xnorxnor / dll-shared-memory

Simple project to show possible problems when using shared memory structures between DLL and DLL host.

dll-shared-memory

Simple project to show possible problems when using shared memory structures between DLL and DLL host.

Note: this projects shows how not to do it. It is an abstract version of propietary code and is intended to serve as an example of how interprocess communication between a DLL and a host should better not be designed. The task derived from this is to create the same functionality with modern means.

For the sake of simplicity no threads are used.

Features

• DLL can request user input from host
• DLL can request data from database with timeout
• DLL can send logging data to host
• DLL can send processed data to host
• DLL has a main "message loop" where data is processed
• Host can "shutdown" DLL in a safe way

Compilers / IDEs

Tested with

• CLion (CMake based, gcc)
  • .\CMakeLists.txt
• VS 2019 (Community Edition, msvc)
  • projectfiles\dll-shared-memory.sln
• C++ Builder 10.3 (Community Edition, bcc32c (clang based))
  • projectfiles\shared-memory.groupproj

Task and constraints in the context of a Bachelor thesis

Constraints

• Code must compile with bcc32c
• Host and DLL run on the same machine
• The minimum supported C++ standard is C++11

Task

• Which problems could arise by using the shared memory interface?
  • Is it possible to use different compilers for DLL and host?
  • What are possible alternatives to a shared memory interface?
• Find solutions that are C++ compiler independent (the host could be created with bcc32c and the DLL with mscvc)

Optional tasks

• Create a host in a different programming language (Python, Ruby, Java, etc.)
• Allow data exchange over the network
  • of course this implies the use of two "host" - processes (in contrast to the original "host loads DLL" solution)