A broker-based framework for integrated SLA-aware SaaS Provisioning
📝 Abstract
In the service landscape, the issues of service selection, negotiation of Service Level Agreements (SLA), and SLA-compliance monitoring have typically been used in separate and disparate ways, which affect the quality of the services that consumers obtain from their providers. In this work, we propose a broker-based framework to deal with these concerns in an integrated manner for Software as a Service (SaaS) provisioning. The SaaS Broker selects a suitable SaaS provider on behalf of the service consumer by using a utility-driven selection algorithm that ranks the QoS offerings of potential SaaS providers. Then, it negotiates the SLA terms with that provider based on the quality requirements of the service consumer. The monitoring infrastructure observes SLA-compliance during service delivery by using measurements obtained from third-party monitoring services. We also define a utility-based bargaining decision model that allows the service consumer to express her sensitivity for each of the negotiated quality attributes and to evaluate the SaaS provider offer in each round of negotiation. A use-case with few quality attributes and their respective utility functions illustrates the approach.
💡 Analysis
In the service landscape, the issues of service selection, negotiation of Service Level Agreements (SLA), and SLA-compliance monitoring have typically been used in separate and disparate ways, which affect the quality of the services that consumers obtain from their providers. In this work, we propose a broker-based framework to deal with these concerns in an integrated manner for Software as a Service (SaaS) provisioning. The SaaS Broker selects a suitable SaaS provider on behalf of the service consumer by using a utility-driven selection algorithm that ranks the QoS offerings of potential SaaS providers. Then, it negotiates the SLA terms with that provider based on the quality requirements of the service consumer. The monitoring infrastructure observes SLA-compliance during service delivery by using measurements obtained from third-party monitoring services. We also define a utility-based bargaining decision model that allows the service consumer to express her sensitivity for each of the negotiated quality attributes and to evaluate the SaaS provider offer in each round of negotiation. A use-case with few quality attributes and their respective utility functions illustrates the approach.
📄 Content
International Journal on Cloud Computing: Services and Architecture (IJCCSA) Vol. 6, No. 2, April 2016 DOI: 10.5121/ijccsa.2016.6201 1
A BROKER-BASED FRAMEWORK FOR INTEGRATED SLA-AWARE SAAS PROVISIONING
Elarbi Badidi
College of Information Technology, United Arab Emirates University, Al-Ain, United Arab Emirates ABSTRACT
In the service landscape, the issues of service selection, negotiation of Service Level Agreements (SLA), and SLA-compliance monitoring have typically been used in separate and disparate ways, which affect the quality of the services that consumers obtain from their providers. In this work, we propose a broker-based framework to deal with these concerns in an integrated mannerfor Software as a Service (SaaS) provisioning. The SaaS Broker selects a suitable SaaS provider on behalf of the service consumer by using a utility-driven selection algorithm that ranks the QoS offerings of potential SaaS providers. Then, it negotiates the SLA terms with that provider based on the quality requirements of the service consumer. The monitoring infrastructure observes SLA-compliance during service delivery by using measurements obtained from third-party monitoring services. We also define a utility-based bargaining decision model that allows the service consumer to express her sensitivity for each of the negotiated quality attributes and to evaluate the SaaS provider offer in each round of negotiation. A use-case with few quality attributes and their respective utility functions illustrates the approach.
KEYWORDS
Cloud computing; Quality-of-Service; Key Performance Indicators; Utility function; SLA monitoring; Brokerage service
- INTRODUCTION
Over the last few years, Software as a Service (SaaS) has emerged as one of the most promising service delivery models in cloud computing. The number of SaaS services in various business domains grows continually, and new SaaS service offerings emerge on a steady basis. SaaS is becoming an accepted delivery model for many enterprise applications, including accounting, collaboration, customer relationship management, enterprise resource planning, human resources management, etc. As SaaS services proliferate, users and organizations are becoming more demanding when consuming such services. They increasingly demand services that meet their functional and non-functional requirements. Therefore, SaaS providers need to negotiate Service Level Agreements (SLAs) with their service consumers and adhere to their service level commitments if they want to remain competitive in a changing and demanding business environment.
Given the variety of consumers’ requirements, SaaS providers need to manage an increasing number of SLAs, all with potentially changing quality requirements. The SLA lifecycle, as described in the SLA Management Handbook [24], includes six main phases: SLA Establishment, Negotiation and Sales, Implementation, Execution, Assessment, and Decommissioning. Initiatives in standardizing the use of SLAs are (1) WSLA [11] by IBM, (2) the WS-Agreement specification [1] by the Open Grid Forum, and (3) the SLAng Specification Language [14]. Several efforts– that we discuss in the Related Work section– investigated the issue of SLA Negotiation [8] [10] [11] [22] [25]. This work shares with these efforts the common goal of International Journal on Cloud Computing: Services and Architecture (IJCCSA) Vol. 6, No. 2, April 2016
2 providing support for automated SLA negotiation and management. Finding the right SaaS provider is a daunting task for consumers given the abundance and the variety of SaaS offerings. In the service landscape, the critical issues of service-based systems include service discovery, service selection, SLA negotiation, and SLA-compliance monitoring. These concerns were investigated separately using different approaches. We propose in this work an integrated framework to deal with these issues in the context of a SaaS environment. Its principal components are the SaaS Broker and the Monitoring Infrastructure. The SaaS Broker 1) mediates between service consumers and SaaS providers, 2) selects suitable SaaS providers capable of delivering required functionality and quality-of-service, 3) negotiates SLAs on behalf of service consumers, and 4) assesses compliance of service delivery with agreed upon SLA. In each round of negotiation, the SaaS Broker and the selected SaaS provider bargain on multiple SLA parameters by trying to maximize their global utility functions. The Monitoring Infrastructure is in charge of observing service delivery, during SLA implementation, using measurements obtained from independent third party monitoring services.
The remainder of the paper is organized as follows. Next section presents background information on the issues of n
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