Apache Celix is a framework for C and C++14 to develop dynamic modular software applications using component and in-process service-oriented programming. Apache Celix is inspired by the OSGi specification adapted for C and C++.
Modularity in Celix is achieved by runtime installable bundles and dynamic - in process - services.
A Celix bundle is set of resources packed in a zip containing at least a manifest and almost always
some shared library containing the bundle functionality.
A Celix bundle can be created using the Celix CMake function add_celix_bundle.
A Celix bundle is activated by executing the bundle entry points. For C++ bundles these bundle entry points are generated using the CELIX_GEN_CXX_BUNDLE_ACTIVATOR macro.
Celix applications (Celix containers) can be created with the Celix CMake function add_celix_container.
This function generates a C++ main function and is also used to configure default installed bundles.
This can be bundles provided by Celix, an other project or build by the project self.
//src/MyBundleActivator.cc #include <iostream> #include "celix/BundleActivator.h" class MyBundleActivator { public: explicit MyBundleActivator(const std::shared_ptr<celix::BundleContext>& ctx) { std::cout << "Hello world from bundle with id " << ctx->getBundleId() << std::endl; } ~MyBundleActivator() noexcept { std::cout << "Goodbye world" << std::endl; } }; CELIX_GEN_CXX_BUNDLE_ACTIVATOR(MyBundleActivator)
#CMakeLists.txt find_package(Celix REQUIRED) add_celix_bundle(MyBundle SOURCES src/MyBundleActivator.cc ) add_celix_container(MyContainer BUNDLES Celix::ShellCxx Celix::shell_tui MyBundle )
#bash #goto project dir cd cmake-build-debug #assuming clion cmake-build-debug dir cd deploy/MyContainer ./MyContainer #Celix shell -> lb -a #list of all installed bundles -> help #list of all available Celix shell commands -> help celix::lb #Help info about the shell command `celix::lb` -> stop 3 #stops MyBundle -> start 3 #starts MyBundle -> stop 0 #stops the Celix framework
In the Celix framework, a service is a C++ object or C struct registered in the Celix framework service registry under one interface together with properties (meta information). Services can be discovered and used by bundles.
//include/ICalc.h #pragma once class ICalc { public: virtual ~ICalc() noexcept = default; virtual int add(int a, int b) = 0; };
//src/CalcProviderBundleActivator.cc #include "ICalc.h" #include "celix/BundleActivator.h" class CalcProvider : public ICalc { public: ~CalcProvider() noexcept override = default; int add(int a, int b) override { return a + b; } }; class CalcProviderBundleActivator { public: explicit CalcProviderBundleActivator(const std::shared_ptr<celix::BundleContext>& ctx) { reg = ctx->registerService<ICalc>(std::make_shared<CalcProvider>()) .build(); } private: std::shared_ptr<celix::ServiceRegistration> reg{}; }; CELIX_GEN_CXX_BUNDLE_ACTIVATOR(CalcProviderBundleActivator)
#CMakeLists.txt find_package(Celix REQUIRED) add_celix_bundle(CalcProviderBundle SOURCES src/CalcProviderBundleActivator.cc ) target_include_directories(CalcProviderBundle PRIVATE include) add_celix_container(CalcProviderContainer BUNDLES Celix::ShellCxx Celix::shell_tui CalcProviderBundle )
#bash #goto project dir cd cmake-build-debug #assuming clion cmake-build-debug dir cd deploy/CalcProviderBundle ./CalcProviderBundle
//include/ICalc.h #pragma once class ICalc { public: virtual ~ICalc() noexcept = default; virtual int add(int a, int b) = 0; };
//src/CalcUserBundleActivator.cc #include <iostream> #include "ICalc.h" #include "celix/BundleActivator.h" class CalcUserBundleActivator { public: explicit CalcUserBundleActivator(const std::shared_ptr<celix::BundleContext>& ctx) { ctx->useService<ICalc>() .addUseCallback([](ICalc& calc) { std::cout << "result is " << calc.add(2, 3) << std::endl; }) .setTimeout(std::chrono::seconds{1}) //wait for 1 second if a service is not directly found .build(); } }; CELIX_GEN_CXX_BUNDLE_ACTIVATOR(CalcUserBundleActivator)
#CMakeLists.txt find_package(Celix REQUIRED) add_celix_bundle(CalcUserBundle SOURCES src/CalcUserBundleActivator.cc ) target_include_directories(CalcUserBundle PRIVATE include) add_celix_container(CalcUserContainer BUNDLES Celix::ShellCxx Celix::shell_tui CalcProviderBundle CalcUserBundle )
#bash #goto project dir cd cmake-build-debug #assuming clion cmake-build-debug dir cd deploy/CalcUserContainer ./CalcUserContainer
//include/ICalc.h #pragma once class ICalc { public: virtual ~ICalc() noexcept = default; virtual int add(int a, int b) = 0; };
//src/CalcTrackerBundleActivator.cc #include <mutex> #include "ICalc.h" #include "celix/BundleActivator.h" class CalcTrackerBundleActivator { public: explicit CalcTrackerBundleActivator(const std::shared_ptr<celix::BundleContext>& ctx) { tracker = ctx->trackServices<ICalc>() .build(); for (auto& calc : tracker->getServices()) { std::cout << "result is " << std::to_string(calc->add(2, 3)) << std::endl; } } private: std::shared_ptr<celix::ServiceTracker<ICalc>> tracker{}; }; CELIX_GEN_CXX_BUNDLE_ACTIVATOR(CalcTrackerBundleActivator)
find_package(Celix REQUIRED) add_celix_bundle(CalcTrackerBundle SOURCES src/CalcTrackerBundleActivator.cc ) target_include_directories(CalcTrackerBundle PRIVATE include) add_celix_container(CalcTrackerContainer BUNDLES Celix::ShellCxx Celix::shell_tui CalcProviderBundle CalcTrackerBundle )
#bash #goto project dir cd cmake-build-debug #assuming clion cmake-build-debug dir cd deploy/CalcTrackerContainer ./CalcTrackerContainer
//src/FilterExampleBundleActivator.cc #include <iostream> #include "celix/BundleActivator.h" #include "celix/IShellCommand.h" class HelloWorldShellCommand : public celix::IShellCommand { public: void executeCommand(const std::string& /*commandLine*/, const std::vector<std::string>& /*commandArgs*/, FILE* outStream, FILE* /*errorStream*/) { fprintf(outStream, "Hello World\n"); } }; class FilterExampleBundleActivator { public: explicit FilterExampleBundleActivator(const std::shared_ptr<celix::BundleContext>& ctx) { auto reg1 = ctx->registerService<celix::IShellCommand>(std::make_shared<HelloWorldShellCommand>()) .addProperty(celix::IShellCommand::COMMAND_NAME, "command1") .build(); auto reg2 = ctx->registerService<celix::IShellCommand>(std::make_shared<HelloWorldShellCommand>()) .addProperty(celix::IShellCommand::COMMAND_NAME, "command2") .build(); regs.push_back(reg1); regs.push_back(reg2); auto serviceIdsNoFilter = ctx->findServices<celix::IShellCommand>(); auto serviceIdsWithFilter = ctx->findServices<celix::IShellCommand>(std::string{"("} + celix::IShellCommand::COMMAND_NAME + "=" + "command1)"); std::cout << "Found " << std::to_string(serviceIdsNoFilter.size()) << " IShelLCommand services and found "; std::cout << std::to_string(serviceIdsWithFilter.size()) << " IShellCommand service with name command1" << std::endl; } private: std::vector<std::shared_ptr<celix::ServiceRegistration>> regs{}; }; CELIX_GEN_CXX_BUNDLE_ACTIVATOR(FilterExampleBundleActivator)
#CMakeLists.txt find_package(Celix REQUIRED) add_celix_bundle(FilterExampleBundle SOURCES src/FilterExampleBundleActivator.cc ) target_link_libraries(FilterExampleBundle PRIVATE Celix::shell_api) #adds celix/IShellCommand.h to the include path add_celix_container(FilterExampleContainer BUNDLES Celix::ShellCxx Celix::shell_tui FilterExampleBundle )
#bash #goto project dir cd cmake-build-debug #assuming clion cmake-build-debug dir cd deploy/FilterExampleContainer ./FilterExampleContainer #Celix shell -> command1 -> command2 -> help