Is binary compatibility so important?

[Michael G.]

Hi!

When all calls to COM objects maintained through ProgIds, e.g. "Component.Method",
is binary compatibility which maintains continuous GUIDs important? Every
time new component is installed it will register the ProgId with proper GUID.
Why to preserve binary compatibility?

Thaks in advance,
Michael

[K.Poongundran]

Hi,
Call to COM objects are maintained by ProgID ->ClassID. So if you don't put
binary compatibility every time a new ClassID is assigned to the ProgID.
So your ProgID cannot identify the old ClassID. So You need to Re-register
the Component and you need to re compile all the programs whether it is a
normal exe or an activeX dll for your ProgID to identify.

Have a nice day!
Krish Poongundran

"Michael G." <michaelg@pos.co.il> wrote:
>
>Hi!
>
>When all calls to COM objects maintained through ProgIds, e.g. "Component.Method",
>is binary compatibility which maintains continuous GUIDs important? Every
>time new component is installed it will register the ProgId with proper
GUID.
>Why to preserve binary compatibility?
>
>Thaks in advance,
>Michael

[Michael Culley]

Michael,

If you have a component that is used by several apps, which could be updated
by installing a different app, then binary compatability is vital.

But if you have a component that is specific to your app then it is optional.
But you must always distribute the exe and the component together and not
use it in any other apps.

Michael Culley

"Michael G." <michaelg@pos.co.il> wrote:
>
>Hi!
>
>When all calls to COM objects maintained through ProgIds, e.g. "Component.Method",
>is binary compatibility which maintains continuous GUIDs important? Every
>time new component is installed it will register the ProgId with proper
GUID.
>Why to preserve binary compatibility?
>
>Thaks in advance,
>Michael

[Colin McGuigan]

Michael G. <michaelg@pos.co.il> wrote in message
news:3a23695e$1@news.devx.com...
>
> Hi!
>
> When all calls to COM objects maintained through ProgIds, e.g.
"Component.Method",
> is binary compatibility which maintains continuous GUIDs important? Every
> time new component is installed it will register the ProgId with proper
GUID.
> Why to preserve binary compatibility?
>
> Thaks in advance,
> Michael

_If_ all calls are maintained through ProgIDs, then, no, binary
compatibility isn't important.

However...

You must always make sure that, when updating the DLL, you reregister.
ProgID lookup is done in the registry, where a ProgID is matched up to a
GUID. If you overwrite a DLL with one that has different GUIDs, but don't
register it (so it doesn't update the registry), COM won't be able to create
the object.

--
Colin McGuigan