Project proposal Java Bluetooth stack
What is a Bluetooth stack? n n In short, to get any functionality out of a Bluetooth device, one needs to implement pretty high stack of protocol layers, quite similar to OSI referent model If you buy a Bluetooth device, you get that stack already implemented, and it exposes profiles(services) to the user, such as Serial port profile, LAN access, OBEX file transfer & other
Then why bother… …coding your own Bluetooth stack? Because you get the complete stack (with the hardware you bought), you have no other choice than to use the profiles it has exposed (most commonly used profile is Serial port profile) as virtual COM ports. This results in a limited functionality, and inability to explore the most exciting Bluetooth features: creating pico- and scatter-nets of interoping devices running custom services.
Out there… …there are few alternatives: n Buy commercial stack (library) – you become bound to a single manufacturer, and at his mercy for updates n Use Blue. Z, a free-source Linux Bluetooth stack written in C, or it’s JNI wrapped Java brother, JBlue. Z n That’s about it, there is no free-source Java Bluetooth stack available* (* not quite true, read on )
Goal Is to: n Create open-source, full-featured, all Java Bluetooth stack n Build a flexible solution for accessing Bluetooth hardware and harvesting its possibilities to the fullest, leaving enough space for customization
More goals n To provide a solution for using Bluetooth from Java with all ‘Java’ benefits – portability being the main one – so one could use the same stack to access Bluetooth abilities of mobile phones and a Bluetooth PC Card connected to a standard PC running Linux or Windows
Where to start? From scratch? n Harald Bluetooth stack, created by Johan Eker n (http: //www. control. lth. se/~johane/haral d/), is a good start.
What’s a Harald Bluetooth stack? “a small Bluetooth stack for wireless communication between Java applications” , author calls it n Originally created for testing Bluetooth performance in distributed wireless control application (you can find more here) n
What’s implemented? n n n JOL – Java objects layer, a thin layer for passing Java objects using serialization, non-standard L 2 CAP – converts higher-layer data into HCI packets HCI – communicates with the Bluetooth device through a set of commands and responses
What’s missing? n n n Any type of service discovery – an implementation of SDP – Service Discovery Protocol Serial port emulation based on RFCOMM protocol, is widely used by most of the profiles Custom services can be built even on top L 2 CAP, but SDP is indispensable
Hardware For testing purposes, one could use: n Bluetooth PC Card (PCMCIA card), such as Xircom CBT or other n Bluetooth serial module (like one in Ericsson Application Toolkit) n Bluetooth USB dongle (only on Linux with kernel support for USB, USB not yet implemented in Harald stack)
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