3. Compiling client applications

3.1. Compiling the library

Important

If you cloned Anjay from a Git repository, ensure that you updated submodules by calling git submodule update --init before continuing.

Anjay uses CMake for project configuration. To compile the library with default settings, call the following command in Anjay root directory:

cmake . && make

3.2. Cross-compiling

Note

Cross-compilation is necessary only if you are compiling the library to use on a different system, than the one used for compilation. If you, for example, want to use Anjay on Raspberry Pi, then you can perform compilation on Raspberry Pi as described above or cross-compilation on your PC.

3.2.1. ARM Cortex-M3-powered STM3220

First, prepare a CMake toolchain file (see CMake documentation), then pass CMAKE_TOOLCHAIN_FILE when configuring Anjay:

cmake -DCMAKE_TOOLCHAIN_FILE=$YOUR_TOOLCHAIN_FILE . && make

An example CMake toolchain file for an ARM Cortex-M3-powered STM3220 platform may look like so:

set(CMAKE_SYSTEM_NAME Generic)
set(CMAKE_SYSTEM_VERSION 1)

set(CMAKE_C_COMPILER arm-none-eabi-gcc)

# CMAKE_C_FLAGS set in a toolchain file get overwritten by CMakeCInformation.cmake
# unless they are FORCEfully set in the cache
# See http://stackoverflow.com/a/30217088/2339636
unset(CMAKE_C_FLAGS CACHE)
set(CMAKE_C_FLAGS "-mcpu=cortex-m3 -mthumb -msoft-float -ffunction-sections -fdata-sections -fno-common -fmessage-length=0 -std=gnu99 --specs=nosys.specs" CACHE STRING "" FORCE)

set(CMAKE_EXE_LINKER_FLAGS "-Wl,-gc-sections")

3.2.2. Android

Compilation on Android platform is rather straightforward. First you have to get Android NDK. To configure Anjay you have to pass CMAKE_TOOLCHAIN_FILE from the NDK (we assume that ANDROID_NDK variable contains a path to the folder where Android NDK is extracted):

cmake -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK/build/cmake/android.toolchain.cmake \
      -DDTLS_BACKEND="" \
      -DANDROID_ALLOW_UNDEFINED_SYMBOLS=ON \
      -DANDROID_PLATFORM=android-18 \
      -DANDROID_ABI=armeabi .

After that Anjay can be compiled as usual via make.

Note

Android platforms older than android-18 are not supported.

Note

ANDROID_ALLOW_UNDEFINED_SYMBOLS is set, so that unresolved symbols required by the libanjay.so are not reported during the linking stage. They shall be resolved by providing dependencies to the final executable as it is illustrated in the next section.

Note that we did not set any DTLS_BACKEND and therefore Anjay is compiled without DTLS support. To enable DTLS support you have to provide a value to DTLS_BACKEND (see README.md for more details) along with specific variable indicating where the required DTLS libraries are to be found, i.e. one of:

  • OPENSSL_ROOT_DIR (as FindOpenSSL.cmake suggests),

  • MBEDTLS_ROOT_DIR,

  • TINYDTLS_ROOT_DIR

depending on the chosen backend.

3.3. Installing the library

3.3.1. Building with CMake

The preferred way of building Anjay is to use CMake.

To install Anjay headers and libraries in /usr/local:

cmake . && make && sudo make install

A custom installation prefix may be set using CMAKE_INSTALL_PREFIX:

cmake -DCMAKE_INSTALL_PREFIX=/custom/path . && make && make install

3.3.2. Alternative build systems

Alternatively, you may use any other build system. You will need to:

  • Prepare your avs_commons_config.h, avs_coap_config.h and anjay_config.h files.

  • Configure your build system so that:

    • At least all *.c and *.h files from src, include_public, deps/avs_coap/src, deps/avs_coap/include_public, deps/avs_commons/src and deps/avs_commons/include_public directories are preserved, with the directory structure intact.

      • It is also safe to merge contents of all include_public directories into one. Merging src directories should be safe, too, but is not explicitly supported.

    • All *.c files inside src, deps/avs_coap/src, deps/avs_commons/src, or any of their direct or indirect subdirectories are compiled.

    • deps/avs_commons/src and deps/avs_commons/include_public directories are included in the header search path when compiling avs_commons.

    • deps/avs_coap/src, deps/avs_coap/include_public and deps/avs_commons/include_public directories are included in the header search path when compiling avs_coap.

    • src, include_public, deps/avs_coap/include_public and deps/avs_commons/include_public directories are included in the header search path when compiling Anjay.

    • include_public, deps/avs_coap/include_public and deps/avs_commons/include_public directories, or copies of them (possibly merged into one directory) are included in the header search path when compiling dependent application code.

Example

Below is an example of a simplistic build process, that builds all of avs_commons, avs_coap and Anjay from a Unix-like shell:

# configuration
cp -r example_configs/linux_lwm2m10 config
# you may want to edit the files in the "config" directory before continuing

# compilation
cc -Iconfig -Iinclude_public -Ideps/avs_coap/include_public -Ideps/avs_commons/include_public -Isrc -Ideps/avs_coap/src -Ideps/avs_commons/src -c $(find src deps/avs_coap/src deps/avs_commons/src -name '*.c')
ar rcs libanjay.a *.o

# installation
cp libanjay.a /usr/local/lib/
cp -r include_public/avsystem /usr/local/include/
cp -r deps/avs_coap/include_public/avsystem /usr/local/include/
cp -r deps/avs_commons/include_public/avsystem /usr/local/include/
cp -r config/* /usr/local/include/

3.4. Including the library in an application

3.4.1. CMake projects

The preferred method of using Anjay in custom projects is to use CMake find_package command after installing the library:

find_package(anjay)
include_directories(${ANJAY_INCLUDE_DIRS})
target_link_libraries(my_executable ${ANJAY_LIBRARIES}) # or ANJAY_LIBRARIES_STATIC for a static library

Note

If a custom installation path is used, you need to set anjay_DIR CMake variable to $YOUR_INSTALL_PREFIX/lib/anjay.

3.4.2. Alternative build systems

If Anjay itself has been compiled using CMake, flags necessary for other build systems can be retrieved using cmake command:

cmake --find-package -DNAME=anjay -DLANGUAGE=C -DCOMPILER_ID=Generic -DMODE=<mode>

Where <mode> is one of:

  • EXIST - check whether the library can be found,

  • COMPILE - print compilation flags,

  • LINK - print linking arguments.

Note

If a custom installation prefix is used, you need to also pass -Danjay_DIR=$YOUR_INSTALL_PREFIX/lib/anjay.

3.4.3. Anjay compiled without CMake

If Anjay has been compiled without using CMake, you will need to provide necessary flags manually.

Specific dependencies will vary according to:

  • compile-time configuration, including:

    • avs_compat_threading backend

    • avs_crypto backend, if any

    • avs_net DTLS backend, if any

    • AVS_COMMONS_HTTP_WITH_ZLIB setting, if avs_http is enabled

  • target platform

  • build environment

Example

For the following conditions:

  • Anjay compiled with all optional features enabled, and:

    • mbed TLS security enabled as avs_net DTLS backend and/or avs_crypto backend

    • PThread used as avs_compat_threading backend

    • avs_http enabled with zlib support

  • Target platform being a typical desktop GNU/Linux distribution

  • GCC or Clang used as the compiler

  • Anjay compiled and installed as shown in the example in the Alternative build systems section

the flags necessary to link client applications would be:

-lanjay -lz -lmbedtls -lmbedcrypto -lmbedx509 -lm -pthread