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COMsource Frequently Asked Questions

 Updated: 8/9/01

COMsource Product Offering

Security in COMsource

Porting COMsource

COMsource on UNIX vs. COM on NT

Using COMsource

Getting Help with COMsource

Q - What are the COMsource deliverables?

COMsource contains source code reference implementations on Sun Solaris 2.6 (32-bit reference platform) and Compaq Tru64 UNIX 4.0D (64-bit reference platform) along with reference documentation and a test suite.

Q - Can you just give me a big picture of COMsource availability and pricing?

COMsource source code is available & can be downloaded via ftp just as soon as a signed Licensing Kit is received by The Open Group. Pricing (in USD) is $3,000 for Universities, $7,000 for a Developers License, and $35,000 for a Full Distribution License. Object code redistribution fees and rights are included, subject to the Terms and Conditions of the license type. The Documentation Set and Interoperability Test Suite are also included.

COMsource information and ordering details can be found at

Q - What media is used to provide the COMsource deliverables?

COMsource deliverables are made available to purchasers of the product via ftp download.

Q - How large is the COMsource release?

There are five compressed tar files in the COMsource release. The disk space requirements for both the downloadable compressed tar files and the unexpanded sources are provided below.

Compressed Tar File

Unexpanded Sources

32-bit-source.tar.gz 10.8 MB 53.0 MB
64-bit-source.tar.gz 10.9 MB 58.2 MB
documentation.tar.gz 5.3 MB 46.2 MB
interop.tar.gz .2 MB .8 MB
tet.tar.gz 1.3 MB 5.3 MB

Q - What's contained in the documentation set provided with COMsource?

The documentation set includes the COMsource Reference Documentation (ActiveX Core Technology Reference Documentation), Release Notes, Testing Guide, and Interoperability Test Suite results. The Reference Documentation contains documentation on each of the COM APIs and Interfaces. This document is also available separately from The Release Notes contain full instructions for installing and building the COMsource reference implementations. The Testing Guide provides a detailed description of each of the tests in the Interoperability Test Suite. There are also test results from running the Interoperability Test Suite against the reference implementations.

Q - Are testing results provided for the reference implementations?

Yes, the release contains detailed test reports with test results from running the Interoperability Test Suite on each of the reference implementations.

Q - What is the definition of the reference platforms on which COMsource was developed and tested?

32-bit Reference Platform

64-bit Reference Platform


Sun UltraSparc Compaq Alpha AXP Workstation
Operating System:

Sun Solaris 2.6 Tru64 UNIX 4.0D, 4.0E and 4.0F
Compilers: SUNPro v5.0
(runs in both native version 5.0 mode and compatibility mode)
Tru64 UNIX C++ v5.7,
Tru64 UNIX C v5.6

Q - What about a third party redistributing the product that I have created from COMsource, and object code fees?

The COMsource Source License with Full Distribution Rights includes a fully paid-up Object Code license for unlimited redistribution, as defined in The Open Group’s COMsource Standard Supplement (Terms and Conditions). The Licensee may make whatever licensing arrangements they want with their redistributors. Source code is not allowed to be redistributed to a third party, unless that party has a valid COMsource source license obtained from The Open Group.

Q - What if I want to install the source code on more than five (5) systems for parallel development?

An additional source code license is required, which provides an additional five (5) systems usage (up to five (5) systems per license allowed).

Q - How stable is COMsource?

COMsource is stable and is being used in production environments. However, we have not performed stringent stress testing on COMsource. Users's of Microsoft's COM have found that they do not achieve 100% reliability, and as COMsource is a derivative of COM, it is not recommended for applications which require near 100% uptime.

Q - What security model does COMsource support?

COMsource supports the Windows NT 4.0 security model, which is pass-through NTLM security.

Q - What is the difference between the version supporting 128-bit encryption and the 40-bit encryption version of COMsource?

The only difference is in the level of encryption supported. All other code & functionality is the same.

The 128-bit encryption version of COMsource supports full 128-bit encryption, provided that the operating system on which it is running supports 128-bit encryption. COMsource supports 128-bit encryption between UNIX systems and between UNIX - NT 4.0 Service Pack 4 and above.

Q - Is the actual encryption software provided as part of the COMsource release?

No, the reference implementations do not contain the low-level encryption libraries. To include encryption, you must obtain the encryption software independently. In order to build the COMsource release as delivered with security enabled, you must have a low-level encryption library. There is an option in the software to disable security, which would enable you to install, build and use COMsource prior to obtaining encryption software.

Q - What encryption software was used during development and testing of COMsource?

The reference implementations use BSAFE Version 3.0 libraries and header files from RSA Security.

Q - How long should it take to port COMsource to a new platform?

The port, including all necessary testing, should take anywhere from 1.5 to 3 months.

Q - Porting Limitations/Restrictions - Will there be any for porting to other platforms?

The key limitations/restrictions are:

  1. Licensees may only distribute derivative works which contain the entire functionality of the release - they may not distribute subsets or portions of the COMsource technology.
  2. Derivative works must pass the Interoperability Test Suite, which must be ported to the licensees platform. Results of the successful run of the Interoperability Test Suite must be provided to The Open Group prior to shipment of the derivative work.

Details of limitations/restrictions are found in the COMsource Standard Supplement, section 3.1, Restrictions.

Q - How does COMsource compare to COM on Windows NT?

COMsource is based on the Windows NT 4.0, Service Pack 3 version of COM. It has been enhanced to work with Window NT 4.0 service packs 4, 5, 6a and Windows 2000. COMsource provides the same basic functions, libraries and tools as COM. COM applications written for Windows NT are easily ported to any of the COMsource reference implementations.

From a user perspective, the functionality of COMsource is the same as COM on Windows NT -- the data types are the same, the wire format is the same, the APIs are the same.

Q - Does COMsource contain the Windows NT version of COM?

No, COMsource does not contain the Windows NT COM sources. It contains only those for the two reference implementations, on Solaris and Tru64 UNIX.

In order to test a COMsource derivative product against Windows NT, you will need to obtain an machine running Window NT with COM supported.

Q - Are there any plans to extend COMsource to support COM+ on UNIX?

At this time, we do not have specific plans to extend COMsource to support the new COM functionality provided in COM+. However, COM is backwards compatible and the existing COMsource will run on newer versions of Microsoft operating systems and interoperate with newer versions of COM, such as COM+.

Q - What about potential differences in endian types between Windows NT and UNIX?

The MSRPC packets going across the wire are identical whether originating from a Windows NT platform or a UNIX platform. On UNIX we unmarshal into the proper format for the specific UNIX platform -- for example, Solaris is 32-bit big endian (high order byte first), Tru64 UNIX is 64-bit little endian, and there are differences with the internal representation.

Q - What is the relationship between Microsoft RPC and DCE RPC?

Microsoft Remote Procedure Call (MS RPC) is an implementation of The Open Group's Distributed Computing Environment (DCE) Remote Procedure Call (RPC) Specification. MS RPC is wire-level compatible (as opposed to call-level compatible) with DCE RPC.

Q - What is required to create a COM or DCOM object on a UNIX system?

The only requirement is that the COMsource environment must be running. Then, COM/DCOM objects are created in the same way as they are under Windows NT.

Q - What is required to compile a C++ program in UNIX such that it can access a COM object in COMsource?

You need to build and run the COMsource environment, which includes a number of utilities described in the documentation. For example, to build the environment on Solaris, you will need a SUN C++ compiler (Workshop 5.0). If you build the secure version, you'll need the Bsafe security library.

Q - How does COMsource handle type information?

Type information is handled the same as for COM. COMsource uses MIDL to process the type information in the IDL.

Q - Is there a newsgroup or mailing list where I can discuss COM on UNIX issues?

YES, subscription information is available at: This list provides a mechanism for discussion of issues regarding the use and programming of COM technology on UNIX.


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