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Q257540: DCOM Program Does Not Work After Suspend or Docking Change

Article: Q257540
Product(s): Microsoft Windows 95.x Retail Product
Version(s): Win2000:95
Operating System(s): 
Keyword(s): kbhw kbnetwork win95 kbHardware
Last Modified: 27-JUL-2001

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The information in this article applies to:

- Microsoft Windows 95 
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SYMPTOMS
========

If you run a Distributed Component Object Model (DCOM) client program on your
computer, shut it down, and then suspend and resume the computer, the program
may not reconnect to the server when you run it again. In general, this problem
can occur if device re-enumeration causes the network adapter to unbind from and
rebind to the network transport. For example, undocking or docking a laptop
computer may cause this issue.

The program may generate an error message indicating that the Remote Procedure
Call (RPC) server is unavailable, is too busy, or that an RPC call did not
succeed.

The following error message may occur subsequent to performing normal
CoCreateInstanceEx and QueryInterface calls:

  Function: ConnectionPointContainer::FindConnectionPoint()
  Error: RPC_S_SERVER_UNAVAILABLE

The following error message has been reported to occur when you are using a
Microsoft Visual Basic client that communicates with a Microsoft Windows
NT-based ATL COM server:

  Function: CreateObject(class,[servername])
  Error: RPC_S_SERVER_UNAVAILABLE

The following error messages have also been reported:

  Function: IConnectionPoint::Advise()
  Error: RPC_CALL_FAILED

For all cases, this error message must occur instead:

  Error: RPC_SERVER_TOO_BUSY

CAUSE
=====

In general terms, the client proxy object for the remote component is not
properly reinitialized if the transport has been unbound and then rebound to the
network adapter. More specifically, the client RPC Locator service does not
synchronize with the server socket connection when the program attempts to
obtain the object connection point.

The network transport does not maintain enough internal status through the
suspend and resume process to allow RPC bindings to be cached successfully.

The problem in Windows 95 is essentially structural, encompassing NDIS, most of
the TCP/IP transport components, Windows Sockets (WinSock), and Configuration
Manager. Extensive enhancements to power-state handling in the equivalent
Microsoft Windows 98 components resolve this issue.

Note that this problem is not caused by any problems in DCOM, which is
essentially identical for both Windows 95 and Windows 98.


RESOLUTION
==========


Microsoft recommends that you upgrade to Windows 98 if this problem precludes
efficient usage of DCOM programs on your computer.

WORKAROUND
==========

To work around this problem, restart your computer to cause the DCOM program to
work normally again.

STATUS
======

Microsoft has confirmed that this is a problem in the Microsoft products that
are listed at the beginning of this article.

MORE INFORMATION
================

DCOM connection management uses a ping mechanism for detecting remote object
abnormal termination. On the client, this exists as a separate thread within the
RPC Locator service (RPCSS).

The following sample output is an edited version of the RPC ping activity from a
Windows 98-based client that refreshes the DCOM interface on the RPC Locator
service connection. This client/server communication does not occur between a
Windows 95-based client and the server mainly because the protocol stack
(TCP/IP) does not maintain internal persistent address objects through the NDIS
unbind and rebind process:

  

  Src Dst Protocol Description
  --- --- -------- ----------------------------------------------------------------
  CLI SRV MSRPC    c/o RPC Request: call 0x2  opnum 0x2  context 0x0  hint 0x40
       TCP:     .AP..., len:112, seq:x-x, ack:y, win:a, src:1046 dst: 135 
  SRV CLI MSRPC    c/o RPC Response: call 0x2  context 0x0  hint 0x10 cancels 0x0
       TCP:     .AP..., len: 64, seq:y-y, ack:x, win:b, src: 135 dst:1046 
  CLI SRV TCP      .A...., len:  0, seq:x-x, ack:y, win:c, src:1046 dst: 135


When the client attempts to bind to the remote object (which is carried out
through a Windows Sockets connect), the server tries to synchronize the
connection to the client locator service (on well-known port 135).

The following sample output is an edited version of the RPC problem that occurs
between a Windows 95-based client and the server. The error message that is
returned by the server as a result of the unsuccessful connection
synchronization attempt is returned to the program:

  

  Src Dst Protocol Description
  --- --- -------- ----------------------------------------------------------------
  CLI SRV MSRPC    c/o RPC Alt-Cont: UUID <value> call 0x2 ...
  SRV CLI MSRPC    c/o RPC Alt-Cont Rsp: call 0x2 ...
  CLI SRV MSRPC    c/o RPC Request:      call 0x3 opnum 0x5 context 0x2 hint 0xBA
  SRV CLI TCP      ....S., len:  0, seq:n-n, ack:0, win:z, src:1055 dst: 135
  CLI SRV TCP      .A.R.., len:  0, seq:0-0, ack:m, win:0, src: 135 dst:1055
  SRV CLI TCP      ....S., len:  0, seq:n-n, ack:0, win:z, src:1055 dst: 135
  CLI SRV TCP      .A.R.., len:  0, seq:0-0, ack:m, win:0, src: 135 dst:1055
  SRV CLI TCP      ....S., len:  0, seq:n-n, ack:0, win:z, src:1055 dst: 135
  CLI SRV TCP      .A.R.., len:  0, seq:0-0, ack:m, win:0, src: 135 dst:1055
  SRV CLI TCP      ....S., len:  0, seq:n-n, ack:0, win:z, src:1055 dst: 135
  CLI SRV TCP      .A.R.., len:  0, seq:0-0, ack:m, win:0, src: 135 dst:1055
  SRV CLI MSRPC    c/o RPC Fault: call 0x3  context 0x2 status 0x800706BA ...

  NOTE: 0x800706BA is the RPC_S_SERVER_UNAVAILABLE error value.

Additional query words:

======================================================================
Keywords          : kbhw kbnetwork win95 kbHardware 
Technology        : kbWin95search kbZNotKeyword3
Version           : Win2000:95
Issue type        : kbprb

=============================================================================

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