[plantuml]
....
@startuml
!includeurl https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/v2.0.1/C4_Container.puml

' uncomment the following line to make proposals
'LAYOUT_AS_SKETCH()

title System Container diagram for Decidim Applications (https://decidim.org)


Person_Ext(visitor_user, "Visitor User", "Anonymous, non registered user.")
Person(participant_user, "Participant User", "A registered user. Could also be verified.")
Person(administration_user, "Administration User", "A registered user with special permissions.")

System_Boundary(decidim_system, "decidim"){
    Container(web_app, "Web Application", "Ruby on Rails 5.2", "Allows participants to make decisions collaboratively through participatory processes, assemblies, initiatives, etc.")
    ContainerDb(rel_db, "Relational Database", "PostgreSQL 9.5.x", "Stores users, participatory processes, assemblies, initiatives, proposals, meetings, etc.")
    Container(filesystem, "File System", "Local or remote", "Stores uploads (images, documents, etc.)")
    Container(worker, "Worker", "Ruby on Rails 5.2", "ActiveJob queues for non synchronous jobs. Works for open data requests, sending emails, etc.")
}

System_Ext(mail_system, "SMTP system (e-mail)", "Sends mails to users, like confirmations, reminders, notifications, etc.")
System_Ext(etherpad_system, "Etherpad-Lite system", "Optional. Allows real-time text edition in Meetings.")
System_Ext(geocoding_system, "Geocoding system", "Optional. An Open Street Maps provider, allows geographical localization of Proposals and Meetings..")
System_Ext(oauth_system, "OAUTH2 System", "Optional. Third party sign on systems. Could be Twitter, Facebook, Google or any other OAUTH2 providers.")

Rel(visitor_user, web_app, "Uses")
Rel(participant_user, web_app, "Uses")
Rel(administration_user, web_app, "Uses")
Rel_Back(participant_user, mail_system, "Sends e-mails to")
Rel_Back(administration_user, mail_system, "Sends e-mails to")
Rel_Neighbor(worker, mail_system, "Sends e-mails", "SMTP")
Rel(web_app, rel_db, "Uses")
Rel(web_app, filesystem, "Uses")
Rel(web_app, oauth_system, "Uses")
Rel(web_app, geocoding_system, "Uses")
Rel(web_app, etherpad_system, "Embeds", "Through an Iframe")
@enduml
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