WSI itself don’t have any strange requirements. Any decent host should be ok with the following:
- PHP >= 5.3.0 installed
- WSI Endpoint URLs reachable
- PHP’s default SESSION handling
- PHP/cURL/SSL Extension enabled
- PHP/JSON Extension enabled
- PHP/REGISTER_GLOBALS Off
You can do a simple requirements test by using the wsi test file located right in the plugin. Just install the free version and go to the debug tab.