C++11, C++14, and even C++17 present opportunities for new designs and behaviors. How do these new opportunities actually work out when the project is non-trivial, performance sensitive, and interoperable with other languages? In this session, we will discuss the challenges faced and lessons learned with the use of modern C++ in two recent projects. Aaron is a high performance messaging transport that provides a C++ API that must transparently interoperate with its Java, .NET, and Go APIs. ReactiveSocket is an application protocol providing Reactive Streams semantics over various communication media. Whether you are just curious about modern C++ or are an experienced C/C++ developer, this session will provide some new perspectives.