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Role(s):
Customer
Component(s):
Semantic Enhanced
Service Selector (SESS)
SLA Translator
Service
Discovery Registry (SDR)
License:
LGPL
Usage Instructions
Installation Requirements
Deployment Tips
Service Broker API
Usage Instructions
The Service Broker
toolkit provides the functionalities required to select the best
service which fits the customer requests from providers’ offers.
Basically, this selection involves both the discovery and selection
of the service considering both semantic functional and
non-functional properties. The non-functional properties are
described in terms of SLA terms such as Quality of Service (QoS)
metrics located in SLA templates. All the descriptions will be
semantically enhanced by the usage of OWL-S for service functional
descriptions and semantic annotations of SLA files for the
non-functional descriptions.
The broker thereby can
return the ‘best fit’, which may however not meet all conditions
specified by the customer.
This functionality will leverage the service discovery by means of
the selection of the best choice of the discovered candidate
services that are available to perform the service requested by the
customer.
As seen in the previous
section, the Service Broker toolkit is composed of three components:
the Semantic Enhanced Service Selector (SESS), the SLA Translator,
and the Service Discovery Registry (SDR).
The toolkit installs
all the components as Web services. The SESS performs the service
selection, contacting the SLA Translator to translate SLA terms if
required. The selection is made from a list of available services
and depends on the SLA templates content. The Service Discovery
Registry is used for service publication and advertising; to request
for the list of published services, to remove a service publication,
and so forth.
A general interaction
between the components is as follows:
·The
Client (in the BREIN framework the Workflow Enactor) sends to the
Service Discovery Registry the service profile representing the
service to be searched;
·The
Service Discovery Registry matches the received profile against the
profiles stored in the registry;
·The
Service Discovery Registry sends to the Client the matched profiles
together with the associated SLA templates;
·The
Client sends the services profiles and the associated SLA templates
to the SESS;
·The
SESS translates SLA terms through the SLA Translator, if required;
·The
SESS selects the proper service and sends it to the Client.
It is worth noticing
that the SESS, alternatively, can directly interact with the Service
Discovery Registry component
the dashed lines denote alternative required interactions). So, two
behaviours are possible. In the first case, the SESS receives the
list of available services from the calling client and makes the
selection. In the second case, the SESS receives the services list
directly from the Service Discovery Registry and makes the
selection. The first approach is the standard approach and it is
used in the Virtual Engineering scenario where the Workflow Enactor
contacts the Service Discovery Registry to get the services list and
then the SESS to perform the service selection.
Service Broker Installation
Installation Requirements
·SESS
and SLA Translator: Java 5 or higher, Tomcat 5.5 or higher;
·Service
Discovery Registry: Windows Platform, Microsoft .NET Framework 3.5
or higher, IIS with WCF capability enabled, Java 5 or higher, Tomcat
5.5 or higher.
Service
Broker Deployment Components
Deployment Tips
The SESS and the SLA
Translator, as Web services, can be installed in different hosts and
interact through their Web service interface. However, in general,
it is recommended to install both in the same host. The Service
Discovery Registry is generally installed in a third-party
organisation, which provides discovery services to customers. The
Service Discovery Registry can also be deployed in more than one
instance in different hosts. This way it is possible to achieve a
distributed network of service registries, and the discovery of
services is improved since performed through this network.
Software Installation
The Service Broker
toolkit installer installs all the application / components required
to provide the functionalities required to select the best service
which fits the customer requests from providers’ offers. The
installation of these components is described in the following.
Service Broker API
see
SLA Translator API
see
SDR API
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