System Goals

Shirako is a toolkit for constructing service managers, brokers, and authorities, based on a common, extensible leasing core. A key design principle is to factor out any dependencies on resources, applications, or resource management policies from the core. This decoupling serves several goals:

• The resource model should be sufficiently general for other resources such as bandwidth-provisioned network paths, network storage objects, or sensors. It should be possible to allocate and configure diverse resources alone or in combination.

• Shirako should support development of guest applications that adapt to changing conditions. For example, a guest may respond to load surges or resource failures by leasing additional resources, or it may adjust to contention for shared resources by deferring work or reducing service quality. Resource sharing expands both the need and the opportunity for adaptation.

• Shirako should make it easy to deploy a range of approaches and policies for resource allocation in the brokers and sites. For example, Shirako could serve as a foundation for a future resource economy involving bidding, auctions, futures reservations, and combinatorial aggregation of resource bundles. The software should also run in an emulation mode, to enable realistic experiments at scales beyond the available dedicated infrastructure.

Note that Shirako has no globally trusted core; rather, one contribution of the architecture is a clear factoring of powers and responsibilities across a dynamic collection of participating actors, and across pluggable policy modules and resource drivers within the actor implementations.