A break in the clouds: towards a cloud definition

Vaquero, Luis M.; Rodero-Merino, Luis; Caceres, Juan; Lindner, Maik

This paper discusses the concept of Cloud Computing to
achieve a complete definition of what a Cloud is, using the
main characteristics typically associated with this paradigm
in the literature. More than 20 definitions have been studied
allowing for the extraction of a consensus definition as well
as a minimum definition containing the essential characteris-
tics. This paper pays much attention to the Grid paradigm,
as it is often confused with Cloud technologies. We also de-
scribe the relationships and distinctions between the Grid
and Cloud approaches.


Cloud-based Enterprise Mashup Integration Services for B2B Scenarios

Siebeck, Robert G.; Janner, Till; Schroth, Christoph; Hoyer, Volker; Worndl, Wolfgang; Urmetzer, Florian

We observe a huge demand for situational and ad-hoc ap-
plications desired by the mass of business end-users that
cannot be fully implemented by IT departments. This is
especially the case with regard to solutions that support in-
frequent, situational, and ad-hoc B2B scenarios. End users
are not able to implement such solutions without the help of
developers. Enterprise Mashup-/ and Lightweight Composi-
tion approaches and tools are promising solutions to unleash
the huge potential of integrating the mass of end users into
development and to overcome this “long-tail” dilemma. In


A Comparison of Flexible Schemas for Software as a Service

Aulbach, Stefan; Jacobs, Dean; Kemper, Alfons; Seibold, Michael

A multi-tenant database system for Software as a Service
(SaaS) should offer schemas that are flexible in that they
can be extended for different versions of the application and
dynamically modified while the system is on-line. This pa-
per presents an experimental comparison of five techniques
for implementing flexible schemas for SaaS. In three of these
techniques, the database “owns” the schema in that its struc-
ture is explicitly defined in DDL. Included here is the com-
monly-used mapping where each tenant is given their own
private tables, which we take as the baseline, and a map-

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