Re: Would COM still be recognized? - COM Discussion Boards

How to instantiate an .net object with parameterized constructor in VB6?

3-Jul-08 22:13

Just create a new ATL DLL project. It will put a few export functions there. Search for one of those functions to see how your code is different.

I've just extended my COM DLL using such by-example technique, it worked fine.

Saranya B3-Jul-08 19:07

Saranya B

3-Jul-08 19:07

Hello everybody,

I hope someone can help me...

My .net code goes like this...

public class ProxyFacade : BaseProxyFacade

{

ProxyConfiguration _configuration = new ProxyConfiguration();

public ProxyFacade(Uri Uri)

{

_configuration.Url = Uri;

}

public Student IncreaseAge(Student StudObj)

{

StudentServiceClient client;

base.ProxyConfiguration = _configuration;

base.PreProceedHandler();

client = new StudentServiceClient(base.BaseProxy, base.BaseProxy.EndPointAddress);

client.Open();

return client.IncreaseAge(StudObj);

}

}

My Issue: I have registered this dll as COM component.
When I try to instantiate this ProxyFacade from VB6, I am not able to give the object reference with New Keyword?

Do I have to set anything in the .net side? What is the correct way to instantiate this .net object registered as COM?

My VB6 code:

Private Sub cmd_CallCOM_Click()
Dim objStud As New ProxyLibrary.Student
Dim a As Integer
objStud.Age = 11
objStud.Name = "Johnie"
objStud.IsOutStanding = False
Dim objFacade As ProxyLibrary.StudentServiceClient
Dim b As ProxyFacade

 'a = objFacade.IncreaseAge()
'Set objFacade = GetObject("http://localhost:3507/StudentException/Student%20Service.svc/rest")
lbl_Age.Caption = objFacade.IncreaseAge(objStud).Age
End Sub

When i tried with GetObject, again error...

I think i am taking a wrong way to instantiate this object which has parameterized constructor...

Any help plssssssssss

Tnx in advance,
Saran

CoCreateInstance

alchong3-Jul-08 13:44

alchong

3-Jul-08 13:44

For a while my code has been running fine on a server, but for the last week it's been failing consistently. I started debugging and found out that it's failing when I call CoCreateInstance. The error code returned is:

0x8007000E

When I looked it up, the corresponding message is:

"Not enough storage is available to complete this operation."

What does this really mean? I looked at the server and there seems to be plenty of free memory (RAM) for applications. I'm fairly new to COM, but from what I understand, this method is called to create an object using a Class ID or Program ID (from MSDN), I've tried this app on another server and it seems to work. I'm fairly new to COM, so any information you can share would be helpful.

Re: CoCreateInstance

alchong8-Oct-08 12:45

alchong

8-Oct-08 12:45

Hmm, never came back to this, there were so many things running on this particular box, it was resource related.

Would COM still be recognized?

Vitaly Tomilov3-Jul-08 13:00

Re: Would COM still be recognized?

3-Jul-08 13:00

Hi All,

I've been planning for some time to do a project with COM for the community of software developers.

The project, in essense, is to generalize access to all information on the PC in a simple way, something like what WMI does, only better (read simpler).

I wonder, however, if i'm not too behind doing this (a few years), and whether a COM project, if it is good, can still be applaused by .NET developers?

Any opinions here are welcome!

Cheers!

Vitaly Tomilov3-Jul-08 23:16

Re: Would COM still be recognized?

3-Jul-08 23:16

I know this is a bit early to wonder if this post would ever be answered, but i published information about the idea here: http://www.codeproject.com/script/Forums/View.aspx?fid=1641[^]

It's titled Researching Opinions: Professional System Library

I think this might be of interest to all COM developers.

Cheers!

dementia12314-Jul-08 4:32

dementia123

14-Jul-08 4:32

you know i have heard similar things about people flaming com

you know what it works its easy and it gets the job done so it is fine ill applaud anything created

that is the whole point of the framework so we can build on top of stuff made and the object oriented paradigm

we dont need to know certain things except what needs to be exposed to our classes and functions inheritance polymorphism

etc

so com makes it easy by dragging a control and building off of it

use anything that works bro

Re: Would COM still be recognized?

Vitaly Tomilov15-Jul-08 22:45

Convert Visual Studio 2005 ATL project into VC 6.0

15-Jul-08 22:45

Thank you for the encouragement, I appreciate it very much. I also came to the conclusion that there's no way to evaluate any idea until you show results, so I started on this project two weeks ago. I got a website for it: www.prosyslib.com, net, org. So, I’m seriously planning to be back here with some first results soon, something a lot more tangible than the theory (even changed my signature Smile | :)

)

Cheer'o!

Professional System Library on www.prosyslib.com, simplifying life for software developers.

dolly3-Jul-08 1:51

dolly

3-Jul-08 1:51

Hello Friends,

I have an ATL project in Visual Studio 2005, but now I want it in Visual C++6.0.

I have used one utility available on Code Project only i.e.

prjconverter.exe

it converted .sln to .dsw BUT on building the project,

I am having many error, mainly

"C:\Program Files\Microsoft Visual Studio\VC98\ATL\INCLUDE\atlcom.h(2945) : error C2065: '_Module' : undeclared identifier"

Because even in converted project,

class Coeapi_sampleModule : public CAtlDllModuleT< Coeapi_sampleModule >
{
public :
DECLARE_LIBID(LIBID_oeapi_sampleLib)
DECLARE_REGISTRY_APPID_RESOURCEID(IDR_OEAPI_SAMPLE, "{2FB8F87B-D079-497D-8948-F2F060162392}")
};

Coeapi_sampleModule _AtlModule;

BUT

what I want (generated by compiler if we build in vc 6) is

CComModule _Module;

and i read that CComModule is obsolete now, but I have to use it anyway because I have to code & build the project in Visual C++ 6.0 only not in Visual Studio 2005.

Please Help.

Thanks well in Advance!

dolly,
N,IN

VC# for MTA COM component development

scody2-Jul-08 23:36

scody

2-Jul-08 23:36

Hi,

I am in need of a MTA (Multithreaded) COM component for one of my application.

I would like to know if VC# can be used to develop the MTA COM component instead of VC++? If possible, how? or any info regarding it will be helpful.

Thanks in advance.

Re: VC# for MTA COM component development

Ju@ncho4-Jul-08 3:19

Ju@ncho

4-Jul-08 3:19

Hi,

When you program COM components in C++ you genereally use ATL, wich helps you a lot to deal with the COM gore details.

Since C# is a managed Language that runs over the .NET framework it was not designed to support COM developing which is an older unmanaged technology

If you want to use COM components from you C# App I strongly recommend you to program them in C++ and loading them into your C# project.

But you should first evaluate if its strongly necessary to use COM instead of a .NET component programmed in C#

pass character string to COM

MKUser29-Jun-08 21:34

29-Jun-08 21:34

I want to make a function in COM dll which receive one character string and returns one character string. Since scripting languages dont use char* please suggest how to make this function in COM and how to use it. Please give any sample.

Manoj Kumar Chauhan

Vi229-Jun-08 21:54

Vi2

29-Jun-08 21:54

[id(...)] HRESULT SomeMethod([in] BSTR inString, [out,retval] BSTR * outString);

In script this method can be used as

string2 = obj.SomeMethod(string1)
string2 = obj.SomeMethod("text1")

With best wishes,
Vita

MKUser29-Jun-08 22:50

29-Jun-08 22:50

Thanks it's working
Now if i use CHAR* instear of BSTR* then will it work for scripting language?
Please give some samples where to use BSTR* and CHAR* for scripting & non scripting language. If function inside COM dll takes CHAR* then i should pass BSTR if i'm using dll in scripting language
please give some samples for this

Manoj Kumar Chauhan

Vi229-Jun-08 23:14

Vi2

29-Jun-08 23:14

Now if i use CHAR* instead of BSTR* then will it work for scripting language?

No. At the most, [in] parameter might be considered as WCHAR*.

Please give some samples where to use BSTR* and CHAR* for scripting & non scripting language. If function inside COM dll takes CHAR* then i should pass BSTR if i'm using dll in scripting language

COM object doesn't use "CHAR*" in specification of functions, but can convert "CHAR*" to "BSTR" and viceversa.

With best wishes,
Vita

MKUser29-Jun-08 23:45

29-Jun-08 23:45

Thanks for explanation
So you mean it's always preferable to use BSTR for COM not any char*
And if i make any function in COM which takes char* as input then i need to pass char* when i call this function. Is it right?
Because ATL gives the option to make char* for any function argument so i can give it. My question is how i'll handle this char* in scripting language

Manoj Kumar Chauhan

Vi230-Jun-08 21:04

Vi2

30-Jun-08 21:04

When I spoke "COM object doesn't use "CHAR*" in specification of functions", I meant that for string parameter, not for CHAR parameter, which is valid in COM. So you can write

f(..., [in] CHAR* c, ...)
f(..., [in,out] CHAR* c, ...)
f(..., [out] CHAR* c, ...)
f(..., [out,retval] CHAR* c)

but you will be able to pass only one symbol (or one byte), not the whole string.

With best wishes,
Vita

MKUser1-Jul-08 3:20

1-Jul-08 3:20

Thanks for your explanation

Is it possible if we pass any iostream object to COM function and COM function write some text in the file attached to iostream object and return.

Manoj Kumar Chauhan

Vi21-Jul-08 17:40

Vi2

1-Jul-08 17:40

"iostream" object is C++ object, not accessible directly from scripts and non-C++ clients and unallowed in COM accordingly.

With best wishes,
Vita

MKUser1-Jul-08 18:42

1-Jul-08 18:42

Thanks. There is one more doubt please clear this also.
If i want to return any variable length string from COM then i can allocate memory in COM and return it to exe (return BSTR*). Finall exe which's using the COM will free the memory. Is this OK? How to make same parameter as input/output in COM function?
How to return more than one string through COM function. suppose if i have function
int func(BSTR inputstring, BSTR* outstring1, BSTR* outstring 2);
Here i want to return 2 strings from this function.
COM dont give the option to pass output argument when we call the function

Manoj Kumar Chauhan

MKUser1-Jul-08 21:22

1-Jul-08 21:22

I implement one function in COM which allocate some memory to array and return this.
int AllocateData(int length, BSTR* OutArray)
{
// there is some data in a ansi array, i return this data from this COM function

wchar_t* wstr = (wchar_t*)calloc(sizeof(WCHAR),length+1);
MultiByteToWideChar(CP_ACP, 0, ansiarray, length, wstr, length) ; free(ansiarray);
*OutArray = (BSTR)wstr;
}

When i use this dll i call this function like
BSTR st;
st = cominterface->AllocateData(500);
When this function is called i get some error for memory leak. Please suggest how to fix it.

Manoj Kumar Chauhan

CPallini1-Jul-08 22:05

CPallini

1-Jul-08 22:05

MKUser wrote:
COM dont give the option to pass output argument when we call the function

That's not true (see the [OUT] IDL attribute).
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

MKUser1-Jul-08 23:19

1-Jul-08 23:19

Thanks. As per your comments i have solved the error when use [out] in idl file. But if i use [out,retval] then i get error.

I create a sample. Please check the below code.

main()
{
BSTR ab;
ab = allocmem();//i get run time memory error when return from this function
}

_bstr_t allocmem()
{
BSTR x;
allocmem2(&x);
return _bstr_t(x, false);
}

void allocmem2(BSTR *x)
{
char ansi[27];
memset(ansi,0,27);
for(int i = 0; i < 26; i++)
ansi[i] = 48 + i + 1;
wchar_t* wstr = (wchar_t*)calloc(sizeof(WCHAR),26);
MultiByteToWideChar(CP_ACP, 0, ansi, 26, wstr, 26) ;
*x = (BSTR)wstr;
}

Please suggest how to solve this error.

Manoj Kumar Chauhan