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Add CMakeLists.txt for Mbed CLI v2 #35

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37 changes: 37 additions & 0 deletions CMakeLists.txt
Original file line number Diff line number Diff line change
@@ -0,0 +1,37 @@
add_library(mbed-mqtt INTERFACE)
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Please add a license header

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Does this need to be an interface? I suspect STATIC would work for this library (no weak linking symbols) ?

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Would this license header be sufficient? No names, just copyright, and SPDX identifier.

# Copyright (c) 2021 ARM Limited. All rights reserved.
# SPDX-License-Identifier: Apache-2.0

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Does this need to be an interface? I suspect STATIC would work for this library (no weak linking symbols) ?

I think you are right. Give me a couple more days and I will figure it out how to make it compile being STATIC. I'm not really competent neither with cmake nor with mbed-os' CMakeLists.txt files organization.

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I've changed my mind. Here is the reason why I think this library should be declared as INTERFACE:

  1. When it is declared as STATIC, it anyways turns out to be built alongside with mbed-os in any project. Therefore it uses all the same macros passed to the compiler on invocation. Consider an example when I have mbedtls-config-changes.h file in the root of my project and I pass it as "MBEDTLS_USER_CONFIG_FILE=\"mbedtls-config-changes.h\"" in mbed_app.json. This MBEDTLS_USER_CONFIG_FILE macro is passed to mbed-mqtt sources too when it is being built and this config header file cannot be found, because mbed-mqtt is being built separately as a static library and it is not aware of my project's root directory where the file is located. To mitigate this error I have to declare something like this in my project's root CMakeLists.txt: target_include_directories(mbed-mqtt PRIVATE .). When mbed-mqtt declared as INTERFACE there is no such problems.

  2. When it is declared as STATIC, all mbed-mqtt dependencies are built separately from the project and number of files to be compiled becomes almost twice as many than if it was declared as INTERFACE - 868 files when INTERFACE vs 1717 when STATIC in my case. Basically the whole OS is being built twice. This is inconvenient.

  3. I have no evidence of any library for mbed-os declared as STATIC - they all are declared as INTERFACE. Why mbed-mqtt should not be declared as INTERFACE?


target_include_directories(mbed-mqtt
INTERFACE
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/
./paho_mqtt-sn_embedded_c/MQTTSNClient/src/
./paho_mqtt_embedded_c/MQTTPacket/src/
./paho_mqtt_embedded_c/MQTTClient/src/
./paho_mqtt_embedded_c/MQTTClient/src/mbed/
./src/
)

target_sources(mbed-mqtt
INTERFACE
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNSerializePublish.c
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNSubscribeServer.c
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNUnsubscribeServer.c
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNPacket.c
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNConnectServer.c
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNSearchClient.c
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNUnsubscribeClient.c
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNSubscribeClient.c
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNSearchServer.c
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNConnectClient.c
./paho_mqtt-sn_embedded_c/MQTTSNPacket/src/MQTTSNDeserializePublish.c
./paho_mqtt_embedded_c/MQTTPacket/src/MQTTSerializePublish.c
./paho_mqtt_embedded_c/MQTTPacket/src/MQTTConnectServer.c
./paho_mqtt_embedded_c/MQTTPacket/src/MQTTConnectClient.c
./paho_mqtt_embedded_c/MQTTPacket/src/MQTTDeserializePublish.c
./paho_mqtt_embedded_c/MQTTPacket/src/MQTTUnsubscribeServer.c
./paho_mqtt_embedded_c/MQTTPacket/src/MQTTPacket.c
./paho_mqtt_embedded_c/MQTTPacket/src/MQTTUnsubscribeClient.c
./paho_mqtt_embedded_c/MQTTPacket/src/MQTTSubscribeClient.c
./paho_mqtt_embedded_c/MQTTPacket/src/MQTTSubscribeServer.c
./paho_mqtt_embedded_c/MQTTPacket/src/MQTTFormat.c
./src/MQTTClientMbedOs.cpp
)
16 changes: 16 additions & 0 deletions README.md
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,22 @@ See [mbed_lib.json](mbed_lib.json) for all configurable options.

See [test README](TESTS/mqtt/README.md) to find out about tests-specific configuration configuration.

### Building with CLI V2

Assuming you have this repository cloned or somehow available at the `<your-project-root>/mbed-mqtt` directory.

Add to your project's `CMakeLists.txt` file the following lines:

```
add_subdirectory(mbed-mqtt)

target_link_libraries(${APP_TARGET} mbed-mqtt)
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group them together to one target_link_libraries()

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Okay, I'll do it.

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Done. I've declared all dependencies explicitly, so this list has shrunk to just single entry mbed-mqtt.

target_link_libraries(${APP_TARGET} mbed-mbedtls)
target_link_libraries(${APP_TARGET} mbed-nanostack)
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why nanostack is required , shouldn't this be up to a consumer of this library (mqtt) to choose a stack (netsockets/nanostack, etc) ?

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Well, it is up to a consumer here, since it is just a suggestion in README.md for a user. It provides an example of how you link all dependencies while linking against mbed-mqtt library.

It now fails to compile, though, when I began tinkering with STATIC declaration you've mentioned above: TCPSocket.h: No such file or directory. I need some time to figure out how properly declare dependency on a network stack.

Anyway, thank you very much for the review so far!

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@Oxore Oxore May 18, 2021

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It now has mbed-netsocket explicitly declared as it's dependency.

target_link_libraries(${APP_TARGET} mbed-greentea)
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is greentea required? I dont think so (testing with greentea needs work to be enable with CMake)

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Technically it is required for now, because otherwise it won't compile. But if PR #34 would be merged, then it will no longer be required and mbed-mqtt will be compileable without greentea dependency.


```

### API and usage

Mbed-os uses [Eclipse paho project emmbedded c implementation of MQTT protocol](https://github.com/eclipse/paho.mqtt.embedded-c) and [MQTT-SN protocol](https://github.com/eclipse/paho.mqtt-sn.embedded-c/).
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