BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  TServerSocket SendText Exception Goto page 1, 2  Next          BorlandTalk.com Forum Index -> C++ Builder (Internet Socket) View previous topic :: View next topic   Author Message Eric Patterson Guest Posted: Mon Apr 17, 2006 3:03 pm    Post subject: TServerSocket SendText Exception I am having this akward exception being thrown randomly by the SendText method in a TServerSocket component. I check to make sure there is an active connection right before I do a SendText and pass it an ansistring. The exception is being thrown at random times usually after running more then 6 hours. The exception that is being thrown is an invalid integer exception. Then right after that one, the same line throws an eaccess violation. As anyone seen this problem before or know what is wrong. Here is my code snippet: while(Server->ServerSocket1->Socket->Connections[ii]->SendText(AnsiString(AMsg+"\n"))==-1) { Sleep(10); // allow some time for Socket to send the queued up data. } I am using BCD 5. Thanks. Eric Back to top Remy Lebeau (TeamB) Guest Posted: Mon Apr 17, 2006 6:03 pm    Post subject: Re: TServerSocket SendText Exception "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:44439c71$1 (AT) newsgroups (DOT) borland.com... Quote: I check to make sure there is an active connection right before I do a SendText and pass it an ansistring. Your code is not using SendText() correctly in general. You are not taking into account that SendText() may not send all of your data in a single operation, requiring you to re-call SendText() multiple times in a loop in order to send all of your string. Please go to http://www.deja.com and search through the newsgroup archives. Sample code has been posted many times before. The exception is being thrown at random times usually after running more Quote: then 6 hours. The exception that is being thrown is an invalid integer exception. Do you mean that you are getting an EListError exception with a message of "List index out of bounds (12345)" ? If so, then the only way that particular exception can occur in the code you showed is if you are passing an incorrect index value to the Connections[] property. Gambit Back to top Eric Patterson Guest Posted: Mon Apr 17, 2006 7:03 pm    Post subject: Re: TServerSocket SendText Exception After thinking a minute, what about this: int len = AMsg.Length(); while(len > 0) { len -= Server->ServerSocket1->Socket->Connections[ii]->SendText(AnsiString(AMsg+"\n")) if( len != 0) { Sleep(10); // allow some time for Socket to send the queued up data. } } That way it will continue to send until no more length is detected. The only thing I don't like is that when it returns a negative value I won't do anything but add to my length (which is probably wrong) but I figure if a negative is returned then the OnError event should catch it. Eric "Remy Lebeau (TeamB)" <no.spam (AT) no (DOT) spam.com> wrote in message news:4443ca2a$1 (AT) newsgroups (DOT) borland.com... Quote: "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:44439c71$1 (AT) newsgroups (DOT) borland.com... I check to make sure there is an active connection right before I do a SendText and pass it an ansistring. Your code is not using SendText() correctly in general. You are not taking into account that SendText() may not send all of your data in a single operation, requiring you to re-call SendText() multiple times in a loop in order to send all of your string. Please go to http://www.deja.com and search through the newsgroup archives. Sample code has been posted many times before. The exception is being thrown at random times usually after running more then 6 hours. The exception that is being thrown is an invalid integer exception. Do you mean that you are getting an EListError exception with a message of "List index out of bounds (12345)" ? If so, then the only way that particular exception can occur in the code you showed is if you are passing an incorrect index value to the Connections[] property. Gambit Back to top Eric Patterson Guest Posted: Mon Apr 17, 2006 7:03 pm    Post subject: Re: TServerSocket SendText Exception Thanks for the insight. I understand what you mean but can't find an example on the newsgroup to help. So I should continue to call SentText until it returns a value of ???. I would think zero but it does state that the return value can be less then zero also. What values less then zero can be returned and what do they mean? Should an OnError event be written since I will continue to SendText until it goes through? Since I am writing the same message to multiple connected clients can I use the OnClientWrite event somehow? Thanks. Eric "Remy Lebeau (TeamB)" <no.spam (AT) no (DOT) spam.com> wrote in message news:4443ca2a$1 (AT) newsgroups (DOT) borland.com... Quote: "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:44439c71$1 (AT) newsgroups (DOT) borland.com... I check to make sure there is an active connection right before I do a SendText and pass it an ansistring. Your code is not using SendText() correctly in general. You are not taking into account that SendText() may not send all of your data in a single operation, requiring you to re-call SendText() multiple times in a loop in order to send all of your string. Please go to http://www.deja.com and search through the newsgroup archives. Sample code has been posted many times before. The exception is being thrown at random times usually after running more then 6 hours. The exception that is being thrown is an invalid integer exception. Do you mean that you are getting an EListError exception with a message of "List index out of bounds (12345)" ? If so, then the only way that particular exception can occur in the code you showed is if you are passing an incorrect index value to the Connections[] property. Gambit Back to top Eric Patterson Guest Posted: Mon Apr 17, 2006 8:03 pm    Post subject: Re: TServerSocket SendText Exception What about this: int len = AMsg.Length(); while(len > 0) { int sendReturn = Server->ServerSocket1->Socket->Connections[ii]->SendText(AnsiString(AMsg+"\n")); if(sendReturn == -1) { //need to wait for OnClientWrite while( OnClientWriteBool != true ) { Sleep(10); } OnClientWriteBool = false; }else { len -= sendReturn; } if( len != 0) { Sleep(10); // allow some time for Socket to send the queued up data. } } The OnClientWriteBool is turned 'true' by the OnClientWrite event. Eric "Remy Lebeau (TeamB)" <no.spam (AT) no (DOT) spam.com> wrote in message news:4443ca2a$1 (AT) newsgroups (DOT) borland.com... Quote: "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:44439c71$1 (AT) newsgroups (DOT) borland.com... I check to make sure there is an active connection right before I do a SendText and pass it an ansistring. Your code is not using SendText() correctly in general. You are not taking into account that SendText() may not send all of your data in a single operation, requiring you to re-call SendText() multiple times in a loop in order to send all of your string. Please go to http://www.deja.com and search through the newsgroup archives. Sample code has been posted many times before. The exception is being thrown at random times usually after running more then 6 hours. The exception that is being thrown is an invalid integer exception. Do you mean that you are getting an EListError exception with a message of "List index out of bounds (12345)" ? If so, then the only way that particular exception can occur in the code you showed is if you are passing an incorrect index value to the Connections[] property. Gambit Back to top Remy Lebeau (TeamB) Guest Posted: Mon Apr 17, 2006 10:03 pm    Post subject: Re: TServerSocket SendText Exception "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:4443e13c$1 (AT) newsgroups (DOT) borland.com... Quote: What about this: You are still not checking the reason why -1 is being returned. The only condition that is valid for the OnWrite event to be triggered is when WSAGetLastError() returns WSAEWOULDBLOCK. You are also not taking into account that non-blocking sockets require window messages to be processed in order for the OnWrite event to be triggered at all, so your code is going to deadlock indefinately since you do not process pending messages at all. And you are still not adjusting the writing to not send characters that have already been sent. Gambit Back to top Remy Lebeau (TeamB) Guest Posted: Mon Apr 17, 2006 10:03 pm    Post subject: Re: TServerSocket SendText Exception "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:4443d955$1 (AT) newsgroups (DOT) borland.com... Quote: I understand what you mean but can't find an example on the newsgroup to help. Did you do a search for SendText? Did you search for SendBuf()? I know that code examples exist in the archives on this topic. SendText() calls SendBuf() internally. Since SendText() does not allow you specify an index into the string, it is generally more efficient to call SendBuf() directly and not use SendText() at all. Quote: So I should continue to call SentText until it returns a value of ???. That is not the way to handle it. If you want to send 50 characters, and SendText() only accepts 10, you have to remove the first 10 from the string and then call SendText() again pass in only the remaining 40 characters, repeating as needed until all 50 characters have been sent. Quote: I would think zero No. A return value of zero means that the socket was disconnected by the other party. Quote: but it does state that the return value can be less then zero also. That means that a socket error occured. You have to use WSAGetLastError() to find out which error occured. The only error you can safely ignore is WSAEWOULDBLOCK. Quote: What values less then zero can be returned -1 is the only one. It is the same value as SOCKET_ERROR, as SendText() (and SendBuf()) simply returns whatever value the socket API send() function returns. Quote: Should an OnError event be written since I will continue to SendText until it goes through? If an error other than WSAEWOULDBLOCK occurs, SendText() will throw an exception, unless the OnError event handler prevents it. Quote: Since I am writing the same message to multiple connected clients can I use the OnClientWrite event somehow? The only time the OnWrite event is triggered is when a socket becomes writable after a blocking send occured on a non-blocking socket. When send() returns SOCKET_ERROR and WSAGetLastError() then returns WSAEWOULDBLOCK, nothing can be sent to that socket until the OnWrite event occurs. Any attempt to send data before that time will just produce more WSAEWOULDBLOCK errors. Gambit Back to top Remy Lebeau (TeamB) Guest Posted: Mon Apr 17, 2006 10:03 pm    Post subject: Re: TServerSocket SendText Exception "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:4443dd4e (AT) newsgroups (DOT) borland.com... Quote: After thinking a minute, what about this: snip That way it will continue to send until no more length is detected. No, because you are re-sending the entire string contents every time, even for portions of it that are successfully sent in previous loop iterations. Youare not adjusting the sending to send only the characters that are actually pending. A more accurate approach is as follows: TCustomWinSocket *Socket = Server->ServerSocket1->Socket->Connections[ii]; AnsiString temp = AMsg + "\n"; int len; while( temp.Length() > 0 ) { len = Socket->SendText(temp); if( len > 0 ) { temp = temp.SubString(len+1, MaxInt); continue; } if( (len == -1) && (WSAGetLastError() == WSAEWOULDBLOCK) ) { Sleep(10); continue; } break; } Alternatively: TCustomWinSocket *Socket = Server->ServerSocket1->Socket->Connections[ii]; AnsiString temp = AMsg + "\n"; int sent, len = temp.Length(); char *ptr = temp.c_str(); while( len > 0 ) { sent = Socket->SendBuf(ptr, len); if( sent > 0 ) { ptr += sent; len -= sent; continue; } if( (sent == -1) && (WSAGetLastError() == WSAEWOULDBLOCK) ) { Sleep(10); continue; } break; } Quote: I figure if a negative is returned then the OnError event should catch it. SendText/Buf() will still return the negative value regardless of whether the OnError event is used. All the OnError event can do is choose whether to stop the error from throwing an exception or not. Gambit Back to top Eric Patterson Guest Posted: Wed Apr 19, 2006 1:03 pm    Post subject: Re: TServerSocket SendText Exception Thank you for all your help. Eric "Remy Lebeau (TeamB)" <no.spam (AT) no (DOT) spam.com> wrote in message news:4443ca2a$1 (AT) newsgroups (DOT) borland.com... Quote: "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:44439c71$1 (AT) newsgroups (DOT) borland.com... I check to make sure there is an active connection right before I do a SendText and pass it an ansistring. Your code is not using SendText() correctly in general. You are not taking into account that SendText() may not send all of your data in a single operation, requiring you to re-call SendText() multiple times in a loop in order to send all of your string. Please go to http://www.deja.com and search through the newsgroup archives. Sample code has been posted many times before. The exception is being thrown at random times usually after running more then 6 hours. The exception that is being thrown is an invalid integer exception. Do you mean that you are getting an EListError exception with a message of "List index out of bounds (12345)" ? If so, then the only way that particular exception can occur in the code you showed is if you are passing an incorrect index value to the Connections[] property. Gambit Back to top Eric Patterson Guest Posted: Thu Apr 20, 2006 4:03 pm    Post subject: Re: TServerSocket SendText Exception Mr. Gambit I believe I understand how the ServerSocket should be used. I have though had this setup working flawlessly until I moved to windows xp; I was running on nt which makes me reluctent to change my code drastically. I did finally get a good stack call trace of the exception that is being thrown and it is an invalid pointer exception and the stack looks like this: Module Unit Method Line ----------------------------------------------------- VCL50.BPL System.pas _FreeMem VCL50.BPL System.pas _LStrClr VmeServer.exe MsgServer.cpp Execute 56 The starting point of the exception is coming from this line (line 56 in MsgServer.cpp): while(Server->ServerSocket1->Socket->Connections[ii]->SendText(AnsiString(AMsg+"\n"))==-1) I also did some digging into onError errorCodes that the serverSocket can be throwing and I found at no time does my application go into the onError function. So I am hoping you have some insight into this invalid pointer exception coming from SendText. Thanks again Eric "Remy Lebeau (TeamB)" <no.spam (AT) no (DOT) spam.com> wrote in message news:4443ca2a$1 (AT) newsgroups (DOT) borland.com... Quote: "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:44439c71$1 (AT) newsgroups (DOT) borland.com... I check to make sure there is an active connection right before I do a SendText and pass it an ansistring. Your code is not using SendText() correctly in general. You are not taking into account that SendText() may not send all of your data in a single operation, requiring you to re-call SendText() multiple times in a loop in order to send all of your string. Please go to http://www.deja.com and search through the newsgroup archives. Sample code has been posted many times before. The exception is being thrown at random times usually after running more then 6 hours. The exception that is being thrown is an invalid integer exception. Do you mean that you are getting an EListError exception with a message of "List index out of bounds (12345)" ? If so, then the only way that particular exception can occur in the code you showed is if you are passing an incorrect index value to the Connections[] property. Gambit Back to top Remy Lebeau (TeamB) Guest Posted: Thu Apr 20, 2006 5:03 pm    Post subject: Re: TServerSocket SendText Exception "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:4447a6f6$1 (AT) newsgroups (DOT) borland.com... Quote: I believe I understand how the ServerSocket should be used. Apparently you don't, because you didn't pay attention to a word I've told you. Your code is still wrong. You are not even close to using the kind of code I gave you earlier. Did you even try it? Quote: The starting point of the exception is coming from this line (line 56 in MsgServer.cpp): while(Server->ServerSocket1->Socket->Connections[ii]->SendText(AnsiString(AM sg+"\n"))==-1) As I explained to you earlier, that is a very bad way to send text to a socket. Gambit Back to top Eric Patterson Guest Posted: Thu Apr 20, 2006 6:03 pm    Post subject: Re: TServerSocket SendText Exception That is all fine but why? I would love to fix my issue but I am not a person to shoot shotguns in the dark and hope to hit the target. If what you have gave me before will fix it then someone here should be able to tell me why that will fix it. What causes the invalid pointer exception? Why did this work in NT and now it doesn't in XP? Please tell me the reason why I have this problem instead of telling me your way will fix it. Thanks. Eric "Remy Lebeau (TeamB)" <no.spam (AT) no (DOT) spam.com> wrote in message news:4447b917$3 (AT) newsgroups (DOT) borland.com... Quote: "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:4447a6f6$1 (AT) newsgroups (DOT) borland.com... I believe I understand how the ServerSocket should be used. Apparently you don't, because you didn't pay attention to a word I've told you. Your code is still wrong. You are not even close to using the kind of code I gave you earlier. Did you even try it? The starting point of the exception is coming from this line (line 56 in MsgServer.cpp): while(Server->ServerSocket1->Socket->Connections[ii]->SendText(AnsiString(AM sg+"\n"))==-1) As I explained to you earlier, that is a very bad way to send text to a socket. Gambit Back to top Bob Gonder Guest Posted: Thu Apr 20, 2006 7:03 pm    Post subject: Re: TServerSocket SendText Exception Eric Patterson wrote: Quote: That is all fine but why? I would love to fix my issue but I am not a person to shoot shotguns in the dark and hope to hit the target. If what you have gave me before will fix it then someone here should be able to tell me why that will fix it. What causes the invalid pointer exception? Why did this work in NT and now it doesn't in XP? Please tell me the reason why I have this problem instead of telling me your way will fix it. Thanks. Remy explained the "why" in the same message where he explained the "correct" way to do it. In short: If SendText() fails to send the entire amount (due to a slow network perhaps, or a smaller packet size on the XP machine), then you are resending the entire string again, and again, and again... Quote: while(Server->ServerSocket1->Socket->Connections[ii]->SendText(AnsiString(AM sg+"\n"))==-1) In addition to that, you are creating and destroying a temporary AnsiString each time, which may or may not be a further problem (but, if you follow Remy's solution, this particular "problem" would also go away.) Back to top Eric Patterson Guest Posted: Thu Apr 20, 2006 8:03 pm    Post subject: Re: TServerSocket SendText Exception Thank you. I did do the change and I am getting different problems now which I am trying to fix but if SendText doesn't send the entire amount and I fill the socket buffer wouldn't it call the ServerSocket OnError event? My network is a 10/100 hub which is sitting right on top of the computer and another computer sitting next to it (they are the only two items on the hub) so I don't think speed is an issue. Did XP shrink it default packet size versus what they had on NT? Thanks again. Eric "Bob Gonder" <notbg (AT) notmindspring (DOT) invalid> wrote in message news:4mkf429644ao82ak653gcltqtf4v2g698j (AT) 4ax (DOT) com... Quote: Eric Patterson wrote: That is all fine but why? I would love to fix my issue but I am not a person to shoot shotguns in the dark and hope to hit the target. If what you have gave me before will fix it then someone here should be able to tell me why that will fix it. What causes the invalid pointer exception? Why did this work in NT and now it doesn't in XP? Please tell me the reason why I have this problem instead of telling me your way will fix it. Thanks. Remy explained the "why" in the same message where he explained the "correct" way to do it. In short: If SendText() fails to send the entire amount (due to a slow network perhaps, or a smaller packet size on the XP machine), then you are resending the entire string again, and again, and again... while(Server->ServerSocket1->Socket->Connections[ii]->SendText(AnsiString(AM sg+"\n"))==-1) In addition to that, you are creating and destroying a temporary AnsiString each time, which may or may not be a further problem (but, if you follow Remy's solution, this particular "problem" would also go away.) Back to top Remy Lebeau (TeamB) Guest Posted: Thu Apr 20, 2006 11:03 pm    Post subject: Re: TServerSocket SendText Exception "Eric Patterson" <eric.patterson (AT) bepco (DOT) com> wrote in message news:4447d8b4$1 (AT) newsgroups (DOT) borland.com... Quote: I did do the change and I am getting different problems now which I am trying to fix What problems are you having now? Please elaborate. Quote: if SendText doesn't send the entire amount and I fill the socket buffer wouldn't it call the ServerSocket OnError event? No. The OnError event is only triggered for actual socket errors. A blocking send is not an error. WSAEWOULDBLOCK will never trigger the OnError event. 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