Remembers which assertions have been accepted, so none is accepted twice (the one-time use SAML Profiles 4.1.4.5 asks of a bearer assertion).
Give the service provider one shared by every process when the application runs more than one.
Records id as used until expiresAt, and answers whether it had ALREADY been recorded. Must be
atomic: two concurrent calls with one id must not both answer false.
Remembers which assertions have been accepted, so none is accepted twice (the one-time use SAML Profiles 4.1.4.5 asks of a bearer assertion). Give the service provider one shared by every process when the application runs more than one.