Requirements#

Communication Requirements
status: valid
security: YES
safety: ASIL_B
Support for Time-based Architecture
status: valid
security: NO
safety: ASIL_B

The communication framework shall provide API to support a time-based architecture.

Support for Data-driven Architecture
status: valid
security: NO
safety: QM

The communication framework shall provide API to support a data-driven architecture.

Support for Request-driven Architecture
status: valid
security: NO
safety: QM

The communication framework shall provide API to support a request-driven architecture.

Event Type
status: valid
security: NO
safety: ASIL_B

An event-type is part of a communication interface and has:

  • a name

  • a data type

The producer can assign a value to it. Consumers can subscribe to value-changed events of the element or poll unseen, cached events.

Method
status: valid
security: NO
safety: ASIL_B

A method is part of a communication interface and has:

  • a name

  • a specified application routine with a given set of parameters and a return type

When a communication partner issues a call to the method with the required parameters:

  1. it shall invoke the application routine with the provided parameters, and

  2. return its result to the communication partner

A method call shall be possible both synchronously and asynchronously.

Signal
status: valid
security: NO
safety: QM

A signal is part of a communication interface and has:

  • a name

A client can trigger the signal. The service instance offering the trigger can:

  • wait for the signal to be triggered

  • check if the signal was triggered

Note

Signals can not transport data. They are meant to be fast synchronization mechanism with low setup cost. Thus, depending on the location of the communication partners primitives like Linux Signals or QNX Pulses or Hypervisor Signalling APIs may be chosen.

Producer-Consumer Pattern
status: valid
security: NO
safety: ASIL_B

Communication shall be cached based on the producer-consumer pattern.

Service Instance
status: valid
security: NO
safety: ASIL_B
tags: com
reqtype: Functional

Multiple service instances shall be able to offer the same interface.

Note

A communication interface that is offered to consumers is called a service instance.

Service Instance Names
status: valid
security: NO
safety: ASIL_B
tags: com
reqtype: Functional

A service instance is offered under one or more unique names by which it can be discovered. Names follow a POSIX path style.

Note

The resolution from a service instance name to the protocol-specific identifier is handled by the service discovery.

Versioning
status: valid
security: NO
safety: ASIL_B
tags: com
reqtype: Functional

The communication framework shall support versioning of service instances:

  • Version information of a service instance is binding-specific.

  • Version information is provided in the deployment configuration.

Note

Multiple service instances can have the same interface and version.

Service location transparency
status: valid
security: NO
safety: ASIL_B
tags: com
reqtype: Functional

The interface to access service instances is agnostic to the binding used to communicate with the service.

Note

Deployment information may require manual changes based on where the service is located.

Stateless communication
status: valid
security: NO
safety: ASIL_B
tags: com
reqtype: Functional

The communication framework shall support stateless communication.

Note

  • In case of events, the producer is not aware of its consumers.

  • In case of RPC, the skeleton is not aware of the proxy, this request originated from.

Service instance_granularity
status: valid
security: NO
safety: ASIL_B
tags: com
reqtype: Functional

The communication framework shall support multiple service instances per software architecture element.

Note

A software architecture element is for example an application, activity, proces, …

Service discovery
status: valid
security: NO
safety: ASIL_B
tags: com
reqtype: Functional

The communication framework shall provide service discovery to find available services during runtime. Service discovery shall consider version compatibility. Service discovery shall be handled implicitly (where possible).

Note

The service discovery may be restricted/impacted by availability of deployment information.

Mixed-Criticality safety systems#

Safe communication over criticality levels
status: valid
security: YES
safety: ASIL_B
tags: com
reqtype: Functional

The communication framework shall support safe communication involving communication partners on the same or multiple criticality levels.

Data Corruption
status: valid
security: YES
safety: ASIL_B
tags: com
reqtype: Functional

Consumers with lower criticality shall not be able to corrupt data consumed by partners with higher criticality.

Data Reordering
status: valid
security: YES
safety: ASIL_B
tags: com
reqtype: Functional

Consumers with lower criticality shall not be able to modify the order of data consumed by partners with higher criticality.

Data Repetition
status: valid
security: YES
safety: ASIL_B
tags: com
reqtype: Functional

Consumers with lower criticality shall not be able to duplicate data consumed by other communication partners with higher criticality.

Data Loss
status: valid
security: YES
safety: ASIL_B
tags: com
reqtype: Functional

Consumers with lower criticality shall not be able to drop data before it is consumed by partners with higher criticality.

Performance#

Zero-Copy Approach
status: valid
security: NO
safety: QM

The communication framework shall enable Zero-Copy communication without copying to-be-transferred data.

Note

It has to be evaluated on binding level if a Zero-Copy approach is applicable for the respective binding.

User friendly API for information exchange#

Support for multiple programming languages
status: valid
security: NO
safety: QM
tags: com
reqtype: Non-Functional

The communication framework shall provide a public API for each supported programming language of S-CORE.

Support for programming language idioms
status: valid
security: NO
safety: QM
tags: com
reqtype: Non-Functional

Each public API shall support the idioms of the programming language it is written in.

Use programming language infrastructure
status: valid
security: NO
safety: QM
tags: com
reqtype: Non-Functional

Each public API shall use core infrastructure of its programming language and accompanying standard libraries, whenever possible and meaningful.

Note

This includes error handling.

Full testability for the user facing API#

Fully mockable public API
status: valid
security: NO
safety: QM
tags: com
reqtype: Non-Functional

The public API shall be fully mockable.

Fake binding
status: valid
security: NO
safety: QM
tags: com
reqtype: Non-Functional

The communication framework shall provide a fake binding.

Multi-binding support#

Multi-binding support
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional

The communication framework shall support multiple bindings.

Note

A binding performs the conversion of user communication to the respective communication protocol. It does this either directly or via a gateway approach.

Binding-agnostic public API
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional

The public API of the communication framework shall be binding-agnostic.

Note

Binding-agnostic in this context means, that the public API is independent of the binding underneath. E.g., if the binding is exchanged, the public API remains syntactically and semantically unchanged.

Multi-binding deployment configuration
status: valid
security: NO
safety: ASIL_B
tags: com
reqtype: Functional

The association of a service instance and the appropriate binding shall be specified in the deployment configuration.

Cross-VM Extensions#

One-way data sharing into a VM
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

The system shall support one-way data sharing into a Virtual Machine (VM) for vehicle state read-only for the VM (snapshot state).

Read-only access for VM
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

The consumer (VM) shall have read-only access to the shared data.

Consistent data-sets
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

The system shall support consistent data-sets, allowing the consumer to obtain a consistent version of related data items.

Lock-free access
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

Consistent access to data must be lock-free.

Producer time stamps
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

Producer time stamps shall be available for related data-sets.

Streamed data based on shared queues
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

The system shall support streamed data based on shared queues (stream of events or data).

Configurable queues
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

Queues shall be configurable by the client (VM), including the number of elements and buffer allocation.

Lock-free queue access
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

Queues shall support lock-free access to data elements.

Bi-directional communication
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

The system shall support bi-directional communication via writable data elements by the client.

Asynchronous support
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

The system shall provide asynchronous bi-directional support via multiple queues.

Shared memory chunks
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

The system shall support multiple chunks of shared memory to allow required access control.

Data update notifications
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

Notifications for data updates shall be available (virtual IRQs in a VM).

Configurable notifications
status: valid
security: NO
safety: QM
tags: com
reqtype: Functional
valid_from: v1.0.0

Notifications shall be configurable by consumers of data (using flags or watermarks in shared memory from client to producer).

Dynamic deployment at runtime#

Deployment configuration at runtime
status: valid
security: YES
safety: ASIL_B

Deployment configuration shall be read from an integrity-checked configuration file at runtime.

Tracing#

Support for Tracing
status: valid
security: NO
safety: ASIL_B

The communication framework shall provide infrastructure to enable binding-agnostic, zero-copy, read-only tracing of communication.

Security Impact#

Access Control List Placement
status: valid
security: YES
safety: QM

The communication framework shall support an Access Control Lists in the deployment configuration.

Access Control List per service instance
status: valid
security: YES
safety: QM

The communication framework shall support an Access Control List per service instance.

Access Control List for producer
status: valid
security: YES
safety: QM

The communication framework shall support an Access Control List for the communication partner offering a service instance (producer). An entry in the ACL corresponds to an allowed consumer.

Access Control List for consumer
status: valid
security: YES
safety: QM

The communication framework shall support an Access Control List for the communication partner consuming a service instance. An entry in the ACL corresponds to an allowed producer.

Safety Impact#

Communication ASIL level
status: valid
security: YES
safety: ASIL_B
tags: com
reqtype: Functional

The communication framework shall support safe communication up to ASIL-B.