Semian is a library for controlling access to slow or unresponsive external services to avoid cascading failures.Resource drivers are monkey-patched to be aware of Semian, these are called Semian Adapters. Thus, every time resource access is requested Semian is queried for status on the resource first. If Semian, through the patterns above, deems the resource to be unavailable it will raise an exception. The ultimate outcome of Semian is always an exception that can then be rescued for a graceful fallback. Instead of waiting for the timeout, Semian raises straight away.