1. COTS-Aware Requirements Engineering and Software Architecting
Lawrence Chung and Kendra Cooper
Department of Computer Science
University of Texas at Dallas
{chung,

2. Why COTS (Commercial-Off-The-Shelf)?
Perceived benefits
– cheaper, faster, better software development
by orders of magnitude!
Issues
Gaps between requirements and COTS components
- high degree of usage vs. high degree of satisficing
- COTS components must meet both functional and non-functional requirements, … and at the same time fit with the architecture
Many (more types of) stakeholders
Many more sources of changes
- Customer needs, new technology – hw/sw/infrastructure, new/similar products, etc.
- Evolution of COTS components & Discontinued components
- Legal issues ((chain of) licensing, open-source,…) & Standards

3. Outline Bridging the gap
Defining, Matching, Ranking, and Selecting COTS Components in the CARE/SA Process
Capturing Requirements (FR & NFR) & Architecture Components
Matching, Ranking, and Selecting COTS Components

4. Bridging the Gap: COTS Components Capabilities System Under Development (SUD) Requirements
SUD Goal
Exact match G - j G - i
Transformed SUG Goal
Transformed Component G -
j1’ G -
i1’
Transformed SUG Goal
Transformed Component G -
i1’’ G -
j1’’ G - i
is an agent's goal
Another exact match
Transformed SUG Goal G - k G -
j2’
How do we bridge the gap systematically?

5. Defining Goals; Matching, Ranking, and Selecting COTS Components in the CARE/SA Process
Define Goals
create a System Goal Model using scenarios
Select Components
Based on ranking, select set of COTS components
Match Goals
search for COTS components with goals that match SUG soals (functional & non-functional)
Negotiate
Changes
Rank Components
Perform a gap analysis to rank COTS components using the NFR Framework
What do we represent and where ?

6. Architecture Components
Capturing Requirements (FRs & NFRs) &
Architecture Components
Component Repository
(Foreign Goals, Specifications, …)
System Under Development
(Native Goals, Requirements, …)
in SUD Product Repository
Customer
Manager
End User
Development Manager
Requirements Engineer
Component Repository …
External
System
++ (NFR)
Softgoal2
Softgoal3
HardGoal1 …
Component 2
(whitebox) …
System
Requirement
Architectural
Subsystem
System
Requirement
Architectural
Subsystem
Software
Requirement …
SUD
Artifacts
Software
Requirement
Component 1
(blackbox)
Legend
Agent
Mapping System Goals to Component Goals
Mapping System, Software Requirements to Component Specification
Softgoal
Hardgoal
Requirement
Architecture Subsystem

7. Matching, Ranking, and Selecting COTS Components.
With a non-functional candidate goal
COTS Architecture to
(other) COTS NFR
SUD NFR to COTS NFR
COTS NFRs to (other) SUD NFRs
SUD Product
COTS
Component
SUD Product
COTS
Component
SUD Product
Model Repository
COTS
Component
Repository
Model Repository
Repository
Model Repository
Repo
sitory C j … C … C … … … … R … R A R A … … … …
NFR
NFR j
NFR k
NFR i i i
Legend
Softgoal (non -
functional)
Candidate softgoal
COTS Component
Possib
le Match
Hardgoak
Candidate Hardgoal
And Decomposition
C Component, A Architecture, R Requirement, FR Functional requirement, NFR Non-Functional Req.

8. Matching, Ranking, and Selecting COTS Components.
With a functional candidate goal
COTS Architecture to
COTS NFR
SUD FR to COTS FR
COTS NFRs to (other) SUD NFRs
COTS
Component
SUD Product
COTS
Component
SUD Product
COTS
Component
SUD Product
Repository
Model Repository j
Model Repository
Repository
Repository
Model Repository i C C … C … … … … … … R R A R A … … … FR
NFR FR i
NFR FR i i i
Legend
Softgoal (non -
functional)
Candidate softgoal
COTS Component
Possib
le Match
Hardgoak
Candidate Hardgoal
And Decomposition
C Component, A Architecture, R Requirement, FR Functional requirement, NFR Non-Functional Req.

9. Preliminary Softgoal Interdependency Graph and COTS Component Repository
part of the CARE/SA knowledge base - populated for a DLS before
the Goals of the SUD are matched, ranked and selected wrt the Goals of the components).
COTS Component Repository
SUD Product Model Repository
Java Authentication &
Authorization Service C …
Secure
Good Performance
Easy to Use Interface …
Search theCatalog - …
Requirements R A
Architecture …
Configurable Interface
Variety of
Non -
functional Requirements
Functional Requirements
Interface Options
Encryption
NFR FR
PC platform
Role Based
Tivoli C
PDA Protect C
Touch Screen Interface
Access Control
Novice Configuration
GUI C
Authentication
Audio/Video …
Security, communication, multimedia, compressi
on, etc. components
Expert Configuration
User Interface

10. Results of Matching, Ranking, and Selecting COTS components
part of the CARE/SA knowledge base - populated for a DLS after
the Goals of the SUD are matched, ranked and selected wrt the Goals of the components).
COTS Component Repository
SUD Product Model Repository
Java Authentication &
Authorization Service …
Secure
Good Performance
Easy to Use Interface … C
Search theCatalog - … R A
Configurable Interface +
Variety of
Tivoli C +
Encryption
Interface Options
PC platform C +
PDA Protect R A +
Role Based
Access Control +
Novice Configuration
Touch Screen Interface R A
GUI
Authentication … +
Audio/Video
Expert Configuration
Security, communication, multimedia, compression, etc. components - -
User Interface +
Inadequte: {PDA Protect}
Potentially good-enough: {JAAS, Tivoli}

11. Conclusions Contributions
Systematic methodology for using COTS components in developing software architecture
COTS components as aggregates of FRs, NFRs, and architectures
Requirements-driven matching, ranking and selection
Future Work
More matching, ranking and selection heuristics
Definition of meta-model (in relation to the UML)
Web-based tool support