protected override async Task <T> InvokeExportAsync <T>(
NodeInvocationInfo invocationInfo, CancellationToken cancellationToken)
{
var payloadJson = JsonConvert.SerializeObject(invocationInfo, jsonSerializerSettings);
var payload = new StringContent(payloadJson, Encoding.UTF8, "application/json");
var response = await _client.PostAsync("http://localhost:" + _portNumber, payload, cancellationToken);
if (!response.IsSuccessStatusCode)
{
// Unfortunately there's no true way to cancel ReadAsStringAsync calls, hence AbandonIfCancelled
var responseErrorString = await response.Content.ReadAsStringAsync().OrThrowOnCancellation(cancellationToken);
throw new Exception("Call to Node module failed with error: " + responseErrorString);
}
var responseContentType = response.Content.Headers.ContentType;
switch (responseContentType.MediaType)
{
case "text/plain":
// String responses can skip JSON encoding/decoding
if (typeof(T) != typeof(string))
{
throw new ArgumentException(
"Node module responded with non-JSON string. This cannot be converted to the requested generic type: " +
typeof(T).FullName);
}
var responseString = await response.Content.ReadAsStringAsync().OrThrowOnCancellation(cancellationToken);
return((T)(object)responseString);
case "application/json":
var responseJson = await response.Content.ReadAsStringAsync().OrThrowOnCancellation(cancellationToken);
return(JsonConvert.DeserializeObject <T>(responseJson, jsonSerializerSettings));
case "application/octet-stream":
// Streamed responses have to be received as System.IO.Stream instances
if (typeof(T) != typeof(Stream) && typeof(T) != typeof(object))
{
throw new ArgumentException(
"Node module responded with binary stream. This cannot be converted to the requested generic type: " +
typeof(T).FullName + ". Instead you must use the generic type System.IO.Stream.");
}
return((T)(object)(await response.Content.ReadAsStreamAsync().OrThrowOnCancellation(cancellationToken)));
default:
throw new InvalidOperationException("Unexpected response content type: " + responseContentType.MediaType);
}
}
/// <summary>
/// Asynchronously invokes code in the Node.js instance.
/// </summary>
/// <typeparam name="T">The JSON-serializable data type that the Node.js code will asynchronously return.</typeparam>
/// <param name="invocationInfo">Specifies the Node.js function to be invoked and arguments to be passed to it.</param>
/// <param name="cancellationToken">A <see cref="CancellationToken"/> that can be used to cancel the invocation.</param>
/// <returns>A <see cref="Task{TResult}"/> representing the completion of the RPC call.</returns>
protected abstract Task <T> InvokeExportAsync <T>(
NodeInvocationInfo invocationInfo,
CancellationToken cancellationToken);