TCP/IP via http connection

You can use sockets, using http port (port 80), but for avoid firewall problems, the client must initiate the connection with the server.

If you have a webserver that can runs scripts (writen in Delphi, php or any other languaje), the easiest communication is use a Indy http client component and get urls calling to the scripts and pass to the scripts parameters for send data to the server.

What kind of client/server application is? what data will be send/received?

Have you consider using web services?

it's will work on Http and firewall friendly

Hi guys,
thank's for all of the comment, I really appreciate., application that I want to build is client server program which connected using tcp/ip connection, so they will be always connected, scuch as yahoo mesangeer,etc.
The problem of using tcp/ip connection is, sometimes firewall or architecture in client side doesn't allways allow tcp/ip connection.

Is the solution as simple as changing port to 80?

regards

Hi Radikal03,
That's right, what I meant by firewall is the networks firewall, and usually client terminal can navigate with browser directly, but the problem is usually the administraotr only allowing HTTP/HTTPS protocol, and as far as I know, I can't use those protocl to build real time connection as what I can do by using socket connection (TCP/IP).

I've read some interesting article about HTTP tunnelling, but I still can't figured out how to implement it using delphi?

matelindonesia!
use my Solution 2.

Did you try ICS (Internet Components Suite) - http://www.devarchive.com/f1340.html ?
It's free with sources. I used it recently and it looks very nice

Hi AFZDeveloper,
Sorry for being late giving response of yours, actually I've made client-server program which used your method (number 2), but I need something more realtime, just what tcp/ip based program, but still can run with some limitation environment, and that is the usage of Http/s protocol.

Sorry, I have never seen firewall that it discriminates protocols... only ports and IPs... (and maybe some kind of packets)
So that firewall can discriminate protocols, it would have to inspect the content that is sent through the connection.  I have never seen firewall thus.
I have done serveral programs that use tcp/ip connection trought the port 80 (witch a propietary protocol) and never had problems with firewalls...
Sorry, maybe my knowdeledge in this area is limited...

Via Google, I have found documents related this technique, called "HTTP Tunneling" and also "Port 80 Cloaking".
Consist in 'simulate' a http client-server conversation in order to be able to deceive to the firewall.
If this is you case, you can make this using indy http components (client and server) and using geturl in the client for get data and post (or get) method to send data to the server (with the loss of performance that that would entail with all the redundand data to be send&receive)

Or... you can also use a tcp/ip connection but... adding to the send data frames a copy of the the simplest http conversation between a http server and a http client for "simulate" the http protocol (I dont know the level of severity of that firewalls or how can they discriminate the http data).

Hai radikal03,
I think you're right about firewall, it just discriminates Ip an port, but how if the client side terminal connect to outside world via proxy server which can discriminate protocols, for exmaple yahoo masenger, there's connection preference which decide whether use no proxy,http proxy or socket proxy, can you give me an explanation what should I do to make such application like that? coz I didn't see any proxy property in Indy TCP component?

Ya, Ok.
You are talkink about a proxy connection, not a firewall...
In this case, tcpip indy connection havent got a proxy property because is not neccesary...

The rest of indy clients yes, have an proxy property to override the port... the client request the web page to the proxy trought a different port (by example port 8080) and then the proxy request the web page to the remote server trought the http port (80) and send it back to the client.

A proxy is not a transparent thing... its yo say: a http proxy server, listen in a port but, connect to outside using a different port, but it interprets the request... for example for make a web cache, deny a list of illegal urls, etc...

By example, a proxy can be listen the 8080 port, and, if it permits the connection, this request is made to the outside via 80 port, so... you tcpip indy component must use the proxy port, instead of use the direct port, but... an http proxy is not a bouncer... dont pass any kind of data, insted of this, the proxy is like a web server, make a conversation with the client so... is not valid for your propietary tcp/ip connection, unless the your disguises of ' HTTP conversation'...

I repeat this... if you want connect trought proxyes & firewalls, you must make you connection like a Web Explorer talking with a web server, and, in the middle... send and receive your data...

Ok then...,
let's talk about technical issue, can you show me what kind of component I can use to make tcp/ip connection through proxy port, or maybe if using existing default indy component, what should I've do to override those connect function with server via proxy server?

regards

You can make this with the standard http client & server Indy Components.
You can use any demo of idhttpserver and start working with it.

By example, this is a simple web server done with a TidHttpServer.
Simply put this in the OnCommandGet event:

procedure TForm1.IdHTTPServer1CommandGet(AThread: TIdPeerThread;
  ARequestInfo: TIdHTTPRequestInfo; AResponseInfo: TIdHTTPResponseInfo);
var
  html         : String;
  TheResponse  : string;
begin

  //Default response
  TheResponse:= 'No response for the commnad: '+ARequestInfo.Document;


  //Commands discriminate the request by the url requested
  if ARequestInfo.Document='/time' then begin
    TheResponse:='The time is:'+TimeToStr(Now);
  end;

  if ARequestInfo.Document='/date' then begin
    TheResponse:='The date is:'+DateToStr(Now);
  end;

  if ARequestInfo.Document='/command1' then begin
    TheResponse:= 'This is the answer for command1, and the params: '+ARequestInfo.UnparsedParams;
  end;

  AResponseInfo.ContentType := 'text/HTML';

  //Generate the response:
  html := '<html><head><title>Server Response</title></head><body>'+
          TheResponse+
          '</body></html>';
  AResponseInfo.ContentText := html;
end;

Now, you can test it, accesing to 'http://localhost' with you internet browser.
If you get the URL:  'http://localhost/time', the server will return the time of the server, id you request the URL 'http://localhost/date', the server will return the server's date, and if you request http://localhost/command1?parameter="Aparameter"&parameter2="OtherParameter" the server will return a copy of the command requested.
You can test it with your internet browser, and this will work in a client accesing to your server trought a proxy.... if he can navigate trought web pages, he can navigate trought your indy server.
Now, you can use Indy http client to make a private connection, for interactuate with your server.
Instead of request '/time', you can request... anything, and returns... anything, so... you have a valid connection for request & answer commands between your applications.
And... instead of connect trought 80 port, the client must connect with the proxy port (8080 is the usual port).
You can also use Post method for a longer send data capacity (the Get method is limited in long)

Hi RadikalO3,
Thanks for your code, but it is works on HTTTP protocol, what I mean after all is tcp/ip connection, just like chat program, but it can through proxy server, if use abovementioned code, than it was in http protocol.

Hufff...the code is a example of web server made with Indy.
We are talking about http tunneling trought http proxys no?, this example can send and receive data between two applications trought a http proxy server.
If you can connect trught a http proxy server, you cant use a tcp/ip connection, you must pass the data like http requests.
I think that this was clear in previous comments...

Is you question answered?

No not yet Eugene-biruza,
but I've found a component http tunnel for delphi, HTTPort by Dmitry Dvoinikov
That's exactly what I mean by http tunneling

matelindonesia,
glad to see that you resolved your problem. WHere did you find the HTTPort component? I'd like to look at it too :-)

Is your problem resolved? Maybe it would be fair to split points between guys who tried to help?