Elle, the coroutine-based asynchronous C++ development framework

Elle is a collection of libraries, written in modern C++ (C++14). It contains a rich set of highly reusable concepts, algorithms, API wrappers, ...

Elle is split into different specialized sub-libraries to provide elegant ways to approach asynchronism (using coroutines), networking, formatting, serialization, logging, RPCs, etc.

Notes:

• Elle is under development, used and maintained by Infinit as a core library. APIs, structures and concepts may change over time. You can use it as is but we don't guarantee any API backward compatibility.
• Elle has a sub-library also called elle, which might change name in a near future.

Example

Here is an example showing an asynchronous HTTP operation in a natural form (no callbacks) and basic JSON serialization.

// Initialize the HTTP Request.
elle::reactor::http::Request r("https://en.wikipedia.org/w/api.php",
                               elle::reactor::http::Method::GET);
r.query_string({
  {"format", "json"},
  {"action", "query"},
  {"prop", "extracts"},
  {"explaintext", ""},
  {"exintro", ""},
  {"titles", "JSON"}
});
// Perform the HTTP request and yield until response is available.
r.finalize();
// Deserialize the json response.
std::cout << elle::json::pretty_print(elle::json::read(r)) << std::endl;

Getting Elle

To download the source code and build Elle by yourself, get it from GitHub.

git clone https://github.com/infinit/elle --recursive # Clone elle and its submodules.

Note: If you cloned it using the GitHub "clone" button, do not forget to run git submodule update --init --recursive!

Note: If you forked Elle, you'll also need to fork the following repositories too: drake, dokan, libutp, miniupnp. The reason why is detailed on following GitHub issue.

Structure

As mentioned earlier, Elle is composed of a set of sub-libraries, designed to ease C++ development through robust and flexible implementations, including:

• elle: Utilities including serialization, logs, buffer, formatting, ...
• reactor: An asynchronous framework using a coroutines scheduler
• cryptography: Object-oriented cryptography wrapper around OpenSSL
• protocol: Network communication designed to support RPCs
• das: Symbol-based introspection
• athena: Byzantine environment algorithms (Paxos)
• service/aws: reactorified AWS API wrapper
• service/dropbox: reactorified Dropbox API wrapper
• nbd: A Network Block Device implementation.

How to build Elle (or parts of Elle)

Requirements

• gcc (>= 4.9.2) or clang (>= 3.5.0) or mingw (>= 5.3.0).
• python3 (>= 3.4.0) and pip3.

Build system

Elle uses Drake and has it as a submodule.

How to compile

For a detailed procedure, visit our wiki: How to build.

First you need to install drakes requirements.

sudo pip3 install -r elle/drake/requirements.txt # Install Drake dependencies.

Note: If you don't want Drake dependencies to be installed system-wide, you should consider using virtualenv.

Change directory to elle/_build/<architecture> where you can find a generic Drake configuration script.

GNU/Linux

cd elle/_build/linux64
./drake //build -j 2 # Build all libraries using 2 jobs.

macOS

cd elle/_build/osx
./drake //build -j 2 # Build all libraries using 2 jobs.

Because Elle was designed to be modular, you can build specific parts of Elle by running ./drake //<module>/build:

./drake //src/elle/cryptography/build -j 2 # To build libcryptography and its dependencies.
./drake //src/elle/reactor/build -j 2 # To build the libreactor and its dependencies.
./drake //src/elle/protocol/build -j 2 # To build the libprotocol and its dependencies.
./drake //...

It will result on <module>/lib/libelle_<module>.so and its dependencies on GNU/Linux, <module>/lib/lib<module>.dylib on macOS, ...

Dependencies

Elle depends on a few libraries which are automatically downloaded and built for your system by Drake if needed.

• Boost (v1.60.0, patched)
• PatchELF (v0.9)
• zlib (v1.2.11)
• OpenSSL (v1.0.2g)
• curl (v7.48.0, patched)
• libarchive (v3.1.2, patched)
• OpenLDAP (v2.4.44)

List of projects using Elle

• Infinit

Wiki

Consult Elle's wiki for more information about Elle.

Maintainers

• Website: https://infinit.sh/open-source
• Email: [email protected]