libfaas.md

Libfaas

This package provides a binary (python-faas2.7) for executing serverless python functions as well as a library (libfaas) with c++ bindings that can be used to for developing binary serverless functions.

libfaas library

A very basic example function might look like this:

#include <l4/libfaas/faas>

/**
 * @brief Do nothing
 * This is a function implementation that immediately returns
 */
std::string
Main (std::string /* args */)
{
  return "Hello from function";
}

faas header utilities

The faas header also provides utility methods. These can for example be used to call another function.

#include <l4/libfaas/faas>

std::string
Main (std::string /* args */)
{
  // ... other code
  std::string ans = L4Re::Faas::invoke (
    "function1", // <-- name as declared by the client
    "hello fn1"  // <-- argument
    );
  // ... other code
}

This invoke function blocks until an answer is received.

For more information, read the comments in the header.

linking

To build these binaries, the Makefile should include:

REQUIRES_LIBS += libfaas

python-faas2.7 binary

This binary will be used automatically by the server in case a python function is provided. It contains a python 2.7 runtime and executes a dataspace containing python code.

A python serverless function might look like this:

def main(arg):
  print "Hello from python: ", arg, "!"
  return "im done"

Additionally, the python binary provides a module called faas which contains python wrappers for the server-worker interface.

These can be used like this:

import faas

def main(arg):
  ret = faas.action_invoke(name="function2", arg="hey from fn1");
  return ret;

For more information about available methods and their calling scheme, have a look at py-faas-lib.cc.