COM and DCOM OS Design Development
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8/28/2008
The Component Object Model (COM) is an operating system-independent object-oriented system for creating binary software components that can interact with other COM-based components.
This interaction can occur in the same process space, in other processes, or on remote computers.
The following levels of run-time support for COM-based applications are supported:
- Minimal COM provides a baseline API set for COM object creation. This Catalog item requires about 10–20K of memory and is only available in headless OS designs.
- COM provides a midrange implementation of COM and Automation that supports only in-process free-threaded objects and requires about 100–200K of memory.
- The Distributed Component Object Model (DCOM) provides a full-featured COM implementation equivalent to Microsoft Windows NT® 4.0 SP5 and requires more than 700K of memory.
In addition, you can add storage functionality to any one of the three COM implementations by adding the COM Storage Catalog item.
Note
Distributed COM (DCOM), sometimes also referred to as "COM Remoting", is not included in Windows Embedded CE. Please see Remote DCOM Support for more information.
OS Design Information
The following table shows operating system design information for COM and DCOM.
| Concept | Description |
|---|---|
Dependencies |
None |
Hardware considerations |
None |
Modules and Components
The following table shows the components and modules that implement COM and DCOM.
| Item | Module | Component |
|---|---|---|
Minimal COM |
uuid, ole32, oleaut32, mcombase, mcommem, mcomstr, mcommon, mcomlib, ole232, docfile, msf, exp |
None |
COM |
uuid, ole32, oleaut32, ole232, com, docfile, msf, exp |
None |
DCOM |
dllhost, dcomssd, rpcrt4, rpcltccm, rpcltscm, ole32, oleaut32, uuid, dcomole, idisproxy |
None |
COM Storage |
stg or mcomstm, depending on the previous COM choices |
None |
Implementation Considerations
The following table shows the Sysgen variables that control COM and DCOM Catalog items.
| Sysgen variable | Description |
|---|---|
SYSGEN_OLE |
Adds a midrange implementation of COM and Automation that supports only in-process free-threaded objects. |
SYSGEN_OLE_GUIDS |
Adds support for CoCreateGuid used with the standard COM implementation. |
SYSGEN_OLE_STG |
Adds structured storage functionality to the standard COM implementation. |
SYSGEN_DCOM |
Adds a full-featured COM implementation equivalent to Microsoft Windows NT® 4.0 Service Pack 5 (SP5). This catalog item no longer brings in the DCOM component libraries. See DCOM Remote Access For more information, see Component Services (COM and DCOM). > [!NOTE] > Distributed COM (DCOM), sometimes also referred to as "COM Remoting", is not included in Windows Embedded CE. Please see Remote DCOM Support for more information. |
SYSGEN_DCOM_STG |
Adds structured storage functionality to DCOM. |
SYSGEN_MINICOM |
Adds a minimal COM implementation that provides a baseline API for COM object creation. |
SYSGEN_MINICOM_GUIDS |
Adds support for CoCreateGuid used with the minimal COM implementation. |
SYSGEN_MINICOM_STG |
Adds structured storage functionality to the minimal COM implementation. |
Application Development Topics
Component Services (COM and DCOM)
COM and DCOM Registry Settings
Creating and Initializing COM Objects