Cost-Based Optimization of Integration Flows - Datenbanken ...

1 Introduction
I can’t change the direction of the wind,
but I can adjust my sails to always reach my destination.
— Jimmy Dean
Advances in information technology combined with rising business requirements lead to
a rapidly growing amount of digital information created and replicated worldwide. For
example, recent studies [IDC08, IDC10] conducted by the market research organization
IDC, report a yearly information increase by over 60% to 1.2 zettabyte (ZB) in 2010.
Beside this huge amount of digital information, due to technical and organizational issues,
the information is distributed across numerous heterogeneous systems, applications and
small devices [IDC08, Haa07]. For these reasons, the integration of heterogeneous systems
and applications becomes more and more crucial for an IT infrastructure. In another
recent study [Gar09], the market research organization Gartner reveals that the revenue
of the worldwide application infrastructure and middleware market increased by 6.9% from
14.17 billion USD in 2007 to 15.15 billion USD in 2008. In conclusion, the integration of
heterogeneous systems is seen as one of the biggest and most cost-extensive challenges
information technology faces today [BH08].
Historically, the predominant integration approaches were materialized and virtually integrated
systems [DD99], where both types provide a homogeneous global view over data of
several source systems. Nowadays, we observe emerging requirements of complex integration
tasks that (1) stretch beyond simple read-only applications, (2) involve many types of
heterogeneous systems and applications, and (3) require fairly complex procedural aspects.
To meet these requirements, typically, imperative integration flows are modeled and executed
in order to exchange data between the heterogeneous systems and applications of an
IT infrastructure [HAB + 05]. There are plenty of application examples for this type of imperative
integration flows, including, for instance, enterprise information systems [BH08],
health care management [CHX08, GGH00], energy data management [SAP03], financial
messaging [MS09], telecommunications [ACG + 08], and context-aware mobile applications
[CEB + 09]. For example, large health care management system infrastructures include
up to 20-120 different applications and systems [Mic07] and rely on domain-specific standards
for data exchange such as HL/7 (Health Level 7) [hl707] or DICOM (Digital Imaging
and Communications in Medicine) [dic09]. The deployed integration flows are repeatedly
executed by an integration platform. Examples of such platforms are ETL tools (Extraction
Transformation Loading) [KC04], EAI servers (Enterprise Application Integration)
[Lin99] or MOM systems (Message-Oriented Middleware) [HW04], which have converged
more and more in the past [Sto02, HAB + 05] and this trend is expected to continue in the
future as well [HAB + 05].
From a business perspective, we classify all information systems of an enterprise according
to the three levels of an information system pyramid [Sch97] as operational systems,
dispositive systems, or strategical systems. In this context, typically, two major use cases
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