CROWN: A Service Grid Middleware for e-Science - Grid Computing: Infrastructure, Service, and Applications - page 17

RIS

RIS

RIS RIS RIS

RP 1

RP 3

RP 2

RCT: {PA = CPU}

RCT 2 : {PA = Disk}

RCT: {PA = Mem}

RCT 1 : {PA = CPU}

RIS: RCT Index Service
RP: Resource Provider

FIGURE 1.8 Resource organization with RCT.

the rightmost HR; the former has no left neighbor and the latter has no
right neighbor. As shown in Figure 1.7 , C2 and B2 are neighbors of A,
while C2 is the L-neighbor of A and B2 is the R-neighbor of A. Note that
C1 does not have a left neighbor and B2 has no right neighbor.
As resources are owned and managed by different resource providers, the
providers may dei ne different PAs for their resources, which results in
constructing multiple RCTs. In Figure 1.8, we present a two-layer architecture
for organizing resources across resource providers by using RCT. In the lower
layer, each resource provider dei nes a set of PAs that can best describe their
resources. Based on PAs, resources are organized through a certain number
of RCTs. To enable wide-area resource discovery across different providers,
an RCT index service (RIS) is deployed by each service provider in the upper
layer. An RIS is a basic service that stores information about the PAs of a pro-
vider and the entry points of RCTs. RISs can be implemented, for example, as
Web services or grid services, and i nd each other using services like UDDI.
In practice, a resource may have many attributes, but only a few of them
are chosen as the primary attributes, so there will not be too many RCTs.
When a query request cannot be satisi ed by a resource provider, the RIS
will contact other RISs to recommend another resource provider for
further discovery operations.

1.4 Security Architecture in CROWN

1.4.1 Overview of CROWN Security

CROWN provides a hierarchical security solution to secure virtual organ-
izations established via the CROWN middleware system. There are three