Sever Side Chat Application with Borland Delphi/Indy - Handling commands: name, file
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Command: name
When this command is received, the server searches for the specified recipient on the list and passes the message on. Here’s how:
procedure TMyContext.SendMsg(const ANick: String; const
AMsg:String);
var
List: TList;
Context: TMyContext;
I: Integer;
begin
//lock the list, so nothing is added while searching for the name
List := FContextList.LockList;
try
for I := 0 to List.Count-1 do
begin
//start the search
Context := TMyContext(List[I]);
if Context.Nick = ANick then
begin
try
//if found sent the message
Context.Connection.IOHandler.WriteLn(AMsg);
except
end;
Exit;
end;
end;
finally
FContextList.UnlockList;
end;
//if not found sent an error msg
Self.Connection.IOHandler.WriteLn('The name you send the
message to does not exist. Please click on ''Get list of Names on
Chat'' button to get a full list of names.');
end;
This procedure searches for the recipient name and sends the message on. If it does not find the name on the list, it sends an error msg back to the sender.
Command: file
procedure TMyContext.SendFile(const ANick,Fn:string);
var
List: TList;
Context: TMyContext;
I: Integer;
FStream,fstream2: TFileStream;
IdStream,idstream2: TIdStreamVCL;
MStream: TMemoryStream;
begin
// lock the list
List := FContextList.LockList;
try
for I := 0 to List.Count-1 do
begin
//search for the recipient name
Context := TMyContext(List[I]);
if Context.Nick = ANick then
begin
try
//found it, now create the file
FStream := TFileStream.Create(fn, fmOpenRead or
fmShareDenyWrite);
try
IdStream := TIdStreamVCL.Create(fstream);
try
//send it!
Context.Connection.IOHandler.WriteLn
('pic@'+fn+';Sending file...');
Context.Connection.IOHandler.Write(IdStream, 0,
True);
Context.Connection.IOHandler.WriteLn('done!');
finally
IdStream.Free;
end;
finally
FStream.Free;
end;
//if recipient name not found
except
end;
Exit;
end;
end;
finally
FContextList.UnlockList;
end;
Self.Connection.IOHandler.WriteLn(‘ The name you send the
message to does not exist. Please click on ''Get list of Names on
Chat'' button to get a full list of names.');
end;
This procedure basically sends the file to the intended recipient, like so:
Sender -->-----server---->----------->Recipient
As long as the recipient's name is on the list, the file will be sent to them.
This is not the world's most sophisticated chat application, but it can handle all of the basics found in chat applications like Microsoft Messenger and others. And it will be very easy to develop an image based chat by tweaking the procedures in this code.
Next
In the next installment we will finish off this part of the chat application.
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