DDE Application (DDEApp) is a Dynamic Data Exchange (DDE) based inter-process communication protocol created to exchange data and perform functions call between applications.
Back in 2009, when I was still programming in Borland C++ Builder, I needed to find a solution to call function remotely between two applications. We had decided to make use of DDE for this purpose. Using VCL control in Borland, we managed to get DDE up within few days. However, soon we realized that existing DDE protocol was not able to fully meet our requirement, we created DDE Application to simplify the usage in application.
Read more in my blog: http://www.codearteng.com/2012/06/ddeapp-dde-based-inter-process.html