Talk:DistOS-2011W Observability & Contracts

Observability

• How do we define 'public' action? How do we monitor 'public' action without monitoring every action?
• How can you make sure your agent is acting according to your instructions?
• How can we ensure that information we receive through a third-party is legitimate?

Contracts

• What can or can't be contracted?
• How can you quantify abstract resources?
• How can two or more parties agree with a minimum of intervention?

Some forms of contracts exist in the form of Service Level Agreements, and there have been efforts made to automate this process:

AURIC

AURIC: A Scalable and Highly Reusable SLA Compliance Auditing Framework from Lecture Notes in Computer Science, by Hasan and Burkhard Stiller, 2007.

Abstract

Service Level Agreements (SLA) are needed to allow business interactions to rely on Internet services. Service Level Objectives (SLO) specify the committed performance level of a service. Thus, SLA compliance auditing aims at verifying these commitments. Since SLOs for various application services and end-to-end performance definitions vary largely, automated auditing of SLA compliances poses the challenge to an auditing framework. Moreover, end-to-end performance data are potentially large for a provider with many customers. Therefore, this paper presents a scalable and highly reusable auditing framework and a prototype, termed AURIC (Auditing Framework for Internet Services), whose components can be distributed across different domains.

Bandwidth

SLA-Driven Flexible Bandwidth Reservation Negotiation Schemes for QoS Aware IP Networks from Lecture Notes in Computer Science by Gerard Parr and Alan Marshall, 2004.

Abstract

We present a generic Service Level Agreement (SLA)-driven service provisioning architecture, which enables dynamic and flexible bandwidth reservation schemes on a per- user or a per-application basis. Various session level SLA negotiation schemes involving bandwidth allocation, service start time and service duration parameters are introduced and analysed. The results show that these negotiation schemes can be utilised for the benefits of both end user and network provide such as getting the highest individual SLA optimisation in terms of Quality of Service (QoS) and price. A prototype based on an industrial agent platform has also been built to demonstrate the negotiation scenario and this is presented and discussed.

Dynamic Adaptation

Context-Driven Autonomic Adaptation of SLA from Lecture notes in Computer Science, by authors Caroline Herssens, Stéphane Faulkner and Ivan Jureta, 2008.

Abstract

Service Level Agreements (SLAs) are used in Service-Oriented Computing to define the obligations of the parties involved in a transaction. SLAs define the service users’ Quality of Service (QoS) requirements that the service provider should satisfy. Requirements defined once may not be satisfiable when the context of the web services changes (e.g., when requirements or resource availability changes). Changes in the context can make SLAs obsolete, making SLA revision necessary. We propose a method to autonomously monitor the services’ context, and adapt SLAs to avoid obsolescence thereof.

Heuristics for Enforcing Service Level Agreements

Heuristics for Enforcing Service Level Agreements in a Public Computing Utility A masters thesis paper by Balasubramaneyam Maniymaran.

Abstract

With the increasing popularity of consumer and research oriented wide-area applications,there arises a need for a robust and efficient wide-area resource management system. Even though there exists number of systems for wide area resource management, they fail to couple the QoS management with cost management, which is the key issue in pushing such a system to be commercially successful. Further, the lack of IT skills within the companies arouses the need of decoupling service management from the underlying complex wide-area resource management. A public computing utility (PCU) addresses both these issues, and, in addition, it creates a market place for the selling idling computing resources.

This work proposes a PCU model addressing the above mentioned issues and develops heuristics to enforce QoS in that model. A new concept called virtual clusters (VCs) is introduced as semi-dynamic, service specific resource partitions of a PCU, optimizing cost, QoS, and resource utilization. This thesis describes the methodology of VC creation, analyses the formulation of a VC creation into an optimization problem, and develops solution heuristics. The concept of VC is supported by two other concepts introduced here namely anchor point (AP) and overload partition (OLP). The concept of AP is used to represent the demand distribution in a network that assists the problem formulation of the VC creation and SLA management. The concept of overload partition is used to handle the demand spikes in a VC.

In a PCU, the VC management is implemented in two phases: the first is an off-line phase of creating a VC that selects the appropriate resources and allocates them for the particular service; and the second phase employs on-line scheduling heuristic to distribute the jobs/requests from the APs among the VC nodes to achieve load balancing. A detailed simulation study is conducted to analyze the performance of different VC configurations for different load conditions and scheduling schemes and this performance is compared with a fully dynamic resource allocation scheme called Service Grid. The results verify the novelty of the VC concept.

Service Level Agreement in Cloud Computing

SLAs in Cloud Computing A paper written by Pankesh Patel, Ajith Ranabahu, Amit Sheth.

Abstact

Cloud computing that provides cheap and pay-as-you-go computing resources is rapidly gaining momentum as an alternative to traditional IT Infrastructure. As more and more consumers delegate their tasks to cloud providers, Service Level Agreements(SLA) between consumers and providers emerge as a key aspect. Due to the dynamic nature of the cloud, continuous monitoring on Quality of Service (QoS)attributes is necessary to enforce SLAs. Also numerous other factors such as trust (on the cloud provider) come into consideration, particularly for enterprise customers that may outsource its critical data. This complex nature of the cloud landscape warrants a sophisticated means of managing SLAs. This paper proposes a mechanism for managing SLAs in a cloud computing environment using the Web Service Level Agreement(WSLA) framework, developed for SLA monitoring and SLA enforcement in a Service Oriented Architecture (SOA). We use the third party support feature of WSLA to delegate monitoring and enforcement tasks to other entities in order to solve the trust issues. We also present a real world use case to validate our proposal.