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178 Selected Studies on Software and Information Systems
The service profile contains information usable by a seeking agent to search and find
a service which meets its needs. The profile can be used also by a service seeking agent to
express its needs, so the match-maker has a convenient dual-purpose representation.
The service model describes what happens when the service is carried out. This can be
used for deeper analysis of whether the service meets the requirements. Other usage is in
the situation when the service is a part of a composed service. Model is also used to monitor
the execution of the service.
The service grounding specifies the details how an agent can access the service. It
specifies the communication protocol, message formats, serialization techniques, and other
service specific details.
In [53] other details about OWL-S are presented. The paper discusses the benefits of the
richer service description supported by OWL-S. It describes how OWL-S is used in context
of other standards, such as WSDL, UDDI and BPEL (Business Process Execution Language).
input
precondition
output}
Condition effect
{
Process
hasProfile
hasProcess
Profile
AtomicProcess
realizes
realizedBy
SimpleProcess
expandsTo
collaps
computedInput
CompositeProcess computedOutput
computedEffect
computedPrecondition
invocable
composedBy
components
ControlConstruct
ProcesComponent =
Proces U ControlConstruct
Sequence
RepeatUntil
Figure 6-9. Top level of the OWL-S process ontology (retrieved from [63]).
OWL-S defines a subclass of the ServiceModel called ProcessModel. It is used to describe the
service as a process. The process ontology adopts two views of processes. First, a process
transforms input data into output data. Inputs specify the information required for the
execution of the process. The outputs specify the information which is produced by the
execution of the process. Second, the process transforms a world’s state from one into
another, what is described by preconditions and effects. The process model identifies three
types of processes, see Figure 6-9:
– Atomic process: a directly executable process. It has no sub-processes and executes
in one step. The requester has no visibility into the service’s execution. For each