Shahzad Bhatti Welcome to my ramblings and rants!

One of pattern I learned earlier in my career was to separate control flow from the data flow. For example, when I first looked at FTP protocol, I noticed it listened to two separate ports for communication between client and server. It used a data port to transfer files and used a control port to send/receive commands for managing transfer. This allows the server to respond quickly if your data port is busy transferring large files. In some ways, this is similar to Bulkhead pattern for partitioning components and limiting the blast radius. When a service reaches its capacity, it will slow down all requests including any requests to control or configure it. Thus, it helps to define a separate channel where you can manage the control-service. Also, you may need to define special access-control policies to manage the control-service. For example, an admin may need to be on a trusted network for administration. In some cases, you may build a control-service for management behind the firewall but the data-service is publicly accessible. Another use-case is to update service’s configuration at runtime where you might store the service configuration via the control-service that can update the configuration and then publishes it to the data-service.