Merging of TOSCA Cloud Topology Templates - IAAS

Abstract
Abstract
The paradigm of Cloud Computing requires standardization to avoid vendor lock-in for its
users. The Topology and Orchestration Specification for Cloud Applications (TOSCA) provides
a standardization approach enabling portability of cloud services between different
Cloud Computing providers. The main goal of the TOSCA specification is to enable a cloud
provider and environment independent description of these services concerning structure
and management aspects during their life cycle. TOSCA specifies so-called Service Templates
whose structure is described by a Topology Template.
The TOSCA specification provides means to model enterprise applications in a standardized
way. In view of mergers and acquisitions, data center consolidation, for breaking up silo
structures in IT departments and for support of modeling experts it is necessary to find concepts
for analyzing already modeled TOSCA Topology Templates for similar elements and
for unifying these elements and, thus, two Topology Templates.
This master’s thesis develops a matching concept for finding similar elements inside and
between two Topology Templates by systematically exploring all different constellations
TOSCA elements can take. Similar elements are indicated by the notion of a Correspondence.
The matching concept is automated by developing algorithms that determine Correspondences
and incorporate domain-specific knowledge via type-specific plugins. The
plugins handle the matching of properties that cannot be conducted generically. Furthermore,
a merging concept and appropriate algorithms are developed that utilize the identified
Correspondences for unifying similar elements. All algorithms are designed with the goal of
practical computational complexity.
A further part of this work is the design and prototypical implementation of the extendable
TOSCAMerge framework that allows for a convenient integration of type-specific plugins.
The framework facilitates the assessment and manipulation of the determined Correspondences
by domain experts prior to merging. A set of example TOSCA Service Templates for
testing the different matching and merging cases complements the implementation.
An extensive evaluation of the concepts and algorithms reveals the algorithms’ greedy
properties including local optimality but quadratic computational complexity in most cases.