INFO: Interprocess Communication on Windows Platforms

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This article was previously published under Q95900

SUMMARY

The following are some of the standard mechanisms available for interprocess communication (IPC): NetBIOS, mailslots, windows sockets (winsock), named pipes, anonymous pipes, semaphores, shared memory, and shared files. Other IPC mechanisms available on Microsoft systems include DDE, OLE, memory-mapped files, Windows messages, Windows atoms, the registration database, and the clipboard.

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MORE INFORMATION

The table below denotes what platforms and subsystems provide which IPC mechanisms (this does not imply that all the mechanisms will interoperate between different subsystems):

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Interprocess Communication Mechanisms

IPC Mechanism   Win2000  WinNT  Win9x   Win32s(1)  Win16(2)  MS-DOS(2)  POSIX  OS/2
   -------------  -----  -----  ------  --------   --------  --------   -----  -----

             DDE  YES     YES    YES      YES        YES       NO        NO     NO
         OLE 1.0  YES     YES    YES      YES        YES       NO        NO     NO
         OLE 2.0  YES     YES    YES      YES        YES       NO        NO     NO
         NetBIOS  YES     YES    YES      YES        YES       YES       NO     YES
     Named pipes  YES     YES    YES(3)   YES(3)     YES(3)    YES(3)    YES(4) YES
 Windows sockets  YES(5)  YES(5) YES      YES        YES(5)    NO        NO(6)  NO
       Mailslots  YES     YES    YES      YES(3)     NO        NO        NO     YES
      Semaphores  YES     YES    YES      NO         NO        NO        YES    YES
             RPC  YES     YES    YES(7)   YES(8)     YES       YES       NO     NO
 Mem-Mapped File  YES     YES    YES      YES        NO        NO        NO     NO
     WM_COPYDATA  YES     YES    YES      YES(9)     YES       NO        NO     NO

NOTES:

Win32s IS an extension to Windows 3.1 which allows Win32-based applications to run under Windows 3.1. Win32s supports all the Win32 APIs, but only a subset provides functionality under Windows 3.1. Those APIs that are not functional return ERROR_CALL_NOT_IMPLEMENTED.
This is technically not a subsystem.
Cannot be created on Win16, Windows 95 and MS-DOS workstations, but can be opened.
The POSIX subsystem supports FIFO queues, which do not interoperate with Microsoft's implementation of named pipes.
Through the Windows sockets API.
Currently BSD-style sockets are under consideration for the POSIX subsystem.
Windows 95 supports the RPC 1 protocol only. The NetBios protocol is not supported. Namedpipe servers are not supported.
Win32s version 1.1 provides network support through Universal Thunks.
Under Win32s, WM_COPYDATA does not actually copy the data -- it only translates the pointers to the data. If the receiving application changes the buffer, then the data is changed for both applications.
OLE objects created in a Win32 service must be in the same user context as a logged on user that wishes to use them. Any attempt to access these objects from a different user context will result in failure. For example, a service that runs under the LocalSystem account creates an object that an application running in Domain\User's context attempts to access will fail.

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