Related Work - User-Level Workflow Design: A Bioinformatics Perspective - page 172

data-flow modeling, on control-flow modeling, or whether they apply an ex-
plicit hybrid approach that combines both kinds of models. It reflects the al-
ready mentioned tendency of specifically developed bioinformatics workflow
systems towards data-centric modeling. Note, however, that most systems do
not base their workflow models on formal definitions, and that often data-
flow models are extended by particular control-flow features, and vice versa.
Hence one cannot assume per se that general results regarding the capabilities
of control-flow and data-flow structures (e.g., [321, 152, 262]) apply.
The study was carried out by realizing the selected benchmark workflows
in Bio-jETI (Section 8.2.2) and Taverna (Section 8.2.3), which are characteris-
tic representatives of control-flow- and data-flow-based systems, respectively.
Both approaches are often considered to be capable of expressing the same
workflows, but in fact there are limitations with respect to the inclusion of
elaborate control structures when using the data-flow approach. Consequently,
results show that linear and parallel workflows can be realized by both frame-
works without problems. In Taverna, the realization of conditional branching is
already dicult, while workflows that involve dedicated iterations or param-
eter sweepings can sometimes not be realized at all. The control-flow based
models of Bio-jETI, on the other hand, also cover these more complex work-
flow structures.
The study was carried on by Sariette Bille in her diploma thesis [42], where
she systematically analyzed a selection of DDBJ workflows [4] with respect
to the general workflow patterns described in [326]. In essence, her results
confirmed the findings of the initial study. Analogous results have also been
obtained by similar studies (e.g., [52, 281, 106, 336, 314, 117]), all together
covering a wide range of scientific and business workflow systems.

Tabl e 8.2 Data-flow, control-flow, and hybrid systems
control-flow systems data-flow systems hybrid systems

BioMoby clients

BioSPICE Dashboard

DDBJ Workflow Nav. System

Galaxy
GenePattern
jORCA
Kepler
Proteomatic
SADI/SHARE
SeaLife Argumentation Interface
Semantic Workflow Tool
Taverna
Triana
Wildfire
Wings

BPEL

Bio-jETI JOpera

GNU make DiscoveryNet

RSEQTools