This paper explains in deep one of the trickiest feature of the BPEL specifications: “The correlation”. In the first part, we explain some basic concepts needed for a good understanding. Then, through a simple business process, we introduce the different steps you will have to understand to design a multi-party conversation with a BPEL engine. In order to enjoy reading this paper and benefit from it. we assume that you are able to understand XML Schemas, WSDL and BPEL documents.
This link propose a complet and royalty free Powerpoint presentation on BPEL Correlation associated with the technical paper as well. You can use or modify it for training purpose or lecture on BPEL. Link to Open Training