We have implemented a rule based extension of jPDL and BPEL which exploits Reaction RuleML (ruleml.org and Reaction RuleML) as platform-independent Web rule standard and the Rule Responder ESB middleware (responder.ruleml.org) with the Prova 
(prova.ws) rule engine as platform-specific execution environment. The conditional control flow of a business process is defined by the order of sending and receiving message constructs in Prova's messaging reaction rules. These messaging reaction rules maintain a local conversation state which reflects the process execution state and support performing of different activities within process instances managed in simultaneous conversation branches. The behaviour of the inbound links defined by the messaging reaction rules correspond to the BPEL links, but provide an additional rule execution layer with a much more expressive and compact declarative rule-based programming language to represent complex event processing logic in arbitrary combination with conditional decision logic implemented in terms of derivation rules. As an independent system, the Rule Responder Enterprise Service Bus middleware with the Prova rule engine is running as a parallel running platform that analyses and processes events. The BPM- and the RuleResponder-platform correspond via events which are produced by the jBPM-workflow engine and by the IT services which are associated with the business process steps. Rule Responder (http://responder.ruleml.org) is a middleware for distributed intelligent rule-based inference services and complex event processing on the Web. It adopts the OMG model driven architecture (MDA) approach:

1. On the computational independent level rules are engineered computational independent e.g. in a natural controlled English language using blueprint templates and user-defined controlled vocabularies. 

2. The rules are mapped and serialized in a interchange format such as Reaction RuleML (or RIF XML) which is used as platform independent rule interchange format to interchange rules between the rule inference services and other arbitrary execution environments. 

3. The Reaction RuleML rules are translated into the platform specific rule language for execution, e.g. the Prova rule language. 
Arbitrary (reaction) rule engines and CEP engines can be deployed on an enterprise service bus (ESB). Translator services translate from the respective execution syntax of the platform-specific rule / CEP engine into Reaction RuleML which is used as common rule interchange format and vice versa. Arbitrary transport protocols (>30 protocols) 
such as MS, SMTP, JDBC, TCP, HTTP, XMPP can be used to transport rule sets, queries and answers (e.g. event instance data) between distributed inference service endpoints on the Web. For workflow-like intelligent message processing it employs the Web rule engine Prova (http://prova.ws) and messaging reaction rules to describe 
(abstract) processes / situations and complex event processing logic in terms of messagedriven conversations between inference services / agents, i.e. it represents their associated interactions via constructs for asynchronously sending and receiving event messages. The control flow of a process is defined by the order of sending and receiving message constructs in messaging reaction rules. In contrast to standard Event-Condition-