The C++ Dependency Manager contains a static library which can be used to manage (dynamic) services on a higher abstraction level in a declarative style. The Apache Celix C++ Dependency Manager is inspired by the Apache Felix Dependency Manager.
The C++ Dependency Manager uses fluent interface to make specifying DM components and service dependencies very concise and relies on features introduced in C++11.
The C++ Dependency Manager is build on top of the C Dependency Manager. To get a good overview of the C++ Dependency Manager please read the Dependency Manager documentation
The C++ Dependency Manager consist out of four main parts: celix::dm::DmActivator
, celix::dm::DependencyManager
, celix::dm::Component
and celix::dm::ServiceDependency
.
The DmActivator
class should be inherited by a bundle specific Activator.
DmActivator::create
method needs to be implemented and should return a bundle specific subclass instance of the DmActivator.DmActivator::init
method should be overridden and can be used to specify which components to use in the bundle.DmActivator::deinit
method can be overridden if some cleanup is needed when a bundle is stopped.The DependencyManager
act as an entry point to create (DM) Components.
The (DM) Component
manages the life cycle of a component (of the template type T). For example, when all required service dependencies are available the Component
will call the start
specified callback function of the component.
Component::setInstance
method can be used to set the component instance to used. If no instance is set the (DM) Component
will (lazy) create a component instance using the default constructor.Component::addInterface
method can be used to specify one additional C++ service provided by the component.Component::addCInterface
method can be used to specify one additional C service provided by the component.Component::createServiceDependency
method can be used to specify one additional typed C++ service dependency.Component::createCServiceDependency
method can be used to specify one additional typed C service dependency.The (DM) ServiceDependency
can be used to specify C++ service dependencies for a component and the (DM) CServiceDependency
can be used to specify C service dependencies for a component.
When these dependencies are set to required the Component
will ensure that components will only be started when all required dependencies are available and stop the component if any of the required dependencies are removed.
This feature should prevent a lot of boiler plating code compared to using a service tracker or services references directly.
A service dependency update strategy can also be specified (suspend or locking. Default this strategy is set to DependencyUpdateStrategy::suspend
this strategy will stop and start (suspend) a component when any of the specified service dependencies changes (are removed, added or modified).
When correctly used this strategy removes the need for locking services during updates/invocation. See the dependency manager_cxx example for more details.
(C)ServiceDependency::setCallbacks
methods can be used to specify the function callback used when services are added, set, removed or modified.(C)ServiceDependency::setRequired
methods can be used to specify if a service dependency is required.(C)ServiceDependency::setStrategy
methods can be used to specify the service dependency update strategy (suspend or locking).For more information examples please see