Introduction
Beginning with TWSAPI version 10.35.01, Interactive Brokers has begun to produce the TWS API using Google’s Protocol Buffer. As a result, many new objects are produced using protocol buffer classes directly that developers will need to utilize and understand in order to produce effective code that can access all systems provided by the TWSAPI.
Users unfamiliar with Protocol Buffers should visit the official development page for more insight on what it is, what it may offer, and context for the built-in systems it provides.