The enhanced communication abstraction layer (eCAL) is a middleware that enables scalable, high performance interprocess communication on a single computer node or between different nodes in a computer network. The design is inspired by known Data Distribution Service for Real-Time Systems (see Data distribution service on wikipedia). The current eCAL implementation realizes a subset of such a DDS system, there is only a basic support for Quality of Service (QoS) driven data transport (best effort and reliable).

eCAL is designed for typical cloud computing scenarios where different processes exchange their I/O’s using a publisher/subscriber pattern. The data exchange is based on so called topics. A topic wraps the payload that should be exchanged with additional informations like a unique name, a type and a description. A topic can be connected to more than one publisher and/or subscriber. These are the basic elements of the eCAL API.

Programming language: C++
License: Apache License 2.0
Latest version: v5.7.5

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eCAL - enhanced Communication Abstraction Layer

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The enhanced Communication Abstraction Layer (eCAL) is a middleware that enables scalable, high performance interprocess communication on a single computer node or between different nodes in a computer network. eCAL uses a publish - subscribe pattern to automatically connect different nodes in the network.

eCAL automatically chooses the best available data transport mechanism for each link:

  • Shared memory for local communication (incredible fast!)
  • UDP for network communication

Visit the eCAL Documentation at 🌐 http://ecal.io for more information.


Facts about eCAL

  • eCAL is fast (1 - 10 GB/s, depends on payload size. Check the measured performance here)
  • eCAL provides both publish-subscribe and server-client patterns
  • eCAL is brokerless
  • eCAL provides a C++ and C interface for easy integration into other languages (like python, csharp or rust)
  • eCAL can be used in conjunction with Matlab Simulink as eCAL Simulink Toolbox for simulation and prototyping
  • eCAL has powerful tools for recording, replay and monitoring all your data flows - decentralized
  • eCAL is simple and zero-conf. No complex configuration for communication details and QOS settings are needed
  • eCAL is message protocol agnostic. You choose the message protocol that fits to your needs like Google Protobuf, CapnProto, Flatbuffers...
  • eCAL uses the standardized recording format HDF5
  • eCAL integrates gently into your ROS2 environment with the eCAL RMW
  • eCAL supports Intel and arm platforms

  • eCAL runs on a wide variety of operating systems:

    • Windows (stable)
    • Linux (stable)
    • QNX (stable)
    • MacOS (experimental)
    • FreeBSD (experimental)


We provide binary installers for Windows and Ubuntu. If you need further help installing and configuring eCAL, please refer to the documentation.


Download the latest eCAL Installer and follow the Setup Wizard

[eCAL Setup](doc/rst/getting_started/img/setup.png)

We only support 64bit Windows 7 / 10


Install eCAL from our PPA:

sudo add-apt-repository ppa:ecal/ecal-latest
sudo apt-get update
sudo apt-get install ecal

This PPA will always upgrade you to the latest eCAL Release (-> Rolling Release PPA). If you intend to stay on an specific release, check out other PPAs here.

Ubuntu 16.04, 18.04, 20.04, 20.10, 21.04 for CPU architectures i386, x64, armhf, arm64 are supported at the time of writing.


Using eCAL in your project to exchange data is simple. After you have downloaded eCAL and installed CMake, you are good to go.

Check out the Hello World example from the eCAL documentation for further details.

#include <ecal/ecal.h>
#include <ecal/msg/string/publisher.h>

#include <thread>

int main(int argc, char** argv)
  // Initialize eCAL. The name of our process will be "Hello World Publisher"
  eCAL::Initialize(argc, argv, "Hello World Publisher");

  // Create a String Publisher that publishes on the topic "hello_world_topic"
  eCAL::string::CPublisher<std::string> publisher("hello_world_topic");

  // Infinite loop
  while (eCAL::Ok())
    // Publish a "Hello World" message
    publisher.Send("Hello World");


  // finalize eCAL API

Tools from the eCAL ecosystem

eCAL comes with a set of read-to-use tools that will help you with developing, testing and debugging your software. Command line interface versions and easy to use GUI applications are available.

  • The eCAL Monitor to visualize the data flow and inspect messages sent between publishers and subscribers

  • The eCAL Recorder to record the data sent between your eCAL nodes

  • The eCAL Player to replay the eCAL recordings later on

  • eCAL Sys to define your system configuration and monitor your applications

[eCAL Mon](gfx/app/monitor_imagevisu.png)

Projects using eCAL

Projects used by eCAL

  • fine-ftpserver - FTP functionality to collect distributed measurement artifacts over network
  • tcp_pubsub - Additional TCP transport layer for higher reliability for publication/subscription over network
  • iceoryx - Alternative shared memory transport layer (needs to be activated via CMake options)
  • docker-ecal - Inoffical dockerfiles for eCAL


eCAL is licensed under Apache License 2.0. You are free to

  • Use eCAL commercially
  • Modify eCAL
  • Distribute eCAL

eCAL is provided on an “as is” basis without warranties or conditions of any kind.

*Note that all licence references and agreements mentioned in the eCAL README section above are relevant to that project's source code only.