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cks · Guest

i need to create a Server & Client with Indy component.

My server will need to send command to Client to order it to performance
some job.
Example. Send 'shutdown' to client, then Client will shutdown the PC.
or another way, Send 99, to client to do the same things. (let say 99 means
shut down)

Question 1. Can someone tell me which method is suitable, or any other
method is the best choice?

Question 2. How if sometimes i need to send command 99, 88, 11, and
sometimes the certain command
are passed with parameters in string.

Example: command 88 will show a message dialog, but we need to pass 88 with
'Hi, this is testing' string
or just send everything in string, and extract the meanings from the string?

Question 3. Performance issues on different methods?

thanks in advance

Remy Lebeau (TeamB) · Guest

"cks" <chuaks (AT) dynabook (DOT) com.my> wrote

Ioan Ghip · Guest

Ioan Ghip · Guest

Colonel Tony · Guest

use a tstringlist, then send the commatext with writeln

i.e.
mystringlist.values['command']:= '88';
mystringlist.values['msgstr']:=''Hi, this is testing string';

to send to the server do

myclient.writeln(mystringlist.commatext);
what gets sent across the wire is:
command=88,msgstr="Hi, this is testing string"

if you need to send a multi line message use another tstringlist or
descendent and assign it's commatext to the msgstr value of the first.

mystringlist.values['msgstr']:= memo1.lines.commatext;

Then on the other side create a recieving stringlist and set the commatext

commandlist.commatext:= athread.connection.readln('',5000);
if commandlist.values['command'] = '88' then
begin
//do something with the message
end;

or you could just use readinteger and writeinteger to send just the bytes
for the command.
Either way it's all very easy to do with blocking sockets.

Performance for the stringlist method is good and it is easy to understand
and read the code. Also using stringlists has much less bloat than some xml
based protocols, and you could easily compress your stringlist and stream it
over if you have alot of params/text :-)

Hope this helps you out.

Tony

Remy Lebeau (TeamB) · Guest

"Ioan Ghip" <aaabbb (AT) ccc (DOT) com> wrote

(Typo aside) Rather than forcing every packet to include a fixed sized text
field that may or may not be used at all let alone filled to capacity, you
could use a dynamic-sized field instead. For example:

type
TCommHeader = packed record
Command: Integer;
DataSize: Integer;
end;

TCommBlock = packed record
Header: TCommHeader;
Data: String;
end;

const
CMD_MSGBOX = 88;

--- Client ---

procedure SendCommBlock(AConn: TIdTCPConnection; var SndCmd:
TCommBlock);
begin
AConn.WriteBuffer(SndCmd.Header, SizeOf(SndCmd.Header));
if SndCmd.Header.DataSize > 0 then AConn.Write(SndCmd.Data);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
SendCmd: TCommBlock;
begin
//...
SndCmd.Data := 'bye bye';
SndCmd.Header.Command := CMD_MSGBOX;
SndCmd.Header.DataSize := Length(SndCmd.Data);
SendCommBlock(IdTCPClient1, SndCmd);
//..
end;

--- Server ---

procedure ReadCommBlock(AConn: TIdTCPConnection; var RecCmd:
TCommBlock);
begin
AConn.ReadBuffer(RecCmd.Header, SizeOf(RecCmd.Header));
if RecCmd.Header.DataSize > 0 then RecCmd.Data :=
AConn.ReadString(RecCmd.Header.DataSize);
end;

procedure TForm1.IdTCPServer1Execute(AThread: TIdPeerThread);
var
RecCmd: TCommBlock;
begin
//...
ReadCommBlock(Athread.Connection, RecCmd);

if RecCmd.Command = CMD_MSGBOX then
begin
Windows.MessageBox(nil, PChar(RecCmd.Data), 'Client Message',
MB_OK);
end;

//...
end;

Gambit

Remy Lebeau (TeamB) · Guest

"Colonel Tony" <tcaduto (AT) amsoftwaredesign (DOT) com> wrote

cks · Guest

if i have many commands need to be identify,
is it good to code everything inside the IdTCPServer1Execute

means inside the IdTCPServer1Execute will have a lot of if (or case)
if cmd = '88'
...
if cmd = '89'
...
if cmd = '90'
if msg = 'xxxxx'
....
if msg = 'yyyy'
...
...
...
...

just to figure out whether this is the normal way people doing ALL the
'processess' inside Execute ?
or is there any other way of doing ?

Remy Lebeau (TeamB) · Guest

"cks" <chuaks (AT) dynabook (DOT) com.my> wrote

Tony Caduto · Guest

Remy Lebeau (TeamB) wrote: