Problem that WebAssembly addresses

Make the browser as generic as a computer, i.e. execute most programs

Principles

• But: Make it possible to reuse components coded in C, C++, Rust, etc. directly in the browser

• How: Convert C/CPP/Rust into LLVM representation

• Theoretical workflow: compile/export c/cpp file in wasm format, serve wasm to client browser, interact with wasm module from javascript code

  flowchart LR;
      subgraph web[webservice]
          direction TB
          jscode[service.js]--interacts-->wasm
      end
      code[opencv.cpp]--export-->wasm[opencv.wasm]
      web--served-->client
  
  

• WebAssembly is not a virtual machine, it is processed

Other notes

• 2 formats: Wat (text file), Wasm (binary)
• Explorer: https://mbebenita.github.io/WasmExplorer/
• JS / WA Interactions:
  • Fetch the file and read it (binary)
  • Use of the WebAssembly module (native) initialize WA module
  • Instantiate module
  • Then, whenever functions defined in the WA are called, the WA runtime will execute and deliver results to the JS runtime through a share memory

Limitations:

• No DOM interactions but possible to interact with external functions
• Interoperability between JS and WA only through integers and floats --> glue code
• No garbage collector (memory management is important)
• WA Runtime dependent on the browser

Quetions

• Is it possible to export anything from a C/CPP/etc. program ? What are the limitations ?

References

• https://www.youtube.com/watch?v=P1xIKrrncS8
• https://webassembly.org/
• https://developer.mozilla.org/fr/docs/WebAssembly