Analysis and Testing of Ajax-based Single-page Web Applications

Figure 4.1 A screenshot taken from eBay. The user has to constantly click the
“Refresh” button to see any updates.
• How does a push-based web data delivery approach compare to a pullbased
one, in terms of data coherence, scalability, network performance,
and reliability?
This chapter is further organized as follows.
We start out, in Section 4.2, by exploring current techniques for real-time
HTTP-based data delivery on the web. Subsequently, in Section 4.3, we discuss
the push-based Bayeux protocol and the DWR library, the two open source
push implementations that we will use in our experiments. In Section 4.4, we
present the experimental design by articulating our research questions and
outlining the proposed approach. The independent and dependent variables
of our experiment are also discussed in this section. A detailed presentation
of our distributed testing framework called Chiron 2 as well as the environment
and applications that we use to conduct our experiments, is shown in
Section 4.5. In Section 4.6 the results of our empirical study involving push
and pull data delivery techniques are covered, followed by a discussion of the
findings of the study and threats to validity in Section 4.7. Finally, in Section
4.8, we survey related work on this area, after which we conclude our
2 In Greek mythology, Chiron, was the only immortal centaur. He became the tutor for a
number of heroes, including Ajax.
Chapter 4. Performance Testing of Data Delivery Techniques for Ajax 77