Niu at 15:29, 11 April 2018

2018-04-11T15:29:57Z

Niu: Created page with "=== tcp_server and tcp_client === The main functions of the ''socket''-module are ''socket'', ''bind'', ''listen'', ''accept'', and ''connect''. The [http://www.sternwarte.un..."

2018-04-11T15:21:55Z

Created page with "=== tcp_server and tcp_client === The main functions of the ''socket''-module are ''socket'', ''bind'', ''listen'', ''accept'', and ''connect''. The [http://www.sternwarte.un..."

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=== tcp_server and tcp_client ===

The main functions of the ''socket''-module are ''socket'', ''bind'', ''listen'', ''accept'', and ''connect''. The [http://www.sternwarte.uni-erlangen.de/isis ISISscripts] functions [http://www.sternwarte.uni-erlangen.de/git.public/index.cgi?p=isisscripts;a=blob;f=src/misc/tcp.sl tcp_server and tcp_client] use these functions to provide a simple server-client-implementation.

===== Example: quick_send and quick_get =====
As an example usage for these functions, you can find the code of [http://www.sternwarte.uni-erlangen.de/git.public/index.cgi?p=isisscripts;a=blob;f=src/misc/quick_send_get.sl quick_send and quick_get] here:

<pre>
% LAYOUT
%
% quick_send quick_get
% tcp_server -> tcp_client
%

% global variable for the object: we need this globally to
% use the object during the hook functions (e.g., _quick_send)
private variable _quick_obj = NULL;
% name of the receiver (quick_send) or the sender (quick_get)
private variable _quick_host = "";

% greet_hook of quick_get (tcp_client): check the greet message of
% the server, which should be its hostname
define _quick_get_greet(c, greet) {
if (greet == _quick_host) { return getenv("HOST"); }
return 0;
}

%%%%%%%%%%%%%%%%%%%%
define quick_get()
%%%%%%%%%%%%%%%%%%%%
%!%+
%\function{quick_get}
%\synopsis{gets an SLang object sent from another machine}
%\usage{Any_Type quick_get(String_Type from_host);}
%\example
% % receive an object from 'indus'
% variable obj = quick_get("indus");
%\seealso{quick_send, tcp_client}
%!%-
{
switch (_NARGS)
{ case 1: (_quick_host) = (); }
{ help(_function_name); return; }

variable client;
% try to connect to the sender until a connection is established
do {
client = tcp_client(
_quick_host;
chatty = 0,
greet_hook = &_quick_get_greet % use user-defined greet message (see above)
);
% client == 0 -> connection failed, e.g., server is not running
if (typeof(client) == Integer_Type && client == 0) { sleep(1); }
} while (typeof(client) != Struct_Type);
% connection is established
if (typeof(client) == Struct_Type) {
% receive the object
client.config.chatty = 1; % enabled progress bar
_quick_obj = client.receive();
client.config.chatty = 0; % disable further messages
% disconnect from the server
()=client.disconnect();
% return the object
return _quick_obj;
}
}

% established_hook of quick_send (tcp_server): send the object and
% shut down the server afterwards
private define _quick_send(s, c) {
c.config.chatty = 1; % temporarily enable progress bar
()=c.send(_quick_obj);
()=s.shutdown();
}

% greet_hook of quick_send (tcp_server):
% 1) define the greet message to be sent to the client, which is
% the server's hostname
% 2) check if the re-greet message is equal to the expected receiver
private define _quick_send_greet() {
variable s, c, greet = NULL;
switch (_NARGS)
% send greet message
{ case 2:
(s,c) = ();
return getenv("HOST");
}
% check greet message
{ case 3:
(s,c,greet) = ();
if (greet == _quick_host) { return 1; }
% greet not accepted -> trigger the shutdown of the server
% after execution of its main loop
()=s.shutdown(; trigger);
return 0;
}
}

%%%%%%%%%%%%%%%%%%%%
define quick_send()
%%%%%%%%%%%%%%%%%%%%
%!%+
%\function{quick_send}
%\synopsis{sends an SLang object to another machine}
%\usage{quick_send(String_Type to_host, Any_Type object);}
%\example
% % send an array of doubles to 'ara'
% quick_send("ara", Double_Type[10000]);
%\seealso{quick_get, tcp_server}
%!%-
{
switch (_NARGS)
{ case 2: (_quick_host, _quick_obj) = (); }
{ help(_function_name); return; }

()=tcp_server(;
maxclients = 1,
chatty = 0,
greet_hook = &_quick_send_greet, % use user-defined greet message (see above)
established_hook = &_quick_send % send the object by this hook
);
}
</pre>

← Older revision		Revision as of 15:29, 11 April 2018
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Socket - Revision history

Niu at 15:29, 11 April 2018

Niu: Created page with "=== tcp_server and tcp_client === The main functions of the ''socket''-module are ''socket'', ''bind'', ''listen'', ''accept'', and ''connect''. The [http://www.sternwarte.un..."