Web Testing for Reliability Improvement - Advances in Computers - page 194

profiles (OPs): Musa's flat OP [33] and Markov OP [30,56] or its variation, unified
Markov models (UMMs) [20,49] . Musa OP's key advantage is its simplicity, allow-
ing us to focus on frequently used individual pages or web components. On the other
hand, Markov models such as UMMs are generally more appropriate for selective
testing of web navigations. Therefore, we have selected UMMs as the central test-
ing models to work under the guidance of high-level Musa OPs in our overall web
testing framework, to form a three-tiered strategy [50] :
1. The high-level operational profile (OP) enumerates major functions to be sup-
ported by web-based applications and their usage frequencies by target cus-
tomers. This list-like flat OP will be augmented with additional information and
supported by lower-level models based on unified Markov models (UMMs).
The additional information includes grouping of related functions and mapping
of major external functions to primary web sources or components.
2. For each of the high-level function groups, a UMM can be constructed to
thoroughly test related operation sequences and related components. UMMs
capture desired behavior, usage, and criticality information for web-based ap-
plications, and can be used to generate test cases to exhaustively cover high-
level operation sequences and selectively cover important low-level implemen-
tations. The testing results can be analyzed to identify system bottlenecks for
focused remedial actions, and to assess and improve system performance and
reliability.
3. Critical parts identified by UMMs can be thoroughly tested using lower-level
models based on traditional testing techniques. Other quality assurance alter-
natives, such as inspection, static and dynamic analyses, formal verification,
preventive actions, etc. [38,48] , can also be used to satisfy user needs and ex-
pectations for these particular areas.
Therefore, existing techniques that attempt to “cover” certain web aspects or ele-
ments, particularly those we described in Section 4 , can still be used, but under the
guidance of our mid-level UMMs as well as our top-level Musa OPs. Our hierarchi-
cal strategy can also accommodate other quality assurance activities, mostly at the
bottom-level, much like for coverage-based testing:
Support for software inspection can be provided in two ways: (1) selective in-
spection of critical web components by relating frequently used services to
specific web components; (2) scenario based inspection [40] guided by our
UMMs where usage scenarios and frequencies can be used to select and con-
struct inspection scenarios.
Selective formal verification can be carried out similar to the way inspection
is supported above. Specific formal verification models can also be associated