One of the biggest promises of Business Process Management was that the business people can model and execute their business processes without involvement from IT folks. This promise was kept in a simple workflow sceanarios by utilizing limited number of 'built-in' activity types of BPMS packages but once you face little more complex business process sceanarios providing transactional integration with existing software and complex interactions with human beings, this limited expression power make it hard to drag and drop process modeling, and finally it brings a huge help from software vendors or system integrators and write a lot of code that is making processes utterly inflexible downstream. That means, concurrent BPMS is extremely lack in something like 'Technical Abstraction' and 'Expression Extensibility'.