Code:

{

Loading Delphi apps without a browser and on Win as Linux as well needs a

decision once.

With a loader on the client side, no further installation is in charge.

We had the requirement starting different Delphi apps from a

linux or windows server, wherever you are.

We call it Delphi Web Start (DWS).

The dws-client gets a list and after clicking on it, the app is

loading from server to client with just a stream.

First we had to choose between a ftp and a tcp solution. The

advantage of tcp is the freedom to define a separate port, which

was "services, port 9010 - DelphiWebStart".

You will need indy. Because it is simple to use and very fast.

The tcp-server comes from indy which has one great advantage:

CommandHandlers is a collection of text commands that will be

processed by the server. This property greatly simplify the

process of building servers based on text protocols.

First we start with DWS_Server,

so we define two command handlers:

}

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 Morth 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

}