Information Technology Reference
In-Depth Information
the client as shown in the following figure. Finally the business service (in this
scenario, a match for a given game) and its associated SLA Contract are delivered
to the Gamer.
Fig. 12.4: High-level to Low-level QoS requirements mapping
After the business service has been delivered, it is necessary to ensure that the
contractual terms are respected. This is done though the Monitoring and Evaluation
subsystem (M&E). The M&E subsystem is logically divided into three main blocks:
• Application-specific monitoring: offers the ability to retrieve at run-time infor-
mation about the users participating in a game, and other general information
about the match like its lifecycle, number of users playing the match and some
game statistics;
• Infrastructure monitoring: offers the ability to monitor resources virtualized
as Grid services. In this experiment, it is possible to monitor parameters like
the CPU cycle and the memory consumed by the match (service instance) at
runtime;
• Evaluation layer: offers the ability to collect (through the two above mentioned
modules) the monitored values in order to verify whether the measurements
are within the thresholds defined in the SLA contract assigned to every player.
Whenever the execution of a match does not satisfy these SLA conditions, the
module will launch a notification event (using a WS-Notification mechanism)
about this potential breach of contract.
More information can be found in D'Andria et al. (2008).
12.2.2 Online Gaming Scenario at Runtime
The gaming scenario is perhaps best told from the end user's perspective. In online
gaming, a user typically wants to play a game online within a community of liked-
minded players. He wants to take part in various games where other players play as
well as he or she does. Response time and availability are therefore critical. So is
the overall security of the underlying systems. The player's interaction starts when
Search WWH ::




Custom Search