Port 259

Efficient Short Remote Operations (ESRO) is designed as an application protocol to enable lightweight, efficient communication for remote procedure calls (RPCs), especially on constrained network environments like embedded systems and IoT devices. It emphasizes reduced overhead, optimizing data packets for minimal size while maintaining operational integrity. The protocol accommodates both connection-oriented and connectionless transport modes, utilizing TCP and UDP, to balance reliability and latency according to application requirements.

ESRO structures its messages with compact headers and payloads. It supports multiplexing multiple operations within a single session and offers mechanisms for error reporting and flow control. Due to its flexibility, ESRO can be integrated into custom protocols or applications requiring efficient transaction models without the complexity of heavier alternatives like SOAP or REST.

The design goals of ESRO include minimal bandwidth consumption and low processing overhead. While no longer widely adopted today, it once filled a niche in industrial controls, specialized embedded communications, and early mobile data solutions, where network performance and resource constraints demanded protocol efficiency.