Rialto Application State Changes

Not Running→Inactive

@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager

ApplicationManager             ->  RialtoServerManager:               initiateApplication(application_id, AppState::Inactive, app_config)
note right: app_config allows app manager to specify the socket name to use for Rialto client/server session management
opt 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
RialtoServerManager            ->  RialtoServerManager:               Generate socketpair for Rialto Session Server to Server Manager communication
RialtoServerManager            ->  RialtoApplicationSessionServer **: Spawn(socket)
RialtoServerManager            ->  RialtoServerManager:               Start [1] second READY timer
RialtoServerManager            --> ApplicationManager:                OK/ERROR
RialtoApplicationSessionServer ->  RialtoApplicationSessionServer:    Set current_state = Uninitiliased

alt RialtoApplicationSessionServer started successfully

RialtoApplicationSessionServer -// RialtoServerManager:               stateChanged(AppState::Uninitialised)
RialtoServerManager            ->  RialtoServerManager:               Cancel READY timer
RialtoServerManager            -// ApplicationManager:                stateChanged(application_id, AppState::Uninitialised)
RialtoServerManager            ->  RialtoApplicationSessionServer:    SetConfiguration(session_management_socket_name, AppState::Inactive, resources, log_level)
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

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

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

@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

@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

@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

@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

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

Start Application in Running State

@startuml

autonumber

participant ApplicationManager
participant RialtoApplicationSessionServer

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

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

@enduml

Switch Application from Inactive to Running State

@startuml

autonumber

participant ApplicationManager
participant RialtoApplicationSessionServer
participant Application
participant RialtoClient

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

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

@enduml

Switch Application from Running to Inactive State

@startuml

autonumber

participant ApplicationManager
participant RialtoApplicationSessionServer
participant Application
participant RialtoClient

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

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

@enduml

Stop Application from Inactive State

@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 : [[#RialtoSessionManagementSequenceDiagrams-Inactive→NotRunning Inactive to Not Running]]

@enduml

Stop Application from Running State

@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 : [[#RialtoSessionManagementSequenceDiagrams-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.

@startuml

autonumber

participant ApplicationManager
participant RialtoServerManager

note across : First make App_1 Inactive
ref over ApplicationManager, RialtoServerManager : [[#RialtoSessionManagementSequenceDiagrams-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 : [[#RialtoSessionManagementSequenceDiagrams-Inactive→Active Inactive->Active(app_id_2)]]

@enduml