Re: What is 'managed code'?

Wow, that was the answer of the year, Michael.
Thanks a lot.
I am TAPI developer using vb5.
It is not the easy job, specially that I need to adapt C routines into vb
compatible code.
Jack


"Michael D. Ober" <obermd.@.alum.mit.edu.nospam> wrote in message
news:ormSe.5683$Wd7.3054@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Very simply, managed code is code that the runtime system handles all
> aspects of memory and resource management. The managed code model is that
> of infinite resources. But since we know that resources on any given
> system
> are finite, the runtime must do a lot of work to present this model. To
> do
> this requires that the runtime system present a garbage collector that can
> sweep through the application memory and find all unreferenced resources,
> be
> they memory, IO Ports, files, etc., and properly close and release them
> back
> to the OS. In the case of memory, the garbage collector must also compact
> available memory to consolidate free space for further allocations.
>
> VB 5&6 almost do this for memory only, and then only if you don't use
> direct
> Windows API calls. When using ActiveX components, which are all COM
> Objects, the Component Object Module runtime DLLs perform a simple
> reference
> counting. When an ActiveX component's references go to zero, the COM
> runtime releases the memory of the COM Object. Note that the COM runtimes
> don't close files or other resources - they belong to the process and the
> OS
> will close them when the process exits. In VB 5&6, memory references are
> also reference counted, which means that it is possible to create two
> objects that reference each other, yet are impossible to reference from
> the
> application. The VB 5&6 Garbage Collector will never free these objects.
> Nor can the VB 5&6 Garbage Collector consolidate free memory space.
> Neither
> of these weaknesses of a reference counted memory scheme are usually a
> problem.
>
> Now to the kicker - VB 5&6 are a very sophisticated implementation of a
> COM
> object, to the extent that each form is a COM Object. This is why you
> need
> to be careful when referencing controls on a form during your Form_Unload
> event procedures. Doing so creates a new reference to the form, which
> prevents the form from being reclaimed by the COM runtime.
>
> The major weakness of fully managed code is that it is significantly
> slower
> than unmanaged code. The TAPI API is a near real-time API. Real-time and
> Managed cannot be used in the same sentence. Other common Windows APIs
> that
> fall into this category include the Multimedia API and DirectX. VB 5&6
> are
> partially managed and as such, tend to lie between fully managed code and
> unmanaged code in performance. Runtime resource management of any type
> incurs a performance penalty, regardless of language.
>
> To those of you who think this is a .NET question - it's not. This is a
> question of language design and implementation. In the Microsoft world,
> .NET is fully managed, FoxPro and VB 5&6 are partially managed, and C/C++
> (including the ATL and MFC extensions) is unmanaged. JAVA, APL,
> Smalltalk,
> and Lisp are also fully managed. You can tell unmanaged languages by the
> presence of explicit pointers to memory. Managed code generally doesn't
> support explicit pointers except where required for call backs and event
> handlers.
>
> Mike Ober.
>
>
> "Jack" <replyto@newsgroup> wrote in message
> news:uLY4xBEsFHA.3720@xxxxxxxxxxxxxxxxxxxxxxx
>> From MSN:
>> This article discusses why Telephony Application Programming Interface
>> (TAPI) is not supported from managed code.
>>
>> What is that managed code?
>>
>>
>
>


.

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