Options for application communication between two android phones

I n开发者_JAVA技巧eed to establish communication between two android phones (same application, if it matters).

Is there any possibility for android applications to establish a data stream via bluetooth (so there is no need for internet connection)?

Or (UDP)TCP/IP over internet is currently best solution?

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Since Android 2.0 it should be possible to use the bluetooth API (see here).

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In android 1.5, i believe, there's no file transfer via bluetooth. In order to be version agnostic, bump transfers all the data via their servers i believe.