eCAL vs. Alternatives: Choosing the Right Middleware for Robotics

Basic concepts and architecture

• Topics: Named message channels for pub/sub communication.
• Services: Request/reply RPC-style communication.
• Hosts: Nodes that run eCAL processes; discovery is automatic via multicast or UDP.
• QoS: eCAL provides options for reliability and message history; tune for latency or throughput.

Quickstart example (C++)

1. Publisher:

   cpp
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   #include 
   #include 
   
   int main(int argc, char argv)
   {
   eCAL::Initialize(argc, argv, “publisher”);
     eCAL::string::CPublisher<std::string> pub(“example_topic”);
     while (eCAL::Ok())
     {
       std::string msg = “hello”;
       pub.Send(msg);
       std::this_thread::sleepfor(std::chrono::milliseconds(10));
     }
     eCAL::Finalize();
     return 0;
   }
   

2. Subscriber:

   cpp
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   #include 
   #include 
   
   void OnReceive(const char* /topicname/, const char* msg, const long long /*time*/, const long long /id_/, const long /clock_/)
   {
     printf(“Received: %s “, msg_);
   }
   
   int main(int argc, char argv)
   {
     eCAL::Initialize(argc, argv, “subscriber”);
     eCAL::string::CSubscriber<std::string> sub(“example_topic”);
     sub.AddReceiveCallback(OnReceive);
     while (eCAL::Ok()) std::this_thread::sleep_for(std::chrono::milliseconds(100));
     eCAL::Finalize();
     return 0;
   }