Zephyr coap client #56970
Zephyr coap client #56970
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@SeppoTakalo @juhaylinen @plskeggs please review. |
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This is a good start for use cases where a single request/response at a time is all that is needed.
I wonder if there are use cases for low power IoT devices which would want to POST or PUT multiple items (for example, sensor data readings), and not wait for ACK between each one, but instead handle that at the end. Overlapping transfers could save battery life in that situation.
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| /** | ||
| * @brief Internal structure of CoAP client, shouldn't be modified. | ||
| */ | ||
| struct coap_client { |
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The current implementation has a stack per CoAP client, if I were to do multiple requests at the same time, I either need to do these sequentially or create a client for each request, which is very costly.
This becomes even more apparent if I need to observe multiple server resources (long lasting requests).
It would be great if a single client could support multiple requests.
I think this is doable if you would move some members from struct coap_client to struct coap_client_req to keep track if a single request state. And let the client keep track of al ongoing requests (for example in a linked list).
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The multiple request is planned also, and doesn't need changes to the public API.
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jarlamsa
requested review from
SeppoTakalo,
rlubos,
pdgendt,
jukkar and
plskeggs
| struct coap_client_request *coap_request; | ||
| struct coap_packet request; | ||
| k_tid_t tid; | ||
| struct k_thread thread; |
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Having to spawn a separate thread for each client context seems like a lot of RAM overhead - couldn't the library have a single thread that would monitor all active requests (i. e. sockets)?
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Yes, will be done in the future, as well as the multi-request version of the client.
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Ok, if there are plans to improve this in the future then I guess we can accept that.
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I would've liked to have this functionality in this PR, as users will need to update/refactor their code in the future.
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Wouldn't such a change be transparent for the applications? Yes, the application allocates the client context structure, but it's internals should not be used by the app (coap_client_init() configures the thread).
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Nice work! Could you please add a reference to this new API to the docs, so that the Doxygen comments are rendered and people are aware that the CoAP client exists? |
Yes, I plan to do that in a separate PR and add also similar usage example as is done with the HTTP-client. |
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I was planning on adding the documentation to different PR, but as there was still some changes, I pushed the documentation to this PR as well. |
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Thank you @SeppoTakalo for your review comments, I have addressed those now. Please re-review. |
The coap client takes requests and provides responses asynchronously to callback given in a request. Currently supports only 1 request at a time. Signed-off-by: Jarno Lämsä <jarno.lamsa@nordicsemi.no>
Add tests for coap client and stubs for isolating the tests. Signed-off-by: Jarno Lämsä <jarno.lamsa@nordicsemi.no>
Sample usage and documentation of the CoAP client. Signed-off-by: Jarno Lämsä <jarno.lamsa@nordicsemi.no>
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@rlubos please re-review. |
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This now has 2 approvals with write access, could we get this merged in? @jukkar |
Add an asynchronous coap client.
The coap client processes requests, sends those to server and awaits for response.
Currently supports 1 request at a time.