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10 Part 1 • SyStemS analySiS FundamentalS

In summary, maintenance is an ongoing process over the life cycle of an information sys-
tem. After the information system is installed, maintenance usually takes the form of correcting
previously undetected program errors. Once these are corrected, the system approaches a steady
state, providing dependable service to its users. Maintenance during this period may consist of
removing a few previously undetected bugs and updating the system with a few minor enhance-
ments. As time goes on and the business and technology change, however, the maintenance
effort increases dramatically.

Using CASE Tools
Analysts who adopt the SDLC approach often benefit from productivity tools, called computer-
aided software engineering (CASE) tools, that have been created explicitly to improve their rou-
tine work through the use of automated support. Analysts rely on CASE tools to increase pro-
ductivity, communicate more effectively with users, and integrate the work that they do on the
system from the beginning to the end of the life cycle.
All the information about the project is stored in an encyclopedia called the CASE reposi-
tory, a large collection of records, elements, diagrams, screens, reports, and other information
(see Figure 1.4). Analysis reports may be produced using the repository information to show
where the design is incomplete or contains errors.

Figure 1.4
ADD CUSTOMER SALES ANALYSIS REPORT
The repository concept. ITEM TOTAL
NUMBER XXXXXX DESCRIPTION SALES
XXXXXXXXXXXXXX ZZ,ZZ9 Screen and
NAME XXXXXXXXXXXX XXXXXXXXXXXXXX ZZ,ZZ9
STREET XXXXXXXXXXXX XXXXXXXXXXXXXX ZZ,ZZ9 Report Design
CITY XXXXXXXXXXXX XXXXXXXXXXXXXX ZZ,ZZ9
STATE XX XXXXXXXXXXXXXX ZZ,ZZ9
ZIP XXXXX-XXXX
XXXXXXXXXXXXXX ZZ,ZZ9

System Diagrams
and Models

Item = Number + DO WHILE NOT End of file
Description +
Cost + Read Item record
Price + IF Item is low in stock
Quantity on hand + Print Purchase Order Data Dictionary and
Quantity on order + Update Item record Process Logic
Reorder point +
Monthly sales + ENDIF
Year to date sales ENDDO

System Requirements Deliverables
• Add new customers • Add customer screen
• Identify fast- and slow-selling • Item Analysis Report
items • Customer order entry screen Project Management
• Enter customer orders • Customer inquiry screen
• Look up customer credit •Vendor purchase order
balance program
• Maintain adequate inventory • Seasonal forecasting