  According to recent statistics, more than 1 zettabytes of data is moved over
the Internet annually, which consumes several terawatt hours of electricity,
and costs billions of US dollars to the world economy. HTTP protocol is used in
the majority of these data transfers, accounting for 70% of the global Internet
traffic. We claim that HTTP transfers, and the services based on HTTP, can
become more energy efficient without any performance degradation by
application-level tuning of certain protocol parameters. In this paper, we
analyze several application-level parameters that affect the throughput and
energy consumption in HTTP data transfers, such as the level of parallelism,
concurrency, and pipelining. We introduce SLA-based algorithms which can decide
the best combination of these parameters based on user-defined energy
efficiency and performance criteria. Our experimental results show that up to
80% energy savings can be achieved at the client and server hosts during HTTP
data transfers and the end-to-end data throughput can be increased at the same
time.
