What is all this?

Primarily this is a learning tool to teach me how to use Clojure to build Enterprise Apps. This clearly isn't an Enterprise App :), but it is a play-ground for me to experiement. As such, the requirements are driven by my need for an DevOps tool but also as a play-ground for "how do I do this in Clojure".

The hardest thing I have found in thinking about how to use Clojure is what the shape of the solution should look like. I have spent over a decade training my mind to see (Java) Objects everywhere, both in the design and implementation. This needs some re-learning, and this is (one of) the tool(s) to do that.

Real tool

As well as being a learning tool, this tool will also serve a useful Operations Management goal - ensuring that our internally hosted web sites are available to the outside world. We currently use pingdom but this has a few warts. In the short term, this will be over-engineered. In the long term, this might just turn out to be quite a useful little tool. The tool itself will be a web app which can be configured with a list of URLs to check. A web page will display the statuses of those URLs.

This tool will be heavily inspired (at least at the beginning) by http://pragprog.com/magazines/2011-07/create-unix-services-with-clojure

Future

Initially this tool will be an over-engineered tool with a single web page. In the future, it may grow to be quite rich:

• Check network resources other than URLs (maybe even branching into nagios or zabbix territory here, which is fine)
• External DSL (probably using ANTLR) for defining resources to check
• Extensible notification mechanism (probably event-based so listeners respond to "resourceDown" events etc.)
• Push based web app (using COMET? No idea) rather than Ajax based pull model

Goals

• Solve a problem we currently have (monitoring our services)
• Sandbox for learning Clojure the language and eco-system (libraries, build-tools)
• See what happens when an old OO dude tries to wear functional glasses