/// <summary>
/// Validates requests and responses.
/// </summary>
public static ServiceDelegator Validate(object inner)
{
if (inner is null)
{
throw new ArgumentNullException(nameof(inner));
}
return(async(method, request, cancellationToken) =>
{
if (!request.Validate(out var requestErrorMessage))
{
return ServiceResult.Failure(ServiceErrors.CreateInvalidRequest(requestErrorMessage));
}
var response = await method.InvokeAsync(inner, request, cancellationToken).ConfigureAwait(false);
if (!response.Validate(out var responseErrorMessage))
{
return ServiceResult.Failure(ServiceErrors.CreateInvalidResponse(responseErrorMessage));
}
return response;
});
}
/// <summary>
/// Attempts to handle a service method.
/// </summary>
protected async Task <HttpResponseMessage?> TryHandleServiceMethodAsync <TRequest, TResponse>(HttpMethodMapping <TRequest, TResponse> mapping, HttpRequestMessage httpRequest, Func <TRequest, CancellationToken, Task <ServiceResult <TResponse> > > invokeMethodAsync, CancellationToken cancellationToken)
where TRequest : ServiceDto, new()
where TResponse : ServiceDto, new()
{
if (mapping == null)
{
throw new ArgumentNullException(nameof(mapping));
}
if (httpRequest == null)
{
throw new ArgumentNullException(nameof(httpRequest));
}
if (invokeMethodAsync == null)
{
throw new ArgumentNullException(nameof(invokeMethodAsync));
}
if (httpRequest.RequestUri == null)
{
throw new ArgumentException("RequestUri must be specified.", nameof(httpRequest));
}
if (httpRequest.Method != mapping.HttpMethod)
{
return(null);
}
var pathParameters = TryMatchHttpRoute(httpRequest.RequestUri, m_rootPath + mapping.Path);
if (pathParameters == null)
{
return(null);
}
var context = new ServiceHttpContext();
ServiceHttpContext.SetContext(httpRequest, context);
var aspectHttpResponse = await AdaptTask(RequestReceivedAsync(httpRequest, cancellationToken)).ConfigureAwait(true);
if (aspectHttpResponse != null)
{
return(aspectHttpResponse);
}
ServiceErrorDto?error = null;
object?requestBody = null;
if (mapping.RequestBodyType != null)
{
try
{
var serializer = GetHttpContentSerializer(mapping.RequestBodyType);
var requestResult = await AdaptTask(serializer.ReadHttpContentAsync(mapping.RequestBodyType, httpRequest.Content, cancellationToken)).ConfigureAwait(true);
if (requestResult.IsFailure)
{
error = requestResult.Error;
}
else
{
requestBody = requestResult.Value;
}
}
catch (Exception exception) when(ShouldCreateErrorFromException(exception))
{
// cancellation can cause the wrong exception
cancellationToken.ThrowIfCancellationRequested();
// error reading request body
error = CreateErrorFromException(exception);
}
}
TResponse?response = null;
if (error == null)
{
var request = mapping.CreateRequest(requestBody);
var uriParameters = new Dictionary <string, string?>(StringComparer.OrdinalIgnoreCase);
foreach (var queryParameter in ParseQueryString(httpRequest.RequestUri.Query))
{
uriParameters[queryParameter.Key] = queryParameter.Value[0];
}
foreach (var pathParameter in pathParameters)
{
uriParameters[pathParameter.Key] = pathParameter.Value;
}
request = mapping.SetUriParameters(request, uriParameters);
request = mapping.SetRequestHeaders(request, HttpServiceUtility.CreateDictionaryFromHeaders(httpRequest.Headers, httpRequest.Content?.Headers) !);
context.Request = request;
if (!m_skipRequestValidation && !request.Validate(out var requestErrorMessage))
{
error = ServiceErrors.CreateInvalidRequest(requestErrorMessage);
}
else
{
var methodResult = await invokeMethodAsync(request, cancellationToken).ConfigureAwait(true);
if (methodResult.IsFailure)
{
error = methodResult.Error;
}
else
{
response = methodResult.Value;
if (!m_skipResponseValidation && !response.Validate(out var responseErrorMessage))
{
error = ServiceErrors.CreateInvalidResponse(responseErrorMessage);
response = null;
}
}
}
context.Result = error != null?ServiceResult.Failure(error) : ServiceResult.Success <ServiceDto>(response !);
}
HttpResponseMessage httpResponse;
if (error == null)
{
var responseMappingGroups = mapping.ResponseMappings
.GroupBy(x => x.MatchesResponse(response !))
.Where(x => x.Key != false)
.OrderByDescending(x => x.Key)
.ToList();
if (responseMappingGroups.Count >= 1 && responseMappingGroups[0].Count() == 1)
{
var responseMapping = responseMappingGroups[0].Single();
httpResponse = new HttpResponseMessage(responseMapping.StatusCode);
var responseHeaders = mapping.GetResponseHeaders(response !);
var headersResult = HttpServiceUtility.TryAddNonContentHeaders(httpResponse.Headers, responseHeaders);
if (headersResult.IsFailure)
{
throw new InvalidOperationException(headersResult.Error !.Message);
}
if (responseMapping.ResponseBodyType != null)
{
var serializer = GetHttpContentSerializer(responseMapping.ResponseBodyType);
var mediaType = responseMapping.ResponseBodyContentType ?? responseHeaders?.GetContentType() ?? GetAcceptedMediaType(httpRequest, serializer);
httpResponse.Content = serializer.CreateHttpContent(responseMapping.GetResponseBody(response !) !, mediaType);
if (m_disableChunkedTransfer)
{
await httpResponse.Content.LoadIntoBufferAsync().ConfigureAwait(false);
}
}
}
else
{
throw new InvalidOperationException($"Found {responseMappingGroups.Sum(x => x.Count())} valid HTTP responses for {typeof(TResponse).Name}: {response}");
}
}
else
{
var statusCode = error.Code == null ? HttpStatusCode.InternalServerError :
(TryGetCustomHttpStatusCode(error.Code) ?? HttpServiceErrors.TryGetHttpStatusCode(error.Code) ?? HttpStatusCode.InternalServerError);
httpResponse = new HttpResponseMessage(statusCode);
if (statusCode != HttpStatusCode.NoContent && statusCode != HttpStatusCode.NotModified)
{
var mediaType = GetAcceptedMediaType(httpRequest, m_contentSerializer);
httpResponse.Content = m_contentSerializer.CreateHttpContent(error, mediaType);
if (m_disableChunkedTransfer)
{
await httpResponse.Content.LoadIntoBufferAsync().ConfigureAwait(false);
}
}
}
httpResponse.RequestMessage = httpRequest;
await AdaptTask(ResponseReadyAsync(httpResponse, cancellationToken)).ConfigureAwait(true);
return(httpResponse);
}
/// <summary>
/// Sends an HTTP request and processes the response.
/// </summary>
protected async Task <ServiceResult <TResponse> > TrySendRequestAsync <TRequest, TResponse>(HttpMethodMapping <TRequest, TResponse> mapping, TRequest request, CancellationToken cancellationToken)
where TRequest : ServiceDto, new()
where TResponse : ServiceDto, new()
{
if (mapping == null)
{
throw new ArgumentNullException(nameof(mapping));
}
if (request == null)
{
throw new ArgumentNullException(nameof(request));
}
try
{
// validate the request DTO
if (!m_skipRequestValidation && !request.Validate(out var requestErrorMessage))
{
return(ServiceResult.Failure(ServiceErrors.CreateInvalidRequest(requestErrorMessage)));
}
// make sure the request DTO doesn't violate any HTTP constraints
var requestValidation = mapping.ValidateRequest(request);
if (requestValidation.IsFailure)
{
return(requestValidation.ToFailure());
}
// create the HTTP request with the right method, path, query string, and headers
var requestHeaders = mapping.GetRequestHeaders(request);
var httpRequestResult = TryCreateHttpRequest(mapping.HttpMethod, mapping.Path, mapping.GetUriParameters(request), requestHeaders);
if (httpRequestResult.IsFailure)
{
return(httpRequestResult.ToFailure());
}
// create the request body if necessary
using var httpRequest = httpRequestResult.Value;
var requestBody = mapping.GetRequestBody(request);
if (requestBody != null)
{
var contentType = mapping.RequestBodyContentType ?? requestHeaders?.GetContentType();
httpRequest.Content = GetHttpContentSerializer(requestBody.GetType()).CreateHttpContent(requestBody, contentType);
if (m_disableChunkedTransfer)
{
await httpRequest.Content.LoadIntoBufferAsync().ConfigureAwait(false);
}
}
// send the HTTP request and get the HTTP response
using var httpResponse = await SendRequestAsync(httpRequest, request, cancellationToken).ConfigureAwait(false);
// find the response mapping for the status code
var statusCode = httpResponse.StatusCode;
var responseMapping = mapping.ResponseMappings.FirstOrDefault(x => x.StatusCode == statusCode);
// fail if no response mapping can be found for the status code
if (responseMapping == null)
{
return(ServiceResult.Failure(await CreateErrorFromHttpResponseAsync(httpResponse, cancellationToken).ConfigureAwait(false)));
}
// read the response body if necessary
object?responseBody = null;
if (responseMapping.ResponseBodyType != null)
{
var serializer = GetHttpContentSerializer(responseMapping.ResponseBodyType);
var responseResult = await serializer.ReadHttpContentAsync(
responseMapping.ResponseBodyType, httpResponse.Content, cancellationToken).ConfigureAwait(false);
if (responseResult.IsFailure)
{
var error = responseResult.Error !;
error.Code = ServiceErrors.InvalidResponse;
return(ServiceResult.Failure(error));
}
responseBody = responseResult.Value;
}
// create the response DTO
var response = responseMapping.CreateResponse(responseBody);
response = mapping.SetResponseHeaders(response, HttpServiceUtility.CreateDictionaryFromHeaders(httpResponse.Headers, httpResponse.Content.Headers) !);
// validate the response DTO
if (!m_skipResponseValidation && !response.Validate(out var responseErrorMessage))
{
return(ServiceResult.Failure(ServiceErrors.CreateInvalidResponse(responseErrorMessage)));
}
return(ServiceResult.Success(response));
}
catch (OperationCanceledException) when(!cancellationToken.IsCancellationRequested)
{
// HttpClient timeout
return(ServiceResult.Failure(ServiceErrors.CreateTimeout()));
}
catch (Exception exception) when(ShouldCreateErrorFromException(exception))
{
// cancellation can cause the wrong exception
cancellationToken.ThrowIfCancellationRequested();
// error contacting service
return(ServiceResult.Failure(CreateErrorFromException(exception)));
}
}