1. Introduction

The IFW RTMS Lib package provides the low-latency sender and receiver helpers built on top of the llnetio stack. It is a focused library so the core RTMS helpers can evolve independently from engineering tools and utilities. The RTMS protocol itself is specified in ESO-310635, ELT Instrument Adaptive Optics Real-Time Computer - Real-Time MUDPI Stream Protocol and the library follows that wire format while adding convenience helpers around packet framing, extended leader information and logging.

Scope

This manual is aimed at developers embedding the RTMS sender or receiver in C++ applications and engineers validating data paths between RTMS publishers and subscribers. It describes the library surface, documents configuration knobs and provides minimal end-to-end examples for a C++ publisher and subscriber.

Acronyms

Acronym

Description

BPP

Bytes Per Pixel

DDT

Data Display Tool

FITS

Flexible Image Transport System

IFW

Instrument Framework

LLNETIO

Low-Latency Network I/O stack used for MUDPI/RTMS

MTU

Maximum Transmission Unit

MUDPI

Multicast UDP Interface

RTMS

Real-Time MUDPI Stream

SDK

Software Development Kit

UDP

User Datagram Protocol

Nomenclature

Term

Description

RTMS Sample

One complete transfer composed of a leader, payload packets and a trailer.

Extended Info

Optional leader extension carrying timestamp, datatype and image geometry.

Topic ID

Identifier used by RTMS to match publishers and subscribers on the wire.

Leader / Payload / Trailer

RTMS packet types framing a sample; the leader may include extended info.

Extended Info Mode

Contract deciding whether the leader carries nothing, only a timestamp or the full image metadata block.

SampleExtInfo

Helper class used by the library to pack/unpack the extended leader block.

Publisher

Process that sends RTMS samples (RtmsSender).

Subscriber

Process that receives RTMS samples (RtmsReceiver or derivatives).

Geometry

Width, height and offsets used to interpret the pixel payload.