implentation of XEP-0346 (Form Discovery and Publishing): The former non standard node schema has been replaced by XEP-0346 which uses 2 nodes (one from schema/template and one for submitted values). The implementation is an adapation of the former one, and data validation is still done even if this is not currently specified in any XEP. When the template node is modified, the change is reflected in the node schema.

create table callbacks (
    service text not null,
    node text not null,
    uri text not null,
    PRIMARY KEY (service, node, uri)
);