@startuml

title "Push Notification Enrollment"

hide footbox
autonumber "[0] "

participant "Client App" as Client << (U, #ccebc5) user >>

participant "Orchestration Layer" as Orch << (C, #b3cde3) capital one >>
participant "Messaging Server" as MS << (C, #b3cde3) capital one >>
note over MS
This is where you can put useful information like links to documentation or support processes.
end note

participant "Notification Subscription Server" as NSS << (C, #b3cde3) capital one >>

participant "APNS" as APNS << (E, #fbb4ae) external >>
participant "GCM" as GCM << (E, #fbb4ae) external >>

==Customer Action==

Client -> Client: First time login, or app upgrade, or user toggles notifications on/off in the app.

==Device Registration==

Client -> APNS: If iOS, register device token in APNS
Client -> GCM: If Android, register device token in GCM

==Update Messaging Server==

Client -> Orch: Update device token

Orch -> MS: Get existing subscriptions
MS -> Orch: If success, return all
Orch -> Orch: Check if device token is present

Orch -> MS: If device token is present, stop (skip to next group)

Orch -> MS: If device token not present, add subscription
note left
{ "device_token" : "APA91bE_YiasYasbda..." }
end note
MS -> Orch: Return success/failure

==Update Master Subscription==

Orch -> NSS: Register device token
NSS -> Orch: Return success/failure

Orch -> Orch: Swallow failure 
Orch -> Client: Return success/failure

==Replicate Subscriptions==

Client -> Orch: Update subscriptions 
Orch -> MS: Update subscriptions

MS -> MS: Update subscription in Messaging Server

MS -> Orch: Return success/failure
Orch -> Orch: Swallow failure
Orch -> Client: Return success/failure

@enduml