1. A method comprising: receiving, at a library, a request to register the library with a library manager, the library comprising a plurality of sub-libraries, each sub-library comprising one or more executable software functions and having an associated register function; in response to the request, calling the associated register function of each of the plurality of sub-libraries; and in response to a register function being called, registering, with the library manager, details of the one or more executable software functions which the sub-library associated with the register function called comprises.