ZeroMQ

Configuration

I’ve built several large server products, like the Xitami web server that was popular in the late ’90s, and the OpenAMQ messaging server. Getting configuration easy and obvious was a large part of making these servers fun to use.

We typically aim to solve a number of problems:

• Ship default configuration files with the product.

• Allow users to add custom configuration files that are never overwritten.

• Allow users to configure from the command line.

And then layer these one on top of the other, so command-line settings override custom settings, which override default settings. It can be a lot of work to do this right. For FileMQ, I’ve taken a somewhat simpler tack: all configuration is done from the API.

This is how we start and configure the server, for example:

server = fmq_server_new ();
fmq_server_configure (server, "server_test.cfg");
fmq_server_publish (server, "./fmqroot/send", "/");
fmq_server_publish (server, "./fmqroot/logs", "/logs");
fmq_server_bind (server, "tcp://*:5670");

We do use a specific format for the config files—the ZeroMQ Property Language (ZPL), a minimalist syntax that we started using for ØMQ “devices” a few years ago, but which works well for any server:

# Configure server for plain access # server monitor = 1 # Check mount points heartbeat = 1 # Heartbeat to clients publish location = ./fmqroot/logs virtual = /logs security echo = I: use guest/guest to login to server # These are SASL mechanisms we accept anonymous = 0 plain = 1 account ...