Introduction

The evltgw allows the communication between a VLT instrument software using the ELT software technological stack and a VLT telescope and a VLT IWS. It consists of two components:

  • eltGW: interface exposed to the instrument

  • vltGW: interface to the VLT environment.

The main functionalities of the evltgw are:

  • Forward commands from ELT INSSW to the telescope

  • Forward updates of the VLT OLDB telescope data point to its ELT OLDB counterpart

  • Forward commands from VLT INSSW to an ELT component (e.g. COSMIC)

  • Forward updates of configurable ELT OLDB telescope data points to their VLT OLDB counterparts

  • Instrument alarms forwarding

  • Instrument log and telemetry ingestion in datalab

  • Retrieval of telescope fits header and binary tables

  • Providing the TCS state either with PUB/SUB or REQ/REP

The deployment diagram below gives an overview of the different components:

../_images/deployment.png
The eltGW runs on an ELT IWS whereas vltGW may run in its own VM or on the TCS WS. They communicate with each other using ZMQ.
On the IWS, we will have all the INSSW components (OCM, DPM, FCM, Sequencer) and a filebeat instance to collect logs.
All the CII services for the configuration, online database and telemetry will run either on a specific host or on the ELT IWS. These services can be shared by all instruments relying on CII or they can be specific to an instrument.
COSMIC, a RTC platform, is an example of ELT component to which the EVLTGW will forward commands coming from a VLT instrument.
On the right hand side of the diagram, we have the main components of the VLT environment. DHS is the only system with which the ELT-VLT gateway will not have any direct interaction.

Scope

This document is the user manual for the evltgw. It will describe how to use the evltgw but will not give any information about installation and configuration as these topics are addressed in the transfer manual. The intended audience are users of evltgw i.e. developers of INSSW.

Acronyms

AOF

Adaptive Optics Facility

CAS

Central Alarm System

CII

Core Integration Infrastructure

CCS

Central Control System (VLT)

DAO

Data Access Object

DHS

Data Handling System

ECCS

ELT Telescope Central Control System

ELT

Extremely Large Telescope

evltgw

ELT VLT Gateway

INSSW

Instrument control software

IPC

Inter-process communication

IWS

Instrument Workstation

LGSF

Laser Guide Stars Facility

MAL

Middleware Abstraction Layer

OCM

Observation Coordination Manager

OLDB

Online Database

OT

Observation Tool

TCS

Telescope Control System (VLT)

VM

Virtual Machine

vOT

Visitor Observation Tool

ZMQ

ZeroMQ