Re: how to register a Callback function COM client to a COM server
Not a big deal if the client uses ATL. And a client written in
a different COM-aware language will work this way, but
won't have a chance with a C callback function. Plus the
callback interface is also potentially marshalable.
--
=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: agnickolov@mvps.org
MVP VC FAQ: http://vcfaq.mvps.org
=====================================
"bisuvious" <dhrubamahanta@gmail.com> wrote in message
news:1187679579.896677.164330@x35g2000prf.googlegroups.com...
On Aug 21, 12:39 pm, Senthil <s.senthil...@gmail.com> wrote:
On Aug 21, 9:05 am, bisuvious <dhrubamaha...@gmail.com> wrote:
Dear All
I am writing a COM component using ATL where I need to provide a way
so that clients can register a callback function and when required COM
component will call this function. I have an interface and I am
thinking to add one method say, RegisterCallback to that interface
which supposed to be like this----------
typedef int (*CallbackFpt) (int);
[id(4), helpstring("method ResisterCallback")] HRESULT
ResisterCallback([in] CallbackFpt pCallbackFpt);
please help me to know how to provide this facility. There may be
other ways to do this. please suggest..
thanks.....
bisuvious
Instead of using a callback function you can define a callback
interface in the idl file.
interface ICallBack : IUnknown {
HRESULT PerformCallback();
};
Implement this interface on the client side and In your
Registercallback method pass ICallback* instead of the function
pointer.Now the server can call PerformCallback on the pointer you
provided.
Also have a look into Connectionpoints.However the above discussed
method would be much efficient than using ConnectionPoints.
Best Regards,
Senthil
But in this case client need to implement the interface and need to
override this method as well as QueryInterface,ADDRef and Release.
This is alright straightly....but I am thinking whether it will be a
overwork for the clients.