Is there any standard language for writing business rules in BPM?
Yes, there are some sort of languages considered “standard” for BPM. From the top of my head I can give you the references of BPEL (Business Process Execution Language), BPML (Business Process Modeling Language) and BPSS (Business Process Specification Schema) for ebXML. In a very abstract way I would say that BPEL focus on define the services that you want for your business, BPML is complementary to detail the business process behind the services. BPSS is pretty different from the previous ones, defining a business process for physical business interchanges between parties for collaboration and for transactions to be carried out between commercial business partners. See the article link below.
