BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Closing a TidTCPServer app remotely          BorlandTalk.com Forum Index -> Delphi Internet Winsock View previous topic :: View next topic   Author Message PeterP Guest Posted: Sun May 13, 2007 8:04 pm    Post subject: Closing a TidTCPServer app remotely Hi, all- Please excuse me if this question has been answered previously - there has been a great deal of discussion about how to shut down TidTCPServer, but I wasn't able to locate anything that related to my problem. I'd like to be able to shut down an application which has an instance of TidTCPServer in it, via a command from a client. That is, among all the commands that any client can send to the server, one is "SHUTDOWN", and I want that command to cause the server process to exit. In the command handler for the "shutdown" command I tried the naive procedure TForm1.ShutDownCmd(ASender: TIdCommand); begin server.active := false; Form1.Release; end; which of course doesn't work, as many other people have discovered. There can be multiple clients connected at the time this command arrives, hence multiple threads. Presumably I have to kill all the other threads and then tell the main thread to exit - is that it? I'm new to thread programming, so some guidance here would be greatly appreciated. Thanks Peter --- posted by geoForum on http://delphi.newswhat.com Back to top Jamie Dale Guest Posted: Sun May 13, 2007 8:11 pm    Post subject: Re: Closing a TidTCPServer app remotely TIdTCPServer cannot be shut down from one of it's own threads. If you want to shut it down then you would need to do it from the main program thread. For that reason, I think the best method would be to send a message to the main thread, so that it can de activate the server. "PeterP" <aaa (AT) nowhere (DOT) ca> wrote in message news:46471dbf$1 (AT) newsgroups (DOT) borland.com... Quote: Hi, all- Please excuse me if this question has been answered previously - there has been a great deal of discussion about how to shut down TidTCPServer, but I wasn't able to locate anything that related to my problem. I'd like to be able to shut down an application which has an instance of TidTCPServer in it, via a command from a client. That is, among all the commands that any client can send to the server, one is "SHUTDOWN", and I want that command to cause the server process to exit. In the command handler for the "shutdown" command I tried the naive procedure TForm1.ShutDownCmd(ASender: TIdCommand); begin server.active := false; Form1.Release; end; which of course doesn't work, as many other people have discovered. There can be multiple clients connected at the time this command arrives, hence multiple threads. Presumably I have to kill all the other threads and then tell the main thread to exit - is that it? I'm new to thread programming, so some guidance here would be greatly appreciated. Thanks Peter --- posted by geoForum on http://delphi.newswhat.com Back to top Jamie Dale Guest Posted: Sun May 13, 2007 8:13 pm    Post subject: Re: Closing a TidTCPServer app remotely One other thought, you could use a message queue - Like a TLIST. You could have the main program create another TThread which loops through the TList continually and execute your custom commands. The TThread should (I think) be able to close down the TIdTCPServer as long as it isn't one of the servers own threads. HTH "PeterP" <aaa (AT) nowhere (DOT) ca> wrote in message news:46471dbf$1 (AT) newsgroups (DOT) borland.com... Quote: Hi, all- Please excuse me if this question has been answered previously - there has been a great deal of discussion about how to shut down TidTCPServer, but I wasn't able to locate anything that related to my problem. I'd like to be able to shut down an application which has an instance of TidTCPServer in it, via a command from a client. That is, among all the commands that any client can send to the server, one is "SHUTDOWN", and I want that command to cause the server process to exit. In the command handler for the "shutdown" command I tried the naive procedure TForm1.ShutDownCmd(ASender: TIdCommand); begin server.active := false; Form1.Release; end; which of course doesn't work, as many other people have discovered. There can be multiple clients connected at the time this command arrives, hence multiple threads. Presumably I have to kill all the other threads and then tell the main thread to exit - is that it? I'm new to thread programming, so some guidance here would be greatly appreciated. Thanks Peter --- posted by geoForum on http://delphi.newswhat.com Back to top Marais Guest Posted: Mon May 14, 2007 5:37 pm    Post subject: Re: Closing a TidTCPServer app remotely This looks like a good start. In the command handler I have procedure TForm1.ShutDownCmd(ASender: TIdCommand); var MsgResult : LongBool; begin asender.thread.connection.Disconnect; MsgResult := PostMessage(form1.Handle, CM_SHUTDOWN, 0, 0); end; and in the main thread's message handler, I have procedure TForm1.CMShutdown(var Message: TMessage); begin memo1.Lines.add ('Shutdown received.'); server.active := false; Form1.Release; {probably redundant} application.Terminate; inherited; {probably redundant} end; For testing, I establish three Telnet connections, and I send the shutdown command from one of them. With the above code, at some point before the app shuts down (at least in the IDE) I get two EIDClosedSocket exceptions. Is there some way to traverse the active connections, shut them down cleanly, and then terminate the application? Peter "Jamie Dale" <jamie.dale (AT) yahoo (DOT) com> wrote in message news:46473117$1 (AT) newsgroups (DOT) borland.com... Quote: One other thought, you could use a message queue - Like a TLIST. You could have the main program create another TThread which loops through the TList continually and execute your custom commands. The TThread should (I think) be able to close down the TIdTCPServer as long as it isn't one of the servers own threads. HTH "PeterP" <aaa (AT) nowhere (DOT) ca> wrote in message news:46471dbf$1 (AT) newsgroups (DOT) borland.com... Hi, all- Please excuse me if this question has been answered previously - there has been a great deal of discussion about how to shut down TidTCPServer, but I wasn't able to locate anything that related to my problem. I'd like to be able to shut down an application which has an instance of TidTCPServer in it, via a command from a client. That is, among all the commands that any client can send to the server, one is "SHUTDOWN", and I want that command to cause the server process to exit. In the command handler for the "shutdown" command I tried the naive procedure TForm1.ShutDownCmd(ASender: TIdCommand); begin server.active := false; Form1.Release; end; which of course doesn't work, as many other people have discovered. There can be multiple clients connected at the time this command arrives, hence multiple threads. Presumably I have to kill all the other threads and then tell the main thread to exit - is that it? I'm new to thread programming, so some guidance here would be greatly appreciated. Thanks Peter --- posted by geoForum on http://delphi.newswhat.com Back to top Remy Lebeau (TeamB) Guest Posted: Mon May 14, 2007 10:51 pm    Post subject: Re: Closing a TidTCPServer app remotely "PeterP" <aaa (AT) nowhere (DOT) ca> wrote in message news:46471dbf$1 (AT) newsgroups (DOT) borland.com... Quote: In the command handler for the "shutdown" command I tried the naive You can't do it that way. Setting the Active property inside a command handler is a guaranteed deadlock. The Active property setter closes all of the client sockets and then waits for all of the threads to terminate. But the thread doing the shutdown is waiting for the Active property setter to exit - a catch 22. You need to post an asynchronous request to another thread (such as the main thread) and let that thread handle the shutdown. You could use PostMessage() to send a message to the MainForm window, and then let its message handler do the shutdown. Or use the TIdNotify class instead. Quote: Presumably I have to kill all the other threads and then tell the main thread to exit - is that it? No. Gambit Back to top Remy Lebeau (TeamB) Guest Posted: Mon May 14, 2007 10:57 pm    Post subject: Re: Closing a TidTCPServer app remotely "Marais" <marais (AT) x (DOT) y> wrote in message news:SJY1i.13012$Xh3.7562@edtnps90... Quote: MsgResult := PostMessage(form1.Handle, CM_SHUTDOWN, 0, 0); You have to be careful using the Handle property in a worker thread like that. It is not thread-safe, and can cause problems if the TForm happens to recreate its HWND at the same time, such as during a property change that requires the HWND to be refreshed. It would be better to use PostThreadMessage() instead (there is a global MainThreadID variable available), and then use the TApplication.OnMessage event. Or use the TIdNotify class instead. Quote: Form1.Release; {probably redundant} Yes, that is redundant. There is no need for a form to free itself like that, especially during a shutdown. Also, instead of calling Application.Terminate(), you could just close the MainForm instead. Which will trigger the OnCloseQuery and OnClose events, allowing the MainForm to override the client's request to shut down the program if it wants/needs to. Quote: With the above code, at some point before the app shuts down (at least in the IDE) I get two EIDClosedSocket exceptions. That is perfectly normal. You can ignore those. When you set the Active property to False, the active client sockets where closed, but their threads were still running and the exceptions occured when the threads tried to read the next command on each socket before detecting the termination. Since you are inside the debugger, you see the exceptions. You will not see them when the program is run outside the debugger. And they ar raised in the context of the threads, so the active connections will be shut down quitely and gracefully by TIdTCPServer internally. Quote: Is there some way to traverse the active connections, shut them down cleanly, and then terminate the application? You don't need to do that yourself. TIdTCPServer handles all of that for you. Gambit Back to top Marais Guest Posted: Tue May 15, 2007 2:16 am    Post subject: Re: Closing a TidTCPServer app remotely Remy- Thanks for this. I wasn't aware that the window handle could change. I've implemented your suggestions and all is now well. I have another question, but that will be the subject of a separate posting. 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