There are already plenty of transport protocols (REST, AMQP, etc.) available. The Production Performance Management Protocol aims to provide the very industry specific semantic structure for their payload. So it aims to complete such IoT transport infrastructure and bridge the gap to the manufacturing domain. OPC-DA/UA on the other hand covers full service oriented architecture, security concerns and information model, which makes it more complex and costly to implement and operate. In some use cases, this is not necessary.