Exposing a Ruleset as a Web Service 
Business Rules are available for consumption across the entire application stack. This is because “rules are everywhere” and business applications of all varieties would find it necessary to take advantage of these capabilities. Here is an overview of the various consumption scenarios for business rules:
Compose reusable rules services with SAP NetWeaver Business Rules Management
Composite applications of all types can use business rules capability (rules services) to deliver rules enabled composites. Specifically:
Composite business processes
Composite services and event composites
Composite UIs and mashups
Rules-enabled situational composites
System-to-system processes can consume reusable rules services. Example of a use case is “Destination Determination Rules”
ABAP applications can consume rules services or rules-enabled composite services
You can easily create a WSDL artifact of a ruleset in the rules composer.
Procedure
In the Project Explorer view, expand the rules composer DC and the Rules Modeling nodes.
In the context menu of a ruleset or Flow Ruleset, choose
Web Service 
Create WSDL Artifact 
.In the dialog box that appears, in the Ruleset Name: Service Attributes page, accept default values or make changes. Choose Next.
In the Ruleset Name: Service Signature page, the input and output types appear and the checkboxes are selected by default. Choose Next.
In the Ruleset Name: WSDL Preview page, you should see the contents of the WSDL artifact.
Choose Finish.
The web service is now ready for use.