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70 lines
3.0 KiB
Markdown
70 lines
3.0 KiB
Markdown
# gcoap Example
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This application provides command line access to gcoap, a high-level API for CoAP messaging. See the [CoAP spec][1] for background, and the Modules>Networking>CoAP topic in the source documentation for detailed usage instructions and implementation notes.
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We support two setup options for this example:
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### Native networking
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Build with the standard `Makefile`. Follow the setup [instructions][2] for the gnrc_networking example.
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### SLIP-based border router
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Build with `Makefile.slip`. Follow the setup instructions in README-slip.md, which are based on the [SLIP instructions][3] for the gnrc_border_router example. We also plan to provide or reference the ethos/UHCP instructions, but we don't have it working yet.
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## Current Status
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gcoap includes server and client capability. Available features include:
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* Server and Client provide helper functions for writing the response/request. See the CoAP topic in the source documentation for details. See the gcoap example for sample implementations.
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* Server allows an application to register a 'listener', which includes an array of endpoint paths and function callbacks used to write a response.
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* Server listens on a port at startup; defaults to 5683.
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* Client operates asynchronously; sends request and then handles response in a user provided callback. Also executes callback on timeout.
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* Client generates token; length defined at compile time.
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* Message Type: Supports non-confirmable (NON) messaging.
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* Options: Supports Content-Format for response payload.
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## Example Use
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This example uses gcoap as a server on RIOT native. Then we send a request from a libcoap example client on the Linux host.
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### Verify setup from RIOT terminal
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> coap info
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Expected response:
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CoAP server is listening on port 5683
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CLI requests sent: 0
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CoAP open requests: 0
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### Query from libcoap example client
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gcoap does not provide any output to the CoAP terminal when it handles a request. We recommend use of Wireshark to see the request and response. You also can add some debug output in the endpoint function callback.
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./coap-client -N -m get -p 5683 coap://[fe80::1843:8eff:fe40:4eaa%tap0]/.well-known/core
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Example response:
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v:1 t:NON c:GET i:0daa {} [ ]
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</cli/stats>
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The response shows the endpoint registered by the gcoap CLI example.
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### Send query to libcoap example server
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Start the libcoap example server with the command below.
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./coap-server
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Enter the query below in the RIOT CLI.
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> coap get fe80::d8b8:65ff:feee:121b 5683 /.well-known/core
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CLI output:
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gcoap_cli: sending msg ID 743, 75 bytes
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> gcoap: response Success, code 2.05, 105 bytes
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</>;title="General Info";ct=0,</time>;if="clock";rt="Ticks";title="Internal Clock";ct=0;obs,</async>;ct=0
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[1]: https://tools.ietf.org/html/rfc7252 "CoAP spec"
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[2]: https://github.com/RIOT-OS/RIOT/tree/master/examples/gnrc_networking "instructions"
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[3]: https://github.com/RIOT-OS/RIOT/tree/master/examples/gnrc_border_router "SLIP instructions"
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