Using cooperation to improve the resource utilization in service ecologies

The digital ecosystem (DE) paradigm is a holistic management/design/integration paradigm that is based on the notion of self-interested, self-managing, proactive and autonomous digital entities that evolve and self-organize. While a DE can be realized using different technologies Web services (WS) are particularly promising due to their widespread acceptance within industry and academia, established and open standards, a wealth of development tools and infrastructures, and maybe most importantly the number of successful deployments. A key issue in the development/deployment of any system is the behaviour exhibited by components (e.g. providers & consumers). Service-oriented systems tend to use a contract approach in which implicit, predefined or negotiated service-level agreements (SLAs) are established between providers and consumers. A SLA defines from a provider's point of view the guaranties, responsibilities and warranties (e.g. availability, reliability, performance, throughput, compensations, etc) towards a consumer. While being conceptually fairly straightforward, SLAs have the unfortunate side effect of forcing providers to use reservation/locking of resources as a means of ensuring their availability should the consumer request them. This in turn leads to the problem of resource underutilization that threatens the efficiency of the service-oriented system. This paper focuses on the use of cooperation between providers and consumers in service ecologies as an alternative to the constraining SLAs. By enabling the consumers and providers to exchange information regarding their current needs and capabilities it becomes possible to better utilize the resources and therefore improve overall system performance.