@startuml
!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Container.puml

SHOW_PERSON_OUTLINE()
AddElementTag("backendContainer", $fontColor=$ELEMENT_FONT_COLOR, $bgColor="#335DA5", $shape=EightSidedShape(), $legendText="backend container\neight sided")
AddRelTag("async", $textColor=$ARROW_FONT_COLOR, $lineColor=$ARROW_COLOR, $lineStyle=DashedLine())
AddRelTag("sync/async", $textColor=$ARROW_FONT_COLOR, $lineColor=$ARROW_COLOR, $lineStyle=DottedLine())

title Container diagram for Internet Banking System

Person(customer, Customer, "A customer of the bank, with personal bank accounts")

System_Boundary(c1, "Internet Banking") {
    Container(web_app, "Web Application", "Java, Spring MVC", "Delivers the static content and the Internet banking SPA")
    Container(spa, "Single-Page App", "JavaScript, Angular", "Provides all the Internet banking functionality to customers via their web browser")
    Container(mobile_app, "Mobile App", "C#, Xamarin", "Provides a limited subset of the Internet banking functionality to customers via their mobile device")
    ContainerDb(database, "Database", "SQL Database", "Stores user registration information, hashed auth credentials, access logs, etc.")
    Container(backend_api, "API Application", "Java, Docker Container", "Provides Internet banking functionality via API", $tags="backendContainer")
}

System_Ext(email_system, "E-Mail System", "The internal Microsoft Exchange system")
System_Ext(banking_system, "Mainframe Banking System", "Stores all of the core banking information about customers, accounts, transactions, etc.")

Rel(customer, web_app, "Uses", "HTTPS")
Rel(customer, spa, "Uses", "HTTPS")
Rel(customer, mobile_app, "Uses")

Rel_Neighbor(web_app, spa, "Delivers")
Rel(spa, backend_api, "Uses", "async, JSON/HTTPS", $tags="async")
Rel(mobile_app, backend_api, "Uses", "async, JSON/HTTPS", $tags="async")
Rel_Back_Neighbor(database, backend_api, "Reads from and writes to", "sync, JDBC")

Rel_Back(customer, email_system, "Sends e-mails to")
Rel_Back(email_system, backend_api, "Sends e-mails using", "sync, SMTP")
Rel_Neighbor(backend_api, banking_system, "Uses", "sync/async, XML/HTTPS", $tags="sync/async")

SHOW_LEGEND()
@enduml
