The Classification and Arts of Open Source Cloud Computing: A Review

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1 The Classification and Arts of Open Source Cloud Computing: A Review 1 Hala A. Albaroodi, 2 Selvakumar Manickam, 3 Mohammed Faiz Aboalmaaly *1 National Advanced IPv6 Centre (NAV6) Universiti Sains Malaysia, USM, Penang, Malaysia, [email protected] 2,3 National Advanced IPv6 Centre (NAV6) Universiti Sains Malaysia, USM, Penang, Malaysia, selva, [email protected] Abstract Cloud computing refers to the concept of dynamic processing and optimization of storage allocation of computational resources in the cloud. This system allows users to obtain and release the resources on demand and gain access to data by providing the relegation of the physical location and accurate parameters of the resources. Cloud computing systems are either proprietary or dependent on infrastructure software, which is the focus of this research. Open source (OS), which is a cloud infrastructure software, is popular in particular fields, such as operating systems, programming languages and software application, and, most importantly, cloud computing. However, public administrations, commercial enterprises, and other institutions have yet to incorporate Open source software in the cloud infrastructure of their organizations because of the lack of information and comprehension of such technology. This paper, therefore, will examine the principles of cloud computing, compare proprietary cloud computing and open source cloud computing, examine the OSCC platforms, and examine the open stack platform usage. Keywords: OS (Open source), OSS (Open source software), PaaS (platform as a service), IaaS (infrastructure as a service), SaaS (software as a service), OSCC (Open Source Cloud Computing). 1. Introduction Recently, the phrase cloud computing has been mentioned frequently and is touted to be the next computing revolution after the global takeover by the Internet. Some have compared the inception of cloud computing to the industrial revolution, in terms of providing means for the mass production of certain goods and services, even considering it as the so-called fifth utility, after water, gas, electricity, and telephony. The concept of cloud computing, however, is not new [1] because it has been used for web applications that can be accessed by anyone, anywhere, and anytime. In the beginning of the millennium, a gradual shift from software as a product to software as a service (SaaS) began [2]. This transformation resulted in traditional software, i.e., client-based software, which is typically installed on individual computers, to diminish. Open source software (OSS) is an important innovation for cloud computing because it is interrelated symbiotically with cloud computing. Similar to OSS, cloud computing is accessible, supports experimentation and innovation, reduces the cost of doubt, and causes the same challenge to the industry as the OS has done previously [3]. However, public administrations, commercial enterprises, and other institutions have yet to incorporate Open source software in the cloud infrastructure of their organizations because of the lack of information and comprehension of such technology [2]. In the current paper, we will compare each platform and obtain standards from the literature analysis. Furthermore, gaining comprehension of the architecture, the programming language used, and the varieties of clouds supported is necessary in order to understand how each of the platform functions. Therefore, a differentiation was performed to the samples of public cloud, hybrid software, and private. Besides the introduction, this paper will discuss the principles of cloud computing, compare proprietary cloud computing and Open source cloud computing, examine the OSCC platforms, examine the open stack platform usage, and conclude the paper with the overall findings of the review. 2. Principles of cloud computing Cloud computing is typically designated by its definitions, service models, and deployment models. Advances in information Sciences and Service Sciences(AISS) Volume5, Number16, November

2 2.1. Definition A standardized definition of cloud computing has yet to be formulated [4], resulting in the diverse ways by which cloud computing is perceived. Nevertheless, virtually all of these definitions agree on the general objectives and views of cloud computing [5]. Ultimately, the Internet can be used as a source through which computing services that can include IT platforms, infrastructure, or applications can be accessed and used. The cloud framework is typically structured to enclose visualized resources and services that can be retrieved and utilized by clients through a software, virtual machine, or deployment environment [5]. A previous study [6] defined cloud computing as a substantial pool, from which virtual resources (e.g., development platforms, hardware, and/or services) can be accessed and used by consumers. These resources are customizable because they can be dynamically re-configured to adjust to a variable load (scale), thus, allowing for optimum resource utilization. Furthermore, this substantial pool of visualized resources is typically exploited by a pay-per-use model, in which the infrastructure provider offers guarantees through customized Service Level Agreement (SLAs). According to [7], cloud computing is a substantial paradigm of computing compelled by economies of scale, in which a pool of abstracted, virtualized, dynamically-scalable, and managed computing power, storage, platforms, and services are delivered on demand to external customers over the Internet. Moreover, Cloud computing is defined by the US National Institute of Standards and Technology (NIST) as a model that provides convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction [8]. These diverse definitions of cloud computing emphasize its main three features. Cloud computing services are scalable, hence, requiring minimum operational support to retrieve these services. The rates of the cloud computing service fees are judged based on usage. The cloud services quality depends heavily on the service providers capacity to govern and disperse resources to their clients. Figure 1 illustrates the close relationship among cloud computing characteristics, deployment of cloud models, and service models Service models Figure 1. Cloud computing models Computer resources that are offered to clients are determined by the service model. There are many types of cloud services which all belong to four prominent categories, namely, platform as a service (PaaS), infrastructure as a service (IaaS), software as a service (SaaS), and everything as a service (XaaS). 17

3 2.2.1 SaaS This type of cloud computing provides the capacity to use an application, which functions with cloud computing. Such application can be employed by the client over a web browser or an . Furthermore, this fundamental system can be utilized without being restricted by the time, location, or the type of devices used. There are diverse dominions that use SaaS cloud computing, such as content management, accounting, and customer relationship management. Some examples of SaaS include Gmail, Facebook, and OfficeLive [9] PaaS Applications of this type of cloud computing are deployed and developed by clients based on the supported programming languages employed by cloud providers. The available set of APIs limits the ability to configure this platform. Some of its examples are Google app engine [10], Rackspace [11], Force.com [12], and Windows Azure Platform [13] IaaS In this type of cloud computing, a cloud service provider uses a virtual framework employed to supply computing resources (e.g., storage, network, and processing units) so that the deployment environment for their software systems can be installed. In this system, customers are provided the flexibility to govern (manage and control) the collection of programs required, which include applications, operating systems, and middleware. Some examples of IaaS include Amazon Elastic Compute Cloud (EC2) [14], OpenNebula [15], Openstack [16], and Eucalyptus [16] XaaS In this system, everything can be supplied as a service. Consequently, cloud consumers have the full capacity to tailor the computing environments to suit their needs by constructing cloud-based services that fit their necessities. Examples of this type of cloud computing include SaaS, IaaS, PaaS, as well as NaaS (Network as a Service), DaaS (Data as a Service), FaaS (Information as a Service) Deployment models The confidentiality requirements of the clients determine the type of cloud deployment model to be provided. According to the US NIST [8], there are four diverse cloud deployment models which are: a) Public cloud: resources such as applications and storage are deployed by a service provider to the general public. b) Private cloud: a cloud framework constructed specifically for a particular organization that might be governed by a third party depending on the agreement of the service level. c) Community cloud: a cloud framework jointly used by several organizations that have similar requirements and needs. d) Hybrid cloud: the fusion of different types of cloud computing, which allows clients to retrieve needed data applications from one cloud service provider and transfer it into another application that is deployed by another service provider. 3. Proprietary cloud computing vs. Open cloud computing In general, cloud computing platforms can be classified based on two categories, namely, OS- 18

4 based and proprietary-based. The main parameters of difference include cost, customization, fast bug and security fixed openness, and so forth [17]. Table 1 illustrates the comparison between the platforms of OS cloud and proprietary cloud. Table 1. Comparing OSCC and proprietary cloud computing platforms Vendor lock-in Restrictions and Functionality Cost Run on Open cloud computing You will have greater choice with regards to who you work with as well as the options available for integration with the other IT and cloud technologies Not restricted You will provide what your business actually needs Can add any number of machines to a private cloud, or spin up an unlimited number of machines on public infrastructure, with no increase in operating system costs will be run under the proprietary cloud computing model Proprietary cloud computing You will be attached into the vendor s technology which may cause interoperability issues with future IT and cloud projects Restricted interaction between separate clouds You will get what you are given pay-as-you-go and on demand services, the more you use, the more you pay the applications and software will be run on a specific platform Although the above mentioned comparison deems OS cloud platforms to be a more suitable choice than the proprietary-based platform, providers are still divided regarding whether to integrate OS or proprietary-based platforms. Hence, according to Narcisi (2013), 22% of 260 surveyed cloud providers employ OS cloud platforms while 29% use proprietary-based platforms. Even though proprietary cloud computing is still the accepted standard, many researchers have demonstrated that open cloud computing is the only means by which this technology can expand and mature into something even more powerful and useful. Hence, in the next sections we will examine the OSCC platforms. 4. OSCC Platforms It is fundamental in the OSCC platforms to acknowledge that the supported hypervisors are intended to guarantee suitability with the software already in use within the enterprise [18]. Moreover, the type of data, the VM memory to be provided [19] and a basic understanding of the functions must all be considered [20], along with the appropriate platforms for different application domains, customized user interfaces, OS licenses, and security settings of the software products. Robustness against malfunction as well as interoperability available to transfer applications between clouds, or several cloud's usage at once, also play important role in the daily routine of the system [18, 21]. Furthermore, the probability of making independent virtual machines and making them compatible with other platforms can also be a significant factor in decision making [19]. To conduct the literature analysis, the most well-known OSCC platform management are examined, including OpenStack, Abicloud, Eucalyptus, Nimbus, and OpenNebula OpenStack OpenStack [14] is an OSS for architecting cloud computing [19] which consists of five fundamental projects, namely, Nova, which manages and prepares huge networks of virtual machines; Swift, which originates petabytes of the reliable storage using standard servers; Glance, which manages and lists huge libraries of server images; keystone; and Horizon. Quantum is a new project to be added to the upcoming issues of OpenStack. Object Storage utilizes a distributed architecture with no main 19

5 point of control, and provides greater scalability, redundancy, and stability. Objects are inscribed to multiple hardware devices aided by OpenStack software that is responsible for guaranteeing data integrity and side by side replication with the cluster. The storage of the cluster's horizontal scale is actualized by adding new nodes. If a node fails, OpenStack will work to replicate its component from the other active nodes. Low-cost commodity hard drivers and servers can be used instead of other expensive equipment because OpenStack uses software logic to certify data replication and distribution across devices. In the OS platform, users are not restricted by the proprietary vendor, and the modular design can merge with legacy or third-party systems to incorporate all their requirements. New OpenStack clouds are formed constantly to the point that over 60 leading companies all over the world are participating in OpenStack, including Cisco, Citrix, Dell, Microsoft, and Intel. The OpenStack cloud operating system can control some of the largest public and private clouds all over the world. OpenStack compatibility enables enterprises to easily migrate their data and applications to public clouds, allowing them to comply with security policies, economic models, and other key business standards Eucalyptus Eucalyptus is an OSS for elastic cloud computing architecture which can be used to connect programs to other applications. It was first developed as a project at Santa Barbara University in California, and was used to create an OS private cloud platform [16]. It eventually became under the control and maintenance of Eucalyptus Systems, Inc. Eucalyptus has a unique platform that provides a hierarchical structure. It uses API as an interface, which enables the connection and communication between each of the resources in the cloud computing platforms. Hence, interface users can have access to all the essential resources while also being connected accordingly with the cloud controller (CLC). This will provide global outcome processes that are connected to the cluster controller (CC). All the processes from each of the node controllers (NC) flow within the components of the system. Several NCs on a virtual cluster, which are logically joined with each other, deliver data to the CCs. As the bottom layer, this is where all the virtual devices can flow and run [16]. The possibility of producing errors is greatly decreased by the separate clusters within the confines of this hierarchical architecture [19]. The user interface is represented via using the command line interface (CLI), which may require more knowledge to operate [21]. Data security is guaranteed by a code pairing for authentication [22]. Eucalyptus is managed under the Berkeley Software Distribution (BSD) license as a single platform. This means that the primary program can neither be removed nor its data being copied [23] Nimbus Nimbus is an OS toolkit which makes it possible to modify a cluster into a cloud computing solution especially for the IaaS [24]. It is used for setting up a community cloud and includes different functional components to help the various modules in the platform. Nimbus was initially developed for scientific research. However, its structure is more complicated than the other platforms because the results and commands are inserted in command lines [19]. In addition, the software is especially distinguished for its high degree of flexibility in helping hypervisors. However, it still expects to get extensive support for VMware. In addition, regular backups of work nodes and data are hampered in the event of a failure. OpenNebula and Nimbus are included in the Apache License version two. Under this license, the software can be freely modified, utilized, and distributed [23] OpenNebula OpenNebula was first introduced by Ignacio M. Llorente and Rubén S. Montera in Currently, it is the European Union s flagship research project in the field, with the consideration of vitalization and cloud computing [15]. This platform has been successfully implemented at the central library in Florence. OpenNebula can construct private and public hybrid clouds, and convert these 20

6 clouds into flexible computer cluster and infrastructure that can dynamically balance the resource requisite [15]. The user interface is provided by a command line [19]. The physicist software has three layers. The first layer ( tools ) functions for the administrators and users, it contains the command line for administrators and a planning module that can be used to position virtual machines. The second layer ( core ) is used for requesting user processes and for controlling resources. The third layer ( drivers ) supports the different platforms below it because this level includes drivers for transferring data regularly and for controlling virtual machines included in every host. In addition, the hypervisors are also self-governing. Services from external clouds, such as Amazon EC2, are also designed in this manner [25, 26]. The Linux/Unix background program can be restarted, and all virtual machines that are running can be restored to prevent a malfunction. This process is completed with the benefit of a database, which stores data about virtual machines, networks, and hosts [15]. Intended for purpose completeness, we acknowledge the following with regards the initiation of community clouds: although, Eucalyptus, OpenNebula, and Abicloud do not specifically have the choice of initiating community clouds, this process is still possible. These platforms are also suitable for initiating hybrid clouds, such as the private clouds that can be connected to one another, thereby initiating community cloud Abicloud Abicloud is developed by Abiquo, a company in Barcelona, which is responsible for maintaining the company to enable it to perform the task of generating public, private, or hybrid clouds [27]. The standard-based architecture, with its interoperability, creates multiple clouds or allows clouds to be moved [28]. The main components of Abicloud include the Abicloud server responsible for computer center management and the user interface, web services used for managing the virtual applications, and the Virtual System Monitor (VWS) used to monitor managers [18]. Compared with other platforms, functions in the software are easier to control than using commands on the command line [18, 27]. For example, the drag and drop functions can be used to easily create more virtual machines and to manage the performance services. The comparison of OS cloud management platform characteristics is shown in Table 2. OS products have taken important roles in the market. Various OS solutions have become available, with characteristic sets that are similar to closed/commercial products. The most popular open source cloud computing products have been reviewed above so that the most suitable product depending on the specific needs of the institution is selected. For our work, we chose OpenStack, which is discussed in later. 21

7 Table 2. Comparison of OS cloud management platform characteristics Architecture OpenStack Eucalyptus Nimbus OpenNebula Abicloud OpenStack Compute ("Nova") Hierarchically grouped from Cloud (CLC) via the Cluster (CC) to the Node (NC) Three modules contain all components Three modules contain all components Distinctive web-based management functions Language Python Java Java Java, Ruby Java, C++, Python Cloud Types (Private, Hybrid) Cloud (Private, Hybrid) Cloud (Private, Community) Cloud (Public, Private, Hybrid) Cloud (Public, Private, Hybrid) Cloud Hypervisor Kernel-based Virtual Machine (KVM), XenServer (bare-metal hypervisor), Hyper-V, Linux container(lxc), VMWare VMware, Kernel-based Virtual Machine (KVM), XenServer (bare-metal hypervisor) Python, Bash, Ebtabies, Libvirt, Kernelbased Virtual Machine (KVM), XenServer (bare-metal hypervisor) VMware, Kernel-based Virtual Machine (KVM), XenServer (bare-metal hypervisor) Virtual box, VMware, Kernel-based Virtual Machine (KVM), XenServer (bare-metal hypervisor) Data/ VM Memory OpenStack Object Storage (Swift) Walrus Cumulus File System Backend Storage Network File System or Secure Copy ZFS opensolaris, Logical Volume Manager & ISCSI Linux Application Area Large Commercial Enterprises, Colleges, Universities, Research Institutions Large Commercial Enterprises, Research Institutions Research Institutions Large Commercial Enterprises, Research Institutions Small Medium Enterprises (SEMs) User Interface Nova-API Euca2ools (Command Line Interface (CLI)) Web- Services Specifically (Nimbus Web) Command Line Interface(CLI) Cloud Operator API OS Licenses Apache License 2, Open development Process BSD-License Apache License 2 Apache License 2 Common Public Attribution License 22

8 Cont. Table 2. Comparison of OS cloud management platform characteristics Strength Against Error OpenStack Eucalyptus Nimbus OpenNebula Abicloud To maintain the scalability of a system, several copies of an identical object are dispersed to diverse storage servers within disconnected zones. Zones are perceived as a logical combination of storage servers that are detached to prevent the possibility of a system failure Separate clusters reduce likelihood of correlated errors Regular check and backup of worker nodes Permanent database to store information about hosts, networks and virtual machines No additional data backup Interpretability OpenStack Compute ("Nova") Hierarchically grouped from Cloud (CLC) via the Cluster (CC) to the Node (NC) Three modules contain all components Three modules contain all components Distinctive web-based management functions Security The system uses provisioning of identity, and data authentication and portability to sustain security The cloud controller generates a public, private key code pairing for user authentication Public key infrastructure Authentication by passwords, secure shell and RSA key code pairings Lightweight Directory Access Protocol CAS (Code Access System) VM Tool Quantum plugin Not available Not available Not available Drag & Drop Compatibility Amazon EC2 and Amazon S3 with minimal porting effort Amazon EC2 and Amazon S3 Amazon EC2 and Amazon S3 Amazon EC2 Amazon EC2 As illustrated in Table 2, the conclusion is that OpenStack has overcome other open source cloud computing platforms features, for instance, the it supports an object storage technology while other have missed such a feature. Moreover, in terms of the application area, the advantage was very clear, as OpenStack support most, if not all, of the possible application areas such as for research or industry oriented. 23

9 5. OPEN STACK PLATFORM USAGE As mentioned in Section 4, Open source allows software applications to become accessible for everyone, hence, offering more collaboration and affordability. Cloud computing promises to be highly scalable and easy to use, while Open source provides the flexibility needed. Open source cloud computing solutions, such as the OpenStack, provides important resources for cloud computing applications that can be easily integrated with other applications. Via the use of Open source, various IT infrastructures can exist harmoniously in the clouds. The acceptance level of such technology, especially in the Education sectors, is explored. 6. Conclusion Cloud computing is a convergence of high performance computing architectures, Web 2.0 data models and enterprise-scale computing, which may be considered as the next phase of service-oriented IT. With cloud computing, we can access and run IT services, but the services are most often somewhere beyond the corporate firewall or data center and not subject to the same internal concerns of hardware and software limitations, management problems, and scalability issues. Although, currently, providers are divided regarding whether to integrate OS or a proprietarybased cloud platform, the researchers of this review paper are more inclined toward Open source cloud computing platforms. This disposition is based on the belief of several scholars including Han et al. (2009: p.333) who emphasized that OS cloud platforms will become the mainstream in the future. The researchers of this paper are especially interested with OpenStack due to the fact that OpenStack, with the tremendous growth we are witnessing, may possibly be stable for use in the different sectors. Furthermore, it is fundamental to note that OpenStack stands out among other Open source cloud solutions due to its strong membership of 850 organizations from 87 countries. In addition, large corporations, such as HP and Rackspace, have placed big bets on the project, and its development velocity is very high, making the platform a good long-term option among the Open source cloud contenders. This study has shown that cloud computing combined with Open source software, such as OpenStack, facilitates additional real benefits for enterprises, such as the ones below. a) It allows the deployment of applications, systems, and IT resources as services that reside somewhere in the global connected network. b) It is more cost-efficient than in-house solutions. c) It allows the use of applications, systems, and IT resources of other organizations when needed. d) It realizes the scale of costs more effectively than in-house solutions. e) It provides access to Open source innovations and improvements that can save money and time. f) It improves performance and flexibility in an application that would be unavailable in a traditional packaged solution. The study also demonstrates that Open source cloud deployments can free businesses from vendor lock-ins that can become problematic over time and offer flexible ways to combine public and private applications. 7. References [1] Y. Chen, V. Paxson, and R. H. Katz, "What s new about cloud computing security?," University of California, Berkeley Report No. UCB/EECS January, vol. 20, pp , [2] J. Z. Yangpeng Zhu, "Migration Existing System to SaaS Model," AISS, vol. 5, pp 243 ~ 251, [3] S. M. Hala A. Albaroodi, Mohammed Faiz Aboalmaaly, Hemananthan Palakarnim, "A Pilot Study on Open Source Cloud Computing (OSCC) Awareness in the Universiti Sains Malaysia Education Sector," IJACT, vol. 5, pp , 24

10 [4] C. Baun, Cloud computing: Web-based dynamic IT services: Springerverlag Berlin Heidelberg, [5] H. X.-Y. CHEN Ying, "Cloud-based Resource Scheduling Management and Its Application - with Agricultural Resource Scheduling Management for Example," AISS, vol. 5, pp 191 ~ 196, [6] L. M. Vaquero, L. Rodero-Merino, J. Caceres, and M. Lindner, "A break in the clouds: towards a cloud definition," ACM SIGCOMM Computer Communication Review, vol. 39, pp 50-55, [7] I. Foster, Y. Zhao, I. Raicu, and S. Lu, "Cloud computing and grid computing 360-degree compared?" Grid Computing Environments Workshop, GCE'08, 1-10 [8] P. Mell, and T. Grance, "The NIST definition of cloud computing (draft)," NIST special publication, vol. 800, pp 145, [9] "officelive," [10] M. H. Hugos, and D. Hulitzky, Business in the cloud: what every business needs to know about cloud computing: Wiley, [11] N. Sultan, "Cloud computing for education: A new dawn?," International Journal of Information Management, vol. 30, pp , [12] R. L. Krutz, and R. D. Vines, Cloud security: A comprehensive guide to secure cloud computing: Wiley, [13] "readable web," [14] A. Adamov, and M. Erguvan, "The truth about cloud computing as new paradigm in IT?" Application of Information and Communication Technologies, International Conference on AICT 2009., 1-3 [15] M. Armbrust, A. Fox, R. Griffith, A. D. Joseph, R. H. Katz, A. Konwinski, G. Lee, D. A. Patterson, A. Rabkin, and I. Stoica, "Above the clouds: A Berkeley view of cloud computing (February 2009)." [16] S. Bhardwaj, L. Jain, and S. Jain, "Cloud computing: A study of infrastructure as a service (IAAS)," International Journal of engineering and information Technology, vol. 2, pp 60-63, [17] L. L. Peng Liang, Yingfang Fu, Rong Wang, Yu Li, "On Access Security in Cloud Computing," AISS, vol. 5, pp 63 ~ 70, [18] J. Peng, X. Zhang, Z. Lei, B. Zhang, W. Zhang, and Q. Li, "Comparison of several cloud computing platforms?" Information Science and Engineering (ISISE), 2009 Second International Symposium on, [19] B. P. Rimal, E. Choi, and I. Lumb, "A taxonomy and survey of cloud computing systems?" INC, IMS and IDC, NCM'09. Fifth International Joint Conference on, [20] D. Cerbelaud, S. Garg, and J. Huylebroeck, "Opening the clouds: qualitative overview of the stateof-the-art open source VM-based cloud management platforms?" Proceedings of the 10th ACM/IFIP/USENIX International Conference on Middleware, 22 [21] P. Sempolinski, and D. Thain, "A comparison and critique of eucalyptus, opennebula and nimbus?" Cloud Computing Technology and Science (CloudCom), 2010 IEEE Second International Conference on, [22] D. Nurmi, R. Wolski, C. Grzegorczyk, G. Obertelli, S. Soman, L. Youseff, and D. Zagorodnov, "The eucalyptus open-source cloud-computing system?" Cluster Computing and the Grid, CCGRID'09. 9th IEEE/ACM International Symposium on, [23] F. D. Davis, R. P. Bagozzi, and P. R. Warshaw, "User acceptance of computer technology: a comparison of two theoretical models," Management science, vol. 35, pp , [24] M. D. Dikaiakos, D. Katsaros, P. Mehra, G. Pallis, and A. Vakali, "Cloud computing: Distributed Internet computing for IT and scientific research," Internet Computing, IEEE, vol. 13, pp 10-13, [25] D. Ogrizovic, B. Svilicic, and E. Tijan, "Open source science clouds?" MIPRO, 2010 Proceedings of the 33rd International Convention, [26] T. Cordeiro, D. Damalio, N. Pereira, P. Endo, A. Palhares, G. Gonçalves, D. Sadok, J. Kelner, B. Melander, and V. Souza, "Open source cloud computing platforms?" Grid and Cooperative Computing (GCC), th International Conference on, [27] B. P. Rimal, A. Jukan, D. Katsaros, and Y. Goeleven, "Architectural requirements for cloud computing systems: an enterprise cloud approach," Journal of Grid Computing, vol. 9, pp 3-26, [28] M. Rambhadjan, and A. Schutijser, "SURFnet cloud computing solutions," Universiteit van Amsterdam, System and Network Engineering, vol. pp 25