Target Dimensions of Cloud Computing

Stefan Wind, Klaus Turowski Business Informatics and Systems Engineering

University Augsburg Augsburg, Germany

{stefan.wind, klaus.turowski}@wiwi.uni-augsburg.de

Jonas Repschläger, Rüdiger Zarnekow Information and Communication Management

Berlin Institute of Technology Berlin, Germany

{jonas.repschläger, rüdiger.zarnekow}@tu-berlin.de

Abstract-Over the recent years, Cloud Computing has evolved as a new computing paradigm which aims at providing high-quality, customized and dynamic computing services. Despite initial positive results, it is challenging in theory and practice to find an appropriate provider matching the individual requirements. For doing this, the customer has to be clear about his individual targets that should be achieved with cloud computing. That is quit challenging because there are a lot more dimensions to consider than costs and flexibility. Moreover, the selection process is complicated by a number of new entrants as well as offers of non-transparent services, which sometimes differ significantly. In this paper, target dimensions for cloud computing were developed, based on an international literature analysis and interviews with experts. In special, they have been explained using Infrastructure as a Service here. These dimensions should help enterprises to become clear about their requirements on cloud computing and do further steps, like classifying appropriate providers. The relevance of the target dimensions was evaluated with an additional survey conducted among IT managers.

Keywords: Cloud Computing; target dimension; classification;

I. MOTIVATION In industrial practice, cloud computing is becoming

increasingly established as an option for formulating cost-efficient and needs-oriented information systems. Recent IDC cloud research (IDC Survey, 2011) shows that worldwide revenue from public IT cloud services exceeded $16 billion in 2009 and is forecast to reach $55.5 billion in 2014, representing a compound annual growth rate of 27.4% [1]. This rapid growth rate is over five times the projected growth for traditional IT products (5%). The economic downturn has actually amplified the cloud services adoption due to its excellent cost-cutting mantra. Also Gartner predicts a strong growth of Cloud services with worldwide revenue in 2014 of 146.8 billion US dollar [2].

This growing acceptance will result in an increasing amount of different cloud vendors with various kinds of non-transparent cloud products. On the one hand that makes it difficult to compare the provider and on the other hand their service offerings. In the majority of cases the product portfolios are heterogeneous and combined with complex pricing models and service features. Furthermore the fact that the interoperability between several providers hasn’t been achieved makes a provider selection often irreversible or requires much

effort [3]. A further important point here is that Forrester Research Consultants has investigated eleven different cloud computing vendor offers with regard to fields of application, costs and commercial benefits, and has drawn a sobering conclusion: many offers do not meet - or only partially meet - customers’ requirements [4].

Despite the increasing acceptance of cloud computing within science and industry many important questions remain unanswered or are answered only partially. Besides issues relating to a convenient IT architecture, legal issues and migration aspects, customers of cloud-based solutions are facing questions about appropriate requirements for finding a suitable vendor and a cloud service for their individual situation. The appropriate requirements for each customer will be deduced from special target dimensions.

Based on a literature review and conducted interviews with experts we derived six Cloud target dimensions from a customer’s perspective (see chapter 4). These target dimensions cluster all Cloud characteristics that we have found mutually exclusive, as far as possible. Through the target dimensions we offer a first approach to deduce specific requirements for an individual cloud computing package. These might help enterprises to simplify the provider comparison and selection process. Finally, we evaluated the relevance of each target dimension and checked their applicability.

II. RESEARCH METHODOLOGY First, prior to the literature review five experts were

interviewed on possible target dimensions in Cloud Computing. As a result four target dimensions for the Cloud could be derived. The expert interviews were conducted with five experts from four companies, all holding different positions within their company. Care was taken that those respondents were representative of all perspectives (provider, customer and mediator / consultant) being important for the selection process. The interviews with the experts were structured and conducted referring to Glaeser and Laudel 2010 [16].

Next, in order to describe, synthesize, evaluate and

integrate the results of existing scientific work on comparison of Cloud providers and distinguishing criteria of Cloud

2011 IEEE Conference on Commerce and Enterprise Computing

978-0-7695-4535-6/11 $26.00 © 2011 IEEE

DOI 10.1109/CEC.2011.42

231

offerings, we conducted a systematic literature review following the approach of Webster and Watson [17]. This research method ensures that an extensive number of relevant papers are considered. During the literature review we attempted to match each gathered criterion to a representative target dimension. The necessity emerged to define two more target dimensions in order to allocate all relevant criteria. Afterwards the additional dimensions were discussed and evaluated with the experts as well. The outcomes were six target dimensions for cloud computing.

The first step in the literature selection process was conducted to identify a comprehensive list of literature sources. We started off by taking the top journals based on the VHB-JOURQUAL2 [18] and Saunders’s journal ranking [19]. To complete the analysis, publications of known national and international organizations and associations (e.g. Bitkom) were included.

In a subsequent step, we chose topic related papers from

the selected literature sources. An initial list of papers was generated by using key words such as “Cloud Provider”, “Cloud Vendor”, “Cloud Characteristics”, “Cloud Selection”, “Cloud Taxonomy”, “IaaS”, “Infrastructure as a Service”, “Platform as a Service”, “Software as a Service”, “PaaS” and “SaaS” to search for titles, abstracts and keywords. We only scanned the directories of the journals and conference proceedings manually if no electronic search was possible. Furthermore, we expanded our scientific foundation by reviewing the citations in the identified papers in the first literature exploration cycle to determine prior papers that should be considered for analysis in a subsequent literature exploration cycle.

We identified 55 papers all dealing with comparison of Cloud providers or at least containing related keywords. In order to identify the final set of publications we subjected these papers to a detailed (content-related) review. Therefore, we manually reviewed the papers of the initial list and selected only those papers which primarily deal with comparison of Cloud providers. Thus, 35 articles were selected which deal primarily with the selection of Cloud providers and distinguishing criteria of Cloud offerings. This will be the initial point for developing target dimensions. It is surprising that almost the entire set of finally selected papers consists of conference papers and there is just a small amount of high-quality journal papers available. This probably shows that classification and selection of Cloud providers and distinguishing criteria of Cloud offerings are so far under-researched.

Complementary to the literature review the provider market were investigated. This analysis was based on an extensive internet research where the websites of relevant companies were examined regarding their pricing model, Cloud service offering, company data and customer segment. By means of market studies and business publications on the Cloud market (Experton group [7]), (Gartner [20]), (McKinsey [21]) we detected over 80 relevant providers and essential

characteristics of their Cloud offerings gathered. Based on this analysis we compiled a feature catalog for Cloud providers.

In order to develop a detailed proposal for target dimensions the related criteria from the literature review were matched with the features of the Cloud provider supported by the experts. Thereby a design-oriented approach was used.

III. TARGET DIMENSIONS IN CLOUD COMPUTING In this contribution six target dimensions - such as cost

savings or increasing flexibility - were defined to group and structure the Cloud characteristics (see Figure 1).

FIGURE 1. OVERVIEW TARGET DIMENSIONS IN CLOUD COMPUTING Each target dimension represents a general objective which

the customer pursues and which characterizes his Cloud or IT strategy. Four target dimensions (costs, IT security & compliance, scope & performance, reliability & trustworthiness) were defined together with the experts prior to our analysis. Through our literature review and market research we validated these four dimensions and simultaneously discovered two additional dimensions (flexibility, service & Cloud management), which were evaluated subsequently by the experts as well.

Table 1 shows the relevant sources assigned to these target dimensions. In this context we discovered that practitioners mainly deal with questions about security, reliability and manageability of Cloud Computing. However, the performance as well as the cost / price models has remained largely unnoticed so far. Scientific approaches contrary to industry activity are exploring mostly effects on flexibility, emerging costs and performance criteria of Cloud providers. Also relevant is the IT security but not as important as the other dimensions. Largely unnoticed is the service and Cloud management which deals with characteristics and challenges on the operative level. Both, researchers and companies, take into consideration the flexibility opportunities.

Reliability & Trusttworthines

IT Security & Compliance

Costs

Service & CloudManagement

Scope & Performance

Flexibility

Target Dimensions

232

TABLE 1. RESULTS OF THE LITERATURE REVIEW

A. Target Dimension: Flexibility A related advantage of Cloud Computing, identified in

science and industry, is the gain in flexibility compared to traditional solutions [8].

The flexibility describes the ability to respond quickly to changing capacity requirements. Resources, for example, can be allocated and de-allocated as required, whereas requirements can sometimes vary greatly. The provisioning time is shorter compared to traditional outsourcing such as

Application System Provider (ASP) and with a very small overall commitment period to the vendor [6]. Also other aspects such as standardization (e.g. APIs), the traceability of data, the short-term contracts or a demand-driven and scalable resource recovery have to be considered regarding an appropriate supplier selection.

B. Target Dimension: Costs The decision to choose Cloud Computing and a particular

provider is often guided by monetary considerations [23] and linked with the slogan "pay-as-you-use". Customers who decide to use Cloud services benefit mostly by small capital commitment, low acquisition costs for required servers, licenses or necessary hardware space and the reduced complexity of IT operations. Despite similar services on the IaaS level the pricing and billing models often differentiate between each provider [51].

C. Target dimension: Scope & Performance With this target dimension the scope of services and the

performance of a Cloud provider are described. To select the Cloud provider which meets the requirements best, knowledge about their service and performance is of crucial importance [32]. Here it is essential to consider features regarding performance (latency, or transaction speed), capacity limits (e.g. maximum number of accounts or storage space), service complexity (how many functions are available) and degree of customization (how far the service can be adapted).

D. Target dimension: IT security & compliance The decision on selecting a provider in the Cloud is very

often influenced by company requirements in the areas of security, compliance and privacy [12][31][44][52]. Companies have to be sure that their data and applications, even operated in the Cloud, meet both required compliance guidelines and are adequately protected against unauthorized access. Here, the decision criteria are rather referring to the infrastructure of the provider itself than on the provided service.

E. Target dimension: Reliability and Trustworthiness This target dimension describes how certain the customer

can be that the service from the Cloud has the guaranteed availability [52]. It is important to know what commitment the provider makes, mostly as Service Level Agreements (SLAs). Moreover, the reliability with which these commitments are kept is of great importance. In contrast to the commitment the trustworthiness describes the provider's infrastructural features, which may be evidence of a high reliability. These include disaster recovery, redundant sites or certifications.

F. Target dimension: Service & Cloud Management The service & Cloud management includes features of the

provider that are substantial for appropriate Cloud service operations. These include the offered support and functions for controlling and monitoring as well as the individualization of the web interface [14]. The manageability (usability) of services, especially in a distributed IT architecture, and the Cloud governance, dealing with requirements and responsibilities by the customer, are essential features of this target dimension.

Flexibility

Costs

Scope&

Perform

ance

Reliability

&

Trusttworthines

IT Security &

Com

pliance

Service & C

loud M

anagement

Academic PublicationsGünther et al. (2001) [22]

Hilley (2009) [23]

Hoefer andKaragiannis (2010) [3]

Li et al. (2010) [24]

Prodan and Ostermann (2009) [25]

Annecy (2010) [26]

Vaquero et al. (2009) [14]

Peng et al. (2009) [27]

Weinhardt et al. (2009) [8]

Hay et al. (2011) [28]

Martens et al. (2011) [29]Christmann et al. (2010) [30]Tsvihun et al. (2010) [31]Armbrust et al. (2010) [32]Iyer und Henderson (2010) [10]Anandasivam andPremm (2009) [33]Lehmann et al. (2009) [34]

Rimal et al. (2009) [35]

Schwarz et al. (2009) [36]Talukder et al. (2010) [37]Koehler et al. (2010) (2010) [38]

Saya et al. (2010) [39]

Narasimhan et al. (2011) [40]Russell et al. (2010) [41]

Popularity 36 41 35 30 29 14

Industry Publications

BITKOM (2010) [11]

BSI (2010) [42]

EuroCloud (2010) [43]

ENISA (2009) [44]

CSA (2009) [12]

SaaS EcoSystem(2011) [45]

DMTF (2009) [46]

OpenCloudManifesto(2009) [47]

T-Systems (2008) [48]

Experton Group (2010) [7]The Open Group (2009) [49]

Popularity 21 6 1 24 27 18

Source

Target Dimension

Low priority Average priority High priority

233

IV. TARGET DIMENSIONS: RELEVANCE AND POPULARITY Currently the impact of Cloud Computing regarding the IT

infrastructure is discussed extensively among IT managers [6, 53]. Most of the interviewed IT managers (over 70%) are planning to obtain services from the Cloud [44], [51]. Besides, the customer’s need for standardization and uniform service interfaces in the Cloud, the transparency of the Cloud providers and their services are strongly requested [51].

On the basis of 30 IT managers surveyed the six developed target dimensions were weighted. The results are shown in Figure 2. Around 83% of the IT managers attach high importance to the “IT Security and Compliance” in the Cloud. Over 53% rated the “Reliability and Trustworthiness” dimension as the second most important one. The result of the weighted dimensions reflects the common sense of Cloud topics [11], [12], [54]. The dimensions “Scope & Performance” and “Service & Cloud Management” are relatively unimportant compared to the other four dimensions. One explanation could be a low relevance of these two dimensions for the management level or that they are not directly related to strategic objectives. Based on the expert interviews we assume that the IT department and responsible operators are more interested in these dimensions. Especially if service requirements are defined which require a certain performance level.

FIGURE 2. RELEVANCE OF TARGET DIMENSIONS (SURVEY RESULTS)

V. CONCLUSION & FUTURE WORK Based on a literature and provider review complemented by

interviews with specialists in the respective field we presented in this contribution six target dimensions for cloud computing. We show that flexibility, costs, scope & performance, IT security & compliance, reliability and trustworthiness, service & Cloud management are important target dimensions. Using them, enterprises could set up their cloud strategy and become clearer about the targets they want to achieve with cloud computing.

The next step in further research is to develop a detailed cloud classification (including suitable Key Performance Indicators - KPIs) based on these target dimensions. These KPIs might serve as decision parameters to enable a dynamic resource allocation. Furthermore a framework has to be built to compare appropriate cloud providers in a standardized way, based on pre-defined customer objectives.

REFERENCES [1] IDC Survey (2011) available at http://www.idc.com/prodserv/

idc_cloud.jsp (accessed on18 March 2011) [2] B. Pring, R. H. Brown, A. Frank, S. Hayward, and L. Leong,

“Forecast: Sizing the Cloud; Understanding the Opportunities in Cloud Services,” 2009.

[3] C.N. Hoefer, and G. Karagiannis, “Taxonomy of cloud computing services,” IEEE Globecom 2010 Workshop on Enabling the Future Service-Oriented Internet, 2010.

[4] Forrester: TechRadar For Infrastructure & Operations Professionals: Cloud Computing. Forrester, Q3 (2009)

[5] S. Leimeister, M. Böhm, C. Riedl, and H. Krcmar, “The Business Perspective of Cloud Computing: Actors, Roles, And Value Networks,” 18th European Conference on Information Systems ECIS, 2010

[6] J. Repschlaeger, and R. Zarnekow, „Cloud Computing in der IKT-Branche: Status-quo und Entwicklung des Cloud Sourcing von KMUs in der Informations- und Kommunikationsbranche in der Region Berlin Brandenburg,“ survey by the informations and communication chair from the technical university Berlin in cooperation with Verband der Software-, Informations- und Kommunikations-Industrie in Berlin and Brandenburg (SIBB e.V.), 2011.

[7] Experton Group, „Cloud Vendor Benchmark 2010 Cloud Computing Anbieter im Vergleich Deutschland,“ C. Velton and S. Janata, Experton Group AG, 2010.

[8] C. Weinhardt, A. Anandasivam, B. Blau, N. Borissov, T. Meinl, W. Michalk, and J. Stößer, „Cloud-Computing – Eine Abgrenzung, Geschäftsmodelle und Forschungsgebiete,“ Wirtschaftsinformatik, No. 5:453-462, 2009.

[9] T. Grance, and P. Mell, “The NIST definition of Cloud Computing,” National Institute of Standards and Technology (NIST), 2009.

[10] B. Iyer, and J.C. Henderson, “Preparing for the future: Understanding the seven capabilities of Cloud Computing,” MIS Quarterly Executive Vol. 9, No. 2, 2010.

[11] BITKOM „Cloud Computing – Was Entscheider wissen müssen,“ BITKOM Leitfaden, 2010.

[12] Cloud Security Alliance, “Security Guidance for Critical Areas of Focus in Cloud Computing V2.1,” Cloud Security Alliance (CSA), 2009.

[13] L. Wang, and G.v. Laszewski, “Scientific Cloud Computing: Early Definition and Experience,” in IEEE International Conference on High Performance Computing and Communications, Dalian, China, 2008.

[14] L.M. Vaquero, L.M. Merino, J. Caceres, and M. Lindner, “A Break in the Clouds: Towards a Cloud Definition,” ACM SIGCOMM Computer Communication Review Volume 39, Nr. 1, 2009.

[15] H. Yang, and M. Tate, “Where are we at with Cloud Computing?: A Descriptive Literature Review,” 20. Australasian Conference on Information Systems, 2009.

[16] J. Glaeser, and G. Laudel, „Experteninterviews und qualitative Inhaltsanalyse: als Instrumente rekonstruierender Untersuchungen,“ Vs Verlag; 4. Auflage., 2010.

[17] J. Webster, and R.T. Watson, “Analyzing the past to prepare for the future: Writing a literature review,” MIS Quarterly, 26(2):13–2, 2002.

2 4 11 13

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Target dimension: Flexibility unimportant (1) 2 3 4 very important (5)

1 5 14 10

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Target dimension: Costs

1 8 12 9

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Target dimension: Scope & Performance

3 2 25

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Target dimension: IT Security & Compliance

1 3 10 16

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Target dimension: Reliability & Trustwothiness

9 13 8

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Target dimension: Service & Cloud Management

234

[18] U. Schrader, and T. Hennig-Thurau, “VHBJOURQUAL2,” Business Research 2(2):180–204, 2009.

[19] C. Saunders, „MIS Journal rankings,“ 2009. [20] L. Leong, and T. Chamberlin, „Magic Quadrant for Cloud

Infrastructure as a Service and Web Hosting“. Gartner RAS Core Research, December 2010.

[21] D.J. Hoch, and U. Freking, „Cloud Computing, SaaS und SOA als Bausteine im Outsourcing der Zukunft,“ McKinsey on the 7. Entscheiderforum Outsourcing Bad Homburg v.d.Höhe, November 2009.

[22] O. Günther, G. Tamm, L. Hansen, and T. Meseg, “Application Service Providers: Angebot, Nachfrage und langfristige Perspektiven,” Wirtschaftsinformatik, No. 6, 2001.

[23] D. Hilley, “Cloud Computing: A Taxonomy of Platform and Infrastructure-level Offerings,” CERCS Technical Report, 2009.

[24] A. Li, X. Yang, S. Kandula, and M. Zhang, “CloudCmp: Comparing Public Cloud Providers,” Internet Measurement Conference, 2010.

[25] R. Prodan, and S. Ostermann, “A Survey and Taxonomy of Infrastructure as a Service and Web Hosting Cloud Providers,” IEEE/ACM International Conference on Grid Computing, 2009.

[26] M. Annecy, “XaaS Check 2010 Status Quo und Trends im Cloud Computing,” S.A.R.L. Martin, Forschungsgruppe Service-oriented Computing,Technische Universität Darmstadt und IT Research, 2010.

[27] J. Peng, X. Zhang, Z. Lei, B. Zhang, W. Zhang, and Q. Li, “Comparison of Several Cloud Computing Platforms,” Second International Symposium on Information Science and Engineering, IEEE, 2009.

[28] B. Hay, K. Nance, and M. Bishop, “Storm Clouds Rising: Security Challenges for IaaS Cloud Computing,” Proceedings of the 44th Hawaii International Conference on System Sciences, 2011.

[29] B. Martens, F. Teuteberg, and M. Gräuler, “Design and Implementation of a Community Platform for the Evaluation and Selection of Cloud Computing Services: A Market Analysis,” in Proceedings of the 19th European Conference on Information Systems, Helsinki, 2011.

[30] S. Christmann, H. Hilpert, M. Thöne, S. Hagenhoff, “Datensicherheit und Datenschutz im Cloud Computing – Risiken und Kriterien zur Anbieterauswahl,“ HMD- Praxis der Wirtschaftsinformatik, Heft 275, Oktober 2010, S.62-70.

[31] I. Tsvihun, P. Stephanow, and W. Streitberger, „Vergleich der Sicherheit traditioneller IT-Systeme und Public Cloud Computing Systeme,“ Fraunhofer-Institut für sichere Informationstechnologie (SIT), 2010.

[32] M. Armbrust, A. Fox, R. Griffith, A.D. Joseph, R.H. Katz, A. Konwinski, G. Lee, D.A. Patterson, A. Rabkin, I. Stoica, and M. Zaharia, “Above the Clouds: A Berkeley View of Cloud Computing,” UC Berkeley Reliable Adaptive Distributed Systems Laboratory, 2009.

[33] A. Anandasivam, and M. Premm, “Bid price control and dynamic pricing in Clouds,” in Proceedings of the European Conference on Information Systems, Verona, Italy, 2009.

[34] S. Lehmann, and P. Buxmann, “Pricing Strategies of Software Vendors,” Business Information Systems Engineering (1:6), pp. 452-462, 2009.

[35] B. Rimal, E. Choi, and I. Lumb, “A Taxonomy and Survey of Cloud Computing Systems,” Fifth International Joint Conference on INC, IMS and IDC, IEEE, 2009.

[36] Schwarz, A., Jayatilaka, B. Hirschheim, R. and Goles, T., “A Conjoint Approach to Understanding IT Application Services Outsourcing,” Journal of the Association for Information Systems, Vol. 10: Iss. 10, Article 1, 2010.

[37] A.K. Talukder, L. Zimmerman, and H.A. Prahalad, “Cloud Economics: Principles, Costs, and Benefits,” in Cloud Computing: Principles, Systems and Applications, N.

Antonopoulos and L. Gillam (eds.), Springer-Verlag London, pp. 343-360, 2010.

[38] P. Koehler, A. Anandasivam, M.A. Dan, C. Weinhardt, „Customer heterogeneity and tariffs biases in Cloud Computing“, ICIS, 2010.

[39] S. Saya, L.G. Pee, and A. Kankanhalli, “The impact of insitutional influrences on perceived technological characteristics and real options in Cloud Computing adoption”, ICIS, 2010.

[40] B.Narasimhan, and R. Nichols, “State of Cloud Applications and Platforms: The Cloud Adopters' View”, Journal Computer, Vol.44:3, 2011.

[41] S. Russell, V. Yoon, and G. Forgionne, “Cloud-based decision support systems and availability context: the probability of successful decision outcomes”, Information Systems and eBusiness Management, Vol.8, Iss. 3, p.189-205, 2010.

[42] BSI „BSI-Mindestsicherheitsanforderungen an Cloud-Computing-Anbieter,“ Bundesamt für Sicherheit in der Informationstechnik, 2010.

[43] EuroCloud “Cloud Computing, Recht, Datenschutz & Compliance,” Leitfaden des EuroCloud Deutschland_eco e. V., 2010.

[44] D. Catteddu, and G. Hogben, “Cloud Computing - Benefits, risks and recommendations for information security,” European Network and Information Security Agency (ENISA), 2009.

[45] SaaS-EcoSystem “SaaS-EcoSystem Check-Liste,” SaaS-EcoSystem e. V., 2011. http://www.saasecosystem.org/trust-in-cloud/checkliste/, visited: 2011/04/19.

[46] Distributed Management Task Force (DMTF) “Interoperable Clouds,” Whitepaper from the Open Cloud Standards Incubator, 2009.

[47] Opencloudmanifesto.org „Open Cloud Manifesto -Dedicated to the belief that the cloud should be open,” www.opencloudmanifesto.org, 2009.

[48] T-Systems „White Paper Cloud Computing. Alternative sourcing strategy for business ICT,” T-Systems Enterprise Services GmbH, 2008.

[49] The Open Group, “Cloud Computing Business Scenario Workshop,” T. Blevins, D. Lounsbury, M. Kirk, and C. Harding, Report published by the Open Group, August 2009.

[50] R. Buyya, C.S. Yeo, S. Venugopal, J. Broberg, and I. Brandic, “Cloud computing and emerging IT platforms: Vision, hype, and reality for delivering computing as the 5th utility,” Future Generation Computer Systems, Vol 25:599-616, 2009.

[51] J. Repschlaeger, and R. Zarnekow, „Umfrage zur Anbieterauswahl und Markttransparenz in der Cloud,“ survey from the technical university Berlin within the IT Operations Day, 2011.

[52] P.T. Jaeger, J. Lin, J.M. Grimes, “Cloud Computing and Information Policy: Computing in a Policy Cloud?,” Journal of Information Technology & Politics, Vol. 5(3), 2008.

[53] B. Martens, F. Teuteberg, and M. Gräuler, „Datenbank und Reifegradmodell für die Auswahl und Bewertung von Cloud-Computing-Services,“ HMD-Praxis der Wirtschaftsinformatik, Heft 275, S.52-61, 2010.

[54] IDC “Cloud Computing und Services – Status quo und Trends in Deutschland,” IDC Central Europe GmbH, 2009.

235