Creating and exposing a SOAP service and its WSDL dynamically in C# (with a custom TCP listener!)

Question

I\'ve got a custom HTTP server built in C# which accepts requests for REST services and responds with XML or JSON (depending on what the client needs). The REST services are

Answer 1

Don't parse SOAP unless you really have to, let WCF do the heavy lifting for you, generate service- and datacontracts in C# code from your definitions and compile at runtime . Generate a service implementation that hooks into your "static" code through a well known interface.

Dynamically create endpoints with the correct binding for the new service contracts/data contracts. If bindings don't change dynamically this could be defined in you app.config otherwise set this in runtime as well.

add a Mex endpoint to get the wsdl published.

For "examining" incoming traffic use a MessageInspector

self host the WCF/SOAP service in your HTTP server using ServiceHost -> Self Hosting WCF

Just some ideas on another approach.

Answer 2

To create a wsdl dynamically you can use ServiceDescriptionReflector

For example: for class

public class TestWebService
{
    [WebMethod]
    public string Hello(string namex)
    {
        return "Hello " + namex;
    }
}

you can use this code

StringWriter wr = new StringWriter();
var r = new System.Web.Services.Description.ServiceDescriptionReflector();
r.Reflect(typeof(TestWebService), "http://somewhere.com");
r.ServiceDescriptions[0].Write(wr);
var wsdl = wr.ToString();

But since you've said

Publishing a WSDL generated at runtime from the method definitions in the database

you have to create the Type at runtime

var asm = AppDomain.CurrentDomain.DefineDynamicAssembly(new AssemblyName("MyAsm"), AssemblyBuilderAccess.Run);
var mod = asm.DefineDynamicModule("MyModule");

TypeBuilder typeBuilder = mod.DefineType("TestWebService");

MethodBuilder mb = typeBuilder.DefineMethod("Hello", MethodAttributes.Public, CallingConventions.Standard, typeof(string), new Type[] { typeof(string) });
var cab = new CustomAttributeBuilder( typeof(WebMethodAttribute).GetConstructor(new Type[]{}), new object[]{} );
mb.SetCustomAttribute(cab);
mb.DefineParameter(1, ParameterAttributes.In, "namex");
mb.GetILGenerator().Emit(OpCodes.Ret);

Type type = typeBuilder.CreateType();

Now you can use type to create wsdl

StringWriter wr = new StringWriter();
var r = new System.Web.Services.Description.ServiceDescriptionReflector();
r.Reflect(type, "http://somewhere.com");
r.ServiceDescriptions[0].Write(wr);
var wsdl = wr.ToString();

For reading request and forming response, you can use Linq2Xml. Fiddler can give you an idea about SOAP(xml) format sent between client and server

Answer 3

SOAP is "just" an XML-based protocol for information exchange. Implementing support for it from the ground up would be tedious but not hugely complicated in principle, I don't think.

The official SOAP specifications can be found here.