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Lecture 6

Software Engineering 4453A/B Lecture Notes - Lecture 6: Software Maintenance, Legacy System, Application Software


Department
Software Engineering
Course Code
SOFTENG 4453A/B
Professor
Abdelnasser Hassan Ouda
Lecture
6

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Unit 2
Legacy Systems Management
organizations that rely on legacy systems must choose a strategy for evolving these
systems
scrap the system completely and modify business processes so it is no longer
required
continue maintaining the system
transform the system by reengineering to improve its maintainability
replace the old with the new
strategy chosen should depend on system quality and business value
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Legacy System Management …
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The different strategies:
Low Quality, Low Business Value
should be scrapped
Low Quality, High Business Value
make an important business contribution but are expensive to maintain
should be reengineered or replaced if a suitable system is available
High Quality, Low Business Value
replace with COTS, scrap completely, maintain
High Quality, High Business Value
continue in operation using normal system maintenance
A. Business Value Assessment
assessment should take different viewpoints into account
system end users
business customers
line managers
IT managers
senior managers
B. Issue in Business Value Assessment
the use of the system
only used occasionally or by a small number of people, they have a low business
value
business processes that are supported
system may have a low business value if it forces the use of inefficient business
processes
system dependability
if not dependable, and problems directly affect business customers, system has
low business value
system outputs
if business depends on system outputs, then system has a high business value
C. System Quality Assessment
Business process assessment
how well does the business process support the current goals of the business
Environment assessment
how effective is the system’s environment and how expensive is it to maintain
application assessment
what is the quality of the application software system
D. Business Process Assessment
use a viewpoint oriented approach and seek answers from system stakeholders
defined process model and is it followed?
different parts of the organization use different processes for the same function?
how has the process been adapted?
relationships with other business processes and are they necessary
is the process effectively supported by the legacy application software
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