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6 CONCLUSIONS AND FUTURE
WORK
In this paper we propose the use of a pattern-
oriented approach for ETL modelling and
implementation. Each ETL pattern represents an
ETL task (or set of tasks) that is regularly used in a
real world DWS – SKP, SCD, CDC, DQV, or IDL.
We can look to these patterns as "black boxes" that
given a proper input metadata produce a specific
output, accordingly its internal specification. This
approach provides an easy method to specify
complex ETL processes as also some proven
software engineer practices for ETL systems
implementation. With our approach it’s possible to
reduce some planning problems, especially the ones
related to business requirements changing and
implementation errors. We can change the execution
order of a pattern and its input data without
compromising other tasks or compromise the final
process implementation.
Through the use of YAWL, we demonstrated
how to design a complete ETL system using a set of
ETL patterns. The YAWL specification provides a
simple and very powerful notation that coupled with
powerful execution primitives and data support
structures turns YAWL very suitable for the
validation of ETL processes before proceeding to its
final implementation. Using this ETL modelling
approach, designers and developers only need to
know how to interact with patterns regardless of its
internal specification.
As future work we intend to provide an extended
family of YAWL patterns allowing for building a
complete ETL system from scratch. Additionally,
we expect to provide specific XML schemas for the
definition of patterns’ metadata and explore the use
of selection and exception handling services.
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