=Paper=
{{Paper
|id=Vol-1258/src1
|storemode=property
|title=Model-Driven Engineering Meets the Platform-as-a-Service Model
|pdfUrl=https://ceur-ws.org/Vol-1258/src1.pdf
|volume=Vol-1258
|dblpUrl=https://dblp.org/rec/conf/models/Verdejo14
}}
==Model-Driven Engineering Meets the Platform-as-a-Service Model==
https://ceur-ws.org/Vol-1258/src1.pdf
Model-Driven Engineering meets the
Platform-as-a-Service Model
Adrián Juan-Verdejo
Information Systems Chair
Stuttgart University, Germany
adrianppg@gmail.com
Abstract. Organisations who want to migrate their applications to
Platform-as-a-Service (PaaS) environments have a lot of PaaS vendors to
chose from and many PaaS offerings within them. At the PaaS abstrac-
tion level within the cloud service model, each vendor offers many differ-
ent configurations to meet the specific organisation’s criteria to migrate
to PaaS and the application’s requirements. PaaS providers and their of-
ferings differ in terms of the supplied execution environments, databases,
web servers, or development tools. Enterprises have difficulties to choose
the right PaaS offering for them to deploy their applications to and have
to manually configure their applications according to the PaaS selection.
All in all, this is an error-prone process which model-driven approaches
can facilitate. This paper shows the meta models needed to describe the
application to be deployed to a PaaS offering, the PaaS offering itself, and
the migrated applications with re-scattered components to both the local
premises and PaaS. The InCLOUDer decision support system uses these
meta models to support the deployment of the application to the PaaS
offering which best helps enterprises in achieving the criteria which mo-
tivate them to start using PaaS environments. InCLOUDer keeps some
of the application’s components locally to fulfil the constraints of organi-
sations related to security, data privacy, performance, compatibility, and
governance.
1 Introduction
By deploying their applications to PaaS, today’s software organisations—and
small and medium enterprises (SMEs) in particular—can achieve key competitive
advantages due to their business agility, how quickly they market the products
they offer, and their ability to reach their potential users. PaaS environments
have the potential to let organisations increase their abilities to scale up and
down—by adding or removing resources to a node in use—, or in and out—by
adding or removing nodes to a system—; cut their costs; and shorten the time
they spend to market their software solutions. PaaS offerings hide low-level de-
tails from the developer, such as the underlying infrastructure including load
balancers, virtual machines, servers, data storage and access, and networks. The
PaaS developing environment frees developers from software versioning or re-
source provision and lets them use extra built-in services and capabilities and
write code faster. PaaS vendors provide development tools, libraries, and ap-
plication programming interfaces (APIs) to let developers access their storage
resources and deploy their applications to their runtime environment and execute
them. Due to the faster PaaS application testing and deployment; development
teams easily try different configurations of their applications to test them, as-
sess their applications’ performance, and identify potential compatibility issues
[1]. From a business perspective, as enterprises outsource computation to PaaS
vendors, they can focus on their core business interests and do it better [2].
Problem statement. As a result of the potential advantages offered by
PaaS, the demand of PaaS environments has been increasing for the last years
and the number of PaaS providers accordingly. A myriad of vendors supply
many PaaS offerings at various levels of abstraction with different capabilities,
runtime environments, services, and supported platforms. The huge amount of
PaaS vendors together with the various PaaS offerings with many configurable
parts makes for a lot of options for organisations to chose from. So many options
that organisations find difficulties in selecting the right PaaS offering for their
software system requirements and the goals they want to achieve by using PaaS
environments. These goals range from achieving easier extensibility by using the
services offered in PaaS environments to easing the deployment, including im-
proving the application’s security and portability. Enterprises can choose from
PaaS offerings with various security protocols, QoS guarantees, trust issues, tools
form application migration and porting, followed standards, and cost models.
SMEs’ PaaS migration criteria might lead them to want to select the most reli-
able, performant, well-reputed, or cost-efficient offering [3]. Likewise, they might
simply be interested in using the one which meets their technical requirements
without much adaptation or developing effort. It is not obvious how to compare
PaaS offerings according to these criteria or dimensions [4]. Additionally, it is
not evident how to identify the potential of a PaaS offering over another one,
especially on the long term. There is a lack of standards and metrics to identify
differences and compare PaaS offerings [5].
The six dimensions identified in [4] to compare PaaS offerings are not inde-
pendent. As a result some dimensions or sub-dimensions oppose others in some
cases. Organisations need assistance to incorporate all this knowledge into the
decision-making process involved in migrating applications to PaaS. Addition-
ally, enterprises may face a well-known problem associated with the PaaS model,
the vendor lock-in problem when they want to switch from one PaaS vendor to
another one. The inability of some PaaS vendors to comply to standards hin-
ders the application and data portability. But even if portability is supported in
theory, the high complexity of the process if vendors do not facilitate it and the
switching costs still discourage organisations from porting their applications [6].
Organisations want to be able to switch easily and transparently between PaaS
providers whenever they need. They might want to move to a different provider
due to a Service Level Agreement breach (SLA), a cost increase, or simply be-
cause the vendor went out of business. At the same time, organisations do not
want to set their data and applications at risk in case they have to port their ap-
plications to a different PaaS environment. Typical risky scenarios include data
loss or inability to run the application on a different platform.
Related work. The migration of systems and applications to cloud-enabled
environments attracts a lot of attention from the research community [7] [3].
The REMICS FP7 project [8] reuses and migrates legacy applications to inter-
operable cloud services by using concepts from the Model-Driven Architecture
and Architecture-Driven Modernization worlds. They leverage cloud computing
to provide cost-efficient and reliable services. However, unlike InCLOUDer, they
focus only on the technical dimension of the migration but not on the organ-
isational, policy- and business-related aspects as well as recommended by the
literature [9] [10]. The authors of [11] presented a process framework to migrate
legacy software to cloud environments based on their experiences in migrating
a legacy open source system. They propose seven distinct activities for cloud
migration including the cloud selection but they do not cope with application’s
constraints related to data privacy or other organisation’s criteria.
Goal. This paper describes the process followed by InCLOUDer [12] to mi-
grate applications to PaaS environments and the meta models that support the
process. For the first time, this paper formalises and explains the meta models
used by InCLOUDer and makes contribution on showing how they work when
taking into account the explained six PaaS dimensions. More specifically, In-
CLOUDer uses meta models for application profiling, organisations PaaS criteria
description, and PaaS offerings selection. Prior to migration, this paper addresses
PaaS selection in respect of six PaaS identified dimensions [4]—the application,
SLA, deployment, security, portability and usability dimensions—with empha-
sis in achieving portability to increase the level of service and minimise vendor
lock-in. InCLOUDer assist the PaaS selection and supports the decision on how
to adapt the application to the selected PaaS configuration.
2 Approach to Application Migration to PaaS
The InCLOUDer decision support system assists the migration of applications
to PaaS environments. Fig. 1 shows a high-level description of InCLOUDer
and its three input models marked with red arrows. The organisation migrating
the application to the PaaS specifies both the organisation’s criteria to PaaS
migration—which weights each of the six PaaS migration dimensions in relation
to the importance of each one of them for the organisation; and the application
profile capturing the application’s requirements, constraints, and architecture
according to the meta model in Fig. 3. The third input model lets PaaS vendors
describe their PaaS offerings—or modellers if they do not—according to the meta
model in Fig. 2.
Fig. 1 presents three of the mechanisms used in InCLOUDer, namely the
InCLOUDer application components re-scatterer, the InCLOUDer al-
ternatives generator, and the InCLOUDer alternatives selector. The In-
CLOUDer application components re-scattering and the InCLOUDer
alternatives generator take into account the application profile and the organ-
Fig. 1. High-level description of the InCLOUDer decision support system (DSS)
isation’s criteria to re-scatter the application’s components to the local premises
and the PaaS offerings. The reason to keep components in the local premises
is to meetThe InCLOUDer alternatives selector weights each alternative
to migrate the application—re-scatterings in PaaS Offering—to select the
most beneficial alternative to migrate the application to PaaS—weighted al-
ternatives.
Fig. 2 shows the meta model to describe and validate a PaaS offering.
Each PaaSProvider supplies several PaaSOfferings which provides PaaSChar-
acteristics. PaaSCharacteristics include, exclude, or group other PaaSCharac-
teristics. The GroupRelationship can be an OR or XOR relationship depending
on whether several PaaSCharacteristics can be present at the same time—OR—
or only one of them—XOR. The PaaSCharacteristics present in a PaaSOffering
determines the value of each Property of a PropertyType.
The meta model shown in Fig. 3 lets organisations specify their application’s
requirements, constraints, and architecture. Organisations can model their appli-
cation’s data and application components, specify in which nodes these compo-
nents run, and how these components are connected. Additionally, organisations
can model the application’s requirements and constraints.
Surajbali and Juan-Verdejo described the six PaaS migration dimensions
with more detail in [4]. Once the organisation specifies the organisation’s PaaS
migration criteria and the two input models based on the meta models shown in
Fig. 2 and Fig. 3. InCLOUDer generates the alternatives to migrate to PaaS
consisting in a model describing—according to the meta model presented in Fig.
4—how to re-scatter the application’s components to the local premises and the
PaaS offerings. This meta model specifies which components (AbstractCompo-
nents) to migrate to a PaaSProvider and which to keep in the LocalPremises.
Aditionally, this meta model supports measuring the PaaSOffering score per Di-
mensionType. Each DimensionType is one of the six criteria to PaaS migration.
Fig. 2. PaaS Offerings Meta Model Fig. 3. Application Profile Meta Model
Fig. 4. Meta Model of the Application Re-scattered to PaaS Offerings
Contribution. The uniqueness of the InCLOUDer approach strives in re-
scattering the application components to the local premises and the different
PaaS offerings to maximise the organisation’s PaaS migration criteria. All the
proposed alternatives to migrate to PaaS comply with the application’s con-
straints such as component-to-component communication delays or platform-
dependent specifications—e.g. supplying a MySQL database management sys-
tem or a Tomcat application server. Additionally, the PaaS migration alterna-
tives respect the organisation’s policies related to data protection and sensitivity
by keeping locally components which contain sensitive data. The future work
related to this work includes adding to the quantitative evaluation done for In-
CLOUDer the empirical validation of the approach taken by letting organisations
use InCLOUDer for the migration of their applications to PaaS environments.
References
1. Armbrust, M., Fox, A., Griffith, R., Joseph, A., Katz, R., Konwinski, A., Lee, G.,
Patterson, D., Rabkin, A., Stoica, I.: A view of Cloud Computing. Communications
of the ACM 53 (2010) 50–58
2. Juan-Verdejo, A., Surajbali, B., Baars, H., Kemper, H.G.: Moving business intel-
ligence to cloud environments. In Proceedings IEEE INFOCOMM, Cross Cloud
2014, Toronto (2014)
3. Khajeh-Hosseini, A., Greenwood, D., Sommerville, I.: Cloud migration: A case
study of migrating an enterprise it system to iaas. In: Cloud Computing (CLOUD),
2010 IEEE 3rd International Conference on, IEEE (2010) 450–457
4. Surajbali, B., Juan-Verdejo, A.: A marketplace broker for platform-as-a-service
portability. In: Proceedings of the Third European Conference on Service-Oriented
and Cloud Computing (ESOCC) (to appear), ACM (2014) 275–282
5. Joe, M.: Does platform as a service have interoperability issues (2010)
6. Gonidis, F., Simons, A.J., Paraskakis, I., Kourtesis, D.: Cloud application porta-
bility: an initial view. In: Proceedings of the 6th Balkan Conference in Informatics,
ACM (2013) 275–282
7. Jamshidi, P., Ahmad, A., Pahl, C.: Cloud migration research: a systematic review.
(2013)
8. Mohagheghi, P., Sæ ther, T.: Software Engineering Challenges for Migration to the
Service Cloud Paradigm: Ongoing Work in the REMICS Project. In: 2011 IEEE
World Congress on Services, Ieee (2011) 507–514
9. Juan-Verdejo, A., Baars, H.: Decision support for partially moving applications to
the cloud: the example of business intelligence. In: Proc. of the int. workshop on
Hot topics in cloud services, ACM (2013) 35–42
10. Ahmad, A., Babar, M.A.: A framework for architecture-driven migration of legacy
systems to cloud-enabled software. In: Proceedings of the First International Con-
ference on Dependable and Secure Cloud Computing Architecture - DASCCA ’14,
New York, New York, USA, ACM Press (2014) 1–8
11. Babar, M., Chauhan, M.: A tale of migration to Cloud Computing for sharing
experiences and observations. In: SECloud ’11 Proceedings of the 2nd International
Workshop on Software Engineering for Cloud Computing. (2011)
12. Juan-Verdejo, A., Zschaler, S., Surajbali, B., Baars, H., Kemper, H.G.: In-
CLOUDer: A formalised decision support modelling approach to migrate appli-
cations to cloud environments. In: 40th Euromicro Conference on Software Engi-
neering and Advanced Applications (SEAA 2014), IEEE (2014)