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Last updated 6/24/2009

Model Rationale
Model Description
Papers, Reports, and Presentations
Model Status
Data Collection Program
Research Group
Research Sponsors
Downloads (Software and Documentation)
Cost Estimation Bibliography
Other COTS Related Websites
For Further Information
The COCOMO Suite
CSSE Home Page


Model Rationale

One of the more significant changes in software development practice over the past twenty years is the greatly increased emphasis being placed on building systems incorporating pre-existing software in order to keep overall development and maintenance costs as low as possible. This trend has become so pronounced that some large software system acquirers have even gone so far as to establish policy which demands that their software procurers justify why they are not using such components.

One source of pre-existing software is commercial vendors who supply self-contained off-the-shelf components that can be plugged into a larger software system to provide capability that would otherwise have to be custom built. The two primary distinguishing characteristics of this so-called COTS (commercial-off-the-shelf) software are 1) that its source code is not available to the application developer, and 2) that its evolution is not under the control of the application developer.

The rationale for building COTS based systems is that they will involve less development time by taking advantage of existing, market proven, vendor supported products, thereby reducing overall system development costs. But because of the two defining characteristics noted above (lack of access to product source code and lack of control over product evolution), there is a trade-off in using the COTS approach in that new software development time can indeed be reduced, but generally at the cost of an increase in software component integration work. Moreover, using COTS software also brings with it a host of unique risks quite different from those associated with software developed in-house.

Included among those risks or factors which should be examined when determining the true cost of integrating a COTS software component into a larger system are not only the traditional costs associated with new software development such as the cost of requirements definition, design,code, test, and software maintenance, but also the cost of licensing and redistribution rights, royalties, effort needed to understand the COTS software, pre-integration assessment and evaluation, post-integration certification of compliance with mission critical or safety critical requirements, indemnification against faults or damage caused by vendor supplied components, and costs incurred due to incompatibilities with other needed software and/or hardware.

Because of these unique risks, using COTS components in the development of new systems is not the universal solution to reducing cost and schedule while maintaining desired quality and functionality. However,if these risks can be managed, using COTS components can frequently be the right solution, offering the most cost-effective, shortest schedule approach to assembling major software systems.

COTS components are the right solution when they lie at the intersection of the three determinants of feasibility--technical, economic, and strategic constraints--and do so in a way demonstrably better than if a new system were to be constructed entirely out of original software. The key to success in using COTS components is being able to identify whether they fit the current procurement situation--technically, economically, and strategically. Technically, they have to be able to supply the desired functionality at the required level of reliability. Economically, they have to be able to be incorporated and maintained in the new system within the available budget and schedule. Strategically, they have to meet the needs of the system operating environment--which includes technical, political, and legal considerations--now, and as that environment is expected to evolve in the future.

The determinants of COTS component feasibility: Technical, Economic, and Strategic constraints.

Technical and strategic feasibility is determined during the candidate assessment phase of procuring COTS products, which occurs at the start of a COTS integration activity. How to determine the viability of a COTS product in either of these two dimensions is not a trivial question, and can be partially addressed by using the COCOTS Assessment submodel. However, it is the third dimension of determining economic feasibility which is the main intended use of COCOTS.

To answer the question of economic feasibility, cost estimation models exist which capture the traditional costs associated with new software development noted above, among the most prominent being COCOMO. To date, however, very few estimation models have been developed which try to capture those other costs unique to using COTS components in a software system development. The number of COTS integration cost models available in the public domain currently approaches zero. In response to this situation, USC-CSSE has been actively pursuing COTS integration cost modeling research since 1995. The most recent result of this research is COCOTS (COnstructive COTS), a cost estimation model designed to capture explicitly the most important costs associated with COTS component integration.

Model Description

You can access the Model Description by clicking the link below:
Model Description

Papers, Reports, and Presentations

Journal Papers:

  • "Attribute-Based COTS Product Interoperability Assessment" (2007)
  • Authors: Jesal Bhuta, Barry Boehm
  • Sixth International IEEE Conference on Commercial-off-the-Shelf (COTS)-Based Software Systems (ICCBSS'07)
  • Link
  • "COCOTS Risk Analyzer" (2006)
  • Authors: Ye Yang, Barry Boehm, Dan Wu
  • Fifth International IEEE Conference on Commercial-off-the-Shelf (COTS)-Based Software Systems (ICCBSS'06)
  • Link
  • "Assessing COTS Integration Risk Using Cost Estimation Inputs" (2005)
  • Authors: Ye Yang, Barry Boehm, Betsy Clark
  • International Conference on Software Engineering, Proceedings of the 28th international conference on Software engineering, 2006, pp. 431-438
  • PDF format
  • "COCOTS: A COTS Software Integration Lifecycle Cost Model - Model Overview and Preliminary Data Collection Findings" (2000)
  • Authors: Barry W. Boehm, Christopher M. Abts, Elizabeth K. Bailey
  • Proceedings ESCOM-SCOPE 2000 Conference, 2000, pp. 325-333
  • PDF format



  • "Extending the COCOMO II Software Cost Model to Estimate Effort and Schedule for Software Systems Using Commercial-off-the-Shelf (COTS) Software Components: The COCOTS Model"
  • Author: Christopher M. Abts
  • PhD Dissertation (May 2004)
  • PDF format
  • "Empirical Observations on COTS Software Integration Effort Based on the Initial COCOTS Calibration Database"
  • Authors: Chris Abts, Barry Boehm, Elizabeth Bailey Clark
  • Submitted to the Workshop on Continuing Collaborations for Successful COTS Development, ICSE 2000, Limerick, Ireland, June 4-5, 2000
  • PDF format
  • "COTS Software Integration Cost Modeling Study" (June 1997)*
  • Authors: Christopher M. Abts, Barry W. Boehm
  • Final report under DoD contract F30602-94-C-1095
  • PDF format (174kb)

* Sponsored by the USAF ESC/Rome Laboratory. This report discusses the origins of what subsequently evolved into the "glue code" submodel of COCOTS. This submodel has been refined since the completion of this study, but this report still provides a useful overview into the origins of the COCOTS concept.

  • "USC-CSE Focused Workshop #7: System Integration with Commercial Software (COTS Integration) Proceedings" (November 1996)*
  • Editors: Christopher M. Abts, Barry W. Boehm
  • HTML format
  • PDF format (174kb)

* Complete version available only in hardcopy (592 pages)--free to Affiliates, all others charged $35 to cover cost of reproduction & shipping.

  • "USC-CSE Focused Workshop #4: COCOMO 2.0 - COTS Software Integration Breakout Group Discussion" (May 1995)*
  • Authors: Ellis Horowitz/Facilitator, Christopher M. Abts/Scribe
  • PDF format (28kb)

* This breakout group session was the beginning of the COTS research effort at USC.



  • 2006 USC-CSE Annual Research Review - "COCOTS Risk Analyzer and Process Usage"
  • Author: Ye Yang, Barry Boehm
  • PPT format (334kb)
  • 2005 COCOMO and Software Cost Modeling International Forum 20 - "Experiences/Observations in Developing COCOTS and Early COCOTS "
  • Authors: Betsy Clark, Brad Clark, Chris Abts
  • PPT format (489kb)
  • 2005 COCOMO and Software Cost Modeling International Forum 20 - "COCOTS Risk Analyzer"
  • Authors: Ye Yang, Barry Boehm, Betsy Clark
  • PPT format (146kb)
  • GSAW 2003 - "Managing COTS Integration for High Integrity Systems: Observations from the COCOTS Database"
  • Author: Betsy Clark
  • PDF format (194kb)
  • 2002 COCOMO and Software Cost Modeling International Forum 17 - "Early COCOTS Workshop Out-Brief"
  • Author: Chris Abts
  • PDF format (211kb)
  • 2002 COCOMO and Software Cost Modeling International Forum 17 - "Early COCOTS"
  • Authors: Betsy Clark, Chris Abts, Brad Clark, Ye Yang
  • PDF format (450kb)
  • 2001 COCOMO and Software Cost Modeling International Forum 16 - "COCOTS Life Cycle Estimation: Some Preliminary Observations"
  • Authors: Christopher M. Abts, Betsy Clark
  • PPT format (154kb)
  • 2001 USC-CSE Annual Research Review - "COCOTS Update"
  • Author: Christopher M. Abts
  • PPT format (218kb)
  • 2000 COCOMO and Software Cost Modeling International Forum 15 - "COCOTS Breakout Group"
  • Author: Christopher M. Abts
  • PDF format (220kb)
  • 2000 COCOMO and Software Cost Modeling International Forum 15 - "COCOTS Tutorial"
  • Authors: Christopher M. Abts, Betsy Clark
  • PDF format (1.86mb)
  • 2000 USC-CSE Annual Research Review and Technology Week - "COCOTS Status: Executive Overview"
  • Author: Christopher M. Abts
  • PDF format (1.98mb)
  • 1999 COCOMO and Software Cost Modeling International Forum 14 - "COCOTS Status"
  • Authors: Barry W. Boehm, Christopher M. Abts, Elizabeth K. Bailey
  • PDF format (712kb)
  • 1999 USC-CSE Annual Research Review and Technology Week - "COCOTS Software Integration Cost Model: Insights & Status"
  • Author: Christopher M. Abts
  • PDF format (450kb)
  • Proceedings of the California Software Symposium (October 1998) - "COCOTS Software Integration Cost Model: an Overview"*
  • Authors: Barry W. Boehm, Christopher M. Abts, Elizabeth K. Bailey
  • Abstract - HTML format, PDF format (8kb)
  • PDF format (255kb)

* This is essentially an abbreviated version of the August '98 General Overview briefing below.

  • Most Recent General Briefing (August 1998) - "COCOTS Software Integration Cost Model: an Overview"
  • Authors: Barry W. Boehm, Christopher M. Abts, Elizabeth K. Bailey
  • HTML format

Model Status

COCOTS at this time must still be considered EXPERIMENTAL and evolving. The tools currently available for download should only be used for comparison with other more proven cost estimation methods, not in lieu of these other methods. What the model does offer at this time is insight into the most important factors that should be considered when estimating the cost of integrating COTS components, regardless of the specific tool or methodology used to perform that estimation.

Data Collection Program

The key factor in continuing to improve the predictive accuracy of COCOTS is good data. To that end, we are asking for the help of the software industry in collecting data. If you or the organization you work for has the ability to supply software development project data where COTS components were used in the development, we would like to hear from you. The benefit to you for participating in data collection will be the availability of a more accurate predictive model for estimating your software project costs. Additionally, you will have the opportunity to participate in COTS oriented workshops being planned at USC, and to receive calibrated versions of the implemented model before the general public.

For your convenience, we are providing for download copies of the COCOTS research overview statement, the COCOTS data collection instrument, and the standard confidentiality agreement USC-CSSE enters into with most of our data suppliers. We have proven procedures that we have followed successfully for over four years in the development of COCOMO II to prevent the compromise of any information entrusted to us that could be considered proprietary by data suppliers. We are using these same procedures in the collection of data for COCOTS. We would also be glad to discuss any specific accommodations you might need to permit your participation in this data collection effort. For further information or to discuss participation in the COCOTS data collection program, please contact us.

Data Collection Documents:

  • COCOTS Research Overview Statement - Updated June, 1998
  • HTML format
  • PDF format (10kb)
  • COCOTS Cost Estimation Questionnaire--FAA version*- Updated Sept. 16, 1998
  • PDF format (217kb)

* This version of our survey was prepared specifically for FAA needs, but can be used by anyone reporting data until a more generic version is drafted. To report data for a non-FAA project using this document, in Section 4.1 - Project Domain of the survey, ignore the pre-defined FAA domains and describe your own project domain in the space provided under Other.

  • USC-CSSE Data Nondisclosure Agreement
  • HTML format
  • PDF format (53kb)


Research Group

Research Sponsors

In addition to the on-going support provided by the USC-CSSE Affiliates, the COCOTS research effort has been funded by the USAF Electronic Systems Center/Rome Laboratory, the Federal Aviation Administration, and the Office of Naval Research. We would like to thank these organizations for their assistance while acknowledging that their support does not constitute an endorsement by any of these organizations of the COCOTS model over any other similar cost estimation tool.

Downloads (Software and Documentation)

The spreadsheet and user guide offered below have been developed by Christopher Abts under the guidance of Dr. Barry Boehm. The spreadsheet downloads in winzip compressed format and needs to be unzipped with the appropriate utility. This spreadsheet and its companion user guide represent a prototype implementation of the first of four submodels being proposed for COCOTS, namely, the glue code submodel. As a prototype, this first spreadsheet should be used with caution. The model is not yet mature enough for the estimates it provides to be used with high confidence. However, the cost parameters contained within the model and the criteria used to rate those parameters as described in the user guide certainly offer much insight into the questions a savvy software cost estimator should be considering when working on a system to be built with COTS components. Moreover, to help us improve the model, we would appreciate hearing back from you regarding the kinds of results you get as you explore using the model. Is it accurate much of the time? Is it wrong much of the time? Is it unpredictable in its behavior? These are the kinds of things we need to know, so please consider contacting us with your findings. We have thick skins, so don't be afraid to tell us the truth!


COCOTS Tool (MS Excel) (Updated 2002)

  • USC COCOTS Software (Glue code submodel implementation only): - Released Sept. 30, 1997
  • MS Office '95 excel spreadsheet
    • winzip compressed file (9kb)


COCOTS manual (pdf)
COCOTS Model Description (MS Word)
COCOTS survey (MS Word)

  • USC COCOTS User Guide (Glue code submodel reference only): - Released Sept. 30, 1997
  • PDF format (83kb)

Cost Estimation Bibliography

For an extensive bibliography of software cost estimation related papers and books go here.

Other COTS Related Websites

 Conferences: Papers: Projects: Miscellaneous:

For Further Information Please Contact:

Center for Software Engineering
Salvatori Hall Room 328
University of Southern California
941 W. 37th Place
Los Angeles, CA 90089-0781

Voice: (213) 740-5703
Fax: (213) 740-4927

Link to the COCOMO Page 

COCOMO II is the new cost model replacing COCOMO 81. It is the parent model to COCOTS, capturing software development costs outside the scope of COCOTS relating to the development of new and reuse software components. 

For information on the entire suite of COCOMO-related cost models go here.

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