- Activity
-
Activity.
In the formal PSL ontology, the notion of activity is a basic construct,
which corresponds intuitively to a kind of (manufacturing
or processing) activity.
In PSL, an activity may have associated
occurrences, which
correspond intuitively to individual instances or
executions of the activity.
(We note that in PSL an activity is not a class or type with
occurrences as members; rather, an activity is an object,
and occurrences are related to this object by the
binary predicate
occurrence_of
.)
The occurrences of an activity may impact
fluents (which provide an abstract
representation of the "real world").
In FLOWS, with each service there is an associated
activity (called the "service activity" of that service).
The service activity may specify aspects of the internal
process flow of the service, and also aspects of the
messaging interface of that service to other services.
- Channel
-
Channel.
In FLOWS, a channel is a formal conceptual object,
which corresponds intuitively to a repository and
conduit for messages.
The FLOWS notion of channel is quite primitive,
and under various restrictions can be used to model
the form of channel or message-passing as
found in web services standards,
including WSDL, BPEL, WS-Choreography, WSMO,
and also as found in several research investigations,
including process algrebras.
- FLOWS
-
First-order
Logic Ontology for Web Services.
FLOWS, also known as SWSO-FOL,
is the first-order logic version of the Semantic Web Services Ontology.
FLOWS is an extension of the PSL-OuterCore ontology, to
incorporate the fundamental aspects of
(web and other electronic) services, including service descriptors,
the service activity, and the service grounding.
- Fluent
-
Fluent.
In FLOWS, following PSL and the situation calculii, a
fluent is a first-order logic term or predicate whose
value may vary over time.
In a first-order model of a FLOWS theory, this
being a model of PSL-OuterCore,
time is represented as a discrete linear sequence
of timees, and
fluents has a value for each time in this sequence.
- Grounding
-
Grounding.
The SWSO concepts for describing service activities,
and the instantiations
of these concepts that describe a particular service activity, are
abstract specifications, in the sense that they do not specify
the details of particular message formats, transport protocols,
and network
addresses by which a Web service is accessed. The role of
the grounding is to provide these more concrete
details.
A substantial portion of the grounding can be acheived by
mapping SWSO concepts into corresponding WSDL constructs.
(Additional grounding, e.g., of some process-related aspects
of SWSO, might be acheived using other standards, such
as BPEL.)
- Message
-
Message.
In FLOWS, a message is a formal conceptual object,
which corresponds intuitively to a single message that
is created by a service occurrence, and read by zero
or more service occurrences.
The FLOWS notion of message is quite primitive, and
under various restrictions can be used to model
the form of messages as found in web services standards,
including WSDL (1.0 and 2.0), BPEL, WS-Choreography, WSMO,
and also as found in several research investigations.
A message has a payload, which corresponds
intuitively to the body or contents of the message.
In FLOWS emphasis is placed on the knowledge that
is gained by a service occurrence when reading a message
with a given payload
(and the knowledge needed to create that message.
- Occurrence
-
Occurence (of a service).
In FLOWS, a service S has an associated FLOWS activity
A (which
generalizes the notion of PSL activity).
An occurrence of S is formally
a PSL occurrence of the activity A.
Intuitively, this occurrence corresponds to
an instance or execution (from start to finish) of the activity
A, i.e., of the process associated with
service S.
As in PSL, an occurrence has a starting time
time and an ending time.
- PSL
-
Process Specification Language.
The Process Specification Language (PSL) is a
formally axiomatized ontology
[Gruninger03a,
Gruninger03b]
that has been
standardized as ISO 18629.
PSL provides a layered, extensible ontology
for specifying properties of processes.
The most basic PSL constructs are embodied in
PSL-Core; and PSL-OuterCore incorporates
several extensions of PSL-Core that includes
several useful constructs.
(An overview of concepts in PSL
that are
relevant to FLOWS is given in
Section 6 of the
Semantic Web Services Ontology document.)
- QName
-
Qualified name.
A pair (URI, local-name). The URI represents a
namespace and local-name represents a name used in an XML
document, such as a tag name or an attribute name.
In XML, QNames are syntactically
represented as prefix:local-name, where prefix is
a macro that expands into a concrete URI.
See Namespaces
in XML for more details.
- ROWS
-
Rules Ontology for Web Services.
ROWS, also known as SWSO-Rules,
is the rules-based version of the Semantic Web Services Ontology.
ROWS is created by a relatively straight-forward,
almost faithful,
transformation of FLOWS, the First-order Logic Ontology for
Web Services.
As with FLOWS, ROWS incorporates
fundamental aspects of
(web and other electronic) services, including service descriptors,
the service activity, and the service grounding.
ROWS enables a rules-based specification of a family of
services, including both the underlying ontology and
the domain-specific aspects.
- Service
-
(Formal) Service.
In FLOWS, a service is a conceptual object, that
corresponds intuitively to a web service (or other electronically
accessible service). Through binary predicates a service
is associated with various service descriptors (a.k.a.
non-functional properties) such as Service Name, Service Author,
Service URL, etc.; an activity (in the sense of
PSL) which specifies intuitively the process model associated with the
service; and a grounding.
- Service contract
- Describes an agreement between the service requester and service
provider,
detailing requirements on a service occurrence or family of
service occurrences.
- Service descriptor
-
Service Descriptor.
This is one of several non-functional properties
associated with services.
The Service Descriptors include
Service Name, Service Author, Service Contract Information,
Service Contributor, Service Description, Service URL,
Service Identifier, Service Version, Service Release Date,
Service Language, Service Trust, Service Subject,
Service Reliability, and Service Cost.
- Service offer description
-
Describes an abstract service (i.e. not a concrete instance of the service)
provided by a service provider agent.
- Service requirement description
-
Describes an abstract service required by a service requester agent,
in the context of service discovery, service brokering, or negotiation.
- sQName
-
Serialized QName.
A serialized QName is a shorthand representation of a URI. It is
a macro that expands into a full-blown URI.
sQNames are not QNames: the former are URIs, while the latter are
pairs (URI, local-name).
Serialized QNames were originally introduced in RDF as a notation for
shortening URI representation. Unfortunately,
RDF introduced confusion by adopting the term QName for something that is
different from QNames used in XML. To add to the confusion, RDF uses
the syntax for sQNames that is identical to XML's syntax for QNames.
SWSL distinguishes between QNames and sQNames, and uses the
syntax prefix#local-name for the latter.
Such an sQName expands into a full URI by concatenating the value
of prefix with local-name.
- URI
-
Universal Resource Identifier.
A symbol used to locate resources on the Web. URIs are defined by IETF. See
Uniform Resource Identifiers
(URI): Generic Syntax for more details.
Within the IETF standards the notion of URI is an extension
and refinement of the notions of Uniform Resource Locator (URL)
and Relative Uniform Resource Locators.