Istream beginner help

Hallo Hackers,

for design reason i would like to use separate Istream & Ostream instead of IOstream with call().

ostream.send() does work, but i cant manage istream.receive(). It keeps waiting for ever.

I did edit the client from pkg/examples/clntsrv, the server sends the result, so there should be something to receive. What am i missing?

// pkg/examples/clntsrv/myClient.cc

static L4::Cap<void> server;

static int func_neg_transmit() { L4::Ipc::Ostream oStream(l4_utcb());

l4_uint32_t val = 8;

s << l4_umword_t(Opcode::func_neg) << val; int r = l4_error(s.send(server.cap(), Protocol::Calc)); }

static int getResult() { L4::Ipc::Istream iStream(l4_utcb());

l4_uint32_t val;

// while ( iStream.has_more<l4_uint32_t>()) { // doesnt work neither int r = l4_error(iStream.receive(server.cap())); printf("receive success\n"); // doesnt pass here

iStream >> val; }

int main() { server = L4Re::Env::env()->get_cap<void>("calc_server");

func_neg_transmit(); getResult();

return 0; }

THANK YOU