Frends Connectivity
The Agent requires connectivity to the Azure or Cleura cloud where the Frends Control Panel is hosted. It mainly uses the Azure Service Bus or RabbitMQ as a message bus for communication and Azure Storage or Ceph (Blob storage) for larger data amounts.
Connections to the Message Bus are SSL secured and the Agent uses a limited access connection string for authentication. The Agent uses the Message Bus for the following purposes:
Receiving Process deployments from the Control Panel
Receiving other configuration data from the Control Panel, such as Environment Variables, API Key configurations, OAuth settings, etc
Sending Process log data to the Log Service
Sending Heartbeats and system log data to the Log Service
Requesting Remote Subprocess executions from Agents in the same Environment
Receiving Remote Subprocess execution requests from Agents in the same Environment
Receiving Manual Process execution requests from the Control Panel.
The use of the service bus may cause latency for execution either due to congestion or network latency. Usually, the benefits of having resilience in the message bus or queue outweighs the detriments. Remote Subprocesses work well unless you are dealing with a huge number of messages, large messages or demand strictly real time execution. In those scenarios it is better to build an internal rest API and call it via a HTTP request.
The next article is Introduction to High-availability (HA)