Find Matching OperationContract Based on URI - wcf

Question

...or "How to determine which WCF method will be called based on URI?"
In a WCF service, suppose a method is invoked and I have the URI that was used to invoke it. How can I get information about the WCF end point, method, parameters, etc. that the URI maps to?
[OperationContract]
[WebGet(UriTemplate = "/People/{id}")]
public Person GetPersonByID(int id)
{
//...
}
For instance, if the URI is: GET http://localhost/Contacts.svc/People/1, I want to get this information: service name (Service), Method (GetPersonByID), Parameters (PersonID=1). The point is to be able to listen for the request and then extract the details of the request in order to track the API call.
The service is hosted via http. This information is required before the .Net caching can kick in so each call (whether cached or not) can be tracked. This probably means doing this inside HttpApplication.BeginRequest.
FYI I'm hoping to not use reflection. I'd like to make use of the same methods WCF uses to determine this. E.g. MagicEndPointFinder.Resolve(uri)

Answer 1

Here is what I ended up doing, still interested if there is a cleaner way!
REST
private static class OperationContractResolver
{
private static readonly Dictionary<string, MethodInfo> RegularExpressionsByMethod = null;
static OperationContractResolver()
{
OperationContractResolver.RegularExpressionsByMethod = new Dictionary<string, MethodInfo>();
foreach (MethodInfo method in typeof(IREST).GetMethods())
{
WebGetAttribute attribute = (WebGetAttribute)method.GetCustomAttributes(typeof(WebGetAttribute), false).FirstOrDefault();
if (attribute != null)
{
string regex = attribute.UriTemplate;
//Escape question marks. Looks strange but replaces a literal "?" with "\?".
regex = Regex.Replace(regex, #"\?", #"\?");
//Replace all parameters.
regex = Regex.Replace(regex, #"\{[^/$\?]+?}", #"[^/$\?]+?");
//Add it to the dictionary.
OperationContractResolver.RegularExpressionsByMethod.Add(regex, method);
}
}
}
public static string ExtractApiCallInfo(string relativeUri)
{
foreach (string regex in OperationContractResolver.RegularExpressionsByMethod.Keys)
if (Regex.IsMatch(relativeUri, regex, RegexOptions.IgnoreCase))
return OperationContractResolver.RegularExpressionsByMethod[regex].Name;
return null;
}
}
SOAP
private static void TrackSoapApiCallInfo(HttpContext context)
{
string filePath = Path.GetTempFileName();
string title = null;
//Save the request content. (Unfortunately it can't be written to a stream directly.)
context.Request.SaveAs(filePath, false);
//If the title can't be extracted then it's not an API method call, ignore it.
try
{
//Read the name of the first element within the SOAP body.
using (XmlReader reader = XmlReader.Create(filePath))
{
if (!reader.EOF)
{
XmlNamespaceManager nsManager = new XmlNamespaceManager(reader.NameTable);
XDocument document = XDocument.Load(reader);
//Need to add the SOAP Envelope namespace to the name table.
nsManager.AddNamespace("s", "http://schemas.xmlsoap.org/soap/envelope/");
title = document.XPathSelectElement("s:Envelope/s:Body", nsManager).Elements().First().Name.LocalName;
}
}
//Delete the temporary file.
File.Delete(filePath);
}
catch { }
//Track the page view.
}