Virtual Machines in Grid Environments: Dynamic Virtual Machines - Grid Computing: Infrastructure, Service, and Applications - page 411

resources, properties, and their values, and dei nes them with various types.
The DVM types also dei ne the rules to validate the user coni guration.
After compilation, the coni guration tree is validated according to the
structure and property constraints dei ned by the basic_dvm_type .
As dei ned in its type structure, a DVM has three major components
and two optional components. The major components, hardware, system,
and software, must be dei ned in high-level templates or in the user script.
The optional components are the postinitiation i le or script, and the user
environment. Users may choose to dei ne their tasks or follow-up actions
in the DVM initiation, which can be executed automatically, or perform
these actions manually after the DVM initiation. The package_type dei nes
the semantic of a software package. Name , version , and source are used to
identify a software package. The coni g dei nes the software coni guration
i le, which is specii c to the software. The post-init dei nes additional
actions, which are performed after software installation such as starting a
service. Figure 16.8 illustrates the user coni guration script, which is the
only script provided by the user. At the beginning of the template, the
dvm_cpu2000 is dei ned as an object template that can be instantiated into
a VM. The dvm_prototype and the dvm_functions are two templates declar-
ing the framework and functions to compute or validate a resource prop-
erty. Several templates are then loaded into the coni guration tree. The
user script is not required to reference all these templates. The values of
the resource properties dei ned in the templates are used by default. They
may be overruled by a user script. Figure 16.9 shows the compiled and
validated VMD script in XML.
Experimental testing is conducted to verify the feasibility of the design
and measure the effectiveness of the implementation. The expectation is
to have a working system that achieves minimum time to instantiate (or
install) the client machines, reduces the time required to download and
upload hence reducing bandwidth requirement, and supports maximum
l exibility.
As all the measures of minimum and maximum are relative, we com-
pare our approach with other existing solutions. Experimental testing is

FIGURE 16.8 A DVM user script for the CPU-2000 benchmark package.