public async Task <IActionResult> Pull()
{
// Identify calling client. If now allowed, return RPC failure.
string?clientID = auth.GetClientID(Request);
if (clientID == null)
{
return(Unauthorized());
}
// Read request body (if any). We do not use a [FromBody] parameter, because
// we want to explicitly use our JsonLib for deserializing (and not overwrite the
// user's selected default ASP.NET Core JSON serializer)
RpcCommandResult?lastResult = null;
using (var reader = new StreamReader(Request.Body)) {
var body = await reader.ReadToEndAsync();
if (body.Length > 0)
{
lastResult = JsonLib.FromJson <RpcCommandResult>(body);
}
}
// Report result and query next method
return(Ok(await RpcServerEngine.Instance.OnClientPull(clientID, lastResult)));
}
/// <summary>
/// Call this method after enqueuing the command to wait for the result of its execution.
/// The returned task finishes when the call was either successfully executed and
/// acknowledged, or failed (e.g. because of a timeout).
/// The result is stored in the given command itself. If successful, the return value
/// is also returned, otherwise an <see cref="RpcException"/> is thrown.
/// </summary>
public async Task <T> WaitForResult <T>()
{
try {
// Wait for result until timeout
await Task.WhenAny(runningTask.Task, Task.Delay(TimeoutMs ?? defaultTimeoutMs));
// Timeout?
if (false == IsFinished())
{
throw new RpcException(new RpcFailure(RpcFailureType.Timeout, "Timeout"));
}
// Failed? Then throw RPC exception
var result = GetResult();
if (result.Failure is RpcFailure failure)
{
throw new RpcException(failure);
}
// Return JSON-encoded result (or null for void return type)
if (result.ResultJson is string json)
{
return(JsonLib.FromJson <T>(json));
}
else
{
return(default !);
public async Task <IActionResult> Push()
{
// Identify calling client. If now allowed, return RPC failure.
string?clientID = auth.GetClientID(Request);
if (clientID == null)
{
return(Unauthorized());
}
// Read request body (if any). We do not use a [FromBody] parameter, because
// we want to explicitly use our JsonLib for deserializing (and not overwrite the
// user's selected default ASP.NET Core JSON serializer)
try {
using (var reader = new StreamReader(Request.Body)) {
var body = await reader.ReadToEndAsync();
if (body.Length > 0)
{
// Run command and return the result
var command = JsonLib.FromJson <RpcCommand>(body);
return(Ok(await RpcServerEngine.Instance.OnClientPush(clientID, command, runner)));
}
}
}
catch { // Can happen when the client cancelled the request
}
// Command missing
return(BadRequest());
}
/// <summary>
/// Polls the next command to execute locally from the server. The result of the
/// last executed command must be given, if there is one. The returned Task may block
/// some time, because the server uses the long polling technique to reduce network traffic.
/// If the server can not be reached, an exception is thrown (because the last result
/// has to be transmitted again).
/// </summary>
private async Task <RpcCommand?> PullFromServer(RpcCommandResult?lastResult)
{
// Long polling. The server returns null after the long polling time.
var bodyJson = lastResult != null?JsonLib.ToJson(lastResult) : null;
var httpResponse = await httpPull.PostAsync(clientConfig.ServerUrl + "/pull",
bodyJson != null?new StringContent(bodyJson, Encoding.UTF8, "application/json") : null);
if (httpResponse.IsSuccessStatusCode)
{
// Last result was received. The server responded with the next command or null,
// if there is currently none.
if (httpResponse.Content.Headers.ContentLength > 0)
{
return(JsonLib.FromJson <RpcCommand>(await httpResponse.Content.ReadAsStringAsync()));
}
else
{
return(null);
}
}
else
{
// Remote exception.
throw new Exception("Server responded with status code " + httpResponse.StatusCode);
}
}
public void DequeueCommand(string clientID, ulong commandID)
{
lock (syncLock) {
if (GetLatestFile(clientID) is FileInfo file)
{
var command = JsonLib.FromJson <RpcCommand>(File.ReadAllText(file.FullName));
if (command.ID == commandID)
{
file.Delete();
}
}
}
}
public RpcCommand?PeekCommand(string clientID)
{
lock (syncLock) {
if (GetLatestFile(clientID) is FileInfo file)
{
return(JsonLib.FromJson <RpcCommand>(File.ReadAllText(file.FullName)));
}
else
{
return(null);
}
}
}
/// <summary>
/// Sends the given command to the server now, reads the result or catches the
/// exception, and sets the command's state accordingly.
/// </summary>
private async Task ExecuteOnServerNow(RpcCommand command)
{
RpcCommandResult result;
var bodyJson = JsonLib.ToJson(command);
try {
var httpResponse = await httpPush.PostAsync(clientConfig.ServerUrl + "/push",
new StringContent(bodyJson, Encoding.UTF8, "application/json"));
if (httpResponse.IsSuccessStatusCode)
{
// Response (either success or remote failure) received.
result = JsonLib.FromJson <RpcCommandResult>(await httpResponse.Content.ReadAsStringAsync());
}
else
{
// The server did not respond with 200 (which it should do even in case of
// a remote exception). So there is a communication error.
result = RpcCommandResult.FromFailure(command.ID,
new RpcFailure(RpcFailureType.RpcError, "Remote side problem with RPC call. HTTP status code " +
(int)httpResponse.StatusCode));
}
}
catch {
// Could not reach server.
result = RpcCommandResult.FromFailure(command.ID,
new RpcFailure(RpcFailureType.Timeout, "Could not reach the server"));
}
// When a result was received (i.e. when there was no network problem), the command is finished
if (false == (result.Failure?.IsNetworkProblem == true) && command.ID == serverCache.CurrentCommand?.ID)
{
serverCache.FinishCurrentCommand();
}
// Finish command
command.Finish(result);
}
/// <summary> /// Gets the decoded message parameter with the given index. /// </summary> public T GetParam <T>(int index) => JsonLib.FromJson <T>(MethodParameters[index]);