S'assure que le nœud récepteur n'est pas le fournisseur, puis enregistre l'abonnement et publie l'événement SUBSCRIBE_SET vers les autres nœuds.

declare
        p_sub_set                       alias for $1;
        p_sub_provider          alias for $2;
        p_sub_receiver          alias for $3;
        p_sub_forward           alias for $4;
        v_set_origin            int4;
        v_ev_seqno                      int8;
        v_rec                   record;
begin
        -- ----
        -- Grab the central configuration lock
        -- ----
        lock table sl_config_lock;

        -- ----
        -- Check that this is called on the provider node
        -- ----
        if p_sub_provider != getLocalNodeId('_schemadoc') then
                raise exception 'Slony-I: subscribeSet() must be called on provider';
        end if;

        -- ----
        -- Check that the origin and provider of the set are remote
        -- ----
        select set_origin into v_set_origin
                        from sl_set
                        where set_id = p_sub_set;
        if not found then
                raise exception 'Slony-I: subscribeSet(): set % not found', p_sub_set;
        end if;
        if v_set_origin = p_sub_receiver then
                raise exception 
                                'Slony-I: subscribeSet(): set origin and receiver cannot be identical';
        end if;
        if p_sub_receiver = p_sub_provider then
                raise exception 
                                'Slony-I: subscribeSet(): set provider and receiver cannot be identical';
        end if;

        -- ---
        -- Verify that the provider is either the origin or an active subscriber
        -- Bug report #1362
        -- ---
        if v_set_origin <> p_sub_provider then
                if not exists (select 1 from sl_subscribe
                        where sub_set = p_sub_set and 
                              sub_receiver = p_sub_provider and
                              sub_forward and sub_active) then
                        raise exception 'Slony-I: subscribeSet(): provider % is not an active forwarding node for replication set %', p_sub_provider, p_sub_set;
                end if;
        end if;

        -- ----
        -- Create the SUBSCRIBE_SET event
        -- ----
        v_ev_seqno :=  createEvent('_schemadoc', 'SUBSCRIBE_SET', 
                        p_sub_set::text, p_sub_provider::text, p_sub_receiver::text, 
                        case p_sub_forward when true then 't' else 'f' end);

        -- ----
        -- Call the internal procedure to store the subscription
        -- ----
        perform subscribeSet_int(p_sub_set, p_sub_provider,
                        p_sub_receiver, p_sub_forward);

        return v_ev_seqno;
end;