Workflow Concept of WS-PGRADE/gUSE - Science Gateways for Distributed Computing Infrastructures - page 46

port of the collector node and are processed by the collector node. Of course, this
complex pattern can be further extended, enabling more generators, PS-nodes, and
collectors in many different combinations.
It may be misleading, so we remark that, there is a speci

c case when multiple
generator jobs connected together generating N*M instances ( N come by the rst

and M by each parallel N job instance, respectively). This would imply that they can
be collected correspondingly, namely for collecting all the items, we need two jobs,
both with collector ports, but the truth is that the N*M data items handled in the
same level will result in just one, but a greater set of data. Consequently, one job
with a collector port gets all the data. If we wanted to handle the data split to their
generating job accordingly, we should use the embedding feature of the system.

3.7.2 Enactment of Conditional Branches

Enactment of conditional branches is designed as a composition of deferred choice
and simple merge control patterns, where deferred choice speci

es two alternate

“ ” “ ”

branches representing branches and a single control point before

them. The control point chooses a branch to interpret, ignoring the other one.
Subsequently, the simple merge pattern specifies the case of collecting alternate
branches independently from what was interpreted or ignored before. Its imple-
mentation is shown in Fig. 3.7 .

then and else

Fig. 3.7 Workflow with alternate branches