Getting Started

This documentation is installed locally under /usr/share/doc/libnmbs-dev/html/index.html. You can open this in a web browser directly, or utilise a package such as dochelp to browse for it.

The library contains the root namespace nmbs in C++. The API is primarily based around functions, minimising the use of data structures to simple structs for holding data. The structs themselves have very little, if any, functionality.

Examples

Once you have installed the development files (e.g. libnmbs-dev on Debian), you will be able to integrate libnmbs1 into your project as follows:

find_package(NMBS REQUIRED CONFIG)
 
target_link_libraries(Your-Target
        PRIVATE
        NMBS::NMBS-Library
)

Ensure that the core header is included in your code.

#include <nmbs/nmbs.h>

The following is a minimal example for writing and reading the XMP metadata on an image. Note that the error handling for the library is using nmbs::Expected, which is simply a std::Expected<T, nmbs::Error> typedef. The majority of errors will be reported in this manner. The nmbs::Error contains a human-readable message, and a machine-readable code.

Further examples can be found in the targets/NMBS-Examples folder of the source code.

#include <iostream>
#include <nmbs/nmbs.h>
 
int main()
{
    const std::filesystem::path file{"my-image.jpg"};
 
    std::vector<nmbs::ConfidentialityLabel> labels(1);
    labels[0].confidentiality_information.policy_identifier = "PUBLIC";
    labels[0].confidentiality_information.classification = "UNMARKED";
 
    if (const auto output = nmbs::write_labels(file, labels); !output.has_value())
    {
        std::cerr << output.error().message() << std::endl;
        return output.error().code();
    }
 
    if (const auto result = nmbs::read_binding(file); result && *result)
    {
        for (const nmbs::binding::BindingInformation& binding = **result; const auto& label : binding.labels)
        {
            std::cout << label.confidentiality_information.policy_identifier << " " <<
                label.confidentiality_information.classification << std::endl;
        }
        return nmbs::ExitCode::success;
    }
    else if (!result)
    {
        std::cerr << result.error().message() << std::endl;
        return result.error().code();
    }
    return nmbs::ExitCode::no_label_present;
}