holoscan::Component

Common class for all non-Operator components.

This class is the base class for all non-Operator components including holoscan::Condition, holoscan::Resource, holoscan::NetworkContext, holoscan::Scheduler It is used to define the common interface for all components.

holoscan::Operator does not inherit from this class as it uses holoscan::OperatorSpec instead of holoscan::ComponentSpec.

#include <holoscan/component.hpp>

Inherits from: holoscan::ComponentBase (public)

Methods

set_parameters

virtual void holoscan::Component::set_parameters()

Set the parameters based on defaults (sets GXF parameters for GXF operators).

spec

Component & holoscan::Component::spec(
    const std::shared_ptr<ComponentSpec> &spec
)

spec_shared

std::shared_ptr<ComponentSpec> holoscan::Component::spec_shared()

Get a shared pointer to the component spec.

Returns: The shared pointer to the component spec.

id

int64_t holoscan::Component::id() const

Get the identifier of the component.

By default, the identifier is set to -1. It is set to a valid value when the component is initialized.

With the default executor (GXFExecutor), the identifier is set to the GXF component ID.

Returns: The identifier of the component.

name

const std::string & holoscan::Component::name() const

Get the name of the component.

Returns: The name of the component.

fragment

Fragment * holoscan::Component::fragment()

add_arg

void holoscan::Component::add_arg(
    const Arg &arg
)

args

std::vector<Arg> & holoscan::Component::args()

Get the list of arguments.

Returns: The vector of arguments.

initialize

virtual void holoscan::Component::initialize()

Initialize the component.

This method is called only once when the component is created for the first time, and use of light-weight initialization.

to_yaml_node

virtual YAML::Node holoscan::Component::to_yaml_node() const

Get a YAML representation of the component.

Returns: YAML node including the id, name, fragment name, and arguments of the component.

description

std::string holoscan::Component::description() const

Get a description of the component.

Returns: YAML string.

See also: to_yaml_node()

service

template <typename ServiceT = DefaultFragmentService>
std::shared_ptr<ServiceT> holoscan::Component::service(
    std::string_view id = ""
) const

Retrieve a registered fragment service or resource.

Retrieves a previously registered fragment service or resource by its type and optional identifier. Returns nullptr if no service/resource is found with the specified type and identifier.

Note that any changes to the service retrieval logic in this method should be synchronized with the implementation in Fragment::service() method to maintain consistency.

Returns: The shared pointer to the service/resource, or nullptr if not found or if type casting fails.

Template parameters

Parameters

get_service_by_type_info

std::shared_ptr<FragmentService> holoscan::Component::get_service_by_type_info(
    const std::type_info &service_type,
    std::string_view id = ""
) const

Retrieve a registered fragment service or resource for Python bindings.

This is a helper method for Python bindings to retrieve a service by its C++ type info.

Returns: The shared pointer to the base service, or nullptr if not found.

Parameters

reset_backend_objects

virtual void holoscan::Component::reset_backend_objects()

Reset any backend-specific objects (e.g. GXF GraphEntity).

update_params_from_args

void holoscan::Component::update_params_from_args()

service_provider

void holoscan::Component::service_provider(
    FragmentServiceProvider *provider
)

Set the service provider that owns this component.

Static methods

register_converter

template <typename typeT>
static void holoscan::Component::register_converter()

Register the argument setter for the given type.

If an operator or resource has an argument with a custom type, the argument setter must be registered using this method.

The argument setter is used to set the value of the argument from the YAML configuration.

This method can be called in the initialization phase of the operator/resource (e.g., initialize()). The example below shows how to register the argument setter for the custom type (Vec3):

It is assumed that YAML::convert<T>::encode and YAML::convert<T>::decode are implemented for the given type. You need to specialize the YAML::convert<> template class.

For example, suppose that you had a Vec3 class with the following members:

You can define the YAML::convert<Vec3> as follows in a ‘.cpp’ file:

Please refer to the yaml-cpp documentation for more details.

Template parameters

Example

void MyOp::initialize() {
  register_converter<Vec3>();
}

Example

struct Vec3 {
  // make sure you have overloaded operator==() for the comparison
  double x, y, z;
};

Example

namespace YAML {
template<>
struct convert<Vec3> {
  static Node encode(const Vec3& rhs) {
    Node node;
    node.push_back(rhs.x);
    node.push_back(rhs.y);
    node.push_back(rhs.z);
    return node;
  }
  static bool decode(const Node& node, Vec3& rhs) {
    if(!node.IsSequence() || node.size() != 3) {
      return false;
    }
    rhs.x = node[0].as<double>();
    rhs.y = node[1].as<double>();
    rhs.z = node[2].as<double>();
    return true;
  }
};
}

register_argument_setter

template <typename typeT>
void holoscan::Component::register_argument_setter()

Register the argument setter for the given type.

Please refer to the documentation of register_converter() for more details.

Template parameters

Member variables