[example] add minimum thread commissioner example

[wgtdkp]

This PR adds a minimum Thread Commissioner example that demos how to build a Commissioner Application with the OT Commissioner library.

resolves issue: #165

[krbvroc1]

Here are my initial comments:

Installing the static libraries appear to work now. And uninstall also works.

-rw-r--r--  1 root root  25757164 Feb  3 15:34 libcommissioner.a
-rw-r--r--  1 root root   3420392 Feb  3 15:34 libcommissioner-common.a
-rw-r--r--  1 root root    778910 Feb  3 15:33 libevent_core.a
-rw-r--r--  1 root root     15028 Feb  3 15:33 libevent_pthreads.a
-rw-r--r--  1 root root   2787040 Feb  3 15:34 libfmtd.a
-rw-r--r--  1 root root   5580184 Feb  3 15:34 libmbedcrypto.a
-rw-r--r--  1 root root   1884926 Feb  3 15:34 libmbedtls.a
-rw-r--r--  1 root root   1080600 Feb  3 15:34 libmbedx509.a
-rw-r--r--  1 root root     27516 Feb  3 15:34 libmdns.a

I followed the instructions in BUILDING.md and it does not work. It seems the CMakeList.txt is not complete.

$ cmake -GNinja ..
CMake Error at CMakeLists.txt:29 (project):
  VERSION not allowed unless CMP0048 is set to NEW

CMake Warning (dev) in CMakeLists.txt:
  No cmake_minimum_required command is present.  A line of code such as

    cmake_minimum_required(VERSION 3.13)

  should be added at the top of the file.  The version specified may be lower
  if you wish to support older CMake versions for this project.  For more
  information run "cmake --help-policy CMP0000".
This warning is for project developers.  Use -Wno-dev to suppress it.

I created my own out of tree mini commissioner and I needed the following (I am a cmake novice):

target_link_libraries(mini_commissioner
  commissioner
  commissioner-common
  event_core
  event_pthreads
  mbedtls
  mbedx509
  mbedcrypto
  mdns
  fmtd
  pthread
)

For a command line compile, rather than what is in BUILDING.md, I had to use the following:

c++ main.cpp -o mini_commissioner -lcommissioner -lcommissioner-common -levent_core -levent_pthreads -lmbedtls -lmbedx509 -lmbedcrypto -lmdns -lfmtd -lpthread

Not sure how difficult it is or if you have a suggestion... It would be nice if the ninja install of the libraries would install the associated fmt/fmtlib include files to /usr/local/include so the mini_commissioner can use the installed library. Maybe there is a better way, but right now I have to include ot-commissioner/third_party/fmtlib/repo/include/fmt/ to be able to use the installed library for printing. Maybe this is out of scope.

I also noticed as part of this PR you made a change to src/library/commissioner_impl.cpp and how OnJoinerRequest() is called. What is the purpose of that change?

[wgtdkp]

@krbvroc1

I followed the instructions in BUILDING.md and it does not work. It seems the CMakeList.txt is not complete.

What platform and CMake version are you using? For whatever failure reason, I updated the CMake file to define the mininum required version, please let me know if this still not working for your platform.

Not sure how difficult it is or if you have a suggestion... It would be nice if the ninja install of the libraries would install the associated fmt/fmtlib include files to /usr/local/include so the mini_commissioner can use the installed library. Maybe there is a better way, but right now I have to include ot-commissioner/third_party/fmtlib/repo/include/fmt/ to be able to use the installed library for printing. Maybe this is out of scope.

I think this should not be addressed by the commissioner libary. We don't include any third party headers in the commissioner public headers, so there is no necessary to (and should not) install those thrid-party headers. If your project depends on fmtlib, then I think it is your project that should worry about installing and including fmtlib, either the one in commissioner third-party or another independent copy (e.g. installed in system directories).

I also noticed as part of this PR you made a change to src/library/commissioner_impl.cpp and how OnJoinerRequest() is called. What is the purpose of that change?

It is to make the OnJoinerRequest() called only for the first time a packet from joiner is received, but not every time: We just need the pskd for the first time.

For a command line compile, rather than what is in BUILDING.md, I had to use the following:
c++ main.cpp -o mini_commissioner -lcommissioner -lcommissioner-common -levent_core -levent_pthreads -lmbedtls -lmbedx509 -lmbedcrypto -lmdns -lfmtd -lpthread

Sorry I was building shared libraries, I updated the document to to build shared libraries to get rid of the long list third-party libs.

[krbvroc1]

What platform and CMake version are you using? For whatever failure reason, I updated the CMake file to define the mininum required version, please let me know if this still not working for your platform.

That change is working.

cmake version 3.13.4 - running on the latest Raspbian version. (Compiling on an OTBR).

Thank you!

[wgtdkp]

cmake version 3.13.4 - running on the latest Raspbian version. (Compiling on an OTBR).

That's weird, I am using a CMake with lower version but has no errors. Maybe new CMake is more strict about this...

[codecov-commenter]

Codecov Report

Merging #167 (4fde540) into main (79ad31d) will not change coverage.
The diff coverage is n/a.

❗ Current head 4fde540 differs from pull request most recent head 92ce01f. Consider uploading reports for the commit 92ce01f to get more accurate results

@@           Coverage Diff           @@
##             main     #167   +/-   ##
=======================================
  Coverage   68.90%   68.90%           
=======================================
  Files          55       55           
  Lines        4933     4933           
=======================================
  Hits         3399     3399           
  Misses       1534     1534           

[wgtdkp]

This PR depends on #188: the second commit is a cherry-pick of #188.