Enterprise Rails

Integrating with the MoviesService

Because we’ve ripped our application in two, we need some way to link the data in the two applications back together. I’ve already alluded to the idea that a MovieShowtime object is the “product” of the MoviesService, and that the MoviesService needs to obtain and track product ids returned from the OrdersService. To accomplish this, we need to add a product_id column to the movie_showtimes table, as shown in Example 16-10. Note that the column type is text, rather than integer. Just as OrdersService strives to maintain independence from its clients, so too should clients add a layer of abstraction between themselves and the services they consume. Although the product ids are integers today, they might not be forever. Since there is no explicit reference to maintain within the movies database, the schema can be built to be generic enough to support today’s as well as tomorrow’s needs.

Example 16-10. Modifications to the movie_showtimes table to support an orders service

create table movie_showtimes (
  id integer not null
    default nextval('movie_showtimes_id_seq'),
  movie_id integer not null
    references movies(id),
  theatre_id integer not null
    references theatres(id),
  room varchar(64) not null,
  start_time timestamp with time zone not null,
  primary key (id),
  product_id text,
  unique(movie_id, theatre_id, room, start_time),
  foreign key (theatre_id, room)
    references auditoriums(theatre_id, room) initially deferred
);

We also need to instrument the registration ...