COM
- .NET Interoperability
Host: Yan-Hong Huang & Allen Weng - Sr. Support Engineers,
MS Global Technical Engg. Center - Shanghai, China
March
7, 2002
KunalS[MS]: Welcome everybody
KunalS[MS]: The topic of today's chat is
KunalS[MS]: .NET - COM Interoperability
KunalS[MS]: and the experts on today's chat are
Manish: hello Mr.Yan-Hong
KunalS[MS]: Yanhong and Allen
yhhuang[MS]: Hello
KunalS[MS]: from MS GTEC, Shanghai
Allen[MS]: Nice to meet u
KunalS[MS]: So please go ahead
rami: Hi all nice meeting
Manish: hello Allen
KunalS[MS]: and share all your doubts and queries
rami: sure
Allen[MS]: any question is welcome.
rami: In dotnet do we really need COM components?
yhhuang[MS]: sure
Deepak: hi, quick question: how is COM Interop in terms of performance
Manish: Well for accessing com components in .NET we have RCW, still
we see createobject is supported in VB.NET, so i guess its an unmanaged
call right, please clear
culguy: hi yan n allen , hi everyone
yhhuang[MS]: for the performance, I think it won't be
quicker
Allen[MS]: The performance is not as good as native code.
Deepak: of course, but is it scalable - do we have tangible metrics/numbers
to show it performs?
Allen[MS]: COM marshaling and interop mashaling are invovled
in the interaction between managed code and native code.
Deepak: sorry, let me make myself clear, I am looking for benchmarks
- lets say sending mail using CDO and using native code - now do we
have numbers to indicate how much performance hit we take due to interop
Allen[MS]: Please be more specific.
Allen[MS]: We don
yhhuang[MS]: so you need numbers?
Allen[MS]: we have such benchmark in this regards
Deepak: yup - exact performance metrics
Manish: Well for accessing com components in .NET we have RCW, still
we see createobject is supported in VB.NET, so i guess its an unmanaged
call right, please clearify
Vijay: hi every1
suresh: hello vijay
suresh: ur welcome
Vijay: has the chat session started or not
KunalS[MS]: Yes Vijay it has
yhhuang[MS]: hi
suresh: i think no i just came to this room
yhhuang[MS]: In .NET framework
suresh: ohh..
yhhuang[MS]: if we want to call .com component,
yhhuang[MS]: we need go through InterOp
Vijay: ok
yhhuang[MS]: So I don't think CreateObject is a direct
unmanaged way
Pranav76: yhhuang, can you just give us a brief idea about InterOp
rami: Yanhomg.. a quicky.. In dot net components need not to be registerd..
correct? in such case if i want to maintain transactions do i need
to use component services window?
if i place the DLLs there will it be registerd or what exactly do
component services
Vijay: yhhuang, everytime a question arises whenever i/v think of
interop
Manish: hey, but by using createobject, where are the wrappers created
Vijay: whats the performance loss/gain v get when doing this ?
yhhuang[MS]: Pranav76: CLR provides two mechanisms for
Interop with unmanaged code
Allen[MS]: InterOp is the way the managed world talks
with the naitive world.
yhhuang[MS]: Platform invoke service and COM Interop
Pranav76: whatz the advantages and disadvantages of both
yhhuang[MS]: Vijay: what you can get is from .NET framework
Allen[MS]: We have no benchmarks or exact numbers about
the performance hit caused by InterOp,
yhhuang[MS]: such as versioning, code based security......
Pranav76: yeah I can get it
Manish: Yan, if createobject is a managed call, where are the wrappers
created
culguy: Allen , when we use System.EnterpriseServices in our managed
code, is it all managed code or does it make a umnaged call internally
?
culguy: Allen , when we use System.EnterpriseServices in our managed
code, is it all managed code or does it make a unmanaged call internally
?
Allen[MS]: The managed code that lives in COM+ uses InterOp
to communicate with the COM+ services.
Pranav76: I have a COM component written using VB and a COM component
developed using VB.NET... Can I use these two components in the same
way in any of my .NET apps?
yhhuang[MS]: Hi Manish
yhhuang[MS]: I think the job is done by framework
Deepak: Rami> You'll need to do REGSVCS for it
to be usable as a COM+ component
Manish: Yes Mr Yan, i m still not clear, if we use CreateObject is
the call managed
Allen[MS]: With InterOp you can use the native compoent
in the .NET apps. Manish: ok
yhhuang[MS]: Pranav76: yes, you can use both of these
two components
Pranav76: but, what is to be done from my side to make it usable???
Is there any specific code to be written for that?? or the .NET framework
will take care of that???
Pranav76: you were talking abt Interop helping me in doing that
yhhuang[MS]: Pranav76: For that one implemented by VB,
you need to use COM interop
rami: thanks deepak
Manish: Allen, can u point out a case where a COM component will not
work correctly in .NET interop
Allen[MS]: Pranav76, to use native code in the .net apps,
you need to import it into your project.
yhhuang[MS]: Pranav76: yes. COM Interop can help you
use those components developed in VB or VC 6.0
Allen[MS]: You can use the TLBIMP.EXE to do that.
Pranav76: but, is Interop capable of making my VB.NET components usable
in my VB projects?
Allen[MS]: Sure.
Pranav76: like what I mean is, if the same VB.NEt component is to
be used in my VB app, can it be done?
Allen[MS]: You can use the utility tlbexp to export it
to the unmanaged world.
yhhuang[MS]: Pranav76: That is the work of CCW
Pranav76: whatz that (CCW)???
Allen[MS]: COM Callable Wraper.
Pranav76: ohh ok... can u give me some insight on that?
yhhuang[MS]: Pranav76: a CCW is created from a non-collected
heap which makes it possible for COM clients to reference the wrapper
directly
Pranav76: thats great.. I got it
Saurabh: Allen, I was trying to create a Wrapper around the CDOSYS.dll
.. but the wrapper is not being corectly generated.. al the properties
are being marked as read-only!! I even tried VS.NET .. but same results
.. can you elaborate whats wrong here ??
yhhuang[MS]: Pranav76: The CCW is a proxy for the .NET
object being referenced from unmanaged code
Vijay: whats CCW here ???
Pranav76: ohh ok.. is CCW part of .NET framework or what?
Allen[MS]: COM callable wraper.
Vijay: thanx allen
yhhuang[MS]: Pranav76: yes
Allen[MS]: Saurabh, what do you mean by read only?
dk_krishnan: hello everyone
Saurabh: All the properties the are being generated in the wrapper
class just have a get accessor ... while the API say's I can set properties
also
culguy: Allen , when we use System.EnterpriseServices(for using COM+
in my .NET application) in our managed code, is it all managed code
or does it make a umnaged call internally ?
yhhuang[MS]: Saurabh: If I remember right, there is one
sample on CDO in Framework SDK
yhhuang[MS]: Saurabh: You can refer to it
Allen[MS]: culguy , it also needs to go through interop
Saurabh: Yes I did refer to it, but I need to interOp with CDOSys.dll,
since I need NNTP Support also ...
Pranav76: Can you give me an insight into how COM is different in
.NET
Allen[MS]: In your managed com+ component, you dont'
have to make any InterOp calls.
yhhuang[MS]: Saurabh: I didn't notice it before. Perhaps
we can discuss it offline
Manish: some ActiveX components become terribly slow when used in
.NET, why? and how to solve it ?
culguy: thnx allen
Allen[MS]: Actually all your COM+ component will derive
from ServicedComponent. which wraps the functions of the IObjectContext
and so on.
yhhuang[MS]: Manish: any example?
Allen[MS]: Unmanaged code is Interface-based, while managed
code is object based.
Saurabh: yhhuang[MS]: can I get your e-mail address ?? Actually
the example in the SDK uses Late Binding ... not Wrapper classes
Allen[MS]: the unmanaged code use GUID to identify a
object, while managed code uses strong names to do it.
culguy: allen, so would u say that using COM+ in .NET sacrifices performance
?
Manish: a third party component for skins, dont remember the name,
tool a while to site on my form
Allen[MS]: We have reports on the performance issue,
but we have no exact numbers.
yhhuang[MS]: Manish: That depends on how it designs.
Have you profiled it?
Saurabh: Allen, I don't know if this has been already asked (I came
in a bit late), but what's the avg performance difference in using
Late Binding and Wrapper classes ( C# as language)??
Manish: not really, instead i dropped the idea of using that control,
but why does it happen
Allen[MS]: Personally I have not done such performance
comparation.
yhhuang[MS]: Manish: Since it is designed for skin, can
be caused by drawing Manish: hmm, possibly
culguy: ok allen
Allen[MS]: latebinding may involes registry lookup, but
RCW doens't.
Saurabh: Allen, is that the only performance difference ??? And registry
lookp-up might only be when the COM Component is invoked .. right
??
yhhuang[MS]: Saurabh: should happen when being created
Saurabh: Kool, that does not sound to me as a BIG performance difference
.... what's the MS recomendations on this use Late Binding or Wrappers
??
Allen[MS]: If you have compile-time metadata, you may
want to use the early binding. If you have not, use the Latebinding.
Saurabh: ok!
Saurabh: Also there have been a lot of people debating if while creating
new applications from ground-up COM / COM+ should be used or not ?
Any words on this ?? Does .NET mark the end of COM components ??
yhhuang[MS]: Mark the end of COM components? No.
Allen[MS]: The .NET is an natural evolution of COM.
dhotiman: can we say that .net is just another way of creating our
COM components
Saurabh: So does MS recomend that COm components should be used in
the middle tire while creating new .NET Applications ??
Allen[MS]: I remeber Don box has an titled "Is COM dead"
in MSDN.
Allen[MS]: you can refer to it.
dhotiman: ok
Saurabh: ok
culguy: can u guys give a example where i might have 2 create a COM
component in a .NET application?
Allen[MS]: when you want to use legacy components.
Manish: allen, just a thought, does the .NET framework use any COM
comonents ?
Allen[MS]: I am not sure about that.
culguy: let me be more specific, there are no existing COM components
to be used, still do u see a situation where i have create a component
in VB6
Deepak: its a layer on top of ADSI interfaces - its IMHO not fully
native (yet)
yhhuang[MS]: If you want to do something more quickly
Manish: thanks
Allen[MS]: To develop managed component with .NET is
fast and effiient, we strongly recommend you to use the power of .NET.
Allen[MS]: any more Qs?
culguy: 1 last q
culguy: there r 3 methods to register a .NET component in COM+, which
is the best according to u in terms of performance ?
Allen[MS]: please be more specific.
Sanjay: Hi, Any plans on providing direct support for .NET components
in future releases of COM+. I believe right now it goes through the
COM Interop.
Allen[MS]: I guess so.
KunalS[MS]: Any more questions coming?
Sanjay: But no specific plans yet?
yhhuang[MS]: Till now, all the COM interop should be
go through RCW.
Vijay: RCW ???
Sanjay: The question is that interop thunk will drag the per call
performance down, so it makes sense to add managed CLR in COM+?
yhhuang[MS]: RCW is runtime callable wrapper
Allen[MS]: actually managed CLR is named COM+ 2.0 Sanjay:
with Windows.NET servers?
culguy: when is it expected 2 b released, COM+ 2.0 ?
yhhuang[MS]: Not been confirmed
Sanjay: Thanx
culguy: thnx
yhhuang[MS]: It seems that most are interested in the
performance from COM to .NET
KunalS[MS]: We have another 5 mins, so please shoot of those questions
now
dhotiman: thanks
Vijay: yes numbers could help us
Saurabh: yes .. since that's waht most of your clients worry about
Vijay: bcoz v want to see the trade offs between rewriting a COM Component
in .NET and losing performance using them as such
yhhuang[MS]: In fact, numbers are different in different
scenarios
Vijay: yeah i do understand that
Manish: yeah, but can we get a rough %
Vijay: in one of seminars, Sanjay Vyas was saying
Vijay: its only 15 IL instructions
Vijay: to use COM Interop
Allen[MS]: yes.
Vijay: so does it mean
Vijay: v dont lose much
Manish: thats fine, but the marshalling will take up more time
khozema: hi everybody
Vijay: yes thats true
culguy: agree with manish there
Allen[MS]: it depends.
khozema: hello allen, huang, and kunal
yhhuang[MS]: hi khozema
Allen[MS]: 15 IL is the best we can get.
khozema: sorry for being late
Manish: yeah, well a call will cross the process boundaries (from
CLR) invoke the com and get back
Allen[MS]: but if some data need to be marshaled between
the two worlds, the performance get hit.
KunalS[MS]: There have been no exact percentage numbers that have
been yet published
KunalS[MS]: that mark the performance upgrade...
KunalS[MS]: but the moment we have some definite nos., we shall share
them with you
Manish: cool
culguy: i think most of us would want 2 use COM+ , since COM Interop
is the only way, people would think abt performance , it would b nice
if Microsoft could give us all some numbers
KunalS[MS]: So I believe there are no more questions for our experts.
Saurabh: awaiting the reults
KunalS[MS]: but surprisingly
KunalS[MS]: what limits you from
yhhuang[MS]: Nice to meet you all today
KunalS[MS]: using COM .NET Interop - the performance hit?
Saurabh: Yes, Kunal !!
Manish: thats the main concern kunal
KunalS[MS]: is that the main issue of concern here? or is it the ease
of not having develop your components afresh!
culguy: yes, as saurabh said initially his clients r concrned abt
it
Manish: component are ment to be reused , why reinvent the wheel
Saurabh: Kunal .. if I use COM Intero .. and there is a BIG performance
Hit then may be I will have to shift my attention towards creating
new native .NET Components
KunalS[MS]: i agree...but in all you opinion
KunalS[MS]: is the performance hit so much that you need to consider
building fresh components?
KunalS[MS]: i dont think so!
Manish: I feel there should be more components bundled with Vs.NET
or available from MS like we had for ActiveX controls
Saurabh: That's what we don't know !! Tha's why need the figures from
MS !!
culguy: that's what I want 2 know, exactly how much difference is
there
KunalS[MS]: What do your clients say?
KunalS[MS]: There is one scenario of numbers which give us exact differences...
KunalS[MS]: the other is that there is an apparent hit in performance,
numbers just justify
culguy: even, we as developers and architects hav 2 think twice b4
using COM+ in a .NET application
Vijay: yes true culguy
Vijay: if performance goes even my little that too in a web app
Vijay: u lose ur customers
Vijay: that too to our competitors
Saurabh: Kunal .. we as developers understand things... but as you
know clients are always too cautious of NEW technologies .. they won't
take our words ... they will simply say give proof !!
KunalS[MS]: but the COM - .NET Interop is not a permanent solution
Vijay: yes, true, thats what v face
Vijay: 24 * 7
Vijay: so some documentation from a company like MS
Vijay: will help us
KunalS[MS]: it is a bridge for your customers to move there systems
in a phased manner
KunalS[MS]: and that is what you need to explain to your customers
Vijay: u can benchmark of any one of ur sampel application
Vijay: and just host them on the site
chinese-guy: hi all, i'm looking for a friend in dubai
Saurabh: Kunal, that's what I was trying to ask earlier if COM development
was dead!!
KunalS[MS]: The customer understands that there is a apparent business
benefit
Manish: hmmmm
KunalS[MS]: in moving to .NET
KunalS[MS]: but if you tell the customer
KunalS[MS]: that it is a rip and refit solution
KunalS[MS]: it is not possible to implement the solution
IsolaRam: I have some Engineering items for distributors invited
KunalS[MS]: the idea is to provide the customer with a technolgy growth
path
Vijay: see kunal, customers dont understand as v developers do
Vijay: v understand ur language bcoz v hv been breathing, living,
sleeping technology
KunalS[MS]: Vijay, what customers understand is return on inventment
KunalS[MS]: investment
Vijay: yes u r rite
IsolaRam: any one interested in distributorship
KunalS[MS]: and Total Cost Of Ownership
Vijay: yes
Vijay: yes ROI, TCO is whats they breate
KunalS[MS]: if you explain to the customer
KunalS[MS]: that this the way to move their systems
KunalS[MS]: in a phased manner to a paradigm om computing
KunalS[MS]: then they understand
Vijay: k
Vijay: so what v hv to do is
KunalS[MS]: no CTO can afford to rip and replace!
Vijay: write .NET apps that will use existing COM/COM+ code
KunalS[MS]: COM - .NET Interop is the answer to a roadmap of implementation
Vijay: and then v will slowly do rip and replace in a phased manner
Vijay: is that rite ?
KunalS[MS]: Right Said Fred!
KunalS[MS]: Alright guys,
KunalS[MS]: thank you very much for your time
Vijay: thanx kunal
Manish: THanks Allen,Yon-huang and Kunal
Vijay: u r doing gr8
Vijay: work
KunalS[MS]: we shall try and get back to you with some numbers on
the performance front
Saurabh: thanks
culguy: thnx yan, allen, kunal
KunalS[MS]: For all those present
KunalS[MS]: the next weeks chat is on
KunalS[MS]: XML Web Services and Interoperability
Manish: we will be there
KunalS[MS]: and shall be conducted by
Manish: thanks again
Manish: bye
Vijay: oh gr8 yaar
KunalS[MS]: Ashutosh Danesha
KunalS[MS]: Lead .NET Evangelist
KunalS[MS]: MS India
KunalS[MS]: he is from MS Redmond
Saurabh: good topic .. actually very very intresting ...
Vijay: yes very intresting
Vijay: thanx kunal
KunalS[MS]: and has been part of the initial CLR Development Team
KunalS[MS]: Bye all of you and thanks once again
Vijay: oh gr8 kunal, u bring gr8 people to enlighten us
