Install WASM mono SDK

Download latest Mono WASM SDK built from Mono CI

Detailed explanation at Mono project site.

Set WASM_SDK path to where you unziped the SDK

export WASM_SDK=/Users/cab/Dev/WebAssembly/mono/mono-wasm-ad03563fb46

Build command to compile DLL's

csc /target:library -out:sample.dll /noconfig /nostdlib /r:$WASM_SDK/wasm-bcl/wasm/mscorlib.dll /r:$WASM_SDK/wasm-bcl/wasm/System.dll /r:$WASM_SDK/wasm-bcl/wasm/System.Core.dll /r:$WASM_SDK/wasm-bcl/wasm/Facades/netstandard.dll /r:$WASM_SDK/wasm-bcl/wasm/System.Net.Http.dll /r:$WASM_SDK/framework/WebAssembly.Bindings.dll /r:$WASM_SDK/framework/WebAssembly.Net.Http.dll  /r:$WASM_SDK/framework/WebAssembly.Net.WebSockets.dll /r:$WASM_SDK/wasm-bcl/wasm/Facades/System.Threading.dll  /r:$WASM_SDK/wasm-bcl/wasm/Facades/System.Text.Encoding.dll /r:$WASM_SDK/wasm-bcl/wasm/Facades/System.Net.WebSockets.dll /r:$WASM_SDK/framework/WebAssembly.Net.WebSockets.dll dependency.cs sample.cs wstest.cs WebGatewayMock.cs

To package and publish DLL's as WASM

 mono $WASM_SDK/packager.exe --copy=always --out=./publish --asset=./sample.html --asset=server.py sample.dll

To run the Python server in

cd publish
python server.py