@startuml skinparam { monochrome true shadowing false ParticipantPadding 10 SequenceBoxBackgroundColor white SequenceBoxBorderColor white } hide footbox actor User as user actor Admin as admin #lightgrey box "Hosting" participant Website as web end box box "functions" control push as fc_push control updateFeed as fc_updateFeed control feed as fc_feed control subs as fc_subs end box box "Messaging" participant FCM as fcm end box box "Firestore" database feed as fs_feed end box participant PubSubHubbub as pshb autonumber user -> web : Push notification request web -> fc_push : Send token activate fc_push fc_push -> fcm : Subscribe feed topic deactivate fc_push ... autonumber admin -> pshb : Subscribe feed pshb -> fc_subs : GET subscriber activate fc_subs fc_subs --> fc_subs: Check verify_token fc_subs -> pshb : Response challenge deactivate fc_subs ... autonumber admin -> web : Publish contents web -> fs_feed : Add feed fs_feed -->> fc_updateFeed : (Trigger update) activate fc_updateFeed fc_updateFeed -> pshb : Publish request deactivate fc_updateFeed pshb -> fc_feed : Get feed.xml activate fc_feed fc_feed -> pshb : Response feed.xml deactivate fc_feed pshb -> fc_subs : Post feed activate fc_subs fc_subs --> fc_subs: Check HMAC secret fc_subs -->> fs_feed : (Get latest Feed) fc_subs -> fcm : Send to topic deactivate fc_subs fcm -> user : Send push notification @enduml Submit amiga aws-orange black-knight bluegray blueprint cerulean-outline cerulean crt-amber crt-green cyborg-outline cyborg hacker lightgray mars materia-outline materia metal mimeograph minty plain reddress-darkblue reddress-darkgreen reddress-darkorange reddress-darkred reddress-lightblue reddress-lightgreen reddress-lightorange reddress-lightred sandstone silver sketchy-outline sketchy spacelab spacelab-white superhero-outline superhero toy united vibrant       🎉 Discover the future PlantUML Web Editor! 🚀  PNG  SVG  ASCII Art