem { Name = "X", DataType = typeof(int) });
elements.Add(new FooDataItem { Name = "Y", DataType = typeof(int) });
//note: for a complex type it gets more complicated, but the same idea using reflection during invoke()
//object type = TypeFactory.CreateType(method.Name, elements);
//var arrayOfType = Array.CreateInstance(type.GetType(), 0);
//var parameter = new MessagePartDescription(method.Name + "Operation", contract.Namespace);
//parameter.Type = arrayOfType.GetType();
//parameter.Index = 0;
//requestMessageDescription.Body.Parts.Add(parameter);
var retVal = new MessagePartDescription("Result", contract.Namespace);
retVal.Type = typeof(int);
responseMessageDescription.Body.ReturnValue = retVal;
int indexer = 0;
foreach (var element in elements) {
var parameter = new MessagePartDescription(element.Name, contract.Namespace);
parameter.Type = element.DataType;
parameter.Index = indexer++;
requestMessageDescription.Body.Parts.Add(parameter);
}
operationDescription.Messages.Add(requestMessageDescription);
operationDescription.Messages.Add(responseMessageDescription);
operationDescription.Behaviors.Add(new DataContractSerializerOperationBehavior(operationDescription));
operationDescription.Behaviors.Add(new FooOperationImplementation());
contract.Operations.Add(operationDescription);
}
}
}
protected override System.ServiceModel.ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses) {
return base.CreateServiceHost(serviceType, baseAddresses);
}
在ServiceHostFactory中，您可以定义行为以及元数据，因此您的行为需要实现IOperationBehavior和IOperationInvoker（或者您可以单独实现它们），看起来像这样：
public class FooOperationImplementation : IOperationBehavior, IOperationInvoker {
OperationDescription operationDescription;
DispatchOperation dispatchOperation;
public void AddBindingParameters(OperationDescription operationDescription, BindingParameterCollection bindingParameters) {
}
public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation) {
}
public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation) {
this.operationDescription = operationDescription;
this.dispatchOperation = dispatchOperation;
dispatchOperation.Invoker = this;
}
public void Validate(OperationDescription operationDescription) {
}
public object[] AllocateInputs() {
return new object[2];
}
public object Invoke(object instance, object[] inputs, out object[] outputs) {
//this would ALL be dynamic as well depending on how you are creating your service
//for example, you could keep metadata in the database and then look it up, etc
outputs = new object[0];
switch (operationDescription.Name) {
case "OperationAdd":
return (int)inputs[0] + (int)inputs[1];
case "OperationSubtract":
return (int)inputs[0] - (int)inputs[1];
case "OperationMultiply":
return (int)inputs[0] * (int)inputs[1];
default:
throw new NotSupportedException("wtf");
}
}
public IAsyncResult InvokeBegin(object instance, object[] inputs, AsyncCallback callback, object state) {
throw new NotImplementedException("Method is not asynchronous.");
}
public object InvokeEnd(object instance, out object[] outputs, IAsyncResult result) {
throw new NotImplementedException("Method is not asynchronous.");
}
public bool IsSynchronous {
get { return true; }
}
}
对于复杂类型，这是您需要进行判断调用的地方，这是您的问题的根源，是如何发出类型。这是一个例子，但你可以以任何你认为合适的方式做到这一点。我在我的ServiceHostFactory中调用它（警告：它的演示代码）
static public class TypeFactory {
static object _lock = new object();
static AssemblyName assemblyName;
static AssemblyBuilder assemblyBuilder;
static ModuleBuilder module;
static TypeFactory() {
lock (_lock) {
assemblyName = new AssemblyName();
assemblyName.Name = "FooBarAssembly";
assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
module = assemblyBuilder.DefineDynamicModule("FooBarModule");
}
}
static public object CreateType(string typeName, List<FooDataItem> elements) {
TypeBuilder typeBuilder = module.DefineType(typeName, TypeAttributes.Public | TypeAttributes.Class);
foreach(var element in elements) {
string propertyName = element.Name;
Type dataType = element.DataType;
FieldBuilder field = typeBuilder.DefineField("_" + propertyName, dataType, FieldAttributes.Private);
PropertyBuilder property =
typeBuilder.DefineProperty(propertyName,
PropertyAttributes.None,
dataType,
new Type[] { dataType });
MethodAttributes GetSetAttr =
MethodAttributes.Public |
MethodAttributes.HideBySig;
MethodBuilder currGetPropMthdBldr =
typeBuilder.DefineMethod("get_value",
GetSetAttr,
dataType,
Type.EmptyTypes);
ILGenerator currGetIL = currGetPropMthdBldr.GetILGenerator();
currGetIL.Emit(OpCodes.Ldarg_0);
currGetIL.Emit(OpCodes.Ldfld, field);
currGetIL.Emit(OpCodes.Ret);
MethodBuilder currSetPropMthdBldr =
typeBuilder.DefineMethod("set_value",
GetSetAttr,
null,
new Type[] { dataType });
ILGenerator currSetIL = currSetPropMthdBldr.GetILGenerator();
currSetIL.Emit(OpCodes.Ldarg_0);
currSetIL.Emit(OpCodes.Ldarg_1);
currSetIL.Emit(OpCodes.Stfld, field);
currSetIL.Emit(OpCodes.Ret);
property.SetGetMethod(currGetPropMthdBldr);
property.SetSetMethod(currSetPropMthdBldr);
}
Type generetedType = typeBuilder.CreateType();
return Activator.CreateInstance(generetedType);
}
}
更新：我写了一个快速的例子，它可用here。