Specific systems may fix this behaviour or offer different options based on preferences in a user profile. The logout use case may also be initiated by the system, say after a time-out period, and similarly with the end session use case. There are many specialisations of discover including free-text search, metadata search, browse, view bookmarks, what's new, cited references, cited by, etc. Different systems will offer different discover services, and different discover services will be available in different contexts. User enters required configuration parameters.
Service providers provide results.
Results are presented to user. The system may make the tool available without the user having to select it, for example, a free-text search box may appear on every page. For complex tools, the user may be taken through a series of requests for parameters. There may be too many results, in which case tools for refining the search may be offered. There may be no appropriate results, in which case the user will be offered a choice of discover tools to try again.