Network Communication
MERLIC enables connections and communication with other MERLIC instances and network participants such as programmable logic controllers (PLCs) over a network. MERLIC differentiates between local communication and remote communication.
For local connections between MERLIC components running on the same system, MERLIC uses Unix-domain sockets (UDS) with access control through the file system permissions of the operating system.
For remote connections between MERLIC components running on different systems, MERLIC uses WebSocket connections. If desired, you can configure the remote connections to use Transport Layer Security (TLS) to ensure encrypted communication. The respective MERLIC services and instances map to different WebSocket endpoints but they use the same port. This enables and facilitates working with multiple MERLIC instances even if they are running on the same system.
Internally, available MERLIC services and MERLIC instances are tracked and queried from the MERLIC Directory Agent. For remote connections, the MERLIC Directory Agent exposes the available MERLIC services on the network over HTTP(S) and WebSocket on a TCP port. In the following, you can find more information on the Directory Agent and the configuration of remote connections.
