When i try to implement a server program giving UDP as protocol , it works fine , but if the same c

[Tompyna]

Hi All,

I am a newbie to Socket Programming . I had written a socket
program in perl , implementing client and server.

Now coming to the problem i am stuck:

1.When i implement the program with "UDP" as protocol option, the code
works
fine,but When i try to implement the same program , giving TCP as
the
protocol option, it gives me an error:
"Can't call method "recv" on an undefined value at servermodulenew.pl
line 18"

I believe the method "recv" should be called irrespective of the
protocol option i give.

Hope someone could possibly give me an answer to this problem.

(Below is the code for server implementation)
NOTE: The program is executing on solaris and run as a background
process.

The server Program i implemented is:

/************************************************/
# Server Program

use IO::Socket;

my $port = 1024;

#use ngd_simulator::thomasp:erl::Socket;

my $receive_status;

print ">> Server Program <<\n";

# Create a new socket
$MySocket=new IO::Socket::INET->new(LocalPort=>($port),Proto=>(getprotobyname('udp')));

while(1)
{
#Receiving a message from the client
$receive_status = $MySocket->recv($text,128);

if($text ne '')
{
print "\nReceived message ===>", $text,"\n";

}
# If client message is empty exit
else
{
print "Cilent has exited!";
exit 1;

}
}
#Close the Socket after sending the message
close($MySocket);

/******************************************************/



Thanx.... in advance,
Thomas Poly.

 

[gnari]

1.When i implement the program with "UDP" as protocol option, the code
works
fine,but When i try to implement the same program , giving TCP as
the
protocol option, it gives me an error:
"Can't call method "recv" on an undefined value at servermodulenew.pl
line 18"

I believe the method "recv" should be called irrespective of the
protocol option i give.

UDP is connectionless, TCP is not.

with TCP you have to
make socket
listen
accept connections when they arrive
and then read data

gnari

 

[thumb_42]

1.When i implement the program with "UDP" as protocol option, the code
works
fine,but When i try to implement the same program , giving TCP as
the
protocol option, it gives me an error:
"Can't call method "recv" on an undefined value at servermodulenew.pl
line 18"

Thats because TCP doesn't have a recv.

UDP is connection-less, you're responsible for any network errors and
dropped packets, it has a lot in common with the US postal service, in that
it will loose your mail and not care.

TCP is more like a phone connection, so the methods are different.

(TCP and UNIX sockets are a lot like working with file handles)

Jamie

 

[Anno Siegel]

[...]

1.When i implement the program with "UDP" as protocol option, the code
works
fine,but When i try to implement the same program , giving TCP as
the
protocol option, it gives me an error:
"Can't call method "recv" on an undefined value at servermodulenew.pl
line 18"
[...]

The server Program i implemented is:

/************************************************/
# Server Program

No strict, no warnings. Switch them on.

use IO::Socket;

my $port = 1024;

#use ngd_simulator::thomasp:erl::Socket;

my $receive_status;

print ">> Server Program <<\n";

# Create a new socket
$MySocket=new

You have declared other variables lexicals. Why is $MySocket a package
variable?

IO::Socket::INET->new(LocalPort=>($port),Proto=>(getprotobyname('udp')));

This is the statement that returns an undefined value for $MySocket. Why
don't you ask why?

my $MySocket = new IO::Socket::INET->new(
LocalPort=>($port),Proto=>(getprotobyname('udp'))) or
die "Socket error: $!";

I notice that you call the new() method twice in that statement, once as
as class method and once as an object method. I don't think you want to
do that.

[rest snipped]

Anno

 

[Dr. Ugo Gagliardelli]

Hi All,

I am a newbie to Socket Programming . I had written a socket
program in perl , implementing client and server.

Now coming to the problem i am stuck:

1.When i implement the program with "UDP" as protocol option, the code
works
fine,but When i try to implement the same program , giving TCP as
the
protocol option, it gives me an error:
"Can't call method "recv" on an undefined value at servermodulenew.pl
line 18" [cut]
# Create a new socket
$MySocket=new IO::Socket::INET->new(LocalPort=>($port),Proto=>(getprotobyname('udp')));

while(1)
{
#Receiving a message from the client
$receive_status = $MySocket->recv($text,128);

if($text ne '')

As far as I know to use a connection oriented socket in general (with recv as
well), as tcp is, you must connect first.