The MeerKAT Graphical User Interface Technology Stack · o publish & subscribe o messaging design pattern o publisher is a sender/provider o subscriber is a receiver/consumer o messages

ICALEPCS 2015

The MeerKAT Graphical User Interface Technology Stack

ICALEPCS 2015

Theuns Alberts Francois Joubert

THHC3O01

ICALEPCS 2015

22 October 2015 The MeerKAT Graphical User Interface Technology Stack – M. Alberts, F. Joubert ICALEPCS 2015

background


past = KAT-7


present = MeerKAT


present = MeerKAT

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future = SKA

ICALEPCS 2015


old katgui


old katgui – KAT-7


old katgui – problems

o Adobe dependencies

(based on Adobe Flex framework)

o sluggish

o mouse events not always registered

o not going to scale well (64 antennas)

ICALEPCS 2015


approach

ICALEPCS 2015


method

o user interface technology investigation o responsive web design o various typical use-case prototypes

o bi-monthly discussions with relevant stakeholders to clarify requirements

o most importantly the telescope operators and commissioners (i.e. the end-users)

o iterative development approach

o included monthly demonstrations of prototype displays

ICALEPCS 2015


meerkat gui architecture

ICALEPCS 2015


architecture overview

o client-server architecture o real-time updates of monitor points

o websockets & pubsub

websocket o full-duplex socket

connection o eliminate need for polling o event driven responses

pubsub o publish & subscribe o messaging design pattern o publisher is a sender/provider o subscriber is a

receiver/consumer o messages characterised into

classes o pubs & subs no knowledge of

each other

ICALEPCS 2015


backend

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http://goo.gl/KcebYM

ICALEPCS 2015

22 October 2015 The MeerKAT Graphical User Interface Technology Stack – M. Alberts, F. Joubert

katportal

o katportal = backend component o runs various HTTP web servers

o redis for the pubsub mechanism o client websocket connections subscribe to

monitoring points o telescope system publish updates

ICALEPCS 2015

ICALEPCS 2015


http servers

o auth webserver o provides HTTP connection handling (RESTful API) o authentication = basic o authorisation = role based with session token (JWT)

o monitor webserver o provides websocket connection handling o no authorisation required o exposes subscribe-related commands (JSONRPC)

o control webserver o provides HTTP connection handling (RESTful API) o requires authentication & authorisation

ICALEPCS 2015


example JWT token

ICALEPCS 2015


backend technology stack

ICALEPCS 2015

ICALEPCS 2015


backend technology stack

ICALEPCS 2015

Ubuntu 14.04 LTS

ICALEPCS 2015


frontend

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https://goo.gl/ez2f7Uhttps://goo.gl/ez2f7U

ICALEPCS 2015


katgui

o thick web-application

o build for chrome o but firefox & safari works too

o separate connections for each browser tab

o subscribe to namespaces (groups of of similar monitoring points) o e.g. alarms, sched, obs, ants

o concurrent user interface state updates

ICALEPCS 2015

ICALEPCS 2015


frontend technology stack

ICALEPCS 2015


landing page and navigation

o simple dashboard with customisable widgets

o grouped navigation represented as

“navigation pies”

o sidebars with quick links


landing page and navigation


health displays

o many different health displays to maximise efficient

fault finding

o interactive, customisable

o bold colours

o developed to be on large, heads-up displays

o important information always shown


health displays


receptor health


receptor health (64)


custom health


receptor pointing


sensor list


weather


sensorgraph – historical data


alarms

o pushed via websockets

o alarms dedicated display

o alarm notifications o overlay on every page until operator

acknowledges alarm

o alarm badges on main toolbar


alarms


scheduling observations

o subarray = logical grouping of receptors o i.e. sub-telescope

o MeerKAT supports 4

o schedule block = unit of observation work o executes an observation script

o subarray control is limited based on user role

o guide user through scheduling workflow


scheduling observations


ipython shell


control room

ICALEPCS 2015


conclusion

ICALEPCS 2015


conclusion

o involve the actual users of the interface early in the life cycle o pubsub excellent to provide isolation between consumers and

producers of data o web technologies for control & monitoring applications is a viable

option o growth of computing power makes thick clients possible, reducing

load at server o users enjoy working with attractive interfaces … yes, even scientists

ICALEPCS 2015


questions?

Documents

The MeerKAT Graphical User Interface Technology Stack · o publish & subscribe o messaging design pattern o publisher is a sender/provider o subscriber is a receiver/consumer o messages