xeus
The C++ implementation of the Jupyter Kernel protocol
Let the Jupyter kernel author focus on implementing the language specific components

Introduction

xeus is a library meant to facilitate the implementation of kernels for Jupyter. It takes the burden of implementing the Jupyter Kernel protocol so developers can focus on implementing the interpreter part of the kernel.

Installation

xeus has been packaged on all platforms for the conda package manager.

conda install xeus -c conda-forge

Usage

xeus enables custom kernel authors to implement Jupyter kernels more easily. It takes the burden of implementing the Jupyter Kernel protocol so developers can focus on implementing the interpreter part of the Kernel.

The easiest way to get started with a new kernel is to inherit from the base interpreter class xeus::xinterpreter and implement the private virtual methods:

  • execute_request_impl
  • complete_request_impl
  • inspect_request_impl
  • history_request_impl
  • is_complete_request_impl

as seen in the echo kernel provided as an example.

#include "xeus/xinterpreter.hpp"

using xeus::xinterpreter;
using xeus::xjson;
using xeus::xhistory_arguments;

namespace echo_kernel
{
    class echo_interpreter : public xinterpreter
    {

    public:

        echo_interpreter() = default;
        virtual ~echo_interpreter() = default;

    private:

        xjson execute_request_impl(int execution_counter,
                                   const std::string& code,
                                   bool silent,
                                   bool store_history,
                                   const xjson::node_type* user_expressions,
                                   bool allow_stdin) override;

        xjson complete_request_impl(const std::string& code,
                                    int cursor_pos) override;

        xjson inspect_request_impl(const std::string& code,
                                   int cursor_pos,
                                   int detail_level) override;

        xjson history_request_impl(const xhistory_arguments& args) override;

        xjson is_complete_request_impl(const std::string& code) override;

        xjson kernel_info_request_impl() override;

        void input_reply_impl(const std::string& value) override;
    };
}

Kernel authors can then rebind to the native APIs of the interpreter that is being interfaced, providing richer information than with the classical approach of a wrapper kernel capturing textual output.

Building from Source

xeus depends on the following libraries:

On Linux platforms, xeus also requires libuuid, which is available in all linux distributions (uuid-dev on Debian).

We have packaged all these dependencies for the conda package manager. The simplest way to install them with conda is to run:

conda install cmake zeromq cppzmq rapidjson cryptopp -c conda-forge

On Linux platform, you will also need:

conda install libuuid -c conda-forge

Once you have installed the dependencies, you can build and install xeus:

cmake -D BUILD_EXAMPLES=ON -D CMAKE_BUILD_TYPE=Release
make
make install

If you need the xeus library only, you can omit the BUILD_EXAMPLES settings.

Installing the Dependencies from Source

The dependencies can also be installed from source. Simply clone the directories and run the following cmake and make instructions.

libzmq

cmake -D WITH_PERF_TOOL=OFF -D ZMQ_BUILD_TESTS=OFF -D ENABLE_CPACK=OFF
-D CMAKE_BUILD_TYPE=Release
make
make install

cppzmq

cppzmq is a header only library:

cmake -D CMAKE_BUILD_TYPE=Release
make install

rapidjson

rapidjson is a header only library too, but requires some options to be set:

cmake -D RAPIDJSON_BUILD_DOC=OFF -D RAPIDJSON_BUILD_TESTS=OFF
-D RAPIDJSON_BUILD_EXAMPLES=OFF -D RAPIDJSON_HAS_STDSTRING=ON
-D CMAKE_BUILD_TYPE=Release
make install

cryptopp

cryptopp must be built as a static library. Building cryptopp as a shared library is not supported on Windows.

cmake -D BUILD_SHARED=OFF -D BUILD_TESTING=OFF -D CMAKE_BUILD_TYPE=Release
make
make install

License

We use a shared copyright model that enables all contributors to maintain the copyright on their contributions.

This software is licensed under the BSD-3-Clause license. See the LICENSE file for details.