COM Objects

[haihems]

Hi,
I'm using Crystal Reports with vb.net. I want to know, the references given below are the COM objects or they called something else?

CrystalDecisions.CrystalReports.Engine
CrystalDecisions.Shared
CrystalDecisions.ReportSource
CrystalDecisions.Windows.Form

thanks and regards
Hems.

[jmcilhinney]

They are the namespaces. The COM objects are the DLL files themselves. Usually the DLL will be called <namespace>.dll but not always.

Edit:
Never done COM development so my definition may be slightly incorrect. Perhaps the COM objects are the classes defined in the DLL files, but either way you are quoting namespaces.

[mendhak]

No, I believe they are not.

[haihems]

ok thanks..but anyway how can i know what are all the COM objects i'm using in my project?

And as per ur reply "jmcilhinney" , u r telling "The COM objects are the DLL files themselves.". I saw in my debug window the following:
crystaldecisions.crystalreports.engine.dll
crystaldecisions.shared.dll

Then what are they?

Sorry, if i'm irritating u. Anyway I'm new to COM concept.

[jmcilhinney]

As I said, I'm no COM guru myself. Others with more experience may be able to give better answers.

The references ending in ".dll" are definitely referring to files. If you need to add a reference to these to your project, you right-click the project in the Solution Explorer and select "Add Reference". You can select the COM tab and see whether what you need is listed. If it is, select it by double-clicking or click and press Select. If it is not listed, press Browse and navigate to the DLL file. The file and the components it contains will be added to the list. I think you would then have to select the new item(s) that you want to reference, or it may be done automatically (not sure). Click OK and you can now reference those objects as you do any other. If you want to refer to the new classes without qualifying them (thisnamespace.thatnamespace.classname) you need to import the namespaces at the top of your class file with an Imports statement.

[mendhak]

COM is something we did back in the VB6 days. You could create a COM DLL in Visual Studio 6 using VB6, it would have the .DLL extension too. Difference being, these had to be registered in order to be used.

If you reference a COM DLL in your project, you'll know
First, it'd be under the COM Tab when you add the reference. Second, when you build the project, one or two wrapper class DLLs will be built and you can see them in the bin folder.

These classes allow you to Interoperate with the COM DLL.

[haihems]

Thanks everyone...

First, it'd be under the COM Tab when you add the reference. Second, when you build the project, one or two wrapper class DLLs will be built and you can see them in the bin folder.

These classes allow you to Interoperate with the COM DLL.

Yes Mendhak..I added these reference from the COM tab only. And I checked with the bin directory, there are some wrapper class DLLs (Interop.Crystal.dll etc.,)..So I want to know, the above listed(in my first post) are COM objects or not??? I feel sorry to ask the same question again & again.

Actually without knowing fully about COM, I'm using it I think.... Sorry to say this. But now i want to know about COM..can anybody tell me some useful links which explains about COM??? I need something simple, bcos i gone through some of the books which is very complicated. I couldn't understand that. Thanks in advance...

[mendhak]

Thanks everyone...



Yes Mendhak..I added these reference from the COM tab only. And I checked with the bin directory, there are some wrapper class DLLs (Interop.Crystal.dll etc.,)..So I want to know, the above listed(in my first post) are COM objects or not??? I feel sorry to ask the same question again & again.

Actually without knowing fully about COM, I'm using it I think.... Sorry to say this. But now i want to know about COM..can anybody tell me some useful links which explains about COM??? I need something simple, bcos i gone through some of the books which is very complicated. I couldn't understand that. Thanks in advance...

No, then I made a mistake. They are COM DLLs if that's the case.

Read, read read:

http://www.microsoft.com/com/default.mspx

http://www.cs.umd.edu/~pugh/com/

[haihems]

Thanks for your links Mendhak..sure I'll go thru it and come back later if there any doubts..

[jmcilhinney]

I would suggest that you don't bother learning too much about COM. The fact that, with a little behind the scenes help from the IDE, COM objects can be used just as easily as .NET objects is enough for me. Proceed at your own risk.

[mendhak]

I'll also add that you're pretty lucky to have (apparently) not come from a VB6/COm background, since you'll have a better learning curve than us.