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Table of Contents

Rialto Server Initialisation

...

PlantUML Macro
formatSVGtitleNot Running to Inactive
@startuml

autonumber

participant  ApplicationManager
participant RialtoServerManager

ApplicationManager             ->  RialtoServerManager:               ChangeApplicationStatecreate(applicationstate_idobserver, AppState::Inactiveconfig)
RialtoServerManagernote right: config allows app manager to specify number of preloaded servers, ->path to RialtoServerManager:RialtoApplicationSessionServer binary, startup timer and heathcheck interval
RialtoServerManager -> RialtoServerManager: Read Rialto-Config json file and load Generate unique session_management_socket_name for App to Rialto Session Server communication
RialtoServerManager            ->  RialtoServerManager:               Generate socketpair for Rialto Session Server to Server Manager communication
config.
RialtoServerManager -> RialtoServerManager: Read Rialto-Config json overrides file and override config.
loop For num of preloaded server 
ref over RialtoServerManager, RialtoApplicationSessionServer : [[#RialtoApplicationSessionManagement-NotRunning→Unitialized(serverpreloading) Not Running→Unitialized (server preloading)]] 
end
 RialtoServerManager            --> ApplicationManager:  RialtoApplicationSessionServer     
@enduml


Rialto Application State Changes

Not Running→Unitialized (server preloading)

PlantUML Macro
formatSVG
@startuml

autonumber

participant RialtoServerManager
**: Spawn(socketpair, session_management_socket_name, AppState::Inactive)
RialtoServerManager            ->  RialtoServerManager:               StartGenerate [1]socketpair secondfor READYRialto timer
RialtoServerManagerApplication Session Server to Server Manager  communication
RialtoServerManager     --> ApplicationManager:      ->  RialtoApplicationSessionServer **: Spawn(server_manager_socket)
note left
Spawn preloaded Application
Session Servers to OK/ERROR
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Allocate shared memory buffer
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Create listening socket & bind to session_management_socket_namespeed up app launch time.
end note
RialtoServerManager            ->  RialtoServerManager:               Start [startup] second READY timer
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set current_state = InactiveUninitialised

alt PreviousRialtoApplicationSessionServer steps succeeded (alloc shm, create socket, Connect)started successfully

RialtoApplicationSessionServer -// RialtoServerManager:    StateChanged           stateChanged(AppState::InactiveUninitialised)
RialtoServerManager            ->  RialtoServerManager:     Cancel  READY timer
RialtoServerManager       Cancel READY timer   -// ApplicationManager:     StateChanged(application_id, AppState::Inactive)
ApplicationManager  

else Session Server initialisation failed

RialtoServerManager            ->  RialtoServerManager:     GetAppConnectionInfo()
RialtoServerManager          Cancel READY -timer
RialtoApplicationSessionServer ->  ApplicationManagerRialtoApplicationSessionServer:    Unbind/free session_ management_ socket_name

else Session Server initialisation failed

 (if created)
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer !!: Exit process  Close

else IPCREADY connection with app
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:timer expired

RialtoServerManager        Close listening socket (if created)
RialtoApplicationSessionServer - ->  RialtoApplicationSessionServerRialtoServerManager:    Unmap shared memory (if created)
RialtoApplicationSessionServer -// RialtoServerManager:    StateChanged(AppState::Error)
RialtoServerManager            Kill spawned Rialto Application Session Server process
RialtoApplicationSessionServer ->  RialtoServerManagerRialtoApplicationSessionServer:    CancelUnbind/free READYsession management socket (if created)

end

@enduml

Not Running (no server preloading)/Unitialized (server preloading)→Inactive

PlantUML Macro
formatSVG
titleNot Running to Inactive
@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager

ApplicationManager timer
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer !!: Exit process
RialtoServerManager            -//> ApplicationManager:  RialtoServerManager:               StateChangedinitiateApplication(application_id, AppState::Error)

else READY timer expired
Inactive, app_config) 

alt There are no preloaded servers
RialtoServerManager            ->  RialtoServerManager:              Kill spawned Generate socketpair for Rialto Application Session Server process to Server Manager communication
RialtoServerManager            -// ApplicationManager: >  RialtoApplicationSessionServer **: Spawn(server_manager_socket)
RialtoServerManager         StateChanged(application_id, AppState::Error)

end

@enduml

3. socketpair is used to create the point-to-point IPC channel used for all Rialto Server Manager to Rialto Application Session Server communications

7/8. Session server creates the share memory region and listening socket that the app will use for sending AV data and control respectively.

10. Application Session Server sends first message so Server Manager knows that it is now up and running

13/14. Session Manager has an API to allow the Application Manager to get the socket name that the App will use for communication with Rialto which it should fetch as soon as it is notified that Rialto has moved the app out of the Not Running state so that it can be passed to the app/container when it is launched.

Inactive→Active

PlantUML Macro
titleInactive to Active
@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager

ApplicationManager  ->  RialtoServerManager:    ChangeApplicationState(application_id, AppState::Active)
RialtoServerManager ->  RialtoApplicationSessionServer:    SetState(AppState::Active)
RialtoApplicationSessionServer --> RialtoServerManager:    OK/ERROR
RialtoServerManager --> ApplicationManager:     OK/ERROR
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set current_state = Active
RialtoApplicationSessionServer -// RialtoServerManager:    StateChanged(AppState::Active)
RialtoServerManager -// ApplicationManager:     StateChanged(application_id, AppState::Active)

@enduml

2. RialtoServer manager will need to look up which RialtoApplicationSessionServer to which to send the notification

Not Running→Active

Same sequence as Not Running→Inactive but change target state to Active.

Active→Inactive

PlantUML Macro
titleActive to Inactive
@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager
participant RialtoApplicationSessionServer

ApplicationManager  ->  RialtoServerManager:    ChangeApplicationState(application_id, AppState::Inactive)
RialtoServerManager ->  RialtoApplicationSessionServer:    SetState(AppState::Inactive)
RialtoApplicationSessionServer --> RialtoServerManager:    OK/ERROR
RialtoServerManager --> ApplicationManager:    OK/ERROR
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Free any remaining CDM resources
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Free any remaining Player resources
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set current_state = Inactive
RialtoApplicationSessionServer -// RialtoServerManager:    StateChanged(AppState::Inactive)
RialtoServerManager -// ApplicationManager:     StateChanged(application_id, AppState::Inactive)

@enduml

6. Free any Player resources means close any open GStreamer pipelines, for example those used for AV playback and/or UI audio.

Inactive→Not Running

PlantUML Macro
titleInactive to Not Running
@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager
participant RialtoApplicationSessionServer

ApplicationManager  ->  RialtoServerManager:    ChangeApplicationState(application_id, AppState::NotRunning)
RialtoServerManager ->  RialtoApplicationSessionServer:    SetState(AppState::NotRunning)
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Close IPC connection with app
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Unmap shared memory
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set current_state = NotRunning
RialtoApplicationSessionServer -// RialtoServerManager:    StateChanged(AppState::NotRunning)
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer !!: Exit process
RialtoServerManager -// ApplicationManager:     StateChanged(application_id, AppState::NotRunning)

@enduml

7. The Session Server process should self terminate once it has sent the NotRunning notification to the Server Manager.

Active→Not Running

...

   ->  RialtoServerManager:               Start [startup] second READY timer
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set current_state = Uninitialised

alt RialtoApplicationSessionServer started successfully

RialtoApplicationSessionServer -// RialtoServerManager:               stateChanged(AppState::Uninitialised)
RialtoServerManager            ->  RialtoServerManager:               Cancel READY timer
RialtoServerManager            -// ApplicationManager:                stateChanged(application_id, AppState::Uninitialised)

ref over ApplicationManager, RialtoApplicationSessionServer : [[#RialtoApplicationSessionManagement-Unitialized→Inactive Unitialized→Inactive]]  

else Session Server initialisation failed

RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Unbind/free session management socket (if created)
RialtoApplicationSessionServer -// RialtoServerManager:               stateChanged(AppState::Error)
RialtoServerManager            ->  RialtoServerManager:               Cancel READY timer
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer !!: Exit process
RialtoServerManager            -// ApplicationManager:                stateChanged(application_id, AppState::Error)

else READY timer expired

RialtoServerManager            ->  RialtoServerManager:               Kill spawned Rialto Application Session Server process
RialtoServerManager            -// ApplicationManager:                stateChanged(application_id, AppState::Error)

end
else There are preloaded servers
note over ApplicationManager, RialtoApplicationSessionServer: Pick 1st free preloaded server (it's already in unitialized state)
ref over ApplicationManager, RialtoApplicationSessionServer : [[#RialtoApplicationSessionManagement-Unitialized→Inactive Unitialized→Inactive]]
RialtoServerManager            --> ApplicationManager:                OK/ERROR
end

@enduml

Unitialized→Inactive

PlantUML Macro
formatSVG
titleNot Running to Inactive
@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager 

opt session_management_socket_name not specified in app_config
RialtoServerManager            ->  RialtoServerManager:               Generate unique session_management_socket_name for Rialto Client to Rialto Application Session Server communication
end
note right
 "app_config allows app manager to specify the socket name 
  to use for Rialto client/server session management 
  and the socket name for communication with a display server"
end note


RialtoServerManager            ->  RialtoApplicationSessionServer:    SetConfiguration(session_management_socket_name, AppState::Inactive, resources, log_level, display_name)
note right
"resources" structure will specify the maximum decoder resources that the
application is permitted to use. For now it shall have a max_playback_sessions
property and a supports_web_audio flag. This may be enhanced for things like
HD/UHD, audio only etc in future.
end note
RialtoApplicationSessionServer --> RialtoServerManager:
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Create listening socket & bind to session_management_socket_name
opt display_name defined
 RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set WAYLAND_DISPLAY environment variable
end

alt State transition successful
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set current_state = Inactive
RialtoApplicationSessionServer -// RialtoServerManager:               stateChanged(AppState::Inactive)
RialtoServerManager            -// ApplicationManager:                StateChanged(application_id, AppState::Inactive)
ApplicationManager             ->  RialtoServerManager:               getAppConnectionInfo()
RialtoServerManager            --> ApplicationManager:                session_management_socket_name

else State transition failed

RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Unbind/free session management socket (if created)
RialtoApplicationSessionServer -// RialtoServerManager:               stateChanged(AppState::Error)
RialtoServerManager            -// ApplicationManager:                stateChanged(application_id, AppState::Error)
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer !!: Exit process
end

opt Server preloading is active
	note over ApplicationManager, RialtoApplicationSessionServer: Preload RialtoApplicationSessionServer in place of the one that has just been allocated
	ref over ApplicationManager, RialtoApplicationSessionServer : [[#RialtoApplicationSessionManagement-NotRunning→Unitialized(serverpreloading) Not Running→Unitialized (server preloading)]]
end

@enduml


3. socketpair is used to create the point-to-point IPC channel used for all Rialto Server Manager to Rialto Application Session Server communications
8. Application Session Server sends first message so Server Manager knows that it is now up and running
13. Session server creates the socket that the app will use for sending AV data and control respectively.
17/18. Server Manager has an API to allow the Application Manager to get the socket name that the App will use for communication with Rialto which it should fetch as soon as it is notified that Rialto has moved the app out of the Not Running state so that it can be passed to the app/container when it is launched (this is optional as the app manager can supply the socket name in step 1)

Inactive→Active

PlantUML Macro
formatSVG
titleInactive to Active
@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager
participant RialtoApplicationSessionServer

ApplicationManager             ->  RialtoServerManager:               changeSessionServerState(application_id, AppState::Active)
RialtoServerManager            ->  RialtoApplicationSessionServer:    SetState(AppState::Active)
RialtoApplicationSessionServer --> RialtoServerManager:               OK/ERROR
RialtoServerManager            --> ApplicationManager:                OK/ERROR
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Allocate shared memory buffer

opt State transition successful
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set current_state = Active
RialtoApplicationSessionServer -// RialtoServerManager:               stateChanged(AppState::Active)
RialtoServerManager            -// ApplicationManager:                stateChanged(application_id, AppState::Active)
else State transition failed
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Free shared memory buffer if allocated
RialtoApplicationSessionServer -// RialtoServerManager:               stateChanged(AppState::Error)
RialtoServerManager            -// ApplicationManager:                stateChanged(application_id, AppState::Error)
end

@enduml


2. RialtoServerManager will need to look up which RialtoApplicationSessionServer to which to send the notification

Not Running→Active

Same sequence as Not Running→Inactive but change target state to Active and allocate shared memory buffer after creating session management socket.

Active→Inactive

PlantUML Macro
formatSVG
titleActive to Inactive
@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager
participant RialtoApplicationSessionServer

ApplicationManager             ->  RialtoServerManager:               changeSessionServerState(application_id, AppState::Inactive)
RialtoServerManager            ->  RialtoApplicationSessionServer:    SetState(AppState::Inactive)
RialtoApplicationSessionServer --> RialtoServerManager:               OK/ERROR
RialtoServerManager            --> ApplicationManager:                OK/ERROR
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Free any remaining CDM resources
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Free any remaining Player resources
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Unmap/free shared memory buffer
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set current_state = Inactive
RialtoApplicationSessionServer -// RialtoServerManager:               stateChanged(AppState::Inactive)
RialtoServerManager            -// ApplicationManager:                stateChanged(application_id, AppState::Inactive)

@enduml


6. Free any Player resources means close any open GStreamer pipelines, for example those used for AV playback and/or UI audio.

Inactive→Not Running

PlantUML Macro
formatSVG
titleInactive to Not Running
@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager
participant RialtoApplicationSessionServer

ApplicationManager             ->  RialtoServerManager:               changeSessionServerState(application_id, AppState::NotRunning)
RialtoServerManager            ->  RialtoApplicationSessionServer:    SetState(AppState::NotRunning)
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Close IPC connection with app
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set current_state = NotRunning
RialtoApplicationSessionServer -// RialtoServerManager:               stateChanged(AppState::NotRunning)
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer !!: Exit process
RialtoServerManager            -// ApplicationManager:                stateChanged(application_id, AppState::NotRunning)

@enduml


6. The Session Server process should self terminate once it has sent the NotRunning notification to the Server Manager.

Active→Not Running

Not shown for brevity, but should perform all of the cleanup operations in Rialto Sessions server shown in Active→Inactive & Inactive->Not Running.


Application Management

Start Application in Inactive State

PlantUML Macro
formatSVG
titleLaunch application in Inactive state
@startuml
autonumber
participant ApplicationManager
participant RialtoApplicationSessionServer
ref over ApplicationManager, RialtoApplicationSessionServer : [[#RialtoApplicationSessionManagement-NotRunning→Inactive Not Running to Inactive]]
ApplicationManager             ->  Application ** :                Spawn(AppState::Inactive, listening_socket_name)
Application                    ->  RialtoClient ** :               Load RialtoClient library
Application                    ->  RialtoClient :                  registerClient()
RialtoClient                   ->  RialtoApplicationSessionServer: Connect(rialto_listening_socket)
note right
Connect is not an API call, it is establishing IPC channel with server
end note
opt first registerClient call
    RialtoClient               -> RialtoApplicationSessionServer:  registerClient()
    RialtoApplicationSessionServer --> RialtoClient:               status, AppState::Inactive
end
RialtoClient                   --> Application:                    status, AppState::Inactive
Application                    -// ApplicationManager:             stateChanged(AppState::Inactive)
@enduml


Start Application in Running State

PlantUML Macro
formatSVG
titleLaunch application in Running state
@startuml
autonumber

participant ApplicationManager
participant RialtoApplicationSessionServer

ref over ApplicationManager, RialtoApplicationSessionServer : [[#RialtoApplicationSessionManagement-NotRunning→Active Not Running to Active]]

ApplicationManager             ->  Application ** :                Spawn(AppState::Running, listening_socket_name)
Application                    ->  RialtoClient ** :               load RialtoClient library
Application                    ->  RialtoClient :                  registerClient()
RialtoClient                   ->  RialtoApplicationSessionServer: Connect(rialto_listening_socket)
note right
Connect is not an API call, it is establishing IPC channel with server
end note
opt first registerClient call
    RialtoClient               -> RialtoApplicationSessionServer:  registerClient()
    RialtoApplicationSessionServer --> RialtoClient:               status, AppState::Running
end
RialtoClient                   ->  RialtoApplicationSessionServer: GetSharedMemory()
RialtoApplicationSessionServer --> RialtoClient:                   shm_fd
RialtoClient                   ->  RialtoClient:                   Map shared memory
RialtoClient                   --> Application:                    status, AppState::Running
Application                    -// ApplicationManager:             stateChanged(AppState::Running)
@enduml

Switch Application from Inactive to Running State

PlantUML Macro
formatSVG
titleApplication state change: Inactive to Running
@startuml

autonumber

participant ApplicationManager
participant RialtoApplicationSessionServer
participant Application
participant RialtoClient

ref over ApplicationManager, RialtoApplicationSessionServer : [[#RialtoApplicationSessionManagement-Inactive→Active Inactive to Active]] 

RialtoApplicationSessionServer ->  RialtoClient:                   stateChanged(AppState::Running)
RialtoClient                   ->  Application:                    stateChanged(AppState::Running)
RialtoClient                   ->  RialtoApplicationSessionServer: GetSharedMemory()
RialtoApplicationSessionServer --> RialtoClient:                   shm_fd
RialtoClient                   ->  RialtoClient:                   Map shared memory
RialtoClient                   --> Application:                    status
ApplicationManager             ->  Application :                   NotifyNewState(AppState::Running)
Application                    -// ApplicationManager:             stateChanged(AppState::Running)

@enduml

Switch Application from Running to Inactive State

PlantUML Macro
formatSVG
titleApplication state change: Running to Inactive
@startuml
autonumber

participant ApplicationManager
participant RialtoApplicationSessionServer
participant Application
participant RialtoClient

ApplicationManager             ->  Application :       NotifyNewState(AppState::Inactive)
Application                    -->  ApplicationManager:
RialtoApplicationSessionServer -> RialtoClient:        stateChanged(AppState::Inactive)
RialtoClient                   ->  RialtoClient :      Free CDM & Player resources
RialtoClient                   ->  RialtoClient:       Unmap shared memory
RialtoClient                   --> Application:        stateChanged(AppState::Inactive)

ref over ApplicationManager, RialtoApplicationSessionServer : [[#RialtoApplicationSessionManagement-Active→Inactive Active to Inactive]]
@enduml  

Stop Application from Inactive State

PlantUML Macro
formatSVG
titleApplication state change: Inactive to Not Running
@startuml

autonumber

participant ApplicationManager
participant RialtoApplicationSessionServer
participant Application
participant RialtoClient

ApplicationManager  ->  Application :       NotifyNewState(AppState::NotRunning)
Application         -// ApplicationManager: stateChanged(AppState::NotRunning)
Application         ->  RialtoClient:       Unload library
RialtoClient        ->  RialtoClient !!:
Application         ->  Application !!:

ref over ApplicationManager, RialtoApplicationSessionServer : [[#RialtoApplicationSessionManagement-Inactive→NotRunning Inactive to Not Running]]

@enduml

Stop Application from Running State

PlantUML Macro
formatSVG
titleApplication state change: Running to Not Running
@startuml

autonumber

participant ApplicationManager
participant RialtoApplicationSessionServer
participant Application
participant RialtoClient

ApplicationManager  ->  Application :       NotifyNewState(AppState::NotRunning)

Application         ->  RialtoClient:       setApplicationState(Inactive)
RialtoClient        ->  RialtoClient :      Free CDM & Player resources
RialtoClient        ->  RialtoClient:       Unmap shared memory
RialtoClient        --> Application:        status
Application         -// ApplicationManager: stateChanged(AppState::NotRunning)
Application         ->  RialtoClient:       Unload library
RialtoClient        ->  RialtoClient !!:
Application         ->  Application !!:

ref over ApplicationManager, RialtoApplicationSessionServer : [[#RialtoApplicationSessionManagement-Active→NotRunning Active to Not Running]]

@enduml

Example Application Switch Sequences

Active / Inactive Application Switch

This following diagram shows a typical sequence for when the Application Manager needs to make an application active when a currently running application is using the Player resources that the new application requires. The application manager therefore moves the current application into the inactive state to free up the resources and once that is complete switches the new application into the active state so that it can acquire those resources.


PlantUML Macro
formatSVG
titleActive / Inactive Application Switch
@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager

note across : First make App_1 Inactive
ref over ApplicationManager, RialtoServerManager : [[#RialtoApplicationSessionManagement-Active→Inactive Active->Inactive(app_id_1)]]

note across
Once Application Manager has received
the state change event to Inactive for
app_id_1 it can then make App_2 Active
end note
ref over ApplicationManager, RialtoServerManager : [[#RialtoApplicationSessionManagement-Inactive→Active Inactive->Active(app_id_2)]]

@enduml