RVM is a service where you can upload guest services and execute them in a sandbox. Guests can use either HTTP or QUIC.

The main purpose is as a toy cloud platform for multiplayer apps and games.

The guests have the following limits:

• Limit of 268 KiB of memory per guests
• 100_000_000 of starting fuel for each guest.

Start service: cargo run --release The service automatically starts any module in the module-store folder.

Invoke: curl -X GET -i http://127.0.0.1:8000/python-svc/secret

You can write guests in any language you want, as long as it compiles to webassembly. This example uses python. There are other rust examples in the repo that are more straight forward, those can simply be compiled with something like cargo build -p http-rust --target wasm32-wasip2.

Write your app and import the things you need. There's an example in guests/http-python/http_server.py that implements a HTTP server that can be run in RVM. Right now, the RVM expects all guests to be a HTTP proxy. Every time it receives an invoke request it will run IncomingHandler::handle in your guest, with a forwarded HTTP request.

1. Make sure you have componentize-py, which can be installed via pip install componentize-py
2. Build the wasm module pushd guests/http-python && componentize-py -d ../../wit -w rvm componentize http_server -o http-python.wasm && popd

curl --data-binary "@guests/http-python/http-python.wasm" localhost:8002/deploy/http-python

• Get the SHA of some page: - curl -X GET -i -H 'url: https://webassembly.github.io/spec/core/' http://127.0.0.1:8000/http-python/hash-all
• Echo back a body - curl -X POST -i http://127.0.0.1:8000/http-python/echo -d "xd"
• Print a secret provided by the host - curl -X GET -i http://127.0.0.1:8000/http-python/secret

Edit the host import in wit/world.wit, which will be imported by the rvm world. Edit the rvm::lambda::host::Host impl for HostComponent and add your newly added function. The rust code will automatically run bindgen when compiled.

After you are done with the host changes, you need to make the changes available for the python guest by regenerating the bindings.

1. Make sure you have componentize-py, which can be installed via:

   pip install componentize-py.

2. Generate bindings to output dir guests:

   componentize-py -d wit -w rvm bindings guests/http-python

3. Import your added function in your python code

   from rvm.imports.host import (
       client_secret,
   )

4. Call your function! secret = client_secret() This will run the client_secret function from the host and return the response to your guest.

We use OpenDAL, so switching backing store to something that's not the file system only requires you to use another service.

cargo r
cargo b -p http-rust --target wasm32-wasip2
curl --data-binary "@target/wasm32-wasip2/debug/http_rust.wasm" localhost:8002/deploy/http-rust
curl -X POST -i http://127.0.0.1:8000/http-rust/echo -d "echo this!"