Question

TCPClientSocket in Delphi 7

Asked by: Motaz

I'm trying to connect to a server using TCP/IP, and there are some problems and missconseptions:

1. I'm using Delphi 7, and I tried Indy and Internet TCP Sockets. I make two applications (Server and Client), in Server application I put only Server socket component and in client Client socket component. I can send messages to the server, but the server cann't send message to client. Which component is the best and how does it works?

2. When I'm trying to connect to a server, should I use only client socket or client+Server socket for sending and receiving.

Thanks
Motaz

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Asked On
2006-09-04 at 05:11:17ID21977338
Tags

delphi

,

7

,

socket

Topic

Delphi Programming

Participating Experts
5
Points
300
Comments
10

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Related Solutions

  1. mabrook Motaz:-)
    hi, first the word 'mabrook' means Congratulation in my and motaz language:-) Really you did it and you deserve it so mabrook again and again!!!!,try to take care from you backend not frontend:-) Regards Meer.
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Answers

 

by: mikelittlewoodPosted on 2006-09-04 at 05:15:45ID: 17449285

You need both sockets.
Are you locating the correct Client Connection property to send information to?

 

by: pcsentinelPosted on 2006-09-04 at 05:37:47ID: 17449392

This is the way the IOndy components are designed to work, therefor there is no direct method for the Server to send a message to a client.

There are 2 ways of handling this.

Firstly put a client and server socket on each application. that way both applications can send and receive messages.

Alternatively put a timer on the client.
On the Server do a WriteLn.
when the timer fires on the client, do a ReadLn with a timeout.

If a message is waiting you can then process it.

regards

 

by: jimyXPosted on 2006-09-04 at 06:10:51ID: 17449570

Sir you can send from client to server but when you want to send from server to client you must specify the connection that you want to send to(client).

 

by: jimyXPosted on 2006-09-04 at 06:16:25ID: 17449601

I always use TServerSocket & TClient Socket and it works fine with me.

 

by: ciulyPosted on 2006-09-04 at 12:52:09ID: 17451529

I don't agree with pcsentinel. bad idea.

instead, on the server, you can iterate through the threads property (indy 9) or contexts property (indy 10) which will give you all connections.

one example on what I said here: http://www.experts-exchange.com/Programming/Programming_Languages/Delphi/Q_21973896.html

also, you this only when you want to send a message from server to client when the client didn't just send anything. so the server just wants to send something.
if you want to send something to the client in response to an immendiat message from client, use the onexecute event (which will also give you the thread/connection that just sent the message)

 

by: TheRealLokiPosted on 2006-09-04 at 20:17:15ID: 17453129

It all depends on your program
If your program expects to work in alogical manner
eg.
1) Client sends command to server
2) Server sends response back to the client
3) Client then sends another command to the server....etc

Then you just need 1 server (on teh server app), and 1 client (on the client app)

The client code will look something like this (assuming indy 9)

tcpclient1.WriteLn('what time is it?')
s := tcpclient1.ReadLn;
label1.caption := s;
tcpclient1.WriteLn('thanks!')

the server code would look something like this


procedure TfServerMain.IdTCPServer1Execute(AThread: TIdPeerThread);
var
  s: string;
begin
  s := AThread.Connection.ReadLn;
  if s = 'what time is it?' then
    AThread.Connection.Writeln(datetimetostr(now));
  else if s = 'thanks!' then
    beep;
..


If, however, you wish to send a message from the server to *all* clients, you will need to iterate through the threadlist as mentioned above.

If however, you need to be able to send to a/many client(s), while the client is potentially sending to you - ie. without any natural flow control, then 1 way would be to use a server and client on EACH application (server and client apps)
The reason I say this, is that if you are sending a large amount of data (large buffer), you are unlikley to get the command sent to you, until you have finished. (even with threading)
If you have your own server (for receiving commands) then you can still receive commands in a timely fashion, while sending data.
This is how IRC chat works. you have a basic connection for the chatting, and you open a new connection specifically for sending files.
hth, Loki

 

by: jimyXPosted on 2006-09-04 at 22:43:15ID: 17453530

e.g :

  for j:=0 to SrvrScktFile.Socket.ActiveConnections-1 do
    begin
        SrvrScktFile.Socket.Connections[j].SendText('whatever you want');
    end;

 

by: ciulyPosted on 2006-09-04 at 23:16:14ID: 17453606

adding to lokis code/idea:
you can always create a nice protocol that sends command packets.
an example of a text-based protocol:
/command data

so when sending files you send the packets as a maximum of 1024 bytes for example (1 KB) which should go through pretty fast nowadays so even if you are sending a big file, yuo can always get some otehr commands inbetween (binary data sent in bas64 for example)

 

by: pcsentinelPosted on 2006-09-05 at 04:12:15ID: 17454706

Sorry I thought that the author wanted to send an message from the server back to a client kicked from a server event, in that case you either need a keep alive timer or a client and server on both ends as per my post

 

by: TheRealLokiPosted on 2006-09-05 at 05:39:53ID: 17455160

another difference between the Indy components, and the standard sockets.
indy is a "blocking"  whilst the standard sockets can be non blocking
what this means is that when you go

s := idtcpclient1.ReadLn;
label1.caption := s;
delphi will not move to the "label1.caption := s;" line until it has received a string (with cr/lf at the end) from the indy connection.

with the sockets, you get an OnRead() event when there is data available.

20120131-EE-VQP-002

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