Information Technology Reference
In-Depth Information
The user focus of web-based applications is supported in this integrated strategy
by testing functions, usage scenarios, and navigation patterns frequently used by
web users under our top-tier usage models based on the list-like Musa opera-
tional profiles [33] as well as our middle-tier usage models based on Unified
Markov Models (UMMs) [20,49] .
Individual web functions and internal components can be thoroughly exercised
by using our bottom-tier models based on traditional coverage-based testing [6,
35] , under the guidance of our upper-level usage models.
Appropriate workload measures [52] can be extracted from access logs to cap-
ture the overall workload at different levels of granularity and from different
perspectives. When used in conjunction with failure measurements, they can
provide an objective and stable evaluation of web site operational reliabil-
ity. A potentially significant reliability gain could be achieved under effective
usage-based testing, leading to reliability growth ranging from 58 to 89% in
purification levels [45] within a month of such improvement actions.
The techniques and tools used by us for data collection, model construction and
application, and result analysis and presentation can provide automated support
that is essential for practical implementation and deployment of our strategy in
industry.
There are some limitations to our approach, primarily in data availability and gran-
ularity, assumption of web stability in reliability evaluations, and lack of analyses
based on detailed defect information. Related issues we plan to address in future
studies include:
Overcoming data availability limitations : Some information useful to support
our integrated strategy is missing from existing web logs, such as the bytes
transferred for failed or cached accesses, web navigation based on cached web
contents at the users' side, ambiguity with “empty” referral information, other
types of problems not isolated to the web server alone, etc. A logical next step
is to search for alternative information sources to provide such information for
more effective web testing and reliability improvement. The availability of such
additional data will better support our integrated strategy.
Overcoming limitations of static web contents : Our analyses are based on the
default access logs of web servers, where dynamic errors concerning execution
of dynamic web logic are not recorded. With more and more web sites providing
dynamic information, dynamic logs will become widely available. We plan to
expand and validate our approach on diverse web sites and make use of dynamic
web logs in our future studies.
 
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