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I have been having a lot of difficulty trying to get a simple HTTP server built in to my application. It will be communicating only with other servers on the same local network, so SSL/TLS is not needed.

I tried setting up uWebSockets (I'm happy to take advice of anything else, especially if it is available in cygwin, since that seems to be much easier to make work), but the documentation is not very good. I did manage to get the IDE to say all errors were good by using the command:

vcpkg install libuv uwebsockets --triplet=x64-windows

and using the following CMakeLists.txt:

cmake_minimum_required(VERSION 3.21) project(exchange)

set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake/modules) set(CMAKE_CXX_STANDARD 20) set(CMAKE_C_FLAGS "-lgmp") set(ZLIB_DEPS_DIR /cygdrive/c/src/vcpkg/packages/zlib_x64-windows/bin)

set(HEADER_FILES
    long list of .h files )

set(SOURCE_FILES
    long list of .cpp files )

find_package(GMP REQUIRED)

include_directories(uWebSockets) add_executable(exchange main.cpp  ${SOURCE_FILES} ${HEADER_FILES}) target_link_libraries(exchange gmp gmpxx z uv)
    
set(UWEBSOCKETS_INCLUDE_DIRS /cygdrive/c/src/vcpkg/packages/uwebsockets_x64-windows/include/uwebsockets) set(ZLIB_INCLUDE_DIRS /cygdrive/c/src/vcpkg/packages/zlib_x64-windows/include) set(USOCKETS_INCLUDE_DIRS /cygdrive/c/src/vcpkg/packages/usockets_x64-windows/include)
    
target_include_directories(exchange PRIVATE ${ZLIB_INCLUDE_DIRS}) target_include_directories(exchange PRIVATE ${UWEBSOCKETS_INCLUDE_DIRS}) target_include_directories(exchange PRIVATE ${USOCKETS_INCLUDE_DIRS})
    
add_library(exchange_lib STATIC ${SOURCE_FILES} ${HEADER_FILES})

But, I keep getting this error when I try to build it:

/cygdrive/c/src/vcpkg/packages/uwebsockets_x64-windows/include/uwebsockets/Loop.h:31: undefined reference to `us_loop_ext'

What is an undefined reference/unresolved external symbol error and how do I fix it? explains what the problem is. The libraries are not being linked but it does not explain how to fix it.

If the library was from cygwin i could add uwebsockets to the target link library but since it is not available from that doing so just gives an error.

Matthew Cornelisse
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    Only someone who's familiar with this code would be able to answer something like this. Where do you think you have the best chance of finding someone who is familiar with this "uwebsockets": on a general purpose web site like Stackoverflow, which focuses on general programming topics, or on uwebsocket's own github page, and its discussion forums and issue trackers? – Sam Varshavchik Jun 30 '22 at 22:16
  • pretty sure the problem is I am not linking things correctly in some way. If the library is available in cygwin linking seems easy but if it is not nothing seems to work. – Matthew Cornelisse Jun 30 '22 at 22:18

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