It now occurs to me that I never planned out my testing environment. While I could continue testing through Palantir's web frontend, that frontend will become unavailable after 5 days when Palantir ceases hosting my OCC server instance... meaning I'll need to download the source code and host it myself. So, what does my environment need?
Well, I need to host a web service. I usually prefer working in Linux for anything web-related, it's less restrictive than Windows and finding help online is generally easier. I've mainly worked in Ubuntu in the past, so that's my distribution. For software, I'll go with the standards: Eclipse to work with code and cURL to execute requests against the service. I'll probably need hosting software for the service itself, Apache Tomcat appears to be popular and have nice integration with Eclipse. And finally, I'll need somewhere to keep track of my bugs. I'd like to try JIRA (if a free version is available), otherwise I'll look into Bugzilla.
I don't have a spare machine to run Ubuntu on right now, so I'll be setting up a VM using VitualBox.
UPDATE: May 22, 2014
I've had a busy few days away from the project, now I'm back at it and have more or less completed my environment setup.
Unsurprisingly, my choice of the latest Ubuntu version (14.04) combined with a months-old version of VirtualBox resulted in frequent crashes. Various combinations of Ubuntu and Virtualbox version showed no improvement, apparently due to a conflict between virtualbox and my graphics driver. I don't want to waste any more time on this issue so...
Option 2: set up an Ubuntu dual-boot on my Windows machine. This turned out to be relatively painless; create a bootable Ubuntu USB (following instructions on Ubuntu's website), create an empty unformatted partition on one of my Windows drives, boot the USB and select the dubious 'Install Alongside Windows" option. The installer was smart enough to put Ubuntu in that empty chunk of drive space without asking, and the OS seems to be working just fine.
Software should be an easier matter, Eclipse and cURL are free to install and use, and don't require any further configuration for my purposes. Palantir provides an executable JAR of the OCC service which was able to get itself running locally without any help. For convenience/comfort, I'm also going to install Google Chrome and the POSTMan extension, which is graphical alternative to cURL for sending HTTP requests and viewing the responses. To track bugs, I've gone with a free trial of JIRA which, like OCC was able to get itself up and running with little configuration.