Service Level Objectives (SLOs) - the core of a Service Level Agreement (SLA) - reflect major Quality-of-Service (QoS) requirements of customers on a service for a given price. SLOs need to be updated, if those requirements change. This leads to an update of the SLO auditing implementation. However, in many existing implementations, efforts are required to adapt to SLO changes, and even more efforts are needed for dynamic adaptations. Thus, a new SLO auditing design is essential to be able to reduce such efforts to the bare minimum. This is especially essential, if the service landscape and relevant QoS parameters are changing frequently. Thus, to meet this core functional requirement of an automated auditing, a generic auditing framework, applicable to any SLO, is presented in this paper, where the analysis of a general audit task, the identification of its sequence of subtasks (functional decomposition), and the development of a respective audit specification for each subtask has been performed. A use case and examples are presented to describe and apply the concept in detail. An SLO auditing application, which was prototyped, is not restricted to a certain set of QoS parameters, but it is dynamically reconfigurable and extensible according to changing demands. The work shows that it has become quite easy to instantiate an auditing application for new SLOs. Additionally, third parties would be able to offer SLO auditing services to a service provider separately.

Monitoring of Service Level Objectives (SLOs) determines an essential part of Service Level Agreement (SLA) management, since customers are to be reimbursed, if a provider fails to fulfil them. By automating this process, a timely detection of a violation is possible. The compliance approach must be flexible to adapt to potential changes, must be scalable with respect to the amount of data, and has to support multi-domain environments. This paper determines a Hosted Streaming Services scenario and defines relevant SLOs. Key requirements are derived, the respective architecture is designed, and the approach is implemented prototypically based on a generic auditing framework. Further-more, a new scheme is proposed that considers the degree and duration of SLO violations in calculating reimbursements.

Today's Internet technology is able to support different quality-of-service (QoS) classes to meet different application and user requirements. Combined with the support of user mobility, service providers offer differentiated services not only to their own customers, but also to roaming users. This offer is accompanied normally by more complex pricing schemes which require a complex accounting of the real service consumption. As commercial provisioning of Internet services needs to meet security requirements of providers as well as users, the service consumption must be provable to justify billing and to protect users and providers against other malicious parties. This paper develops the NorCIS architecture (non-repudiation of the consumption of Internet services) and its detailed protocol interactions which allow for the generation and transfer of non-repudiation evidences of service consumptions in a mobile Internet protocol (IP)-based environment. An evidence structure is proposed, supporting a variety of accounting schemes and including information which are used to protect against various attacks. In addition, NorCIS proposes the use of virtual identifiers within evidences to support the privacy of users' identities.

The design of an extended and generic authentication, authorization, accounting, and charging architecture (AAAC Arch.) has been performed within the IST project MobyDick. In addition, this architecture has been implemented to address MobyDick's main objective: to facilitate the deployment of a ubiquitous mobile IPv6-based, quality-of-service (QoS)-aware infrastructure through a flexible and evolutionary AAAC Architecture. While the AAAC Arch. is based on the DIAMETER protocol, basic concepts developed cover session and services models, user profiles to allow for user mobility and QoS-aware authorization. Based on those basic building blocks for the extended AAAC Arch., the implementation of user registration, service authorization, metering, accounting, charging, and auditing is discussed. The paper closes with the presentation of the two trial sites used and their testbeds.

Charging of services in a distributed system will become more and more important for systems which are utilized commercially. Such an important distributed system exists in the form of a computational grid (CG), offering a variety of services on different layers to many users: academic and industrial ones. Although by itself a CG defines a research and operational problem area, the dedicated task of charging CG services, by definition a new grid service has to be considered crucial, once a large number of users share computational resources as well as services offered by a CG. The potential synergies for applying a similar concept to all layers and different types of services within a computational grid should be exploited. Safely assuming that the Internet will form the all-embracing communication technology in use in the near future, differentiated services architecture-based communication layer services will offer the potential to differentiate higher layer and distributed services of the CG.

While differentiated services (DiffServ) offer a suitable technology support for quality-of-service (QoS) in multi-service networks, there is a lack of appropriate and technically feasible pricing schemes which would mainly provide an incentive for customers to choose efficiently among various service classes. This paper presents the basics of an implementation of recent developments in the area of charging differentiated services, in detail an Internet charge calculation and accounting system (ICCAS), including its modular architecture, components, open interfaces and databases. Finally, the explicit application of the newly developed cumulus pricing scheme (CPS) onto the ICCAS and DiffServ is discussed as a suitable example use.

Shared window systems allow collaboration transparent, single-user applications interacted with on multiple users' workstations, enabling the members of a cooperative ensemble to simultaneously share and revise information. The paper presents a system capable of sharing applications running under the X Window System. In contrast to previously implemented systems, the present shared window system addresses issues that are crucial for general-purpose use. The shared window system is policy-free, i.e., there are no preferred policies for handling issues such as admission and floor control. Instead, it offers a set of essential mechanisms on top of which various policies and user paradigms may be realized. Further, the system distributes the sharing functionality among all sites involved in a cooperative activity. Measurements have shown a positive impact of this on the overall performance of the system and thus justified the viability of the design decisions taken.>