BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  DDE Call back and it's parameters and values          BorlandTalk.com Forum Index -> comp.lang.pascal.delphi.misc View previous topic :: View next topic   Author Message Sonnich Jensen Guest Posted: Fri Feb 27, 2004 2:22 pm    Post subject: DDE Call back and it's parameters and values Hi all! I am playing around with DDE inspired by the article here: http://bdn.borland.com/article/0,1410,16177,00.html (correct TCallBack to TFNCallBack - other changes can be done too) Also, I have problems when having more than 14 items on a TDDEClientConv. (I run 42 at the moment) I have a connection and can get data and poke them too. I use Excel as a server for now. But I cannot get my programme to respond when data changes. My problem is that CallType is always 0 or 1 in: function CallbackProc(CallType, Fmt: Word; Conv: HConv; hsz1, hsz2: HSZ; Data: HDDEData; Data1, Data2: Longint): HDDEData; export; Even when looking at Delphi own's function (in DdeMan) I am convinced that it should work, but not. I tried to look for a detailed describtion of this function and it parameters, is there such on the net? I also found that Conv seems to hold the parameter I need sometime. When CallBack is 1, it is when data changes, when callback is 0 it is when the connection is closed, or - sometimes just at random? This has been mentioned before here, in 1997, but there is no answer. BR Sonnich Jensen Back to top Sonnich Jensen Guest Posted: Mon Mar 01, 2004 7:10 am    Post subject: Re: DDE Call back and it's parameters and values "Bjørge Sæther" <bjorge (AT) hahaha_itte (DOT) no> wrote Quote: Sonnich Jensen wrote: Hi all! I am playing around with DDE inspired by the article here: http://bdn.borland.com/article/0,1410,16177,00.html (correct TCallBack to TFNCallBack - other changes can be done too) Also, I have problems when having more than 14 items on a TDDEClientConv. (I run 42 at the moment) I have a connection and can get data and poke them too. I use Excel as a server for now. But I cannot get my programme to respond when data changes. My problem is that CallType is always 0 or 1 in: function CallbackProc(CallType, Fmt: Word; Conv: HConv; hsz1, hsz2: HSZ; Data: HDDEData; Data1, Data2: Longint): HDDEData; export; Even when looking at Delphi own's function (in DdeMan) I am convinced that it should work, but not. I tried to look for a detailed describtion of this function and it parameters, is there such on the net? I also found that Conv seems to hold the parameter I need sometime. When CallBack is 1, it is when data changes, when callback is 0 it is when the connection is closed, or - sometimes just at random? This has been mentioned before here, in 1997, but there is no answer. Do yourself a favor - drop DDE development in favour of COM. It simply doesn't work properly anymore, at least with Excel. There are severe timing problems, for one. Some people might not like my answer, but here it goes. This is not something I can use, as in many cases certain specifications are given by the client or simply needed. I have to say that I dont like when people suggest to use another DB system or something like that, cause it does not help. It might be so, that it is what the client uses or what has been decided, or simply an old project which stays as it is, not giving these options to the programmer. All we have to do is to get it work - as it is. This is not to harm anyone, simply the world as it is. I still need to know more about DDE to get this to work. BR Sonnich Back to top J French Guest Posted: Mon Mar 01, 2004 9:17 am    Post subject: Re: DDE Call back and it's parameters and values On 29 Feb 2004 23:10:48 -0800, [email]sonnich.jensen (AT) elektrobit (DOT) com[/email] (Sonnich Jensen) wrote: <snip> Quote: Some people might not like my answer, but here it goes. This is not something I can use, as in many cases certain specifications are given by the client or simply needed. I have to say that I dont like when people suggest to use another DB system or something like that, cause it does not help. It might be so, that it is what the client uses or what has been decided, or simply an old project which stays as it is, not giving these options to the programmer. All we have to do is to get it work - as it is. This is not to harm anyone, simply the world as it is. I still need to know more about DDE to get this to work. I suspect that there is more to your story than you have let on You say you are using 'Excel as the Server for now' - which suggests that you want to use something else as the server later - what ? I think Bjørge missed that point when he gave you sound advice on how to talk to Excel Personally I have /deliberately/ forgotton everything I knew about DDE - it is a lousy way of skinning a cat If you tell us what you /really/ want to do, then we may have some simple solutions for your /real/ problem - which, I suspect, is nothing to do with Excel Back to top J French Guest Posted: Mon Mar 01, 2004 1:40 pm    Post subject: Re: DDE Call back and it's parameters and values On Mon, 1 Mar 2004 12:34:14 +0100, "Bjørge Sæther" <bjorge (AT) hahaha_itte (DOT) no> wrote: <snip> Quote: If you tell us what you /really/ want to do, then we may have some simple solutions for your /real/ problem - which, I suspect, is nothing to do with Excel You're perfectly right, Jerry, I was talking about Excel specifically.I worked a lot with DDE and Excel some 3-4 years ago, just to find out it doesn't work properly. It *also* lead me to the conclusion that if MS don't care about Excel and DDE, this is a sign that is to be taken into concideration... It really narks me when people post a problem 'disguised' as something else. This lad is obviously looking for inter-App communication - but is afraid of the 'COM' route (that I can understand, my trips into the AX Factory remind me of a midnight visit to an aluminium smelting plant - Breugelesque ) It is utterly pointless using an obsolete mechanism for inter-App communication, especially when (as I suspect) he has to write the server. And his response was ... ungratious - well f***ing impolite. Back to top Sonnich Jensen Guest Posted: Mon Mar 01, 2004 2:58 pm    Post subject: Re: DDE Call back and it's parameters and values "Bjørge Sæther" <bjorge (AT) hahaha_itte (DOT) no> wrote Quote: J French wrote: On 29 Feb 2004 23:10:48 -0800, [email]sonnich.jensen (AT) elektrobit (DOT) com[/email] (Sonnich Jensen) wrote: snip Some people might not like my answer, but here it goes. This is not something I can use, as in many cases certain specifications are given by the client or simply needed. I have to say that I dont like when people suggest to use another DB system or something like that, cause it does not help. It might be so, that it is what the client uses or what has been decided, or simply an old project which stays as it is, not giving these options to the programmer. All we have to do is to get it work - as it is. This is not to harm anyone, simply the world as it is. I still need to know more about DDE to get this to work. I suspect that there is more to your story than you have let on You say you are using 'Excel as the Server for now' - which suggests that you want to use something else as the server later - what ? I think Bjørge missed that point when he gave you sound advice on how to talk to Excel Personally I have /deliberately/ forgotton everything I knew about DDE - it is a lousy way of skinning a cat If you tell us what you /really/ want to do, then we may have some simple solutions for your /real/ problem - which, I suspect, is nothing to do with Excel You're perfectly right, Jerry, I was talking about Excel specifically.I worked a lot with DDE and Excel some 3-4 years ago, just to find out it doesn't work properly. It *also* lead me to the conclusion that if MS don't care about Excel and DDE, this is a sign that is to be taken into concideration... We are using Hirata DDE server (to connect to external hardware). Also in some case other programmes using DDE. In general I just need to get DDE to work. I have tried this now, which _sometimes_ work. The final thing to do is to get a response when something changes on the server. Current: function CallbackProc(CallType, Fmt: Word; Conv: HConv; hsz1, hsz2: HSZ; Data: HDDEData; Data1, Data2: Longint): HDDEData; export; var i : integer; hDdeTemp : HDDEData; DataStr : PChar; // was TDataString; begin CallbackProc := 0; { See if proved otherwise } // Form1.Memo1.Lines.Add(IntToStr(CallType) + ', ' + IntToStr(Fmt) // + ', ' + IntToStr(Conv) + ', ' + IntToStr(hsz1) // + ', ' + IntToStr(hsz2) + ', ' + IntToStr(Data) // + ', ' + IntToStr(Data1) + ', ' + IntToStr(Data2) ); //sjj // new part if (CallType in [0, 1]) then i := Conv else i := CallType; case i of xtyp_Register: begin { Nothing ... Just return 0 } end; xtyp_Unregister: begin { Nothing ... Just return 0 } end; xtyp_xAct_Complete: begin { Nothing ... Just return 0 } end; xtyp_Request, Xtyp_AdvData: begin Form1.Request(Conv); CallbackProc := dde_FAck; // ShowMessage('hello!'); for I := 1 to NumValues do if Form1.ItemHSz[I] = hsz1 then begin hDdeTemp := DdeClientTransaction(nil, 0, form1.ConvHdl {HConversation} , form1.ItemHSz[I], cf_Text, xtyp_Request, 0, nil); if hDdeTemp <> 0 then begin GetMem(DataStr, 21); // sjj DdeGetData(hDdeTemp, DataStr, SizeOf(DataStr), 0); Form1.Memo1.Lines.Add(DataItemNames[I] + '=' + StrPas(DataStr)); end; end; {} end; xtyp_Disconnect: begin ShowMessage('Disconnected!'); // Form1.Close; end; end; end; Back to top Bruce Roberts Guest Posted: Mon Mar 01, 2004 5:42 pm    Post subject: Re: DDE Call back and it's parameters and values "Sonnich Jensen" <sonnich.jensen (AT) elektrobit (DOT) com> wrote Quote: "Bjørge Sæther" <bjorge (AT) hahaha_itte (DOT) no> wrote J French wrote: There was no need to quote the entirety of the previous post. Please watch your quoting as it is extremely annoying to have to scroll through dozens of lines that are not germane to your response. Back to top Sonnich Jensen Guest Posted: Tue Mar 02, 2004 2:06 pm    Post subject: Re: DDE Call back and it's parameters and values "Bjørge Sæther" <bjorge (AT) hahaha_itte (DOT) no> wrote Quote: Sonnich Jensen wrote: We are using Hirata DDE server (to connect to external hardware). Also in some case other programmes using DDE. In general I just need to get DDE to work. I have tried this now, which _sometimes_ work. The final thing to do is to get a response when something changes on the server. The problem that made me abandon Excel via DDE, was the fact that there seems to be timing problems, making the intercommunication unstable. The faster the machine, the longer delays are needed to keep communication going. I don't know whether the problem lies within DDE generally or if it's Excel-specific. To check out this, add a Sleep() line between all of your lines. If this makes it stable/reliable, it may be the same problem. Also, I remember having read a few postings about problems with Delphi's DDE components. This was back in D3, I believe, and I haven't seen it mentioned for quite a while. Was the problem fixed, or have people stopped using DDE ? Thanks, this was waht I needed. The sleep did help, but not as much as I needed - I tried to add a number of sleep(10)'s, with applciation.processmessages in between, and that was the trick. Otherwise it would only update the first item, eventually the one changed, and in some cases the new value would not be present when asking for it. Someone complained that I included the whole code, so here I only add what I changed in case clause: case... xtyp_Request, Xtyp_AdvData: begin Application.ProcessMessages; CallbackProc := dde_FAck; GetMem(DataStr, 21); // sjj hDdeTemp := DdeClientTransaction(nil, 0, data, hsz1, cf_Text, xtyp_Request, 0, nil); if hDdeTemp <> 0 then begin StrPCopy(DataStr, #0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0); DdeGetData(hDdeTemp, DataStr, SizeOf(DataStr), 0); res := StrPas(DataStr); i := Pos(#13, res); res := Copy(res, 1, i-1); for I := 1 to NumValues do if Form1.ItemHSz[I] = hsz1 then Form1.Memo1.Lines.Add(TimeToStr(now) + ', '+DataItemNames[I]+'=' + res); end; FreeMem(DataStr); // sjj end; This works. When one item is updated, all are sent again, and fast enough for me. If one wants the complete code, one might write directlt to me. Next step now is to create some components BR & thanks for the help S Back to top J French Guest Posted: Tue Mar 02, 2004 3:18 pm    Post subject: Re: DDE Call back and it's parameters and values On 2 Mar 2004 06:06:30 -0800, [email]sonnich.jensen (AT) elektrobit (DOT) com[/email] (Sonnich Jensen) wrote: <snip> Quote: Someone complained that I included the whole code, so here I only add what I changed in case clause: No - Bruce complained that you posted the previous post in other words /old/ postings I've a few comments here Quote: case... xtyp_Request, Xtyp_AdvData: begin Application.ProcessMessages; CallbackProc := dde_FAck; GetMem(DataStr, 21); // sjj Are you sure you cannot use a simple string for DataStr - it can be sent as a PChar Procedure Test( Const P :PChar ); Begin P^ := 'A'; End; procedure TForm1.Button1Click(Sender: TObject); Var S :String; begin S := 'BBBB'; // or S := StringOfChar( 'B', 4 ) Test( PChar(S) ); ShowMessage( S ); end; Quote: hDdeTemp := DdeClientTransaction(nil, 0, data, hsz1, cf_Text, xtyp_Request, 0, nil); if hDdeTemp <> 0 then begin StrPCopy(DataStr, #0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0); All those #0s are a bit nasty DdeGetData(hDdeTemp, DataStr, SizeOf(DataStr), 0); I expect this would work S := StringOfChar( #0, 21 ) DdeGetData(hDdeTemp, PChar(S), Length(S), 0); Quote: res := StrPas(DataStr); Res := DataStr StrPas is obsolete i := Pos(#13, res); And what happens if there is no #13 ? res := Copy(res, 1, i-1); Ah ! res := Copy( res, 1, -1 ) <---- Nasty Copy() is pretty tolerant, but I doubt this is deliberate Quote: for I := 1 to NumValues do if Form1.ItemHSz[I] = hsz1 then Form1.Memo1.Lines.Add(TimeToStr(now) + ', '+DataItemNames[I]+'=' + res); end; FreeMem(DataStr); // sjj With a String you don't need to use FreeMem end; I think that you would be well advised to look at some of the later Delphi constructs - they would simplify your code - and that would make it more robust Back to top Sonnich Jensen Guest Posted: Fri Mar 05, 2004 7:25 am    Post subject: Re: DDE Call back and it's parameters and values [email]erewhon (AT) nowhere (DOT) com[/email] (J French) wrote in message news:<4044a099.2989913 (AT) news (DOT) btclick.com>... Quote: On 2 Mar 2004 06:06:30 -0800, [email]sonnich.jensen (AT) elektrobit (DOT) com[/email] (Sonnich Jensen) wrote: snip Someone complained that I included the whole code, so here I only add what I changed in case clause: No - Bruce complained that you posted the previous post in other words /old/ postings Sorry got it wrong then... Quote: I've a few comments here case... xtyp_Request, Xtyp_AdvData: begin Application.ProcessMessages; CallbackProc := dde_FAck; GetMem(DataStr, 21); // sjj Are you sure you cannot use a simple string for DataStr - it can be sent as a PChar Procedure Test( Const P :PChar ); Begin P^ := 'A'; End; I tried, did not work that well. I also found that I had to change the SizeOf to a static number. Quote: procedure TForm1.Button1Click(Sender: TObject); Var S :String; begin S := 'BBBB'; // or S := StringOfChar( 'B', 4 ) Test( PChar(S) ); ShowMessage( S ); end; hDdeTemp := DdeClientTransaction(nil, 0, data, hsz1, cf_Text, xtyp_Request, 0, nil); if hDdeTemp <> 0 then begin StrPCopy(DataStr, #0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0#0); All those #0s are a bit nasty DdeGetData(hDdeTemp, DataStr, SizeOf(DataStr), 0); I expect this would work The problem here is SizeOf(DataStr), which is always 4. This works: GetMem(DataStr, 256); DdeGetData(hDdeTemp, DataStr, 256, 0); Quote: S := StringOfChar( #0, 21 ) DdeGetData(hDdeTemp, PChar(S), Length(S), 0); res := StrPas(DataStr); Res := DataStr StrPas is obsolete i := Pos(#13, res); And what happens if there is no #13 ? res := Copy(res, 1, i-1); Ah ! res := Copy( res, 1, -1 ) <---- Nasty Copy() is pretty tolerant, but I doubt this is deliberate I realised that these 2 problems, and found that the copy solution is not good. In order to keep compatability with the original component I use a TString component, which works just as wanted (and the original component) Quote: for I := 1 to NumValues do if Form1.ItemHSz[I] = hsz1 then Form1.Memo1.Lines.Add(TimeToStr(now) + ', '+DataItemNames[I]+'=' + res); end; FreeMem(DataStr); // sjj With a String you don't need to use FreeMem end; I think that you would be well advised to look at some of the later Delphi constructs - they would simplify your code - and that would make it more robust As above, a large number of changes have been done after I turned it into components (rewrote it). Thaks for the help! BR Sonnich Back to top J French Guest Posted: Fri Mar 05, 2004 8:43 am    Post subject: Re: DDE Call back and it's parameters and values On 4 Mar 2004 23:25:50 -0800, [email]sonnich.jensen (AT) elektrobit (DOT) com[/email] (Sonnich Jensen) wrote: <snip> Quote: The problem here is SizeOf(DataStr), which is always 4. This works: GetMem(DataStr, 256); DdeGetData(hDdeTemp, DataStr, 256, 0); The SizeOf an ANSIString is always 4 This is because it is really a pointer to the first byte of the contents of the String, the length of the String and various other bits of info are stored /before/ the first byte of the contents of the String. If the String is empty the pointer is Nil To find the length of a String use: Length( AString ) Strings are extremely handy as buffers, because they are much more versatile, and are automatically destroyed. In effect a String can be thought of as an enhanced PChar - the 'String' is actually a PChar to a buffer - it is @S[1] or Addr( S[1] ) Personally I reckon that GetMem and FreeMem are pretty much obsolete, if one wants a buffer then simply create a String - it is easy to skip Freeing a manually allocated buffer One of the problems with Delphi is that it is actually /enhanced/ Pascal, so older more cumbersome constructs exist alongside newer, slicker ways of doing things - typical examples are memory allocation and ASCIIZ ('C' style) Strings HTH Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> comp.lang.pascal.delphi.misc All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.