Ambient-Oriented Programming

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at:introduction [2007/06/19 16:48] – tvcutsemat:introduction [2007/06/19 16:49] – tvcutsem
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 <code> <code>
-  defstripe InstantMessenger;+  deftype InstantMessenger;
   export: remoteInterface as: InstantMessenger;   export: remoteInterface as: InstantMessenger;
   whenever: InstantMessenger discovered: { |messenger|   whenever: InstantMessenger discovered: { |messenger|
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 </code> </code>
  
-The ''whenever:discovered:'' method takes a stripe and a one-argument closure as parameters. It invokes the closure every time a remote object exported as the given stripe is discovered. The first thing to do when a new messenger is discovered is to ask it for its name, by sending it the ''getName'' message. If the messenger was not previously discovered (i.e. its name is not in the buddy list), the messenger is added and the user is notified of the presence of the new buddy.+The ''whenever:discovered:'' method takes a type tag and a one-argument closure as parameters. It invokes the closure every time a remote object exported with (a subtype of) the given type tag is discovered. The first thing to do when a new messenger is discovered is to ask it for its name, by sending it the ''getName'' message. If the messenger was not previously discovered (i.e. its name is not in the buddy list), the messenger is added and the user is notified of the presence of the new buddy.
  
 Finally, notice how AmbientTalk allows you to deal with //partial failures//: you can register two kinds of //observers// on remote references which are triggered when the remote reference becomes disconnected (because of e.g. network partitions) and when it becomes reconnected. The second argument to ''when:disconnected:'' and ''when:reconnected:'' is a zero-arity closure. In this example, all we do is notify the user that a buddy when offline or came online. AmbientTalk's default semantics is to buffer messages sent to disconnected remote references internally, and to flush such messages if the remote reference should become reconnected. This provides the nice property that we can send messages to disconnected buddies and rest assured that the messages will arrive when the buddy rejoins the ad hoc network. Finally, notice how AmbientTalk allows you to deal with //partial failures//: you can register two kinds of //observers// on remote references which are triggered when the remote reference becomes disconnected (because of e.g. network partitions) and when it becomes reconnected. The second argument to ''when:disconnected:'' and ''when:reconnected:'' is a zero-arity closure. In this example, all we do is notify the user that a buddy when offline or came online. AmbientTalk's default semantics is to buffer messages sent to disconnected remote references internally, and to flush such messages if the remote reference should become reconnected. This provides the nice property that we can send messages to disconnected buddies and rest assured that the messages will arrive when the buddy rejoins the ad hoc network.
at/introduction.txt · Last modified: 2008/07/15 12:19 by tvcutsem