On Sun, Jun 18, 2017 at 12:52 PM, abangkis <abang...@gmail.com> wrote:
> Lets say I have a hashtag entity that i stored in the database and managed > by HashtagDAO (a tapestry service). And then i have a TwitterParserService > that check if a tweet contain a hashtag that i saved in the database. The > problem, if someone add or changed the hashtag in the database i want the > TwitterParserService to immediately know about the change and check the > tweet using the new hashtags. > > In j2se it will be a straight forward pub-sub/observer pattern. Just create > an interface for the listener, let the TwitterParserService implement it > and set as the default listener, and invoke it from HashtagDAO. But i don't > think it would work with tapestry services class. > Why wouldn't it work? Tapestry itself uses this: LinkCreationHub, RegistryStartup, InvalidationEventHub, RegistryShutdownHub, UpdateListenerHub, and that's just the ones I've found in a two-minute search. It would all be synchrononous, though, and messaging services, as far as I know, are asynchronous. -- Thiago
