68 Informatica Economică vol. 19, no. 4/2015 Standard Interfaces for Open Source Infrastructure as a Service Platforms Andrei IONESCU Bucharest University of Economic Studies [email protected] To reduce vendor lock-in and fragmentation and to evolve into a transparent platform, IaaS platforms must adhere to open standards. All the major open source IaaS Platforms offer interfaces compatible with the de facto standards but mostly lacks support for the de jure, open efforts of standardization. Available implementations of open standards are not part of their main development efforts. More development resources as well as consolidation of open standards are needed to achieve increased portability and interoperability. Keywords: Cloud Computing, RESTful API, interfaces, Open Cloud Computing Interface, Cloud Data Management Interface, Cloud Infrastructure Management Interface, Open Virtualization Format Introduction modules in order to achieve a greater 1 Cloud Computing is an already flexibility and extensibility. Separate modules established technology, already having lost its describe aura as one of the hottest and most rapid the core models, defines an abstract developing topics in the industry. At the base representation of real-world resources of its services stack, Infrastructure as a intended to be manipulated through OCCI Service (IaaS) model utilizes well understood renderings [1]. architectures, providing access, mostly, to the the rendering of the code model using same type of computing and storage resources HTTP/REST, describes the interactions across all platform providers. New topics available for an OCCI implementation entered the spotlight, such as integrated with the resources built using the core management of IaaS platforms, selection of an models [2]. IaaS platform, vendor lock-in, interoperability the extensions to the code models specific and identity in the Cloud and efforts were to implementation of an Infrastructure as a made to address them by defining and using Service API [3], defining its parameters standardized interfaces. Standard data models for compute, storage and network. and technologies compatible with both the The main reasons behind the development of IaaS platforms and the existing Internet OCCI were identified in [4] and [5] as: Infrastructure had to be used. This led to Interoperability, demanding a adoption of established standards and standardized API and protocol. technologies such as XML web services or Integration, allowing different service JSON over RESTful services. providers to bring together and interconnect platforms based on different 2 Open Cloud Computing Interface technologies. Open Cloud Computing Interface (OCCI) is a Portability, providing standardized data collection of community generated open formats understood by different providers, specifications built through Open Grid Forum allowing porting between them. [1]. Intended to be an open and interoperable Innovation, considering that established RESTful protocol and an API for all cloud- standards can be a driver for innovation. related management activities, it started with Reusability, Figure 1, working on two a focus on the Infrastructure-as-a-Service levels, first allowing reuse of code through layer but later extended to include all the other basic standardized APIs and, second, layers in the Cloud stack. promoting reuse of standards in different The specifications are broken into several DOI: 10.12948/issn14531305/19.4.2015.06 Informatica Economică vol. 19, no. 4/2015 69 technology fields. Fig. 1. Open Cloud Computing Interface 3 Cloud Data Management Interface allows the management of containers, Cloud Data Management Interface (CDMI) accounts and retrieval of monitoring and describes a functional interface allowing billing information, Figure 2. applications to create, retrieve, update and CDMI is not designed to replace other object delete data elements from the Cloud [6]. The access protocols but to complement them. The standard is developed by SNIA, a global standard uses RESTful protocol for building organization of storage solution providers. its interfaces, to keep it as simple as possible Using a CDMI compatible interface, cloud and to encourage its adoption. Adding data consumers are able to discover the discovery functions, it allows future storage features offered by IaaS platforms. extensions to the standard without breaking Along with data elements, the standard also client compatibility. Fig. 2. Cloud Data Management Interface DOI: 10.12948/issn14531305/19.4.2015.06 70 Informatica Economică vol. 19, no. 4/2015 CDMI serves as both a storage protocol while, to interact with the cloud [7], addressing the at the same time, offering a layer of client to runtime maintenance and provisioning of cloud management and cloud to cloud cloud services. It uses both JavaScript Object standardized interactions. Clients can manage Notation (JSON) and eXtensible Markup credentials to domains defined in the cloud Language (XML) to encode communication. forming a hierarchical structure that have The model described by the standard can be objects attached to them and building a path mapped to any existing cloud infrastructure for accessing and controlling these objects. and it provides the means for the clients to For cloud to cloud interaction it introduces discover which feature are provided by the globally unique identifiers linked to objects cloud implementations. for the whole of their lifetime to persist their There are not many CIMI implementations identity if moved or replicated between but the Apache Deltacloud is one of them and clouds. Serialization and deserialization into having drivers for almost all the major and from JSON format can be used to transfer Infrastructure as a Service platforms means objects and their metadata. Primitives are that any CIMI compatible client is able to defined which permit the clients to build interact with most of the deployed clouds. transfer request indicating source and destination cloud for objects, along with the 5 Open Virtualization Format credentials required for accessing them. Another standard maintained by DMTF, Open Virtualization Format (OVF) describe the 4 Cloud Infrastructure Management means to package and distribute software Interface appliances to be run in virtual machines in a Cloud Infrastructure Management Interface hypervisor independent way. Packages (CIMI) is an open standard providing an API distributed using OVF consist of one XML for administering Cloud Computing descriptor containing the meta-data which infrastructures. The standard is maintained by describes the appliance along with its disk Distributed Management Task Force (DMTF) images, certificates and auxiliary files. Cloud Management Working Group, a non In the lifecycle of a virtual appliance, Figure profit organization of industry members. 3, OVF covers the packaging, distribution and CIMI describes the model and the protocol deployment phases. used by Infrastructure as a Service consumers Fig. 3. Open Virtualization Format scope, adapter after [8] 6 Apache Deltacloud Deltacloud provides a cloud abstraction, Started in 2010 by Red Hat as a solution for standard REST API. It is not another library an increasingly heterogeneously cloud but a web service covering functions for interfaces environment, the project intended management of compute and storage to be a vendor neutral openly developed API. resources. It exposes three different APIs, To escape worries that it will only ever be a wrapping their functionalities for 15 single vendor effort, it was proposed as an Infrastructure as a Service platforms and 7 Apache Software Foundation project and storage engines [9]: graduated to top level status in 2012. Deltacloud classic API. DOI: 10.12948/issn14531305/19.4.2015.06 Informatica Economică vol. 19, no. 4/2015 71 DMTF Cloud Infrastructure Management Initially developed by Rackspace Hosting and Interface (CIMI) API. NASA, OpenStack Consortium, the Amazon Web Services Elastic Cloud maintainer of the platform with the same Computing (EC2) compatible API. name has more than 150 members, including AT&T, Canonical, HP, IBM, Intel and 7 OpenStack Rackspace. OpenStack is an open source operating system There are several service families under for the cloud, a collection of projects used to OpenStack, each with its own API for setup and run compute and storage services. interfacing with the cloud clients and with the other services, Figure 4. Fig. 4. Basic OpenStack architecture, adapted after [10] Nova manages the complete lifecycle of built [11]. The Swift API is compatible with virtual machine instances in an OpenStack AWS S3. deployment. It manages the compute and Keystone provides authentication and network resources along with the required authorization services for OpenStack, authorizations for starting, scheduling and managing domains, users and roles. It’s a stopping virtual machines. Its exposes all its crucial system used by all the other modules functions through its own web services API as using its own REST API (Identiy API). well as a layer compatible with Amazon Web Horizon provides a web portal for interacting Services EC2. Its API server is the only and administering OpenStack. It uses APIs OpenStack component interacting directly provided by the other services to build the with the outside world. cloud’s administrative interface. Glance is the service responsible with storage and retrieval of machine disk images. It can Standards use local file systems,