Icon View Thread

The following is the text of the current message along with any replies.
Messages 1 to 10 of 13 total
Thread EWB Module - CoInitialize has not been called
Thu, Apr 9 2015 4:00 AMPermanent Link

Petter Topp

I use TADOConnection and TADOQuery to handle login on the server side in my EWB Module.
When the module receives a request (getting created?), I get the message "CoInitialize has not been called"

It seems that this is related to threading issues - can someone enlighten me on how to solve this?

Br
Petter
Thu, Apr 9 2015 4:34 AMPermanent Link

Matthew Jones

Petter Topp wrote:

> I use TADOConnection and TADOQuery to handle login on the server side
> in my EWB Module.  When the module receives a request (getting
> created?), I get the message "CoInitialize has not been called"
>
> It seems that this is related to threading issues - can someone
> enlighten me on how to solve this?

In the multi-threaded code I have, where I've needed to access COM
objects, I have the initialization code of the thread call
CoInitialize(nil);

and in closing down the thread, it calls

CoUninitialize();

You'd probably have to be careful to not break any COM in the server
itself, but given it isn't initialised, it is probably safe.

--

Matthew Jones
Thu, Apr 9 2015 5:10 AMPermanent Link

Petter Topp

Hi Matthew.

As for the moment I don't see the need for multi threading - So the place to do this would be in the EWBModuleExecute event?



"Matthew Jones" wrote:

Petter Topp wrote:

> I use TADOConnection and TADOQuery to handle login on the server side
> in my EWB Module.  When the module receives a request (getting
> created?), I get the message "CoInitialize has not been called"
>
> It seems that this is related to threading issues - can someone
> enlighten me on how to solve this?

In the multi-threaded code I have, where I've needed to access COM
objects, I have the initialization code of the thread call
CoInitialize(nil);

and in closing down the thread, it calls

CoUninitialize();

You'd probably have to be careful to not break any COM in the server
itself, but given it isn't initialised, it is probably safe.

--

Matthew Jones
Thu, Apr 9 2015 5:42 AMPermanent Link

Matthew Jones

Petter Topp wrote:

> As for the moment I don't see the need for multi threading - So the
> place to do this would be in the EWBModuleExecute event?

The service you are writing a module will be multi-threaded, so it is
inherently something to consider. However I now walk off the deep end
as I've not written an EWB module. A quick scan of the documentation
shows that it is about "modules", which means that the server will own
the module which is all about the data/connection etc, but there is
nothing on threads. A typical server will have a thread pool, and any
one of those could call your code at any time. Without further
information, I would have a routine which is called "CheckOLEInit" and
put this code in:

threadvar
g_bInitialisedCOM = False;

procedure CheckOLEInit;
begin
 if not g_bInitialisedCOM then
 begin
   CoInitialize(nil);
   g_bInitialisedCOM := True;
 end;
end;

The threadvar is a "global" but on a per thread basis, so it won't be
set for each thread that you get called by. Thus each thread would have
the initialisation done once (or initialization for the US language!).

I'd also then ignore the UnInitialize, and you are going to keep it
alive until the server shuts down, and without explicit thread control,
it would be hard.

I'd prefer to have Tim respond on how sensible this is, or if there is
a better way. IIRC there is a DLL attachment call for each new thread,
but that probably won't apply when the thread already exists. The
ideal, perhaps, would be for the server to do this call for you, just
in case. There's no real harm.



--

Matthew Jones
Thu, Apr 9 2015 10:19 AMPermanent Link

Matthew Jones

Matthew Jones wrote:

> The service you are writing a module will be multi-threaded

Should of course be:

The service you are writing a module *for* will be multi-threaded

That will make better sense!

--

Matthew Jones
Thu, Apr 9 2015 12:27 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

Avatar

Email timyoung@elevatesoft.com

Petter,

<< I use TADOConnection and TADOQuery to handle login on the server side in
my EWB Module. When the module receives a request (getting created?), I get
the message "CoInitialize has not been called"

It seems that this is related to threading issues - can someone enlighten me
on how to solve this? >>

Yes, you want to make sure to call CoInitialize in the initialization of the
project .dpr:

begin
 <<<<<<<<<<<<<<<<<<<<<<<<<   Here !!!!
 Application.Initialize;
 Application.CreateForm(TExampleDataSetModule, ExampleDataSetModule);
 Application.Run;
end.

If you have any other questions, please let me know.

Tim Young
Elevate Software
www.elevatesoft.com
Fri, Apr 10 2015 2:08 AMPermanent Link

Petter Topp

Hi Tim.

I have added CoInitialize(nil) in the initialization of the project, but I still get "CoInitialize has not been called"

Petter



"Tim Young [Elevate Software]" wrote:

Petter,

<< I use TADOConnection and TADOQuery to handle login on the server side in
my EWB Module. When the module receives a request (getting created?), I get
the message "CoInitialize has not been called"

It seems that this is related to threading issues - can someone enlighten me
on how to solve this? >>

Yes, you want to make sure to call CoInitialize in the initialization of the
project .dpr:

begin
 <<<<<<<<<<<<<<<<<<<<<<<<<   Here !!!!
 Application.Initialize;
 Application.CreateForm(TExampleDataSetModule, ExampleDataSetModule);
 Application.Run;
end.

If you have any other questions, please let me know.

Tim Young
Elevate Software
www.elevatesoft.com
Fri, Apr 10 2015 4:15 AMPermanent Link

Matthew Jones

Tim Young [Elevate Software] wrote:

> Yes, you want to make sure to call CoInitialize in the initialization
> of the project .dpr:

Tim,

It is needed in each thread that may make a COM call. Once at the start
is not enough.

--

Matthew Jones
Fri, Apr 10 2015 4:27 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

Avatar

Email timyoung@elevatesoft.com

Matthew,

<< It is needed in each thread that may make a COM call. Once at the start
is not enough. >>

Oops, sorry, was thinking of the database engine initialization.

To initialize for each thread, just call CoInitialize in the OnCreate for
the EWB Web Server module.

Tim Young
Elevate Software
www.elevatesoft.com
Tue, Sep 1 2015 6:01 AMPermanent Link

Petter Topp

"Tim Young [Elevate Software]" wrote:

Matthew,

<< It is needed in each thread that may make a COM call. Once at the start
is not enough. >>

Oops, sorry, was thinking of the database engine initialization.

To initialize for each thread, just call CoInitialize in the OnCreate for
the EWB Web Server module.

Tim Young
Elevate Software
www.elevatesoft.com

Hi Tim.

Calling CoInitialize in the OnCreate for the EWB server module partially helped.
Now the CoInitialize message only the first time the EWBModuleExecute is called.

Any Ideas as to how I can solve this?

Petter
Page 1 of 2Next Page
Jump to Page:  1 2
Image