Mega Code Archive
How to do an application loader with TCP
<![CDATA[
Title: How to do an application loader with TCP
CTR_LIST = 'return_list';
CTR_FILE = 'return_file';
{
By starting the tcp-server it returns with the first command
handler "CTR_LIST" a list of the apps:
}
procedure TForm1.IdTCPServer1Execute(AThread: TIdPeerThread);
...
// comes with writeline from client
if sRequest = CTR_LIST then begin
for idx:= 0 to meData.Lines.Count - 1 do
athread.Connection.WriteLn(ExtractFileName(meData.Lines[idx]));
aThread.Connection.WriteLn('::END::');
aThread.Connection.Disconnect;
{
One word concerning the thread:
In the internal architecture there are 2 threads categories.
First is a listener thread that "listen" and waits for a
connection. So we don't have to worry about threads, the built in
thread will be served by indy though parameter:
}
IdTCPServer1Execute(AThread: TIdPeerThread)
{
When our dws-client is connected, this thread transfer all the
communication operations to another thread.
This technique is very efficient because your client application
will be able to connect any time, even if there are many
different connections to the server.
}
//The second command "CTR_FILE" transfers the app to the client:
if Pos(CTR_FILE, sRequest) 0 then begin
iPos := Pos(CTR_FILE, sRequest);
FileName := GetFullPath(FileName);
if FileExists(FileName) then begin
lbStatus.Items.Insert(0, Format('%-20s %s',
[DateTimeToStr(now), 'Transfer starts ...']));
FileStream := TFileStream.Create(FileName, fmOpenRead +
fmShareDenyNone);
aThread.Connection.OpenWriteBuffer;
aThread.Connection.WriteStream(FileStream);
aThread.Connection.CloseWriteBuffer;
FreeAndNil(FileStream);
aThread.Connection.Disconnect;
{
Now let's have a look at the client side. The client connects to
the server, using the connect method of TIdTcpClient. In this
moment, the client sends any command to the server, in our case
(you remember DelphiWebStart) he gets the list of available apps:
}
with IdTCPClient1 do begin
if Connected then DisConnect;
showStatus;
Host:= edHost.Text;
Port:= StrToInt(edPort.Text);
Connect;
WriteLn(CTR_LIST);
//After clicking on his choice, the app will be served:
with IdTCPClient1 do begin
ExtractFileName(lbres.Items[lbres.ItemIndex])]));
WriteLn(CTR_FILE + lbres.Items[lbres.ItemIndex]);
FileName:= ExpandFileName(edPath.Text + '/' +
ExtractFileName(lbres.Items[lbres.ItemIndex]));
...
FileStream := TFileStream.Create(FileName, fmCreate);
while connected do begin
ReadStream(FileStream, -1, true);
....
{$IFDEF LINUX}
execv(pchar(filename),NIL);
//libc.system(pchar(filename));
{$ENDIF}
{$IFDEF MSWINDOWS}
// shellapi.WinExec('c:\testcua.bat', SW_SHOW);
with lbstatus.items do begin
case shellapi.shellExecute(0,'open', pchar(filename), '',NIL,
SW_SHOWNORMAL) of
0: insert(0, 'out of memory or resources');
ERROR_BAD_FORMAT: insert(0, 'file is invalid in image');
ERROR_FILE_NOT_FOUND: insert(0,'file was not found');
ERROR_PATH_NOT_FOUND: insert(0,'path was not found');
end;
Insert(0, Format('%-20s %s',
[DateTimeToStr(now), filename + ' Loaded...']));
end
{$ENDIF}
{
One note about execution on linux with libc-commands; there will
be better solutions (execute and wait and so on) and we still
work on it, so I'm curious about comments on
"Delphi Web Start"
therfore my aim is to publish improvments in a basic framework on
sourceforge.net depends on your feedback ;)
Many thanks to Dr. Karlheinz M?rth with a first glance.
Test your server with the telnet program. Type telnet
hostname:9010 and then: 'return_list' and you'll get the list
from the apps you defined in a txt-file on the server.
}
meData.Lines.LoadFromFile(ExpandFileName(FILE_PATH));
{
I know that we haven't implement an error handling procedure,
but for our scope this example is almost
sufficient.
Code is available: http://max.kleiner.com/download/dws.zip
}
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