1. Terminal Bridge Extension Over Distributed Architecture MSc. Sami Saalasti

2. Agenda Overview of Current Situation Service Distribution CORBA Wireless CORBA Terminal Bridge Extension Use-Cases Conclusions

3. Overview of Current Situation Wireless networks have become common varying from small Bluetooth networks to large-scale GSM networks Combining different networks provides a situation where we can use “best features from every technology” However, no general model for using these different wireless technologies together

4. Service Distribution Distributed Service Architecture describes a network environment which offers shared services to network users Services can be distributed by using different approaches over CORBA or the Wireless CORBA Both CORBA architectures can support several wireless networking technologies such as Bluetooth, WLAN and GPRS The idea is to provide access to a shared service from different kinds of mobile networks

5. CORBA 1/2 Common Object Request Broker Architecture (CORBA), OMG's open architecture and infrastructure that computer applications use to work together over networks to perform remote invocations Using the standard protocol Internet Inter-ORB Protocol (IIOP), vendor independent interoperability can be reached

6. CORBA 2/2 Network layer is completely hidden from applications, argument marshalling, connection handling, flow control handled by the Object Request Broker (ORB) Underlying network must be reliable because no connection failures are expected

7. Wireless CORBA 1/3 New evolution of CORBA, the Wireless CORBA has been developed to specially operate on wireless networks Wireless CORBA offers a software middleware solution for communication on several platforms with capability of performing flexible change of network access point (handoff)

8. Wireless CORBA 2/3 New components: Terminal Bridge (TB), Access Bridge (AB) and Home Location Agent (HLA) Wireless CORBA utilizes centralized service model which provides one centralized service which can be accessed through several Access Bridges

9. Wireless CORBA 3/3 There may be multiple wireless networks available and the Wireless CORBA lacks methods to detect possible new networks if the current connection drops. No implementation for monitoring the connection status No implementation for handoff automation when connection weakens

10. Terminal Bridge Extension 1/2 Extension automates the handoff process and guards the connection state by monitoring signalling level If the current connection seems to be too weak, the Terminal Bridge extension selects another available access point and commands Terminal Bridge to perform a handoff

11. Terminal Bridge Extension 2/3

12. Terminal Bridge Extension 3/4 Extension was used over the underlying Wireless CORBA architecture which was operating over TCP/IP (WLAN and GPRS) and L2CAP (Bluetooth) The task of the extension was to guide the Terminal Bridge to select always the most suitable network

13. Terminal Bridge Extension 4/4

14. Use-Cases 1/3

15. Use-Cases 2/3

16. Use-Cases 3/3

17. Conclusions 1/2 Wireless CORBA and Terminal Bridge Extension provides very flexible architecture to use distributed services in changing wireless environment Using very different wireless technologies together provides new possibilities for creating and using services

18. Conclusions 2/2 Currently, Bluetooth is problematic technology: inquiry and connection times can kill usability very effectively if user moves a lot from one network area to other If plain Bluetooth network is used, it should be designed very precisely because one gap in the network coverage area breaks the link. Better solution would be to use WLAN in the background and then decide what kind of Bluetooth network can be built GPRS creates completely different possibilities to use services on a wider area because network coverage is no more as restricting factor