Abstract: Mobile agents require access to computing resources on heterogeneous systems across the Internet. They need to be able to negotiate their requirements with the systems on which they wish to be hosted. This paper presents a negotiation infrastructure with which agents acquire time- limited resource contracts through negotiation with one or more mediators instead of individual hosting systems. Mediators represent groups of autonomous hosts. The negotiation protocol and language are based on the WS-Agreement Specification, and have been implemented and tested within the AgentScape framework.
Abstract: A Service Level Agreement (SLA) is an electronic contract between a service user and a provider, and specifies the service to be provided, Quality of Service (QoS) properties that must be maintained by a provider during service provision (generally defined as a set of Service Level Objectives (SLOs)), and a set of penalty clauses specifying what happens when service providers fail to deliver the QoS agreed. Although significant work exists on how SLOs may be specified and monitored, not much work has focused on
actually identifying how SLOs may be impacted by the choice of specific penalty clauses. A trusted mediator may be used to resolve conflicts between the parties involved. The objectives of this work are to: (i) identify classes of penalty clauses that can be associated with an SLA; (ii) define how to specify penalties in an extension of WS-Agreement; and (iii) specify to what extent penalty
clauses can be enforced based on monitoring of an SLA.
Abstract: Service Level Agreements (SLA) are commonly used to define terms and conditions of service provisioning. WS-Agreement1 is an SLA specification that addresses the need of both producers and consumers of services to specify and negotiate terms and conditions of access to these services. This specification has gained wide acceptance in both the Grid computing and Web Services communities. WS-Agreement includes support for both negotiating and specifying penalties that arise from violation of these terms and conditions. It does not, however, include support for monitoring these agreements to determine if any such violations have occurred and, if so, determining which parties are responsible.
This paper proposes a framework and design for secure and reliable monitoring of WS-Agreement specified SLAs. Modifications to WS-Agreement are necessary for effective monitoring. These modifications are outlined, along with an implementation of the framework in the AgentScape middle- ware system.
Abstract: Large-scale use of Grids and service-oriented architectures requires agreement of providers and consumers on the terms of use of services, modelled as Service Level Agreements. WS-Agreement is an evolving standard, using
advertisements to describe available services and negotiation constraints on the terms of use for a service. This allows for more efficient service discovery and negotiation. If multiple advertisements are available at the start of a negotiation, a starting advertisement needs to be selected. This, however, has great impact on the possible outcome of the negotiation process. This paper identifies relevant functions for advertisement selection and characterises their resulting behaviour.
