srvx

srvx is a microservice framework where services simply read and write files to exchange messages. Because of this, services require no client code, and can exchange messages in any format.

This is accomplished by connecting libfuse to zeromq. The srvx command will mount an instance of the filesystem in a temporary directory and run an arbitrary process in it.

Suppose we have a service in node.js that emits two random numbers:

const fs = require('fs')

function emit() {
  let msg = JSON.stringify({ a: Math.random(), b: Math.random() })
  fs.writeFileSync('pub/random', msg)
  setTimeout(emit, 1000)
}

emit()

The path segment pub/ is a virtual top-level directory that deals with pub/sub pattern messages. random is the routing key of the message, which is how other services can filter on this message type. Let's write a service to consume these numbers and multiply them together, then publish the product.

const fs = require('fs')

while (true) {
  const msg = JSON.parse(fs.readFileSync('pub/random'))
  const product = msg.a * msg.b
  fs.writeFileSync('pub/product', JSON.stringify({ product }))
}

Building and Running

srvx depends on libfuse and libczmq, as well as a standard C build toolchain. Install them on Ubuntu or Debian like so:

sudo apt-get install build-essential libfuse-dev libczmq-dev

Then simply running make should be sufficient.

Attempts to compile on OSX against osxfuse have so far been disastrous.

You can run the node examples from the README in separate terminals like so:

$ ./bin/srvx_router

$ ./bin/srvx node examples/node-hello/publisher.js

$ ./bin/srvx node examples/node-hello/subscriber.js