SRU::Server3pm

    package MySRU;
    use base qw( SRU::Server );
    sub explain {
        my $self = shift;
        # $self->request isa SRU::Request::Explain
        # $self->response isa SRU::Response::Explain
    }
    sub scan {
        my $self = shift;
        # $self->request isa SRU::Request::Scan
        # $self->response isa SRU::Response::Scan
        # $self->cql is the root node of a CQL::Parser-parsed query
    }
    sub searchRetrieve {
        my $self = shift;
        # $self->request isa SRU::Request::SearchRetrieve
        # $self->response isa SRU::Response::SearchRetrieve
        # $self->cql is the root node of a CQL::Parser-parsed query
    }
    package main;
    MySRU->new->run;