Server Socket DLL calling external function

Thread View: borland.public.cppbuilder.internet.socket

4 messages

[T] Back to Threads [V] Tree View [G] Group Articles

4 total messages Started by Colin B Maharaj Sun, 12 Mar 2006 13:22

#2583

Author: Colin B Maharaj
Date: Sun, 12 Mar 2006 13:22

7 lines
1157 bytes

Hi all I was considering making a DLL with an Indy Server socket. The 
thing is I want to call a function from the DLL that exists on the 
calling application, whenever the OnExecute fires.

Is it possible to do this in a DLL? Is this what they call callback?

Any pointers will be appreciated.

Re: Server Socket DLL calling external function

#2585

Author: Paul
Date: Sun, 12 Mar 2006 13:35

22 lines
1848 bytes

Hi Colin,

I'm not an expert on DLLs, but I have just finished wrapping a BCB component 
into a DLL, to be used in VC++ and BCB.  It took me quiet some time to get 
it right.  The __stdcall is a good calling convention to use, and use 
standard types for parameters (I used ints and enums and it went horribly 
wrong, so changed them to ulong, char, etc).  You also have to make sure 
that the DLL releases memory it creates and vice versa.  Haven't tried 
callbacks though.

Paul.


"Colin B Maharaj" <noreply@myhost.com> wrote in message 
news:4414209d@newsgroups.borland.com...
> Hi all I was considering making a DLL with an Indy Server socket. The 
> thing is I want to call a function from the DLL that exists on the calling 
> application, whenever the OnExecute fires.
>
> Is it possible to do this in a DLL? Is this what they call callback?
>
> Any pointers will be appreciated.

Re: Server Socket DLL calling external function

#2593

Author: Remy Lebeau (TeamB)
Date: Mon, 13 Mar 2006 20:29

16 lines
1287 bytes

"Colin B Maharaj" <noreply@myhost.com> wrote in message
news:4414209d@newsgroups.borland.com...

> The thing is I want to call a function from the DLL that exists on
> the calling application, whenever the OnExecute fires.

You would need to have the application pass a function pointer to the DLL.
Then the DLL can store that pointer and call it when needed.

> Is this what they call callback?

Yes.


Gambit

Re: Server Socket DLL calling external function

#2594

Author: Remy Lebeau (TeamB)
Date: Mon, 13 Mar 2006 20:39

92 lines
2818 bytes

"Remy Lebeau (TeamB)" <no.spam@no.spam.com> wrote in message
news:4415d5ca$1@newsgroups.borland.com...

> You would need to have the application pass a function pointer to the DLL.
> Then the DLL can store that pointer and call it when needed.

For example:

    --- MyDll.h ---

    #ifndef MyDllH
    #define MyDllH

    typedef void __stdcall (*MYCALLBACKTYPE)(void);

    #ifdef _BUILDING_DLL_
    #define MYAPI __declspec(dllexport)
    #else
    #define MYAPI __declspec(dllimport)
    #endif

    #ifdef __cplusplus
    extern "C" {
    #endif

    MYAPI void __stdcall SetExecuteCallback(MYCALLBACKTYPE);

    #ifdef __cplusplus
    }
    #endif

    #endif


    --- MyDll.cpp ---

    #define _BUILDING_DLL_
    #include "MyDll.h"

    class TMyServer
    {
    private:
        TIdTCPServer *FServer;

        TMyServer();
        TMyServer(const TMyServer&) {}
        TMyServer& operator=(const TMyServer&) {}

        void __fastcall ServerExecute(TIdPeerThread *AThread);

    public:
        MYCALLBACKTYPE ExecuteCallback;

        ~TMyServer();
        static TMyServer& Instance();
    };

    TMyServer::TMyServer()
    {
        ExecuteCallback = NULL;
        FServer = new TIdTCPServer(NULL);
        FServer->OnExecute = ServerExecute;
        //...
    }

    TMyServer::~TMyServer()
    {
        delete FServer;
    }

    TMyServer& TMyServer::Instance()
    {
        static TMyServer inst;
        return inst;
    }

    void __fastcall TMyServer::ServerExecute(TIdPeerThread *AThread)
    {
        if( ExecuteCallback )
            ExecuteCallback();
        else
            Sleep(50);
    }

    void __stdcall SetExecuteCallback(MYCALLBACKTYPE Callback)
    {
        TMyServer.Instance().ExecuteCallback = AppCallback;
    }


Gambit

Thread Navigation

This is a paginated view of messages in the thread with full content displayed inline.

Messages are displayed in chronological order, with the original post highlighted in green.

Use pagination controls to navigate through all messages in large threads.

Back to All Threads