Middies: Passive middleware abstractions for pervasive computing environments

1. Middies: Passive middleware abstractionsfor pervasive computing environments Daniel Cutting, Adam Hudson, Aaron Quigley University of Sydney

2. Pervasive computing Middies Data distribution

3. Pervasive computing • Small mobile devices + large fixed servers • Wireline and wireless communication • Application collaboration • chat, file store, video+audio • matchmaking, games • museum+gallery tours

4. Art gallery scenario Bob was here. Gillian Edward Bob Cynthia Sunflowers, Van Gogh Bob was here.

5. Middleware • Publish-subscribe: good for events • Tuple spaces: good for data persistence • Abstract sockets: good for streaming data

6. Pervasive computing Middies Data distribution

7. Middies • Generalised middleware abstractions • Features of tuple spaces and pub-sub • Store persistent data, publish events and handle streaming data

8. Spaces • Logically centralised shared structures like a tuple space • Physically distributed over several devices

9. Blocks • Data chunks like tuples, events, objects • Stored by spaces permanently (like tuples) or forwarded to interested devices (like events)

10. Matchers • Compare two blocks • Application-defined • Can implement tuple matchers, publish-subscribe subscription languages, etc.

11. Reactors • Callbacks fired by spaces under certain conditions • Can implement events + abstract sockets • Useful for pub-sub and streaming data

12. Pervasive computing Middies Data distribution

13. Data distribution • How do we distribute blocks around the network? • Server? • Single device stores all blocks • Redundant? • Each device stores replicas of all blocks • Or…?

14. Gillian Edward Bob Cynthia Context-aided distribution Group photo at Sunflowers Group photo at Sunflowers Group photo at Sunflowers Nearest situation vector is photo photo digest Unimportant (0.2) Long-lived (0.7) Large size (0.9)

15. Pervasive computing Middies Data distribution