Wt

Hey,

I like the suggestion. I think we need to implement it, it looks like a fun feature, and should be done by using WServer::post().

I think we need to add a utiliy class in Wt that implements this that implements this on behalf of one or more Dbo::Session classes (typically one per listening application), and internally keeps track of interested sessions/listeners. It needs a dedicated database connection, and thread (libpq's API for this is synchronous and requires polling, but they suggest you can select() on the connection). We should thus provide basic support for this in the SqlConnection class.

e.g.

class WDboReactor : public WObject
{
public:
  WDboReactor(SqlConnection *connection);

  void notify(const std::string& message);

  template <typename T>
  std::string encodeMessage(const std::string& event, const Wt::Dbo::ptr<T>& object);

  template <typename T>
  bool decodeMessage(const std::string& message, std::string& event, Wt::Dbo::ptr<T>& object);

  void addListener(WObject *object);
  void removeListener(WObject *object);

  Signal<WObject *object, std::string>& notified(); // emitted within the same application as the object lives, using WServer::post().
};

I would suggest to have both a Dbo::ptr<> and a string as parameters.

Regards,

koen