Group execution service

The flipside of brokering services is the group execution service, which manages hosting issues--deployment and distribution.

Where a brokering service allows a netlet to pull in services, the group execution service determines where netlets should push themselves out to. The group execution service maintains minimum cost/maximum performance balance by seeing where users, netlets and resources are located, and redeploying them as necessary.

For example, Harry can deploy his applications using a general purpose group execution service. It gives him a single point of access for setting policies and monitoring the state of his application as a whole. His group execution service is responsible for monitoring status from his Web servers and migrating them to optimise the performance of his sites as his user base changes.

When his trading game is to deploy in Asia the group execution service subcontracts Web serving to another group execution service managed and run by East-Rim Hosting, Inc. This organisation operates specialised load balancing hardware for Web servers which allows them to offer greater performance for less money. Harry's group execution service delegates control of the Web servers to East-Rim, transparent to his application, and so East-Rim can now migrate them as they see fit.

In a similar way, Harry's group execution service can also delegate control of his major data storage to Zippy Filestores who maintain nodes with specialised hardware. In the event of a failure of one of their nodes, Zippy's own group execution service will restart Harry's netlets on a different nodes, but connected to the same disk array so that redundancy is maintained while copying is minimised, reducing network costs used to maintain this redundancy.

This optimised, best-of-breed hosting is illustrated in Figure .

Figure: The group execution service allows group-level management of hosting. Harry's group execution service outsources Asian hosting to one provider and storage to another. They in turn can use their own group execution services to manage their own internal resource optimisation.