CLOUD INTERCHANGEABILITY
Redefining Expectations
André Monteiro, Joaquim Sousa Pinto
Instituto de Engenharia Electrónica e Telemática de Aveiro, Universidade de Aveiro, Campus Santiago, Aveiro, Portugal
Cláudio Teixeira, Tiago Batista
Instituto de Engenharia Electrónica e Telemática de Aveiro, Universidade de Aveiro, Campus Santiago, Aveiro, Portugal
Keywords: Cloud computing, Systems interoperability, Interchangeability, Standardization, Network resources.
Abstract: The large growth of the last few years in cloud computing has been overwhelming, either on resources,
deployment or complexity. Still, it lacks a sustaining basis such as standard methods and deployment
settings to potentiate a full evolution. Interoperability and interchangeability are expected to overcome
vendor lock-ins. This paper overviews the problem with a state-of-the-art review and reflects some of the
undergoing approaches.
1 INTRODUCTION
The emerging of the Cloud era was a globally
disperse evolution, scattered by different hardware
and technologies but also in infrastructure and
composing layers. Early attempts for standardization
were rather shy because cloud computing originated
in the private sector (Caryer et al. 2009). As a
scattered development, with few defined standards,
each provider developed its cloud infrastructure on
their own, instead of using normalized settings, a
very similar situation to the appearance of the TCP.
This vision from within held back a bit on
standardization (Grossman, 2009).
Standards are important because they ensure
interoperability in a well-designed formalism (Zeller
et al., 2009). They define a persistent basis to allow
sustained development, even though it can be a
bigger start up obstacle. Thus, developing under
standards can be more costly and harder at the
beginning of the process, but on the long term it
compensates in benefits formalism (Zeller et al.,
2009). However, it is widely held that common best
practices and standards will be needed to realize
many of the benefits being touted for cloud
computing (Lee, 2010).
Nonetheless, cloud computing usage went sky
high because of its major functionalities: on-demand
use, ubiquitous access, pay-as-you go service,
resource saving and elasticity. As an obvious result,
the convergence of the whole Cloud eco-system
turns into a colossal task, restricted in edgeless
connectors and in the business lobbies that cause a
dreadful inertia.
Interchangeability, more than interoperability, is
the path to follow. By having a common
representation for operationally important artefacts,
practitioners have some flexibility to move models
from one environment to another formalism (Zeller
et al., 2009). There are some proposals of evaluation
techniques to determine the best cloud service (Chan
and Chieu, 2010), but is avoidance the way? We
change Internet and TV provider as we want,
without changing laptops or TV sets. Why shouldn’t
applications be moved across providers when we
decide to change the service supplier? No doubt that
with the standardization Cloud Computing would
evolve to its maximum potential and would give
users full throttle to their applications. Fulfilling the
cross-cloud paradigm is a hard assignment but it
surely would free the users to the cloud sky.
2 CLOUD PROVIDERS
One of the major problems is to transpose a common
180
Monteiro A., Sousa Pinto J., Teixeira C. and Batista T..
CLOUD INTERCHANGEABILITY - Redefining Expectations.
DOI: 10.5220/0003393301800183
In Proceedings of the 1st International Conference on Cloud Computing and Services Science (CLOSER-2011), pages 180-183
ISBN: 978-989-8425-52-2
Copyright
c
 2011 SCITEPRESS (Science and Technology Publications, Lda.)

application to the cloud structure. As the operating
system’s incompatibility wasn’t already enough, the
crossing between cloud providers gets even more
difficult. The plot gets deeper when analyzing some
of the providers. However, in order not to lose any
share of the market and the train of edge technology,
some providers are going both ways. These few are
moving towards interoperability and open standards,
applying their proposals to task forces to prevail as a
standard. If they succeed, it should give them a head
start to boost their offered services and blow away
the competition outside the taskforces.
2.1 API Overview
An API is by definition the interface where software
can communicate with the infrastructure. As result
of the vendor’s lock-in, the software attached to
some specific API loses some advantages, like
reusability. By analyzing some of the vendor’s
API’s, some of the issues tend to be noticed even
further. For example, naming for operations is not
univocal and even in similar methods input and
outputs are quite separate. As an exemplificative
instance rather not an exhaustive documentation
finding, only three IaaS providers and a small group
of operations were chosen. Table 1, 2 and 3 show
the results of elicitation.
2.2 Amazon EC2 API
Amazon has been one of the greatest propellers for
cloud computing with the launching of a limited
public beta of EC2 on mid-2006 (Barr, 2006). In
fact, its API has become a de facto standard
(Grossman, 2009), being used by cloud-based
applications like Eucalyptus and Nimbus. This
commitment can be overlooked as an advantage but
it can also take out and limit developing control on
the future roadmap.
Table 1: Amazon API example (AWS, 2010).
Create
Image
List images Run instance
Name
CreateImage DescribeImages RunInstances
Input
InstanceId*,
Name*,
Description,
NoReboot
ExecutableBy.n,
ImageId.n,Owner.n,
Filter.n.Name,
Filter.n.Value.m
ImageId*,
MinCoun*t,
MaxCount*,
[…+21]
Output
requested,
imageId
requested, imagesSet
*required
2.3 RackSpace Cloud API
The RackSpace Cloud has been operational since its
creation in 2006. The Cloud Servers API is
implemented using a RESTful web service interface.
Likewise in the Rackspace range, Cloud Servers
share a common token authentication system that
allows seamless access between products and
services (RackSpace, 2010).
Table 2: RackSpace API example (RackSpace, 2010).
Create
Image
List
images
Run instance
Name
image images servers
Input
serverId, name name, imageId,
flavorId, metadata,
personality
Output
id, serverId,
name, created,
status,
progress
id, name,
updated,
created,
status
id, imageIdm hostId,
progress, adminPass,
metadata, addresses
2.4 Sun Cloud API
The Sun Cloud is currently on beta stage at Project
Kenai. The documentation describes an HTTP-based
RESTful API for managing server-side objects (Sun,
2010).
Table 3: Sun Cloud API example (Sun, 2010).
Create Image List
images
Run
instance
Name
Create VM Get Cluster Control VM
start-VM
Input
name*, description,
from_template,
data_disk
Output
op, progress, target_uri,
status_uri, status
name, uri,
tags, vms,
controllers *required
3 CLOUD STANDARDIZATION
To address these communication problems between
clouds, several organizations joined in combined
efforts to deliver cloud standards.
The European Telecommunications Standards
Institute (ETSI) has started a project for
standardizing the use of grid and cloud computing
technology in the context of telecommunication,
with the formation of the Technical Committee
GRID (Rings et al., 2010). These include analysis of
grid and cloud interoperability gaps and surveys,
comparisons between grid, cloud and
telecommunication systems among others related to
grid and Next Generation Networks.
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The IEEE society also created a study group for
cloud standards, with a call for participation open to
all interested. IEEE believes that major impediment
to the growth of cloud computing is the lack of
comprehensive high-level portability and
interoperability standards (IEEE, 2010).
Recently, the Distributed Management Task Force
(DMTF) assumed the need for open management
standards for cloud computing (DMTF, 2009).
DMTF focus its goal in developing cloud resource
management protocols, packaging formats and
security mechanisms to facilitate interoperability and
portability between compute clouds.
Already set is the open standard for cloud images
Open Virtualization Format (OVF), released by
DMTF and almost in a final version. It defines a
portable and extensible format for software to be run
in virtual machines.
4 UNDERGOING PROJECTS
Whereas providers continue to enclose their
specifications in a dark cloud, the key to
interchangeability rests on middleware, API’s and
also OS level. Some may consider it as an evasion
path, but it can offer the services of several
providers, as long as cloud services’ API’s are tested
and included. Some research projects are being
made currently, with focus in simplifying and
unifying the management of applications under a
cloud infrastructure and thus provide
interchangeability. Interchangeability, or portability
between clouds, remains postponed.
4.1 Red Hat DeltaCloud
Red Hat announced in mid-2010 the DeltaCloud
project, defending that third-party governance was
necessary to achieve true interoperability and
portability (McGee, 2010). DeltaCloud is
developing an API to deal with several clouds
service providers and publicizes any-platform access
REST API and backward compatibility across
versions, providing long-term stability for scripts,
tools and applications (Red Hat, 2010). The project
is running and accepts contributions as it is held in
Apache Incubator. With a full implementation it
should be possible to start and run instances on a
private cloud and repeat the operation with public
clouds seamlessly.
4.2 IBM AltoCumulus
As a response to the cloud heterogeneity, IBM
started an effort group to develop a middleware
platform called AltoCumulus (IBM, 2010). The
project, started in mid-2009, aims to provide a
uniform, service oriented interface to deploy and
manage applications in various clouds and also
provides facilities to migrate instances across clouds
using repeatable best practice patterns (Maximilien
et al., 2009). This approach tends to be very
comprehensive since it intends to provide
interoperability for different cloud layers as IaaS,
PaaS and private clouds. As the previous projects, its
API lies on REST support.
4.3 Unified Cloud Interface Project
As DeltaCloud, the UCI sets to develop a
standardized cloud interface for the unification of
various clouds’ API’s (CCIF, 2010). The goal is to
include the entire infrastructure stack as well as
emerging cloud centric technologies through the
merged API. This is done by describing a semantic
cloud data model with Resource Description
Framework (RDF) and therefore using it to control
these web resources.
4.4 Open Cloud Computing Interface
The OCCI working group is developing a clean,
open API for Infrastructure as a Service (IaaS) based
Clouds (Sun, 2009). The API is intended interface
all Cloud providers, private or public, and to ensure
portability, interoperability and integration between
Cloud service providers and end-users. This is being
proposed as an extendable RESTful based API.
4.5 InterCloud
The InterCloud is defined as being a global cloud
interconnecting other clouds within the network.
Identifying a profile of protocols and formats is one
part of the interoperability puzzle (Bernstein et al.,
2009), where peer clouds must dialog. A key
concern must be the assurance that if one component
fails the whole system doesn't collapse.
4.6 Operation System Layer
The Distributed Computing Research Group at the
University of Newcastle proposes a byte-code style
layer (Wallis et al., 2010). Their insight is that this
kind of layer will allow the code execution
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transversely across multiple hardware platforms.
The project is currently running and specifies cross-
platform execution, component swap
communication architecture, associated security,
among others.
5 CONCLUSIONS
Cloud computing has become a phenomenon today,
amongst every single kind of user and provider.
Nevertheless, its unfocused development lead to a
enormous heterogeneity and islets with low
interoperability and rare interchangeability. Yet, the
perspective of a cloud managed by any service
provider or enterprise interoperating is impressive.
Application portability is even more formidable.
This paper reflects a general overview of the state-
of-the-art to show the big path yet to walk.
As standardization and projects converge to a
common point, one can only expect greater
achievements.
REFERENCES
Caryer, G., Rings, T., Gallop, J., Schulz, S., Grabowski, J.,
Stokes-Rees, I. and Kovacikova, T. 2009. Grid/cloud
computing interoperability, standardization and the
NGN. In Intelligence in NGN ICIN 13th International
Conference on.
Grossman, R.L. 2009. The Case for Cloud Computing. IT
Professional, vol.11, no.2, pp.23-27.
Zeller, M., Grossman, R., Lingenfelder, C., Berthold,
M.R., Marcade, E., Pechter, R., Hoskins, M.,
Thompson, W. and Holada, R. 2009. Open standards
and cloud computing: KDD-2009 panel report. In
Proceedings of the 15th ACM SIGKDD international
conference on Knowledge discovery and data mining
(KDD '09), New York, USA, 11-18.
Lee, C. 2010. A perspective on scientific cloud computing.
In Proceedings of the 19th ACM International
Symposium on High Performance Distributed
Computing (HPDC '10). New York, USA, 451-459.
DMTF. DMTF to Develop Standards for Managing a
Cloud Computing Environment, http://dmtf.org/news
/pr/2009/4/dmtf-develop-standards-managing-cloud-
computing-environment, accessed on December 2010
Chan, H., Chieu, T. 2010. Ranking and Mapping of
Applications to Cloud Computing Services by SVD.
In Network Operations and Management Symposium
Workshops 2010. IEEE. Osaka, Japan, 362-369.
Barr, J. Amazon EC2 Beta. http://aws.typepad.com
/aws/2006/08/amazon_ec2_beta.html, accessed on
December 2010
Amazon Web Services. Amazon Elastic Compute Cloud
User Guide. http://docs.amazonwebservices.com/AWS
EC2/latest/UserGuide, accessed on December 2010
RackSpace Cloud, Inc. Cloud Servers Developer Guide.
http://docs.rackspacecloud.com/servers/api/cs-
devguide-latest.pdf, accessed on December 2010
Sun Microsystems, Inc. The Sun Cloud API.
http://kenai.com/projects/suncloudapis/pages/Home,
accessed on December 2010
Rings, T., Grabowski, J. and Schulz, S. 2010. On the
Standardization of a Testing Framework for
Application Deployment on Grid and Cloud
Infrastructures. 2010 Second Advances in System
Testing and Validation Lifecycle, International
Conference on, pp. 99-107.
IEEE Computer Society. IEEE Cloud Computing
Standards Study Group. http:/computer.org/
portal/web/sab/cloud, accessed on December 2010
DMTF. DMTF to Develop Standards for Managing a
Cloud Computing Environment. http://dmtf.org/news/
pr/2009/4/dmtf-develop-standards-managing-cloud-
computing-environment, accessed on December 2010
McGee, T. Red Hat Deltacloud Aspires to Become an
Industry Standard. http://www.linux-magazine.com
/Online/News/Red-Hat-Deltacloud-Aspires-to-
Become-an-Industry-Standard?category=13398,
accessed on September 2010
Red Hat. DeltaCloud, http://deltacloud.org, accessed on
November 2010
IBM. Almaden Services Research Project Altocumulus.
http://www.almaden.ibm.com/asr/projects/cloud,
accessed on September 2010
Maximilien M., Ranabahu, A., Engehausen, R. and
Anderson, L.. 2009. IBM altocumulus: a cross-cloud
middleware and platform. In Proceeding of the 24th
ACM SIGPLAN conference companion on Object
oriented programming systems languages and
applications (OOPSLA '09), New York, USA, pp.
805-806.
Cloud Computing Interoperability Forum. Unified Cloud
Interface Project. http://code.google.com/p
/unifiedcloud, accessed on December 2010
Sun Microsystems. 2009. What is OCCI? http://blogs.
sun.com/intheclouds/entry/what_is_occi, accessed on
December 2010
Bernstein, D., Ludvigson, E., Sankar, K., Diamond, S. and
Morrow, M. 2009. Blueprint for the Intercloud -
Protocols and Formats for Cloud Computing
Interoperability. 4th International Conference on
Internet and Web Applications and Services. IEEE, pp.
328–336
Wallis, M., Henskens, F., Hannaford, M. 2010. Expanding
the Cloud: A Component-Based Architecture to
Application Deployment on the Internet. In Cluster,
Cloud and Grid Computing (CCGrid), 10th
IEEE/ACM International Conference, pp.569-570.
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