Migrating e-Science Applications to the Cloud: Methodology and Evaluation - Cloud Computing with e-Science Applications - page 97

virtualization technology (Menzel and Ranjan, 2012). As we provide support
for the migration of the database layer, we focus on another type of middle-
ware technology. Our approach is also not limited to a specific cloud service
delivery model and migration by using virtualization technology.

5.4 Migration Methodology and Tool Support
As discussed, in this section we introduce a step-by-step methodology for
the migration of the database layer to the cloud and the refactoring of the
application architecture. Before we introduce the methodology, we investi-
gate the requirements to be fulfilled by such a methodology.

5.4.1 Requirements

The functional and nonfunctional requirements we present in this section aim
to provide decision support and guidelines for both migrating an applica-
tion database layer to the cloud and refactoring of the application architec-
ture. The presented requirements have been identified during our work on
various research projects, especially during our collaboration with industry
partners and IT specialists from the e-science domain.

5.4.1.1 Functional Requirements

The following functional requirements (FRs) must be fulfilled by any meth-
odology for migration of the database layer to the cloud and refactoring of
the application architecture:

FR 1 Support of Data Stores and Data Services : The methodology must support the data

migration for both fine- and coarse-grained types of interactions (e.g., through SQL
and service APIs, respectively).

FR 2 On-Premises and Off-Premises Support : The methodology has to support data stores and

data services that are either hosted on the premises or off the premises and using both
cloud and noncloud technologies.

FR 3 Independence from Database Technology : The methodology has to support both established

relational database management systems (Codd, 1970) and NoSQL data stores
(Sadalage and Fowler, 2012) that have emerged in recent years.

FR 4 Management and Coniguration : Any tool supporting such a methodology must provide

management and configuration capabilities for data stores, data services, and
migration projects bundling together different migration actions. This includes, for
example, the registration of a new data store, including its configuration data
(e.g., database schemas, database system end point uniform resource locators [URLs],
etc.). It must also support the creation of new migration projects for documentation
of the decisions and actions taken during migration.