Information Technology Reference
In-Depth Information
T ABLE II
U SAGE F REQUENCIES AND P ROBABILITIES BY
F ILE T YPES FOR SMU/SEAS
File type
Hits
% of total
.gif
438 , 536
57 . 47
.html
128 , 869
16 . 89
directory
87 , 067
11 . 41
.jpg
65 , 876
8 . 63
.pdf
10 , 784
1 . 41
.class
10 , 055
1 . 32
.ps
2737
0 . 36
.ppt
2510
0 . 33
.css
2008
0 . 26
.txt
1597
0 . 21
.doc
1567
0 . 21
.c
1254
0 . 16
.ico
849
0 . 11
Cumulative
753 , 709
98 . 78
Total
763 , 021
100
ent types of files by web users over 26 days and the related probabilities. This OP
can also be viewed as a specialized TAR above, where individual web pages are
grouped by file types to form individual service units. The adaptation and application
of OP-based testing would ensure that frequently used web pages and components
are adequately tested, which in turn, would have a great impact on web site reliability
improvement.
The “operations” represented in the operational profiles are usually associated
with multiple test cases or multiple runs. Therefore, we typically assume that each
“operation” in an OP can be tested through multiple runs without repeating the exact
execution under exactly the same environment. In a sense, each operation corre-
sponds to an individual sub-domain in domain partitions, thus representing a whole
equivalence class [48] . In this example, each item in the table, or each operation,
represents a type of file requested by a web user, instead of individual web pages. Of
course, we could represent each web page as an operation, but it would be at a much
finer granularity. When the granularity is too fine, the statistical testing ideas may
not be as applicable, because repeated testing may end up repeating a lot of the same
test runs, which adds little to test effectiveness. In addition, such fine-granularity
OPs would be too large to be practical. For example, the SMU/SEAS web site has
more than 11,000 individual web pages, while the number of file types is limited to a
hundred or so, including many variations of the same type, such as HTML files with
extensions of “.HTML,” “.html,” “.htm,” etc.
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