70 A Concept of Dynamic Quality Management for Service-Based ...
Input data:
1. the workflow graph G(T, E) with batch data processing tasks,
2. sets of services S
i
= {s
i1
, s
i2
, . . . , s
i|S
i
|
} for each task,
3. quality metrics q
k
ij
of service s
ij
,
4. data sizes d
i
to be processed in particular tasks t
i
.
The goal is to find an assignment ∀
i
t
i
→ (s
i sel(i)
, t
st
i
) (where sel(i) de-
notes the index of the service selected for task t
i
and sel denotes a vector of
these selections) such that execution of services on particular resources does
not consume more resources than available (e.g., more processing cores than
available) and a given QoS function is minimized:
min f
o
(Q, d) (3.1)
where:
• q
k
is a vector of the k-th quality metric for the selected service sel(i)