namespace ara::exec

The namespace provides interfaces for process management and the control of function groups on the AUTOSAR Adaptive Platform. Processes use the client to report their execution state kRunning to Execution Management after successful initialization [SWS_EM_02000]. State Management requests transitions of function groups via interfaces, while impermissible state changes or communication errors are captured via standardized error codes [SWS_EM_02281]. Strict adherence to the transition order is mandatory.

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Context

The namespace ara::exec provides the interfaces of Execution Management on the AUTOSAR Adaptive Platform. The module is responsible for starting, controlling, and monitoring processes as well as coordinating higher-level system and function group states. Central actors include application processes, State Management, and Execution Management itself. Processes use class ExecutionClient to report their internal runtime state to Execution Management. State Management in turn uses the interface StateClient to request state changes between function groups (FunctionGroup and FunctionGroupState). For error events at function group level, the type alias ExecutionError is used [SWS_EM_02541], which can be transported via ExecutionErrorEvent.

Lifecycle

The execution lifecycle of a process is controlled by Execution Management [SWS_EM_02000]. After scheduling, a newly started process is initially in an implicit state Initializing in which no application program code has been executed yet. Execution Management assumes that this initialization state lasts until the process actively reports state ExecutionState::kRunning via its ExecutionClient [SWS_EM_02000]. The enumeration ExecutionState is strictly restricted to those states that can be reported by processes to Execution Management and therefore contains exclusively the state kRunning [SWS_EM_02000]. If Execution Management requests termination, the process transitions to phase Terminating, which concludes with the final termination of the process [SWS_EM_02000].

State diagram: Lifecycle of a process from the perspective of Execution Management with implicit states and reporting of kRunning. Sources: [SWS_EM_02000]

Usage Path

A typical usage flow is divided into the following phases:

• After system startup, the process is created by Execution Management and performs its internal initialization [SWS_EM_02000].
• As soon as initialization has been successfully completed, the process reports the state ExecutionState::kRunning to Execution Management via an instance of ExecutionClient [SWS_EM_02000].
• Execution Management acknowledges this transition; however, if kRunning is reported when the process is already in the running state, this is rejected as an invalid transition ExecErrc::kInvalidTransition [SWS_EM_02281].
• During further operation, State Management requests coordinated state transitions for function groups via StateClient as required.

Sequence diagram: Call sequence during state reporting via ExecutionClient and handling of erroneous transitions. Sources: [SWS_EM_02000], [SWS_EM_02281]

Error Scenarios

Error situations are mapped in namespace ara::exec via the enumeration type ExecErrc and the error domain ExecErrorDomain [SWS_EM_02281]. A reference to the global domain object is returned by the thread- and exception-safe function GetExecErrorDomain() [SWS_EM_02290]. Concrete error objects of type ara::core::ErrorCode are created via the helper function MakeErrorCode() by passing the error code and vendor-specific context data [SWS_EM_02291]; class ExecException is also available for exception handling.

Specified error causes include, among others, [SWS_EM_02281]:

• ExecErrc::kNoCommunication: Signals communication errors between client and Execution Management or between State Management and Execution Management. At system level, such a state would likely require entering an unrecoverable state [SWS_EM_02281]. Question Q-ad08207b6a16c6f9 (open)
• ExecErrc::kInvalidTransition: Invalid transition, for example when a process repeatedly reports kRunning [SWS_EM_02281].
• ExecErrc::kOperationFailed: An operation fails, for instance when a function group transition cannot be completed because kRunning was not reported in time [SWS_EM_02281].
• ExecErrc::kOperationCanceled: A state transition of a function group was canceled by a newer request [SWS_EM_02281].
• ExecErrc::kIntegrityOrAuthenticityCheckFailed: The integrity or authenticity check of a process to be started fails [SWS_EM_02281].
• ExecErrc::kUnexpectedTermination: Abnormal termination during a transition [SWS_EM_02281].
• ExecErrc::kInvalidMetaModelIdentifier as well as ExecErrc::kInvalidArgument: Impermissible metamodel identifiers or invalid parameter values [SWS_EM_02281].