Integration of Services into Workflow Applications

Symbol Description

T a set of workflow tasks

E a set of edges that determine

dependencies between tasks

t

i

task i of the workflow appli-

cation

S

i

a set of alternative services,

each of which can perform

functions required by task t

i

s

ij

the j-th service that is capa-

ble of executing task t

i

c

ij

the cost of processing a unit

of data by service s

ij

P

ij

provider who has published

service s

ij

N

ij

node (cluster/server) on

which service s

ij

was in-

stalled

sp

N

speed/performance of node

N

d

i

size of data processed by

task t

i

d

out

size of output data from task

t

i

f

t

i

() a function that determines

the size of output data based

on the size of input data:

d

out

i

= f

t

i

(d

in

i

)

d

in

ij

size of input ...