what-when-how
In Depth Tutorials and Information
Number of components
Use of COTS software
Maintenance
requirements
CBSE
Integrates many different
components
Can contain all in-house
components
Must maintain
components that are
used in-house
CBS
Can contain many
components, but can also
contain one component
that solves the problem
Must contain at least one
commercial-off-the-shelf
component
May not be responsible
for maintenance if
components are COTS
Figure15.11
DifferencesinCBSEdesignandCBSdesign.(FromKunda,Douglas.
A socio-technical approach to selecting software supporting COTS-based sys-
tems.UniversityofYork(2001).Availablefromhttp://www.cs.york.ac.uk/ftpdir/
reports/2002/YCST/01/YCST-2002-01.pdf.)
he idea of breaking a software package down is shown in Figure 15.12. As can be
seen, a large component, such as the one on top, could be broken down into several
different components. Also, a smaller-scale component such as the one on the bot-
tom in Figure 15.12 could be only broken into one small component because of the
limited functionality of the system itself.
he biggest difference that can be seen between CBSE and CBS methodolo-
gies is seen in the second column of the table in Figure 15.11. In the CBSE model
of designing software packages, it is likely, and actually quite common, that a
software package will comprise only components that are built in-house. he main
guidelines behind the CBSE methodology simply coordinate the breaking down
of a larger software package system into smaller subsystems, or components, as
previously discussed. It is common for all components that make up a software
package to be designed and built in-house. It is not against regulation or method-
ology to purchase outside components, but this is done very infrequently. On the
other hand, for a software design process to be deemed a CBS design process, the
final software package must contain at least one commercial-off-the-shelf compo-
nent. his component can be all-encompassing, meaning the entire software pack-
age is only broken down into one component, or the components can be limited
to only a few pieces of the system as a whole. Regardless of the type of component
breakdown, in order for a software design process to be a CBS process, the final
software package must contain at least one commercial-off-the-shelf component.
15.7 Conclusion
he world of software development has changed considerably since the first few
lines of code were written. It has evolved from a single programmer in a room to
