A Model-Based Proxy for Unified IaaS Management

A Model-Based Proxy for Unified IaaS Management Shixing Yan HP Labs Singapore 1 Fusionopolis Way Singapore 138632 Email: shixing.yan@hp.com Bu Sung Lee HP Labs Singapore, Singapore 138632 & School of Computer Engineering Nanyang Technological University Singapore 639798 Email: ebslee@ntu.edu.sg Sharad Singhal Hewlett-Packard Laboratories 1501 Page Mill Road Palo Alto, California 94304 Email: sharad.singhal@hp.com Abstract The use of Infrastructure-as-a-Service (IaaS) has become more and more prevalent over the past few years. Many IaaS users face the challenge of managing different services and applications running on different IaaS providers. This requires them to interact with different APIs offered by the different providers, and increases the complexity of managing their services. In this paper, we address this problem by modeling IaaS using the DMTF Common Information Model (CIM) meta-model. Based on this model, a generic IaaS proxy was developed using Web2Exchange to enable users to easily manage services provided by variant IaaS providers in a heterogeneous environment. As an initial case study we have prototyped the unified IaaS proxy with capability to support management of Amazon Elastic Compute Cloud (EC2) service. I. INTRODUCTION Over the years we have seen the growth of cloud providers who provide Infrastructure-as-a-Service (IaaS), e.g. Amazon Web Services (AWS) [1], the Rackspace Cloud [2], GoGrid [3]. There is a slow shift in paradigm where users/organizations rent virtualized infrastructure to deploy and run their applications and services without needing to worry about scalability and upfront costs. Users can rapidly provision virtualized IT infrastructure resources by using IaaS. However, concerns about vendor lock-in and reliability of IaaS providers have become an obstacle on the road for the companies who are considering IaaS. For example, even leading IaaS providers like Amazon Web Services have occasionally experienced outages that have lasted for several hours [4], which is unacceptable for mission critical applications/services. Companies which are eager to enjoy the benefits of the new era of cloud computing by using IaaS, but which do not want to put all eggs in one basket may consider using different IaaS providers to deploy their core business applications/services for added redundancy to improve reliability and availability, as well as to avoid vendor lock-in. However, multi-sourcing brings with it the problem of managing heterogeneous IaaS environments where each Iaas provider has its own management portal or tools. Most of the IaaS providers also provide APIs for the users to access and manage their IaaS resources. The users thus need to develop their own management service to manage different IaaS from various providers, which requires additional investment and reduces the advantages of cloud computing offerings. To enable the IaaS users to have a unified service to manage heterogeneous IaaS environments, and the flexibility to switch from one IaaS provider to another, we have defined a unified IaaS proxy which supports the basic management functionality for IaaS from supported providers. The IaaS users can use the unified IaaS proxy easily, and avoid the painful system integration required with the APIs from different IaaS providers. In our work, we use a modelbased approach to service oriented computing to provide a solution for describing services and making service integration easier [5]. The DMTF Common Information Model (CIM) [6] is a widely adopted object-oriented modeling tool for describing managed entities, e.g. compute or network entities [7], [8]. It provides a good framework to enable description of resources provided by IaaS providers. We are using the CIM meta-model to define the new unified IaaS proxy to model IaaS services. Our IaaS proxy model is implemented using Web2Exchange [9], a model-based service integration environment, to provision the unified IaaS management service for various IaaS providers. In this paper we will first briefly describe the model-based Service Integration Environment offered by Web2Exchange in Section 2. In Section 3 the IaaS proxy model and its implementation on Web2Exchange are covered in detail giving the generic entities of IaaS. To illustrate the effectiveness of our proxy model, we interface the IaaS proxy to AWS Elastic Compute Cloud (EC2). This makes EC2 available to other services in Web2Exchange. In Section 4 we will discuss the related work and current issues. Conclusions and future work are described in Section 5. II. MODEL-BASED SERVICE INTEGRATION ENVIRONMENT Service providers have used various approaches to expose their services across the Internet. Since multiple protocols exist to describe specifications for services, it becomes difficult to understand service capabilities and orchestrate the invocations to multiple services. A model-based approach to serviceoriented computing has been introduced in [5] where services are characterized by their interfaces and their locations. The interfaces define what the services can do by defining a set of operations exposed by the service, and the location defines how the services can be accessed. Services can be described

0*!" # $ % & '!" & ' $ $ % ( & )!" & '"!*!" # $ % & '!" & '!* +,!" # +, $ % & '!" & ' $ -.%$ % & ),,!" & '"!*,!" # -.%$ % & ),,!" '"!*, &,, /!" # & ( Fig. 1. $ ), / & &!" /$ -.%$ % &!" '"!* The definition of service model for Name Service in MOF syntax. by service models [5] in a structured way to make service discovery and integration easier. Web2Exchange [9] provides a model-based service integration environment to facilitate the service deployment, discovery, and integrations. The services on Web2Exchange are modeled by an extension of the DMTF CIM [6] meta-model and described by Managed Object Format (MOF) which is a readable and writable syntax to represent the service models. Developers familiar with formal modeling and object oriented concepts can define service models directly in MOF with properties and operations as well as meta-data information in the form of qualifiers supported on Web2Exchange. To simplify development, Web2Exchange has tools that can generate CIM models by run-time introspection of annotations in the service implementation. Web2Exchange introduces a number of implementation specific qualifiers such as Interface and Implements to allow CIM models to naturally be aligned with objectoriented coding practices [9]. Thus service developers who are uncomfortable editing MOF files or who are unfamiliar with formal models can define the service logic directly using source code annotations in Web2Exchange. All services running on Web2Exchange are interpreted and operated upon using their models within the system. All service models and modeled elements inherit from one root of the model, Entity [5]. The entities on Web2Exchange are identified by a Unified Resource Identifier (URI) [10] which can also be used to locate the services. Web2Exchange includes foundation services, such as service catalogs, naming and directory services to provide basic support services used by all other Web2Exchange services. The naming service maps the public name declared by a service to its location on Web2Exchange, which allows other services to communicate with it using its URI. The service model of name service itself is shown in Fig. 1 using MOF syntax. It indicates that the name service inherits from Service which in turn extends Entity. Both services are defined in the schema SIE. It also shows that the operations for registering, deleting, looking up the instances by the friendly name of the service are defined in the model. Web2Exchange can enable services running on it to stay compatible with their models because it generates the models by introspecting annotations present in the code at runtime, and therefore allows the models to evolve as the service implementation evolves over time. III. UNIFIED IAAS PROXY SERVICE ON WEB2EXCHANGE There are an increasing number of IaaS providers on the Internet that are catering to organization/enterprise IT infrastructure needs, as more and more enterprise are exploring the shift from an internally hosted infrastructure to IaaS. While some small IaaS customers may use the management tools provided by IaaS provider to manage their virtual resources, other enterprises wish to have their own management services, even when using an IaaS provider. For these customers, it is very hard to shift from one IaaS provider to another one, not only because of the data migration process, but also because of the need to consider the different management APIs provided by different IaaS providers. Although the concepts of IaaS services provided by different IaaS provider are similar in terms of functionality, most of the IaaS providers have different implementations, and therefore do not share a common interface for their services. Some attempts have been made to create a common interface definition for IaaS. For example, Eucalyptus is an opensource cloud-computing framework and provides compatible interfaces with the leading Amazon AWS [11]. While there are many researchers who have installed Eucalyptus for the implementation of private cloud, we also note that major commercial IaaS providers chose not adopt Eucalyptus or Nimbula [12] or be compatible with Amazon s AWS APIs. The IaaS users would have more flexibility and convenience if they could use a common interface to access the virtual resources provided by different IaaS providers. This would allow users to manage a heterogeneous environment where multiple IaaS services from different providers are employed. It would also ease the process of user s data migration between IaaS providers, and therefore reduce the switching cost. However, established IaaS providers will most likely not have a common interface definition in the near future. Hence, we created a relatively simple model as a unified IaaS proxy, which enables the IaaS users to use IaaS services provided by different service providers without worrying about their

User Interface Model-Based Service Integration Environment Unified IaaS Proxy Service SIE services...... Amazon EC2 GoGrid Cells as a Service IaaS Providers Fig. 2. System architecture of unified IaaS Proxy service. differences. The standard management for IaaS services can be accomplished through interfaces provided by unified IaaS proxy. The advantages of model-based approach for service oriented computing have been demonstrated on Web2Exchange [9]. We used the Web2Exchange platform to develop a modelbased service for unified IaaS proxy on Web2Exchange. The tools for service integration available in Web2Exchange helped us to interface various IaaS APIs with IaaS proxy service on Web2Exchange. The IaaS users need only to interface to unified IaaS proxy to invoke the operations exposed. They can also use RESTful interface [13] available to the IaaS proxy within Web2Exchange. The communication between the IaaS proxy and different IaaS providers is transparent to the users, so the IaaS users can manage all the resources without the need to know the APIs of specific IaaS provider being used. The IaaS proxy can be discovered and made available to other services running on Web2Exchange, allowing the IaaS resources to be integrated into other services through the proxy. The system architecture of unified IaaS proxy is shown in Fig. 2. It can be seen from Fig. 2 that IaaS users will only need use one IaaS proxy service to manage the services provided by IaaS providers such as Amazon EC2, GoGrid, Cells-as-a-Service [14], and so on. A set of service models need to be created to build the IaaS proxy in Web2Exchange. The models should be generic enough to cater to all the IaaS providers and provide operations to fulfill the IaaS users requirements as well. Although some IaaS providers have their own unique features for their services, the basic operations defined in the IaaS proxy model apply to the services from most of the IaaS providers. Since services from the IaaS providers are to allow users to rent the servers and storage in a pay-as-you-go way, some common concepts can be extracted from IaaS services, which are Fig. 3. Models for virtual machine management in unified IaaS Proxy service. Virtual Machine: a software implementation of a server which can run its own operating systems and applications as if it was a physical server. Image: known as virtual appliance which is a virtual machine image to instantiate a virtual machine. It normally includes the operating system and installed software applications. Volume: virtualized logic storage which behaves like local file system. It can be attached to the virtual machine as persistent storage. Network: the networking configuration of the virtual machine. The service model to manage the virtual machines (which is one of the services in our unified IaaS proxy) is shown in Fig. 3 as an example. The IaaS users can invoke the operations on VirtualMachineService including registering (instantiating), starting/stopping, powering on/off, deleting (terminating) virtual machines for any supported IaaS providers. Similar services to manage the Image, Volume, and Network are also implemented as part of offerings by unified IaaS proxy. The services of IaaS proxy will evolve to newer version and have updated models on Web2Exchange if there is a need to support

Fig. 4. Screenshots of Amazon Management Console for test account. new IaaS provider, or add new operations to the services. The models shown in Fig. 3 are only part of the service models used for IaaS proxy. CIM System Virtualization Profile provides more comprehensive models for the representation of host systems and the discovery of hosted virtual systems [15]. We took CIM System Virtualization Profile as reference for developing the models of IaaS proxy. However, we did not implement CIM System Virtualization Profile directly as we want to keep the interface simple and easy for users. We have prototyped the unified IaaS proxy with capability to support management of Amazon EC2 service which is the market-leading IaaS provider. It is just an initial case study for the unified IaaS proxy, and some other IaaS implementations which deliver Amazon EC2-like services such as Eucalyptus and Nimbula are also supported because their APIs are compatible with EC2. For the convenience of demonstration we have set up a test account with Amazon EC2. The test account has launched a sample instance in EC2 where the instance can be seen as the synonym of Virtual Machine used in our model. For the monitoring purpose an Amazon Management Console provided by AWS website is logged in using the testing account. Fig. 4 (a) shows that the status of sample instance is stopped in red colour, we will use unified IaaS proxy to start the EC2 instance in our demonstration. We use the web browser to access the RESTful interface of VirtualMachineService by its URL for the demonstration as shown in Fig. 5. To start the sample instance we need to have the EC2 instance s ID which will be used as VirtualMachineID in our unified IaaS proxy. We retrieved the instance ID from Amazon Management Console and invoke the startvm operation as shown in Fig. 5. After click on Invoke button against startvm the request will be sent to Web2Exchange console, and we can see the response CurrentState - pending; PreviousState - stopped at the bottom of the browser window. The response shows that the EC2 instance is starting from its current state - stopped. Web2Exchange administrator will also see the request sent in Web2Exchange console as shown in Fig. 6. Then we switch back to Amazon Management Console and click Refresh button to update the instances information, and we can see the status of the sample instance has changed to running in green color as shown in Fig. 4 (b). This demonstrated our unified IaaS proxy can provide management services for Amazon EC2 users. There will be more and more IaaS providers supported by unified IaaS proxy, and the users will be able to enjoy the benefit of one common interface to manage all the IaaS services. The users will also be able to enjoy better cloud portability when they decide to port their services to another IaaS provider. IV. RELATED WORK Despite the existence of several groups and standards development organizations working on the standards for cloud computing, there are still no widely accepted cloud standards. We will discuss some of the initiatives related to our topic. The most related one is from the Open Cloud Computing Interface Working Group (OCCI-WG), which is developing a practical solution which covers the provisioning, monitoring

Fig. 5. Screenshot of REST interface of VirtualMachineService in unified IaaS proxy. Fig. 6. Screenshot of request processed in Web2Exchange console. and definition of IaaS [16]. However, it is hard to make the established IaaS providers to change their existing systems to adopt OCCI specification. The OCCI document series are not available to public at the moment. The Open Cloud Standards Incubator from DMTF is to enable portability and interoperability between private and public clouds [17]. The use cases, service lifecycle, and reference architecture have been developed, but the interfaces have not been defined yet. DMTF Open Virtualization Format (OVF) which is an open standard for packaging and distributing virtual appliances [18] has been supported by several industry virtualization players, but it is relatively more focused on a niche area of cloud computing. We understand that most of the cloud standards are still in their very initial stage, and we have not seen a widely-accepted one to be adopted by many cloud providers yet. Simple Cloud API [19] has also similar intention with our idea. The goal of Simple Cloud API is to create a common API to a variety of cloud services. They are creating common interfaces for three cloud application services including File Storage Services, Document Storage Services, and Simple Queue Services, and there are two to four cloud service providers supported for each service by Simple Cloud API. Our unified IaaS proxy is also intended to provide a common API to IaaS users while IaaS is not covered by Simple Clould API. The unified IaaS proxy is model-based in compliance with DMTF CIM and developed in Web2Exchange which has been found to be an efficient way for service integration

[9]. Simple Cloud API is advocating that it brings cloud technologies to PHP and the PHPilosophy to the cloud, so lacks the formal modeling in present in the IaaS Proxy. CIM model for system virtualization has provided comprehensive modeling and profiles for management of system virtualization [20]. It is ideally for IaaS providers to manage their system with implementation of CIM system virtualization profiles. As the goal of our IaaS proxy is to provide a common interface for IaaS users, it is very important to keep the models abstract for ease of use of the IaaS proxy. Thus the CIM System Virtualization Model was heavily referenced but not directly adopted for IaaS proxy in Web2Exchange. Some of the service models for IaaS proxy have been shown in Section 3 as an example. V. CONCLUSION AND FUTURE WORK We have developed the model of a unified IaaS proxy in compliance with DMTF CIM. The key problem we want to solve is to find a way to manage a heterogeneous environment with services from multiple IaaS providers, and also to add the portability for IaaS. The prototype of the service for unified IaaS proxy adopted Web2Exchange where the model-based service integration is supported. We demonstrated the service by using IaaS proxy to manage Amazon EC2 instance as an initial case study. In the future, we will continue to develop the IaaS proxy to support more IaaS providers as well as the virtualized in-house IT infrastructure. The interoperability among various clouds will be supported by our IaaS proxy, and the models and services for IaaS proxy will also evolve to be more comprehensive. We will leverage our knowledge and experience acquired in developing the unified IaaS proxy to make possible improvement on Cells-as-a-Service which is a virtualized cloud computing infrastructure, i.e. IaaS, developed using HP technology by HP Labs Bristol [14]. 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