BPEL elements define hierarchies

In BPEL, the relationship between several basic elements is mainly defined by the following key labels:
<Partnerlink>
<Partnerlinktype>
<Porttype>
<Partnerlink> and <partnerlinktype> are the extended labels of BPEL. In the philosophy of BPEL, a business is a set of services [1, 2]. The business consists of two parts, some services are self-owned and can be called by the outside world, while others are non-existent. External services should be called. Therefore, a business can have at most two rules, at least one. The rules here are defined as the two attributes of <partnerlink> In BPEL, myrole and partnerrole, the role here corresponds to a specific WebService.

On the other hand, the WebService is not directly associated with partlink, which adds another layer, namely <partnerlinktypes>, which uses attributes in <partnerlink>, partnerlinktype. Each <partnerlinktype> is a set of common rules. A rule is used to associate the service interface defined by WebService with the partnerlinktype. Each WebService can correspond to multiple role.

This design allows you to flexibly configure business processes and combine the same ws services in different businesses, you can change role to myrole or partnerrole to define the position of the Service in the business, in the design of BPEL, we think that the completion of a business is nothing more than a service call provided to others or a call to other services. In addition, such a service can only have two directions in a single BPEL Business, that is to say, in the service of BPEL, it is the sum of two and only two Ws services at most, and then these paired small BPEL services are organized into a complete business process.