version 3.x

eTrice Tool Developer’s Reference

Architecture

The basic components of eTrice are depicted in the following diagram.

Additional to that the eTrice project comprises runtime libraries and unit tests which are treated in subsequent sections.

Editor and Generator Components

core
- core.common is an Xtext based language which serves as a base for other eTrice languages. It consists of the plug-ins org.eclipse.etrice.core.common and org.eclipse.etrice.core.common.ui. The base grammar defines recurring items like numbers with literals, annotations and the like.
- core.fsm is an Xtext based language that defines state machines in an abstract way. It consists of the plug-ins org.eclipse.etrice.core.fsm and org.eclipse.etrice.core.fsm.ui. The FSM language is abstract and has to be embedded in a model that defines containers for the state machine with interface items (e.g. ROOM ports or Franca interfaces) and messages. The ROOM grammar of eTrice is derived from this grammar.
- core.room is an Xtext based language called ROOM. It consists of the plug-ins org.eclipse.etrice.core.room and org.eclipse.etrice.core.room.ui. ROOM is the basic modeling language of eTrice.
- core.config is an Xtext based language called Config. It consists of the plug-ins org.eclipse.etrice.core.config and org.eclipse.etrice.core.config.ui. Config is a language designed for the data configuration of model
- core.etphys is an Xtext based language called etPhys. It consists of the plug-ins org.eclipse.etrice.core.etphys and org.eclipse.etrice.core.etphys.ui. etPhys is a language designed for the description of physical systems onto which the logical ROOM systems are deployed.
- core.etmap is an Xtext based language called etMap. It consists of the plug-ins org.eclipse.etrice.core.etmap and org.eclipse.etrice.core.etmap.ui. etMap is a language designed for the mapping of logical to physical systems.
- core.genmodel.fsm is an EMF based aggregation layer for finite state machines. It consists of the plugin org.eclipse.etrice.core.genmodel.fsm. A ModelComponent can be transformed into a ExpandedModelComponent which is an explicit version of the state machine with all the inherited items contained.
- core.genmodel is an EMF based aggregation layer for Room models. It consists of the plugin org.eclipse.etrice.core.genmodel. A Room model can be transformed into a genmodel which allows easy access to implicit relations of the Room model.
ui
- textual
  - fsm.ui is the ui counterpart of core.fsm. It consists of the plug-in org.eclipse.etrice.core.fsm.ui. This plug-in realizes IDE concepts like content assist, error markers and navigation by hyper links for the FSM language.
  - room.ui is the ui counterpart of core.room. It consists of the plug-in org.eclipse.etrice.core.room.ui. This plug-in realizes IDE concepts like content assist, error markers and navigation by hyper links for the Room language.
  - config.ui is the ui counterpart of core.config. It consists of the plug-in org.eclipse.etrice.core.config.ui. This plug-in realizes IDE concepts like content assist, error markers and navigation by hyper links for the Config language.
  - etphys.ui is the ui counterpart of core.etphys. It consists of the plug-in org.eclipse.etrice.core.etphys.ui. This plug-in realizes IDE concepts like content assist, error markers and navigation by hyper links for the etPhys language.
  - etmap.ui is the ui counterpart of core.etmap. It consists of the plug-in org.eclipse.etrice.core.etmap.ui. This plug-in realizes IDE concepts like content assist, error markers and navigation by hyper links for the etPhys language.
- graphical
  - ui.common.base is a set of common code for the diagram editors. It consists of the plug-in org.eclipse.etrice.ui.common.base. It depends only on the FSM part but not on ROOM.
  - ui.common is a set of common code for the two diagram editors. It consists of the plug-in org.eclipse.etrice.ui.common.
  - ui.commands encapsulates some commands related to the navigation between eTrice editors. It consists of the plug-in org.eclipse.etrice.ui.commands.
  - ui.structure is the Graphiti based editor for the Actor structure. It consists of the plug-in org.eclipse.etrice.ui.structure.
  - ui.behavior.fsm is implementing the major part for the graphical state machine editor. It consists of the plug-in org.eclipse.etrice.ui.behavior.fsm. All property dialogs are handled in an abstract way using a factory.
  - ui.behavior is the Graphiti based editor for the Actor behavior. It consists of the plug-in org.eclipse.etrice.ui.behavior. It utilizes the ui.behavior.fsm and provides concrete property dialogs.
generators
- generator.fsm is a set of general classes and language independent parts of all generators. It consists of the plug-in org.eclipse.etrice.generator.fsm. It depends only on FSM but not on ROOM.
- generator is a set of general classes and language independent parts of all generators. It consists of the plug-in org.eclipse.etrice.generator.
- generator.c is the generator for the ANSI-C target language. It consists of the plug-in org.eclipse.etrice.generator.c.
- generator.cpp is the generator for the C++ target language. It consists of the plug-in org.eclipse.etrice.generator.cpp.
- generator.java is the generator for the Java target language. It consists of the plug-in org.eclipse.etrice.generator.java.
- generator.doc is the generator for the model documentation. It consists of the plug-in org.eclipse.etrice.generator.doc.

The Abstract Finite State Machine Concept

eTrice comes with an easy to re-use concept of hierarchical finite state machines (FSM for short). A powerful inheritance concept is used and there is also state machine validation based on semantic rules for messages and abstract execution available.

State machines are an integral part of the ROOM language. But they can also be used independently from that using

for the model part
- org.eclipse.etrice.core.common
- org.eclipse.etrice.core.fsm
- org.eclipse.etrice.core.genmodel.fsm
graphical state machine editor
- org.eclipse.etrice.core.common.ui
- org.eclipse.etrice.core.fsm.ui
- org.eclipse.etrice.core.ui.common.base
- org.eclipse.etrice.core.ui.common
base classes for code generation
- org.eclipse.etrice.generator.fsm
validation by abstract execution
- org.eclipse.etrice.abstractexec.behavior

The first three parts have to be used by concrete implementations that implement the abstract interface. eTrice itself uses the abstract FSMs in exactly this way.

Extending the FSM Model

The eTrice FSM model has to be embedded in a model that introduces components, interfaces and messages. We recommend to use a new Xtext language with a grammar derived from the FSM grammar. This grammar has to specify a component derived from the ModelComponent of the FSM model. It further has to introduce concrete realizations of interface items derived from AbstractInterfaceItem. The interface item is an object contained in a component that has a name (role) and holds a reference to some kind of interface of the component (like a Franca interface or a ROOM protocol). Finally a concrete message type derived from an EObject has to be defined. The minimal requirement is that this concrete message has an attribute called ’name’ of type String.

The minimal interface to be implemented consists of

for the concrete interface item
- EList<EObject> getAllIncomingAbstractMessages()
- EList<EObject> getAllOutgoingAbstractMessages()
- ProtocolSemantics getSemantics()
for the concrete model component
- EList<AbstractInterfaceItem> getAbstractInterfaceItems – the interface items contained in this model component
- EList<AbstractInterfaceItem> getAllAbstractInterfaceItems – all interface items including inherited ones
- String getComponentName() – should return the name of the model component

Extending the State Machine Editor

The concrete state machine editor minimally needs to define

the editor class itself by deriving it from the AbstractFSMEditor
a diagram type provider (which may derive from AbstractDiagramTypeProvider)
a Google Guice module with bindings for
- IFSMDialogFactory
- DiagramAccessBase
- IBehaviorQuickfixProvider
- IResourceSetProvider
concrete implementations of all property dialogs the IFSMDialogFactory produces

Runtimes

Currently eTrice ships with a C and a Java runtime. The C++ runtime is still a prototype. The runtimes are libraries written in the target language against which the generated code is compiled.

Unit Tests

Most plug-ins and other parts of the code have related unit tests.

Component Overview

Room Language Overview

We assume that the reader is familiar with the Xtext concepts. So we concentrate on the details of our implementation that are worth to be pointed out.

Model Tweaks

All language EMF models of eTrice are inferred from their respective grammar. However, this powerful mechanism has to be tweaked in some places.

In order to do so post processors are added that are invoked by the Xtext framework on language generation. This is done for the FSM language by /org.eclipse.etrice.core.fsm/src/org/eclipse/etrice/core/fsm/postprocessing/ImplPostprocessor.xtend.

The following parts of the model are changed or added:

an operation getName is added to the State class
an operation getName is added to the StateGraphItem class
an operation getSemantics is added to the AbstractInterfaceItem
an operation getAllIncomingAbstractMessages is added to the AbstractInterfaceItem
an operation getAllOutgoingAbstractMessages is added to the AbstractInterfaceItem
an interface class IInterfaceItemOwner is added
an operation getAbstractInterfaceItems is added to the AbstractInterfaceItem
an operation getAllAbstractInterfaceItems is added to the AbstractInterfaceItem
IInterfaceItemOwner is made a super class of ModelComponent

All but the first two items in the list are part of the abstract FSM definition and are used to interface to the model embedding the FSM language, e.g. ROOM.

For the ROOM language the post processor is /org.eclipse.etrice.core.room/src/org/eclipse/etrice/core/RoomPostprocessor.ext.

The following parts of the model are changed or added:

the default multiplicity of the Port is set to 1
the operation isReplicated is added to the Port
the default multiplicity of the ActorRef is set to 1
an operation getSemantics is added to the InterfaceItem
an operation getAllIncomingAbstractMessages is added to the InterfaceItem
an operation getAllOutgoingAbstractMessages is added to the InterfaceItem
an operation getExternalEndPorts is added to the ActorClass
an operation getRelayPorts is added to the ActorClass
an operation getImplementedSPPs is added to the ActorClass
an operation getActorBase is added to the ActorClass
an operation getComponentName is added to the ActorClass
an operation getAbstractInterfaceItems is added to the ActorClass
an operation getAllAbstractInterfaceItems is added to the ActorClass
an operation getStructureClass is added to the ActorContainerRef
an operation toString is added to the RefPath
for attribute idx of RefSegment the default is changed to -1
an operation toString is added to the RefSegment
an operation getLiteralValue is added to the EnumLiteral
an operation getFullName is added to the EnumLiteral

Imports by URI Using Namespaces

The import mechanism employed is based on URIs. This is configured for one part in the GenerateRoom.mwe2 model workflow by setting the fragments ImportURIScopingFragment and ImportUriValidator). For the other part it is configured in the Guice modules by binding

PlatformRelativeUriResolver – this class tries to convert the import URI into a platform relative URI. It also replaces environment variables written in $ with their respective values.
ImportedNamespaceAwareLocalScopeProvider – this is a standard scope provider which is aware of namespaces
GlobalNonPlatformURIEditorOpener – this editor opener tries to convert general URIs into platform URIs because editors can only open platform URIs
ImportAwareHyperlinkHelper – turns the URI part of an import into a navigatable hyper link

Naming

Two classes provide object names used for link resolution and for labels. The RoomNameProvider provides frequently used name strings, some of them are hierarchical like State paths. The RoomFragmentProvider serves a more formal purpose since it provides a link between EMF models (as used by the diagram editors) and the textual model representation used by Xtext.

Helpers

The RoomHelpers class provides a great deal of static methods that help retrieve frequently used information from the model. Among many, many others

getAllEndPorts(ActorClass) - returns a list of all end ports of an actor class including inherited ones
getInheritedActionCode(Transition, ActorClass) - get the inherited part of a transition’s action code
getSignature(Operation) - returns a string representing the operation signature suited for a label

Validation

Validation is used from various places. Therefore all validation code is accumulated in the @ValidationUtil@ class. All methods are static and many of them return a Result object which contains information about the problem detected as well as object and feature as suited for most validation purposes.

Config Language Overview

Model Tweaks

A couple of operations are added to the ConfigModel

getActorClassConfigs
getActorInstanceConfigs
getProtocolClassConfigs
getSubSystemConfigs

Imports by URI Using Namespaces

Imports are treated like in Room language, section Imports by URI Using Namespaces.

Util

A set of static utility methods can be found in the ConfigUtil class.

Aggregation Layer Overview

The eTrice Generator Model (genmodel.fsm and genmodel) serves as an aggregation layer. Its purpose is to allow easy access to information which is implicitly contained in the Room model but not simple to retrieve. Examples of this are the state machine with inherited items or a list of all triggers active at a state in the order in which they will be evaluated or the actual peer port of an end port (following bindings through relay ports).

The lower level FSMGeneratorModelBuilder takes a ModelComponent and returns a ExpandedModelComponent which has the inheritance hierarchy of the state machine collapsed into one state machine. This lower level generator model only depends on general parts and doesn’t refer to the ROOM model.

The higher level Generator Model includes the FSM Generator Model. It is created from a list of Room models by a call of the

createGeneratorModel(List<RoomModel>, boolean)

method of the GeneratorModelBuilder class.

The Root object of the resulting Generator Model provides chiefly two things:

a tree of instances starting at each SubSystem with representations of each ActorInstance and PortInstance
for each ActorClass a corresponding ExpandedActorClass with an explicit state machine containing all inherited state graph items

The Instance Model

The instance model allows easy access to instances including their unique paths and object IDs. Also it is possible to get a list of all peer port instances for each port instance without having to bother about port and actor replication.

The Expanded Model Component

The expanded model component contains, as already mentioned, the complete state machine of the model component. This considerably simplifies the task of state machine generation. Note that the generated code always contains the complete state machine of an actor. I.e. no target language inheritance is used to implement the state machine inheritance. Furthermore the ExpandedModelComponent gives access to

getIncomingTransitions(StateGraphNode) – the set of incoming transition of a StateGraphNode (State, ChoicePoint or TransitionPoint)
getOutgoingTransitions(StateGraphNode) – the set of outgoing transition of a StateGraphNode
getActiveTriggers(State) – the triggers that are active in this State in the order they are evaluated

The Expanded Actor Class

The ExpandedActorClass is derived from the ExpandedModelComponent and adds only minor new features.

getActorClass() – for convenience to avoid casts of the ModelComponent to an ActorClass
getVarDeclData(Transition) – for convenience to avoid casts to VarDecl

Transition Chains

By transition chains we denote a connected subset of the (hierarchical) state machine that starts with a transition starting at a state and continues over transitional state graph nodes (choice points and transition points) and continuation transitions until a state is reached. In general a transition chain starts at one state and ends in several states (the chain may branch in choice points). A TransitionChain of a transition is retrieved by a call of getChain(Transition) of the ExpandedActorClass. The TransitionChain accepts an ITransitionChainVisitor which is called along the chain to generate the action codes of involved transitions and the conditional statements arising from the involved choice points.

Generator Overview

There is one plug-in that consists of base classes and some generic generator parts which are re-used by all language specific generators

Base Classes and Interfaces

We just want to mention the most important classes and interfaces. Some of them can be found in the org.eclipse.etrice.generator.fsm and th rest in org.eclipse.etrice.generator.

ITranslationProvider — this interface is used by the DetailCodeTranslator for the language dependent translation of e.g. port.message() notation in detail code
AbstractGenerator — concrete language generators should derive from this base class
DefaultFSMTranslationProvider and DefaultTranslationProvider — a stub implementation of IFSMTranslationProvider and ITranslationProvider from which clients may derive
Indexed — provides an indexed iterable of a given iterable
GeneratorBaseModule — a Google Guice module that binds a couple of basic services. Concrete language generators should use a module that derives from this

Generic Generator Parts

The generic generator parts provide code generation blocks on a medium granularity. The language dependent top level generators embed those blocks in a larger context (file, class, …). Language dependent low level constructs are provided by means of an ILanguageExtension. This extension and other parts of the generator be configured using Google Guice dependency injection.

GenericActorClassGenerator

The GenericActorClassGenerator generates constants for the interface items of a actor. Those constants are used by the generated state machine.

GenericProtocolClassGenerator

The GenericProtocolClassGenerator generates message ID constants for a protocol.

GenericStateMachineGenerator

The GenericStateMachineGenerator generates the complete state machine implementation. The skeleton of the generated code is

definition state ID constants
definition of transition chain constants
definition of trigger constants
entry, exit and action code methods
the exitTo method
the executeTransitionChain method
the enterHistory method
the executeInitTransition method
the receiveEvent method

The state machine works as follows. The main entry method is the
receiveEvent method. This is the case for both, data driven (polled) and event driven state machines. Then a number of nested switch/case statements evaluates trigger conditions and derives the transition chain that is executed. If a trigger fires then the exitTo method is called to execute all exit codes involved. Then the transition chain action codes are executed and the choice point conditions are evaluated in the executeTransitionChain method. Finally the history of the state where the chain ends is entered and all entry codes are executed by enterHistory.

The Java Generator

The Java generator employs the generic parts of the generator. The JavaTranslationProvider is very simple and only handles the case of sending a message from a distinct replicated port: replPort[2].message(). Other cases are handled by the base class by returning the original text.

The DataClassGen uses Java inheritance for the generated data classes. Otherwise it is pretty much straight forward.

The ProtocolClassGen generates a class for the protocol with nested static classes for regular and conjugated ports and similar for replicated ports.

The ActorClassGen uses Java inheritance for the generated actor classes. So ports, SAPs and attributes and detail code methods are inherited. Not inherited is the state machine implementation.

The ANSI-C Generator

The C generator translates data, protocol and actor classes into structs together with a set of methods that operate on them and receive a pointer to those data (called self in analogy to the implicit C++ this pointer). No dynamic memory allocation is employed. All actor instances are statically initialized. One of the design goals for the generated C code was an optimized footprint in terms of memory and performance to be able to utilize modeling with ROOM also for tiny low end micro controllers.

The Documentation Generator

The documentation generator creates documentation in LaTex format which can be converted into PDF and many other formats.