COM and DCOM OS Design Development (Windows Embedded CE 6.0)

Article
01/05/2012

1/6/2010

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.