I am using TIdHTTPProxyServer and now I want to terminate connection when it is success to connect to the target HTTP server but receive no response for a long time(i.g. 3 mins)
Currently I find no related property or event about it. And even if the client terminate the connection before the proxy server receive the response from the HTTP server. OnException Event will not be fired until the proxy server receive the response. (That is, if the proxy server still receive no response from HTTP Server, I even do not know the client has already terminate the connection...)
Any help will be appreciated.
Thanks!
Willy
Indy uses infinite timeouts by default. To do what you are asking for, you need to set the ReadTimeout property of the outbound connection to the target server. You can access that connection via the TIdHTTPProxyServerContext.OutboundClient property. Use the OnHTTPBeforeCommand event, which is triggered just before the OutboundClient connects to the target server, eg:
#include "IdTCPClient.hpp"
void __fastcall TForm1::IdHTTPProxyServer1HTTPBeforeCommand(TIdHTTPProxyServerContext *AContext)
{
static_cast<TIdTCPClient*>(AContext->OutboundClient)->ReadTimeout = ...;
}
Related
I'm using a synchronous bidirectional streaming grpc service, and I've let Server-side to close connection when timeout detected.
// server-side code
if (timeout-detected) {
server_context_->TryCancel();
}
My question is: how do I detect whether the connection still valid on client-side? If so, I could reestablish connection. I've tryed
// client-side code
if (client_reader_writer_->Write(&request)) {
// I consider it connection is still valid
} else {
// connection decided cancelled. Re-establish connection and do something.
}
But client_reader_writer_->Write(&request) return true, even after the server's log has shown cancelled.
If someone could give me some hints on this, I would be much grateful!
If your concern is about link, Keepalive can be used a mechanism to check if the channel is fine by transmitting HTTP2 pings at regular intervals and if there is no response, it is considered as broken.
Other approach is you can also come up with your own "heartbeat" mechanism where you can have the heartbeat sent periodically to check on server/network failure while trying to write to socket.
For server timeout in a typical scenario, indication to client can be done using context.abort(grpc.StatusCode.DEADLINE_EXCEEDED, 'RPC Time Out!')
Here is a reference for the same.
I have an async gRPC server for Windows written in C++. I’d like to detect the loss of connection to a client – whether a network connection is lost, or the client crashes, etc. I see references to the keepalive channel arguments, and I’ve tried various combinations of those settings, such as:
builder.AddChannelArgument(GRPC_ARG_KEEPALIVE_TIME_MS, 10000);
builder.AddChannelArgument(GRPC_ARG_KEEPALIVE_TIMEOUT_MS, 10000);
builder.AddChannelArgument(GRPC_ARG_KEEPALIVE_PERMIT_WITHOUT_CALLS, 1);
builder.AddChannelArgument(GRPC_ARG_HTTP2_MIN_RECV_PING_INTERVAL_WITHOUT_DATA_MS, 9000);
builder.AddChannelArgument(GRPC_ARG_HTTP2_BDP_PROBE, 1);
I've done some testing with a streaming RPC method. If I kill the client process and then try to send data to the client, the lost connection is detected. I don't actually even have to send data. I can set an Alarm object to trigger immediately and that causes the call handler to be cancelled. However, if I don't try to send data (or set an alarm) after killing the client process then there's no notification or callback that I've been able to find/enable. I must not have a complete understanding. So:
How does the detection of a lost connection manifest itself for the server? Is there a callback method, or notification of some type? My server doesn’t receive any errors; the completion queue’s ‘Next()’ method never returns, etc.
Does this detection work for both unary (call/response) and streaming methods?
Does the server detection of a lost connection work whether or not the client has implemented lost connection / keepalive logic?
Is there some method besides the keepalive channel arguments that is preferred?
Thanks - any help is appreciated.
You can use ServerContext::AsyncNotifyWhenDone() to get a notification when the request has been cancelled.
https://grpc.github.io/grpc/cpp/classgrpc__impl_1_1_server_context_base.html#a0f1289f31257e6dbef57bc901bd7b5f2
I'm having issues building an HTTP server using the Cesanta Mongoose web server library. The issue that I'm having occurs when I have an HTTP server built to listen on port 8080, and a client sending an HTTP request to localhost:8080. The problem is that the server processes the request fine and sends back a response, but the client only processes and prints the response after I kill the server process. Basically Mongoose works where you create connections which take an event handler function, ev_handler(). This event handler function is called whenever an
"event" occurs, such as the receiving of a request or a reply. On the server side, the event handler function is called fine when it receives a request from the client on 8080. However, the client-side event handler function is not called when the response sends the reply, but is called only after the server process is killed. I suspected that this may have something to do with the fact that the connection is on localhost, and I was right - this issue does not occur when the client sends requests to addresses other than localhost. The event handler function is called fine. Here is the ev_handler function on the client-side for reference:
static void ev_handler(struct mg_connection *c, int ev, void *p) {
if (ev == MG_EV_HTTP_REPLY) {
struct http_message *hm = (struct http_message *)p;
c->flags |= MG_F_CLOSE_IMMEDIATELY;
fwrite(hm->message.p, 1, (int)hm->message.len, stdout);
putchar('\n');
exit_flag = 1;
} else if (ev == MG_EV_CLOSE) {
exit_flag = 1;
};
}
Is this a common issue when trying to establish a connection on localhost with a server on the same computer?
The cause of such behavior is the fact that client connection does not fire an event until all data is read. How client knows the all data is read? There are 3 possibilities:
Server has sent Content-Length: XXX header and client has read XXX bytes of the message body, so it knows it received everything.
Server has sent Transfer-Encoding: chunked header, and sent all data chunks followed by an empty chunk. When client receives an empty chunk, it knows it received everything.
Server set neither Content-Lenth, nor Transfer-Encoding. Client does not know in this case what is the size of the body, and it keeps reading until server closes the connection.
What you see is (3). Solution: set Content-Length in your server code.
i am using embedded Jetty to implement HTTP/2. At the moment i am trying to add a ServerSessionListener (from: org.eclipse.jetty.http2.api.Session.Listener.Adapter) to my Server.
i tried to add it to the Context and Server via: addEventListener with no success.
Maybe someone can give me a hint about what i am doing wrong..
I want to add a session Listener to my HTTP2 Connection to track the connected Sessions (Clients) and their connection duration.
Regards!
You can add an implementation of Connection.Listener as a bean to the connector itself, for example:
http2Connector.addBean(new Connection.Listener()
{
public void onOpened(Connection connection) { ... }
public void onClosed(Connection connection) { ... }
});
Alternatively you can add the Connection.Listener as a bean to the ConnectionFactory.
In both cases, every time a connection is created, the listener is added to the connection and will be invoked when the connection opens and when it closes.
You can use Jetty's ConnectorStatistics class that already gathers a number of statistics about connections and already implements Connection.Listener.
I'm running an embedded jetty server (jetty 6.1.24) inside my application like this:
Handler handler=new AbstractHandler()
{
#Override
public void handle(String target, HttpServletRequest request,
HttpServletResponse response, int dispatch)
throws IOException, ServletException {
//this can take a long time
doSomething();
}
};
Server server = new Server(8080);
Connector connector = new org.mortbay.jetty.nio.SelectChannelConnector();
server.addConnector(connector);
server.setHandler(handler);
server.start();
I would like to set a timeout value (2 seconds) so that if handler.handle() method takes more than 2 seconds, jetty server will timeout and response to the client with 408 http code (request timeout).
This is to guarantee that my application will not hold the client request for a long time and always response within 2 seconds.
I did some research and tested it with "connector.setMaxIdleTime(2000);" but it doesn't work.
Take a look at the API for SelectChannelConnector (Jetty):
http://download.eclipse.org/jetty/7.6.17.v20150415/apidocs/org/eclipse/jetty/server/nio/SelectChannelConnector.html
I've tried to locate any timeout features of the channel (which controls incoming connections): setMaxIdleTime(), setLowResourceMaxIdleTime() and setSoLingerTime() are available it appears.
NOTE: the reason for your timeout feature not to work has to do with the nature of the socket on your operating system. Perhaps even the nature of Jetty (i've read about it somewhere, but cannot remember where it was).
NOTE2: i'm not sure why you try to limit the timeout, perhaps a better approach is limiting the buffer sizes? If you're trying to prevent denial of service...
Yes, this is possible. You could do this using DosFilter of Jetty. This filter is generally used to configure a DOS attack prevention mechanism for your Jetty web server. A property of this filter called 'MaxRequestMs' provides what you are looking for.
For more details, check this.
https://www.eclipse.org/jetty/javadoc/jetty-9/org/eclipse/jetty/servlets/DoSFilter.html