Re: socket communication: socket doesn't connect

Your server is written in C++. However, what language is your
client in? Java? C#? C++/CLI?

As far as your server code goes, you didn't post where you
accept the listening socket. With blocking socket I/O you
are supposed to spawn a new thread (or process in the original
Unix model) to handle the accepted socket and call accept
again right away. This is a terrible model for a Windows socket
server as it generates a huge amount of threads. I suggest you
investigate the other available socket programming models and
pick a better one for a server. The best scaling model is using
overlapped sockets with an I/O Completion Port (IOCP). It
is also the most complex to program. As a compromise I'd sugest
you use event-based non-blocking model via WSAEventSelect
and spawn a new thread for every 63 sockets. Combined with
a bit of thread management this should do well for a medium load
server. (The 63 comes from the limit of 64 handles you can
simultaneously wait on via WatForMultipleObjects. You need
one slot for a thread termination event, thus you have 63 slots
open for socket events. Fewer if you need additional maintenance
handles to wait for on each thread, like a waitable timer for example.)

--
=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: agnickolov@xxxxxxxx
MVP VC FAQ: http://vcfaq.mvps.org
=====================================

"Ananya" <Ananya@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:E730AA77-F91F-41F4-9C1F-12A17EFBCC97@xxxxxxxxxxxxxxxx
I am trying to establish socket communication between my C++ and Java
program.

I bring up the Java program from the C++ program with ShellExecEx.

Then I start in the Java program with:
int port = 3000;
int rev = 1;
InetAddress address = InetAddress.getLocalHost();
Client client = new Client(port, address, rev);
int[] ints = new int[1];
ints[0] = 1;
client.send_ints(ints, 1);
client.closesocket();
using my Java Client class.

Then I continue in my C++ program with:
int port = 3000;
Server* server = new Server(port);
server->connectServer();
using my C++ Server class.

It looks like the server gets constructed properly and the connectServer
method calls the connect method from WinSock.h, which I have included (and
its library WSock32.Lib is at Additional Dependences in the Input of the
Linker).

Why does this connect method from WinSock.h return - 1?

Just in case, here is the constructor of my Java Client class:
public Client(int p, InetAddress address, int rev) throws IOException,
IllegalArgumentException
{
port = p;

try
{
sock = new Socket(address, port);
input = new BufferedInputStream(sock.getInputStream(), BUFFSIZE);
output = new BufferedOutputStream(sock.getOutputStream(), BUFFSIZE);
}
catch (IOException e)
{
}
catch (IllegalArgumentException ie)
{
}

buff = new byte[BUFFSIZE];
data = new byte[BUFFSIZE];

output.write(rev);
output.flush();
}

and the constructor of my C++ Server class:
Server::Server(int p) throw (string)
{
WSAData wsaData;
if(WSAStartup(MAKEWORD(1,1),&wsaData) != 0)
{
throw string("help!");
}

port = p;

if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
throw string("help!");
}

my_addr.sin_family = AF_INET;
my_addr.sin_port = htons(port);
my_addr.sin_addr.s_addr = INADDR_ANY;

if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr))
==
-1)
{
throw string("help!");
}

if (listen(sockfd, BACKLOG) == -1)
{
throw string("help!");
}
}

Thanks for your time looking at this!


.

Relevant Pages

  • Re: Socket switch delay
    ... both at the client and at the server (and why ... would you set the send buffer size to zero on a non-overlapped ... One glaring error is your client does ... So when you use a single socket, ...
    (microsoft.public.win32.programmer.networks)
  • Re: JVM/Java memory footprint
    ... I found that if I use Java for developing the CLI ... application I will be exhausting the memory of our Application Server ... to make the JVM shareable. ... multiple client processes? ...
    (comp.lang.java.programmer)
  • Re: Locking on async calls
    ... you must synchronize the entire SendMessage routine as an atomic ... operation to prevent mixed messages from being transmitted to the server. ... You are correct that read and write on the socket do not interfere with each ... If you want to handle multiple client connections from one server object ...
    (microsoft.public.dotnet.general)
  • Re: Design issue with WinSock/GetQueuedCompletionStatus
    ... delegate that to a shutdown routine called after all worker threads ... The application I've created is a server accepting connections on a few ... different TCP/IP ports and then lets the client run different commands. ... a TCP/IP socket can be closed for 2 different reasons: ...
    (microsoft.public.win32.programmer.networks)
  • Re: socket communication: socket doesnt connect
    ... Microsoft MVP, MCSD ... As far as your server code goes, ... accept the listening socket. ... Client client = new Client; ...
    (microsoft.public.vc.language)