面向SaaS提供商的数据库迁移和资源供给机制的研究
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摘要
随着云计算商业模式的飞速发展，越来越多的软件企业进入SaaS（Software as aService，软件即服务）市场，降低成本提高效益成为SaaS提供商迫切需要解决的问题。把传统软件迁移成SaaS软件和在IaaS（Infrastructure as a Service，基础架构即服务）平台上部署SaaS服务是SaaS服务运营前后首选的降低成本的方法，也是近几年云计算技术的研究热点。
本文主要对单租户数据库模式向多租户数据库模式的SaaS迁移和IaaS平台上的数据库系统资源供给机制进行了研究，着重进行了以下几个方面的工作：
首先，为了满足租户对数据模式性能和成本的双重需求，本文通过基础模式和元信息数据库的协作设计了混合多租户数据库模式，并通过增加数据访问代理层和统一数据库服务接口实现了该混合模式的轻量级迁移。实例系统的迁移实现证明了该方法能够让迁移后的SaaS软件数据库服务具有多租户访问、安全性、可配置性和可扩展性等特性。
其次，本文提出了IaaS平台上多租户共享数据库的租户安置和调整算法SmartDeploy和SmartAdjust，通过在新租户进入时的租户安置和老租户性能报警时对租户分布位置的调整：尝试报警虚拟机上租户所有可能的调整方法，估算调整后的系统效益变化和数据调整成本，找到效益值提高最大的调整方案，从而优化SaaS提供商的系统效益。模拟对比实验结果表明，该算法对SaaS系统效益优化有良好的效果。
最后，针对现有迁移研究中没有实现的租户数据个性化定制和WebServices个性化定制，本文提出了基于实例系统的实现方法，为其它SaaS软件迁移提供了借鉴实例。
With the rapid development of the business model of cloud computing, more andmore software companies enter the SaaS service market. It’s urgent to address the problemof reducing cost and improving benefit for the SaaS vendors. Migrating traditionalsoftware into SaaS software and deploying SaaS services on the IaaS platform are thepreferred methods to reduce costs before and after running the SaaS services, and they arealso the most popular research topics in recent years in the field of cloud computingtechnology.
This paper focuses on the SaaS transformation from a single-tenancy database modelto a multi-tenancy database model and the resources supply mechanism for databasesystem on the IaaS platform, the main content includes several aspects as follows:
Firstly, to meet the tenants’ cost-saving expectation versus database performancerequirement, a mixed multi-tenancy data model is proposed by the cooperation of threeexisting basic data models and meta-information management database in the paper. Usinga database access proxy and a general data model interface, a light migration approach isdesigned and implemented to transform the new mixed data model. The case studied in thepaper shows that the approach can make the database component of SaaS applicationsmulti-tenancy, secure, scalable and customizable.
Secondly, resources supply algorithms called SmartDeploy and SmartAdjust areproposed for the database system which uses the multi-tenancy shared schema data model.The algorithms adjust the resource and the current distribution of the tenants just when anew tenant comes and old tenants meet the alarm of performance. The basic means ofSmartAdjust is to find the best adjustment plan by estimating the benefit and migrationcost of every possible adjustment plans of all the tenants in the warning virtual machine.The one which increases the maximum of the benefit can optimize the benefit for the SaaSvendors. The simulation experiment shows that our algorithms can optimize the benefit ofthe system better.
Finally, based on the example system, the paper proposes some methods to achievethe migration goals including the customization of tenants’ data and the customization ofWebServices which are not implemented in the existing migration works. The methodsapplied in the example are worth learning for other applications which are waiting for SaaSmigration.
本文主要对单租户数据库模式向多租户数据库模式的SaaS迁移和IaaS平台上的数据库系统资源供给机制进行了研究，着重进行了以下几个方面的工作：
首先，为了满足租户对数据模式性能和成本的双重需求，本文通过基础模式和元信息数据库的协作设计了混合多租户数据库模式，并通过增加数据访问代理层和统一数据库服务接口实现了该混合模式的轻量级迁移。实例系统的迁移实现证明了该方法能够让迁移后的SaaS软件数据库服务具有多租户访问、安全性、可配置性和可扩展性等特性。
其次，本文提出了IaaS平台上多租户共享数据库的租户安置和调整算法SmartDeploy和SmartAdjust，通过在新租户进入时的租户安置和老租户性能报警时对租户分布位置的调整：尝试报警虚拟机上租户所有可能的调整方法，估算调整后的系统效益变化和数据调整成本，找到效益值提高最大的调整方案，从而优化SaaS提供商的系统效益。模拟对比实验结果表明，该算法对SaaS系统效益优化有良好的效果。
最后，针对现有迁移研究中没有实现的租户数据个性化定制和WebServices个性化定制，本文提出了基于实例系统的实现方法，为其它SaaS软件迁移提供了借鉴实例。
With the rapid development of the business model of cloud computing, more andmore software companies enter the SaaS service market. It’s urgent to address the problemof reducing cost and improving benefit for the SaaS vendors. Migrating traditionalsoftware into SaaS software and deploying SaaS services on the IaaS platform are thepreferred methods to reduce costs before and after running the SaaS services, and they arealso the most popular research topics in recent years in the field of cloud computingtechnology.
This paper focuses on the SaaS transformation from a single-tenancy database modelto a multi-tenancy database model and the resources supply mechanism for databasesystem on the IaaS platform, the main content includes several aspects as follows:
Firstly, to meet the tenants’ cost-saving expectation versus database performancerequirement, a mixed multi-tenancy data model is proposed by the cooperation of threeexisting basic data models and meta-information management database in the paper. Usinga database access proxy and a general data model interface, a light migration approach isdesigned and implemented to transform the new mixed data model. The case studied in thepaper shows that the approach can make the database component of SaaS applicationsmulti-tenancy, secure, scalable and customizable.
Secondly, resources supply algorithms called SmartDeploy and SmartAdjust areproposed for the database system which uses the multi-tenancy shared schema data model.The algorithms adjust the resource and the current distribution of the tenants just when anew tenant comes and old tenants meet the alarm of performance. The basic means ofSmartAdjust is to find the best adjustment plan by estimating the benefit and migrationcost of every possible adjustment plans of all the tenants in the warning virtual machine.The one which increases the maximum of the benefit can optimize the benefit for the SaaSvendors. The simulation experiment shows that our algorithms can optimize the benefit ofthe system better.
Finally, based on the example system, the paper proposes some methods to achievethe migration goals including the customization of tenants’ data and the customization ofWebServices which are not implemented in the existing migration works. The methodsapplied in the example are worth learning for other applications which are waiting for SaaSmigration.
引文
[1]Michael Armbrust, Armando Fox, Rean Griffith, et al. A view of cloud computing[J].Communications of the ACM,2010.53(4):50-58.
[2]Peeyush Mathur, Nikhil Nishchal. Cloud computing: New challenge to the entirecomputer industry[A]. In:20101st International Conference on Parallel Distributedand Grid Computing (PDGC)[C]. IEEE,2010:223-228.
[3]Forrester. SaaS and data-driven "smart" apps fueling world wide software growth[EB/OL].http://techcrunch.com/2013/01/03/forrester-saas-and-data-driven-smart-apps-fueling-worldwide-software-growth/.
[4]Salesforce[EB/OL]. https://www.Salesforce.com/cn.
[5]Yaish Haitham. Multi-tenancy in software as a service[EB/OL]. http://yesbut.progsoc.uts.edu.au/media/papers/uploads/hyaish/1300080437.934338/Multi-tenancy_in_SaaS_Haitham_Yaish_v_1.1.pdf.
[6]Carlo Curino, Evan Jones, Yang Zhang, et al. Relational cloud: The case for a databaseservice[J]. New England Database Summit,2010:1-6.
[7]Service-level agreement [EB/OL]. http://en.wikipedia.org/wiki/Servicelevel_agreement.
[8]Gartner identifies five ways to migrate applications to the cloud[EB/OL]. http://www.gartner.com/newsroom/id/1684114.
[9]Zhang Xuesong, Shen Beijun, Tang Xucheng, et al. From isolated tenancy hostedapplication to multi-tenancy: Toward a systematic migration method for webapplication[A]. In:2010IEEE International Conference on Software Engineering andService Sciences (ICSESS)[C].2010:209-212.
[10]Cor-Paul Bezemer, Andy Zaidman. Multi-tenant SaaS applications: maintenancedream or nightmare?[A]. In: Proceedings of the Joint ERCIM Workshop on SoftwareEvolution (EVOL) and International Workshop on Principles of Software Evolution(IWPSE)[C]. ACM,2010:88-92.
[11]Cor-Paul Bezemer, Andy Zaidman, Bart Platzbeecker, et al. Enabling multi-tenancy:An industrial experience report[A]. In:2010IEEE International Conference onSoftware Maintenance (ICSM)[C].2010:1-8.
[12]Cai Hong, Zhang Ke, Zhou Ming Jun, et al. An end-to-end methodology and toolkit forfine granularity SaaS-ization[A]. In:2009IEEE International Conference on CloudComputing (CLOUD '09)[C].2009:101-108.
[13]Cai Hong, Wang Ning, Zhou Ming Jun. A transparent approach of enabling SaaS multi-tenancy in the cloud[A]. In:20106th World Congress on Services (SERVICES-1)[C].2010:40-47.
[14]Scott Chate. Convert your web application to a multi-tenant SaaS solution[EB/OL].http://www.ibm.com/developerworks/cloud/library/cl-multitenantsaas/index.html.
[15]German Goldszmidt, Indrajit Poddar. Develop and deploy multitenant web-deliveredsolutions using IBM middleware, part1: Challenges and architectural patterns[EB/OL]. http://www.ibm.com/developerworks/library/ws-middleware/.
[16]Mary Taylor, Chang Jie Guo. Data integration and composite business services, part3:Build a multi-tenant data tiers with access control and security[EB/OL]. http://www.ibm.com/developerworks/data/library/techarticle/dm-0712taylor/.
[17]Amit Tiwary. Renovating distributed applications to leverage business benefits ofcloud computing[A]. In:2010International Conference on Software and ComputingTechnology (ICSCT2010)[C].2010:V2-356-360.
[18]Christof Momm, Rouven Krebs. A qualitative discussion of different approaches forimplementing multi-tenant SaaS offerings[A]. In: Software Engineering (Workshops)[C].2011.
[19]Ahmed A. Soror, Umar Farooq Minhas, Ashraf Aboulnaga, et al. Automatic virtualmachine configuration for database workloads[J]. ACM Transactions on DatabaseSystems,2010.35(1):47-60.
[20]Xiong Pengcheng, Chi Yun, Zhu Shenghuo, et al. Intelligent management ofvirtualized resources for database systems in cloud environment[A]. In:2011IEEE27th International Conference on Data Engineering (ICDE)[C].2011:87-98.
[21]Kong Shoubin, Ling Feng. Dynamic performance management for databaseapplications in virtualized environments[A]. In:20113rd International Conference onComputer Research and Development (ICCRD)[C].2011:195-199.
[22]Jennie Rogers, Olga Papaemmanouil, Ugur Cetintemel. A generic auto-provisioning framework for cloud databases[A]. In:2010IEEE26th InternationalConference on Data Engineering Workshops (ICDEW)[C].2010:63-68.
[23]Sherif Sakr, Anna Liu. SLA-based and consumer-centric dynamic provisioning forcloud databases[A]. In:2012IEEE5th International Conference on Cloud Computing(CLOUD)[C].2012:360-367.
[24]Sonja Lehmann, Peter Buxmann. Pricing strategies of software vendors[J]. Business&Information Systems Engineering,2009.1(6):452-462.
[25]宋艳,左锋,王晓东.云计算环境下服务计费方法研究[J].计算机与网络,2012.38(5):65-67.
[26]白丽瑞,李彤,谢仲文, et al.基于成本利润Petri网的应用云计费模式分析[J].电信科学,2012.28(1):58-62.
[27]Wikipedia cloud computing[EB/OL]. http://en.wikipedia.org/wiki/Cloud_computing.
[28]Ian Foster, Zhao Yong, Ioan Raicu, et al. Cloud computing and grid computing360-degree compared[A]. In:2008Grid Computing Environments Workshop (GCE '08)[C].2008:1-10.
[29]Naidila Sadashiv, S. M Dilip Kumar. Cluster, grid and cloud computing: A detailedcomparison[A]. In:20116th International Conference on Computer Science&Education (ICCSE)[C].2011:477-482.
[30]Cluster computing[EB/OL]. http://en.wikipedia.org/wiki/Cluster computing.
[31]柳敬.云计算平台的成本效用研究[D].北京:北京邮电大学.2010.
[32]唐元.基于云计算的企业IT基础设施自动供给方案的研究与实现[D].北京:北京邮电大学.2010.
[33]陆洪潮. SaaS模式的ERP系统的研究[D].武汉:武汉理工大学.2009.
[34]何海棠. SaaS模式下企业信息管理平台的研究与实现[D].扬州:扬州大学.2009.
[35]Christoph Fehling. Provisioning of software as a service applications in the cloud[EB/OL]. http://elib.uni-stuttgart.de/opus/volltexte/2009/4766/.
[36]Guo Chang Jie, Sun Wei, Huang Ying, et al. A framework for native multi-tenancyapplication development and management[A]. In: The9th IEEE InternationalConference on E-Commerce Technology and the4th IEEE International Conferenceon Enterprise Computing, E-Commerce, and E-Services (CEC/EEE2007)[C].2007:551-558.
[37]彭荣. SaaS模式下多租户系统架构及关键技术研究[D].大连:大连海事大学.2010.
[38]SaaS系列介绍之十四: SaaS软件开发分析[EB/OL]. http://dev.yesky.com/49/8585049.shtml.
[39]Skip Garvin. The migration advantage[EB/OL]. http://www.ibmsystemsmag.com/aix/administrator/systemsmanagement/The-Migration-Advantage/.
[40]Norihiko Sakamoto. Construction of SaaS-based e-learning system in Japan[J]. FujitsuScientific and Technical Journal,2009.45(3):290-298.
[41]Shang Jia, Yang Ji-Jiang, Wang Qing, et al. The framework of medical simulationeducation and evaluation system for supporting SaaS[A]. In:2010IEEE34th AnnualComputer Software and Applications Conference Workshops (COMPSACW)[C].2010:93-97.
[42]Song Jie, Han Feng, Yan Zhenxing, et al. A SaaSify tool for converting traditionalWeb-based applications to SaaS application[A]. In:2011IEEE InternationalConference on Cloud Computing (CLOUD)[C].2011:396-403.
[43]Jie Song, Zhenxing Yan, Feng Han, et al. Introducing SaaS capabilities to existingWeb-based applications automatically[A]. In: Web Technologies and Applications[C].Springer Berlin Heidelberg,2012:560-569.
[44]Bo Gao, Changejie Guo. Develop and deploy multi-tenant Web-delivered solutionsusing IBM middleware: part3: Resource sharing, isolation and customization in thesingle instance multi-tenant application.[EB/OL]. http://www.ibm.com/developer-works/webservices/library/ws-multitenant/index.html.
[45]Balakrishna Narasimhan, Ryan Nichols. State of cloud applications and platforms: Thecloud adopters' view[J]. Computer,2011.44(3):24-28.
[46]Ding Jianmin, Zhao Zhuo. Towards autonomic SLA management: A review[A]. In:2012International Conference on Systems and Informatics (ICSAI)[C].2012:2552-2555.
[47]程旭.基于SLA的SaaS应用性能管理机制研究[D].济南:山东大学.2010.
[48]Karen Goulart, Features Writer. As cloud's use expands, cloud SLAs more importantthan ever[EB/OL]. http://searchcio.techtarget.com/news/2240171259/As-clouds-use-expands-cloud-SLAs-more-important-than-ever.
[49]陈红.云计算应用引擎计费机制研究与实现[D].长沙:国防科技大学.2011.
[50]Amazon web services[EB/OL]. http://aws.amazon.com/.
[51]Tao Yu, Jie Qiu, Berthold Reinwald, et al. Intelligent database placement in cloudenvironment[A]. In:2012IEEE19th International Conference on Web Services(ICWS)[C]. IEEE,2012:544-551.
[52]Apache jmeter[EB/OL]. http://jmeter.apache.org/.
[53]姜世超.基于SaaS的Multi-Tenant应用的可配置性研究[D].大连:大连海事大学.2010.
[2]Peeyush Mathur, Nikhil Nishchal. Cloud computing: New challenge to the entirecomputer industry[A]. In:20101st International Conference on Parallel Distributedand Grid Computing (PDGC)[C]. IEEE,2010:223-228.
[3]Forrester. SaaS and data-driven "smart" apps fueling world wide software growth[EB/OL].http://techcrunch.com/2013/01/03/forrester-saas-and-data-driven-smart-apps-fueling-worldwide-software-growth/.
[4]Salesforce[EB/OL]. https://www.Salesforce.com/cn.
[5]Yaish Haitham. Multi-tenancy in software as a service[EB/OL]. http://yesbut.progsoc.uts.edu.au/media/papers/uploads/hyaish/1300080437.934338/Multi-tenancy_in_SaaS_Haitham_Yaish_v_1.1.pdf.
[6]Carlo Curino, Evan Jones, Yang Zhang, et al. Relational cloud: The case for a databaseservice[J]. New England Database Summit,2010:1-6.
[7]Service-level agreement [EB/OL]. http://en.wikipedia.org/wiki/Servicelevel_agreement.
[8]Gartner identifies five ways to migrate applications to the cloud[EB/OL]. http://www.gartner.com/newsroom/id/1684114.
[9]Zhang Xuesong, Shen Beijun, Tang Xucheng, et al. From isolated tenancy hostedapplication to multi-tenancy: Toward a systematic migration method for webapplication[A]. In:2010IEEE International Conference on Software Engineering andService Sciences (ICSESS)[C].2010:209-212.
[10]Cor-Paul Bezemer, Andy Zaidman. Multi-tenant SaaS applications: maintenancedream or nightmare?[A]. In: Proceedings of the Joint ERCIM Workshop on SoftwareEvolution (EVOL) and International Workshop on Principles of Software Evolution(IWPSE)[C]. ACM,2010:88-92.
[11]Cor-Paul Bezemer, Andy Zaidman, Bart Platzbeecker, et al. Enabling multi-tenancy:An industrial experience report[A]. In:2010IEEE International Conference onSoftware Maintenance (ICSM)[C].2010:1-8.
[12]Cai Hong, Zhang Ke, Zhou Ming Jun, et al. An end-to-end methodology and toolkit forfine granularity SaaS-ization[A]. In:2009IEEE International Conference on CloudComputing (CLOUD '09)[C].2009:101-108.
[13]Cai Hong, Wang Ning, Zhou Ming Jun. A transparent approach of enabling SaaS multi-tenancy in the cloud[A]. In:20106th World Congress on Services (SERVICES-1)[C].2010:40-47.
[14]Scott Chate. Convert your web application to a multi-tenant SaaS solution[EB/OL].http://www.ibm.com/developerworks/cloud/library/cl-multitenantsaas/index.html.
[15]German Goldszmidt, Indrajit Poddar. Develop and deploy multitenant web-deliveredsolutions using IBM middleware, part1: Challenges and architectural patterns[EB/OL]. http://www.ibm.com/developerworks/library/ws-middleware/.
[16]Mary Taylor, Chang Jie Guo. Data integration and composite business services, part3:Build a multi-tenant data tiers with access control and security[EB/OL]. http://www.ibm.com/developerworks/data/library/techarticle/dm-0712taylor/.
[17]Amit Tiwary. Renovating distributed applications to leverage business benefits ofcloud computing[A]. In:2010International Conference on Software and ComputingTechnology (ICSCT2010)[C].2010:V2-356-360.
[18]Christof Momm, Rouven Krebs. A qualitative discussion of different approaches forimplementing multi-tenant SaaS offerings[A]. In: Software Engineering (Workshops)[C].2011.
[19]Ahmed A. Soror, Umar Farooq Minhas, Ashraf Aboulnaga, et al. Automatic virtualmachine configuration for database workloads[J]. ACM Transactions on DatabaseSystems,2010.35(1):47-60.
[20]Xiong Pengcheng, Chi Yun, Zhu Shenghuo, et al. Intelligent management ofvirtualized resources for database systems in cloud environment[A]. In:2011IEEE27th International Conference on Data Engineering (ICDE)[C].2011:87-98.
[21]Kong Shoubin, Ling Feng. Dynamic performance management for databaseapplications in virtualized environments[A]. In:20113rd International Conference onComputer Research and Development (ICCRD)[C].2011:195-199.
[22]Jennie Rogers, Olga Papaemmanouil, Ugur Cetintemel. A generic auto-provisioning framework for cloud databases[A]. In:2010IEEE26th InternationalConference on Data Engineering Workshops (ICDEW)[C].2010:63-68.
[23]Sherif Sakr, Anna Liu. SLA-based and consumer-centric dynamic provisioning forcloud databases[A]. In:2012IEEE5th International Conference on Cloud Computing(CLOUD)[C].2012:360-367.
[24]Sonja Lehmann, Peter Buxmann. Pricing strategies of software vendors[J]. Business&Information Systems Engineering,2009.1(6):452-462.
[25]宋艳,左锋,王晓东.云计算环境下服务计费方法研究[J].计算机与网络,2012.38(5):65-67.
[26]白丽瑞,李彤,谢仲文, et al.基于成本利润Petri网的应用云计费模式分析[J].电信科学,2012.28(1):58-62.
[27]Wikipedia cloud computing[EB/OL]. http://en.wikipedia.org/wiki/Cloud_computing.
[28]Ian Foster, Zhao Yong, Ioan Raicu, et al. Cloud computing and grid computing360-degree compared[A]. In:2008Grid Computing Environments Workshop (GCE '08)[C].2008:1-10.
[29]Naidila Sadashiv, S. M Dilip Kumar. Cluster, grid and cloud computing: A detailedcomparison[A]. In:20116th International Conference on Computer Science&Education (ICCSE)[C].2011:477-482.
[30]Cluster computing[EB/OL]. http://en.wikipedia.org/wiki/Cluster computing.
[31]柳敬.云计算平台的成本效用研究[D].北京:北京邮电大学.2010.
[32]唐元.基于云计算的企业IT基础设施自动供给方案的研究与实现[D].北京:北京邮电大学.2010.
[33]陆洪潮. SaaS模式的ERP系统的研究[D].武汉:武汉理工大学.2009.
[34]何海棠. SaaS模式下企业信息管理平台的研究与实现[D].扬州:扬州大学.2009.
[35]Christoph Fehling. Provisioning of software as a service applications in the cloud[EB/OL]. http://elib.uni-stuttgart.de/opus/volltexte/2009/4766/.
[36]Guo Chang Jie, Sun Wei, Huang Ying, et al. A framework for native multi-tenancyapplication development and management[A]. In: The9th IEEE InternationalConference on E-Commerce Technology and the4th IEEE International Conferenceon Enterprise Computing, E-Commerce, and E-Services (CEC/EEE2007)[C].2007:551-558.
[37]彭荣. SaaS模式下多租户系统架构及关键技术研究[D].大连:大连海事大学.2010.
[38]SaaS系列介绍之十四: SaaS软件开发分析[EB/OL]. http://dev.yesky.com/49/8585049.shtml.
[39]Skip Garvin. The migration advantage[EB/OL]. http://www.ibmsystemsmag.com/aix/administrator/systemsmanagement/The-Migration-Advantage/.
[40]Norihiko Sakamoto. Construction of SaaS-based e-learning system in Japan[J]. FujitsuScientific and Technical Journal,2009.45(3):290-298.
[41]Shang Jia, Yang Ji-Jiang, Wang Qing, et al. The framework of medical simulationeducation and evaluation system for supporting SaaS[A]. In:2010IEEE34th AnnualComputer Software and Applications Conference Workshops (COMPSACW)[C].2010:93-97.
[42]Song Jie, Han Feng, Yan Zhenxing, et al. A SaaSify tool for converting traditionalWeb-based applications to SaaS application[A]. In:2011IEEE InternationalConference on Cloud Computing (CLOUD)[C].2011:396-403.
[43]Jie Song, Zhenxing Yan, Feng Han, et al. Introducing SaaS capabilities to existingWeb-based applications automatically[A]. In: Web Technologies and Applications[C].Springer Berlin Heidelberg,2012:560-569.
[44]Bo Gao, Changejie Guo. Develop and deploy multi-tenant Web-delivered solutionsusing IBM middleware: part3: Resource sharing, isolation and customization in thesingle instance multi-tenant application.[EB/OL]. http://www.ibm.com/developer-works/webservices/library/ws-multitenant/index.html.
[45]Balakrishna Narasimhan, Ryan Nichols. State of cloud applications and platforms: Thecloud adopters' view[J]. Computer,2011.44(3):24-28.
[46]Ding Jianmin, Zhao Zhuo. Towards autonomic SLA management: A review[A]. In:2012International Conference on Systems and Informatics (ICSAI)[C].2012:2552-2555.
[47]程旭.基于SLA的SaaS应用性能管理机制研究[D].济南:山东大学.2010.
[48]Karen Goulart, Features Writer. As cloud's use expands, cloud SLAs more importantthan ever[EB/OL]. http://searchcio.techtarget.com/news/2240171259/As-clouds-use-expands-cloud-SLAs-more-important-than-ever.
[49]陈红.云计算应用引擎计费机制研究与实现[D].长沙:国防科技大学.2011.
[50]Amazon web services[EB/OL]. http://aws.amazon.com/.
[51]Tao Yu, Jie Qiu, Berthold Reinwald, et al. Intelligent database placement in cloudenvironment[A]. In:2012IEEE19th International Conference on Web Services(ICWS)[C]. IEEE,2012:544-551.
[52]Apache jmeter[EB/OL]. http://jmeter.apache.org/.
[53]姜世超.基于SaaS的Multi-Tenant应用的可配置性研究[D].大连:大连海事大学.2010.