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provider (VSP), for example, PyroSim, can be established for visualizing
the simulation results.
In our experiments, the FDS establishes an SLA with PRsp i rst before
agreeing to SLAs with its clients. In this way, the FDS service provider can
allocate resources to the individual FDS jobs without asking PRsp for each
request. This method avoids the delay caused by the negotiation “on the
l y” where the FDS service provider negotiates with the PRS service
provider on resource allocation each time an FDS request arrives.
The entire platform is developed in Java and we used eclipse [27] as the
IDE for program development. The SLA templates, the SLA proposals, and
the SLAs are Java instances associated with a certain lifetime. The service
models are stored in MOF i les, which are in turn uploaded to the SAPs for
activating the service. FDS clients have the ability to query the FDS service
for SLA templates, specify their requests, and submit their proposal to the
FDS service provider. Another important step in the process is to accurately
predict resource requirements for running the job when an FDS client sub-
mits a request. We call this process SLA decomposition. We perform SLA
decomposition by combining performance modeling and proi ling. We use
a constraint satisfaction solver called “Cauldron” [28] for deriving resources
requirements for executing the FDS jobs. If the FDS service provider accepts
a request, the client will receive an offer with specii cations of response time,
service price, penalty, deadline to reply, and so on.
10.5.2
Performance Study
We conducted experiments to study the communication delay caused in
various stages of SLA management, as shown in Table 10.1. In this
experiment, we did not consider the processing delay caused by the SLA
decomposition and pricing calculations, as it may vary widely due to
other service components not controllable by SLA Manager. We only
TABLE 10.1
Various Stages of a Simple SLA Negotiation Sequence in FDS SLA Management
Index
Action
Responsible Component
0
Client pulls SLA template from the SAP
SLA-based service
1
Client pushes SLA proposal to the SAP
SLA client
2
FDS SP pulls SLA proposal from the SAP
SLA-based service
3
FDS SP pushes signed SLA to the SAP
SLA-based service
4
FDS SP pushes counter SLA proposal to the SAP
SLA-based service
5
Client pulls counter SLA proposal from the SAP
SLA-based service
6
Client adds signature to the counter SLA proposal
SLA client
7
Client pushes SLA proposal to the SAP
SLA client
8
FDS SP pulls signed SLA from the SAP
SLA client
 
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