About Alljoyn daemons, clients and services

asked 2014-04-21 04:12:44 -0700

hjjang gravatar image

updated 2014-04-21 11:26:28 -0700

bspencer gravatar image


I have some questions about the way a client finds services on a remote device.

The question comes from the following scenario : Let's assume there are three devices A,B and C. The device A supports only WiFi as its transport, B supports only BT and C supports both WiFi and BT.

My first question here is that is it possible a client on the device A to communicate with a service on the device B through the C device ?

And if it is possible, does the device C relay "Advertise-name" requests from the device B to the device A by default?

(It seems that it is not possible a daemon on the device A to receive "Advertise-name" requests directly from the device B because of their difference of transports, and this is why I am asking this question.)

Thank you.

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answered 2014-04-21 11:33:44 -0700

bspencer gravatar image

AllJoyn as it exists is transport independent and as such can work in the above scenario. There are some need-to-know bits of information in order to discuss. First in the current software stack with the AllJoyn Standard Library there is support for IP transports only. That being said it would be possible to run AllJoyn over BT but it becomes a challenge on only having certain devices able to participate in the BT connection and it fragments the user experience.

The use of BT really makes sense for an AllJoyn Thin Library implementation. Where Device B is some sensor or device that uses the Thin Library and has a BT connection to device C that has the AllJoyn Router software updated to include a BT implementation for Thin Library applications. Using this setup because B is a Thin Library application device C is going to advertise and publish session-less signals on behalf of device B. Now A can easily find and connect to B.

In contrast if the applications were all AllJoyn Standard Library applications then the situation is different. Device A could not discover B because C would not forward advertisements. If there was a session established between A and C when B joined that session (assume multi-point session) then A will be able to interact and communicate with B. C is the only device that would "find" both A and B, again, it does not forward advertisements.

The above device situation really makes the most sense when using the Thin Library running on device B.

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Asked: 2014-04-21 04:12:44 -0700

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Last updated: Apr 21 '14