public async Task Invoke(IDictionary <string, object> environment)
{
IOwinContext context = new OwinContext(environment);
var request = context.Request;
var response = context.Response;
//capture details about the caller identity
var identity = (request.User != null && request.User.Identity.IsAuthenticated)
? request.User.Identity.Name
: "(anonymous)";
var apiPacket = new ApiPacket
{
CallerIdentity = identity
};
//buffer the request stream in order to intercept downstream reads
var requestBuffer = new MemoryStream();
request.Body = requestBuffer;
//buffer the response stream in order to intercept downstream writes
var responseStream = response.Body;
var responseBuffer = new MemoryStream();
response.Body = responseBuffer;
//add the "Http-Tracking-Id" response header
//adding the tracking id response header so that the user
//of the API can correlate the call back to this entry
var responseHeaders = (IDictionary <string, string[]>)environment["owin.ResponseHeaders"];
responseHeaders["http-tracking-id"] = new[] { apiPacket.TrackingId };
context.Response.OnSendingHeaders(state =>
{
var ctx = state as IOwinContext;
if (ctx == null)
{
return;
}
var resp = ctx.Response;
}, context);
//invoke the next middleware in the pipeline
await _next.Invoke(environment);
//rewind the request and response buffers to record their content
WriteRequestHeaders(request, apiPacket);
requestBuffer.Seek(0, SeekOrigin.Begin);
var requestReader = new StreamReader(requestBuffer);
apiPacket.Request = await requestReader.ReadToEndAsync();
WriteResponseHeaders(response, apiPacket);
responseBuffer.Seek(0, SeekOrigin.Begin);
var reader = new StreamReader(responseBuffer);
apiPacket.Response = await reader.ReadToEndAsync();
//write the apiPacket to the database
//await database.InsterRecordAsync(apiPacket);
System.Diagnostics.Debug.WriteLine("TrackingId: " + apiPacket.TrackingId);
//make sure the response we buffered is flushed to the client
responseBuffer.Seek(0, SeekOrigin.Begin);
await responseBuffer.CopyToAsync(responseStream);
}
private static void WriteRequestHeaders(IOwinRequest request, ApiPacket packet)
{
packet.Verb = request.Method;
packet.RequestUri = request.Uri;
packet.RequestHeaders = request.Headers;
}
private static void WriteResponseHeaders(IOwinResponse response, ApiPacket packet)
{
packet.StatusCode = response.StatusCode;
packet.ReasonPhrase = response.ReasonPhrase;
packet.ResponseHeaders = response.Headers;
}