Information Technology Reference
In-Depth Information
The last three groups of problems above can be addressed by the “global” web
community using existing techniques, while web source or content failures are typ-
ically directly related to the services or functions that web-based applications are
trying to provide. In addition, although usability is one of the primary concerns for
novice web users, reliability is increasingly becoming a primary concern for sophis-
ticated web users
[55]
. Therefore, we focus on web source failures and trying to
ensure
reliability
of such web-based applications in this chapter.
With the above differentiation of different sources for web problems and the focus
of source contents problems, we need to test the web (1) to ensure that individual
components behave as expected, and (2) to ensure that the overall navigational facil-
ity works as expected. We will first describe testing models that attempt to “cover”
those basic elements and navigation patterns in Section
4
. However, such coverage-
based testing would soon run into difficulties for web sites with numerous functions
or diverse usage patterns, leading us to usage-based web testing in Section
5
.
3 . 2 I n f o r m a t i o n S o u r c e s f o r Te s t i n g a n d A n a l y s e s : N e w
O p p o r t u n i t i e s
Information sources for testing models can generally be divided into two broad
categories: (1) internal components and structures and (2) external functions and
related usages. For the web environment, the easy access to source files (primar-
ily HTML documents) is a significant difference from traditional software systems
where the users typically do not have access to program source code. This difference
would blur the distinction between black-box testing and white-box testing, and al-
low independent testers and users to perform white-box testing for different web
components in addition to black-box testing.
Although external functions for web-based applications and web sites are rarely
formally specified, we do have abundant information about web usages available,
typically recorded in various server log files. In fact, monitoring web usage and keep-
ing various logs are necessary to keep a web site operational. Therefore, we would
only incur minimal additional cost to use the information recorded in these logs for
testing and reliability analyses.
Two types of log files are commonly used by web servers: Individual web accesses,
or hits, are recorded in
access logs
, and related problems are recorded in
error logs
.
A “hit” is registered in the access log if a file corresponding to an HTML page, a
document, or other web content is explicitly requested, or if some embedded content,
such as a graphic file or a Java class within an HTML page, is implicitly requested
or activated. Some sample entries from the access log for the
www.seas.smu.edu
web site using Apache Web Server
[4]
is given in
Fig. 2
. Specific information in this
access log includes:
