Il s'agit de savoir comment des composants distribués vont discuter entre eux... Communication "directe" (couplage fort, RPC/RMI) ou par message (couplage faible, JMS).
Quelques explications par Sun (auteur des specs JMS) sur l'intérêt d'un couplage lâche et des situations dans lesquelles on pourra en tirer avantage, dans le tutorial JMS (Java Messaging Service) de Sun.

An enterprise application provider is likely to choose a messaging API over a tightly coupled API, such as Remote Procedure Call (RPC), under the following circumstances.

  • The provider wants the components not to depend on information about other components' interfaces, so that components can be easily replaced.
  • The provider wants the application to run whether or not all components are up and running simultaneously.
  • The application business model allows a component to send information to another and to continue to operate without receiving an immediate response.

Tout lire parce que c'est passionant