Can I detect if a magento function is being run as an API call?

I know I can detect if a function is being run by an admin using:

Mage::getSingleton('admin/session')->isLoggedIn开发者_如何转开发();

But I'm not sure if there is a similar call to determine if the environment is an API call versus a web visit.

You could check if the Mage_Api_Model_Server singleton has been initialized:

$apiRunning = Mage::getSingleton('api/server')->getAdapter() != null;

For those of you who are coming across this question who need something that works for v2 of the API, this appears to work for me:

Mage::getSingleton('api2/request')->getApiType() !== null