Component based Middleware for real-time embedded systems. Ansgar Radermacher CEA-List

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1 Component based Middleware for real-time embedded systems Ansgar Radermacher CEA-List

2 Agenda Introduction Demands of RT & Embedded Applications Towards a common component model for this domain Convergence of models Extensions for Embedded & RealTime applications Complementary activities validation, model of computation Specific usage: fault tolerance mechanisms Model Driven Development From Models to executable middleware code ec3m UML Models (within Papyrus UML) Code generation

3 Demands of RT & Embedded applications Real-time: timing constraints (soft or hard deadlines) Resource constraints (small memory, RAM/ROM) OS constraints (fixed number of threads, Semaphores, message sizes,...) software tailored to specific target, costly to port and to adapt Quote from ITEA-Merced project, same spirit behind IST-Compare move from performance-centric to complexity-centric.....without loosing performance and time support! Laboratoire d' Intégration des Systèmes et des Technologies

4 Component Approach CORBA Component model as good base candidate OMG Standard Separation of component & container enabling better portability Lightweight variant exists But only pre-defined container with fixed services But only supports small set of interaction patterns with specific and fixed implementations Synchronous method calls (via CORBA) Event based communications Streaming (recently added) Not enough for embedded systems Laboratoire d' Intégration des Systèmes et des Technologies

5 Excursion: CORBA Component Model Component has provided and required ports (interfaces, events) Lightweight CCM = CCM w/o introspection, simple container type (no security/persistence/transaction) receptacle facet Attributes for component configuration, re-use Container, manages Connections, delegates interactions component executor = business logic

6 Packaging and Deployment Classic CORBA: No standard means of... Instantiation& Configuration, Deployment on nodes Deployment & Configuration (OMG standard) Components are packaged into a self-descriptive package Packages can be assembled Assemblies can be deployed Deployment tools are based on XML descriptors Deployment Plan.cdp Component Description Deployment tool static dynamic bootloader file Connector fragments TFTP (or similar) additional compilation step

7 Towards an enhanced component model Better container support New simple container with interception plug-ins OMG Standard QoS for CCM Connector support allows to specify Interaction pattern during component development time Interaction implementation during deployment time Basic principles: Connectors are like components: can be configured, have implementations like connections: ports don t have fixed interface types, need to be generated, are split into connector ends (fragments)

8 Towards an enhanced component model Configuration of services/connectors in declarative way Advantage: keep platform specific programming (Mutex, Conditions,...) out of business logic within component ec3m embedded Component-Container-Connector Middleware ( Ongoing convergence actions among: CCM, Fractal, Autosar, IMA Ongoing project focus on CCM & Fractal Take Model Driven Development in Account MARTE for declarative NFPs

9 Connector/Container Service Examples Connector Examples Synchronous Calls via CORBA, OSEK messages FIFO in shared memory or distributed via CORBA Events (making pre-defined event ports obsolete) Connectors supporting Fault Tolerance, Communication avec FPGA (current projects) Container Service Examples Access protection via n-readers, 1 writer Logging/Tracing of requests Execution time measurement Limits: focus on structural info + declarative NFP execution model managed implicitly

10 How to define port semantics? Component implementation assumes a certain semantics associated with call on port (and being called on a port) Connector maybe incompatible with a component, even if port interfaces are matching Options Specify required connector type at component design time A bit restrictive with respect to component reuse Via port type definitions Port type captures certain semantics Better component reuse of component implementations Support complex-ports (single port can provide & require)

11 More insight on connectors for CCM (runtime) connectors realizations are fragmented fragments are co-localized with components Implement interface between component and connector communication between fragments is connector specific connector fragment Connector connector fragment

12 Complementary activities: computation models Formal technique: compute execution paths from finite state machine Rules to trigger transitions, consume events, chain actions are parameters Symbolic execution engine Applied to test generation, property verification Reuse free tools for formal techniques reduce symbolic expressions, optimize trees, solve constraints Integrated to MDE technologies (Eclipse, EMF, ATL, Papyrus) Manage heterogeneity by dynamically changing execution rules Global view of system architecture: components (// state machines) Limits: rules are defined case by case Laboratoire d' Intégration des Systèmes et des Technologies

13 Réponse = OK?o := NomObjet ; touch(?x)?o := NomObjet ; touch(?x) in(?x) ; NomObjet := Objet(?x) ; Réponse := InStock?(NomObje t) Réponse = OK Réponse = NO!z := NomObjet touch(?x) touch(?x) in(?x) ; NomObjet := Objet(?x) ; Réponse := InStock?(NomObjet) Réponse = NO Réponse = OK?o := NomObjet ; touch(?x)!z := NomObjet touch(?x) in(?x) ; NomObjet := Objet(?x) ; Réponse := InStock?(NomObjet) Réponse = NO!z := NomObjet touch(?x)!t = something!y = something S.timer? T!t = something!x = something reset S.timer!z = something!y = something S.timer> T!t = something!y = something S.timer? T!z = something!z= something!y = something S.timer> T Réponse = OK?o := NomObjet ; touch(?x) in(?x) ; NomObjet:= Objet(?x) ; Réponse:= InStock?(NomObjet ) touch (?x) in(?x) ; NomObjet := Objet(?x) ; Réponse := InStock?(NomObjet) Réponse = OK?o := NomObjet ; touch(?x) in(?x) ; NomObjet := Objet(?x) ; Réponse:= InStock?(NomObjet ) touch(?x) in(?x) ; NomObjet := Objet(?x) ; Réponse:= InStock?(NomObjet ) Réponse = NO!z := NomObjet!t = something!z = something!y = something S.timer T!t = something!y = something S.timer T Σ!t = something!x = something reset S.timer Σ!z = something!y = something S.timer > T!t = something!y = something S.timer T!z = something!z= something!y = something S.timer > T!y = something S.timer > T Σ ΣΣΣ εε Σ Σ ΣΣ ΣΣ!t = something!z = something Σ ΣΣΣΣ Σ Heterogeneity of computation and communication models THeSys (Tackling Heterogeneous Systems) Mathematical foundation (denotational): LEM (Language for expressing Execution Models) Christophe Gaston integrate hierarchy, component, interconnection and (unrestricted) time values and times of exchanged data are synchronised formal description of Model of Computation and Communication (MoCC) Interconnection glue EMTDirection (EMT{?x,!y,?t,!z}Comp, INIT 1!x?x {!x,?y}cli, {!t,?z}cui) Client?y!y time (real, triggering)? 0 timerreal timer_1 time interaction time=comp.time!x?x { when(!x=something)? 1 Desk Repository!t?t?z!z,, {resettimer_1} {!x?x}!z?z!t?t ;!u!y {? 3? 4 when(!y=somethingandtimer_1 T) {!y?y}!y?y?!y?y? w when(!y=somethingandtimer_1>t) {ε}? 8? 9? 10? 11 w when(!z=something) {!z?z} w when(!t =something) {!t?t } } Component set of observable (internal) executions!u!y!u!y!t?t!t?t!z?z!z?z? 16? 17? 18? 19!u!y!u!y? 0? 1? 2? 4? 6? 7 System behaviour set of observable (system) executions =!z = something!t = something!z?z!t?t!y?y 6!t?t!z?z !t?t!t?t 16 3!x?x?y!z?z ε!y!t?t !y?y 10!z?z!z?z !z = something!t = something!z?z!t?t 12!t?t!z?z } Laboratoire d' Intégration des Systèmes et des Technologies

14 Related work (THeSys) Ptolemy II: not formal, heterogeneous (hierarchical), no language for expressing models of computation CommUnity (Univ. Leicester, Lisbon): formal, no time but causality (pre/post). BIP: formal, powerful interaction language, more limited to interactions Time treated externally, not meta model oriented Kermeta: not formal, meta programming language Laboratoire d' Intégration des Systèmes et des Technologies

15 Model Driven Development Meta-Model of component approach ec3m UML Profile UML + MARTE Profile (for NFPs) + ec3m Profile Use of Papyrus ( UML modeler Strong Profile Support Invented here Build model, apply stereotypes/values Generate ec3m descriptor files from model IDL, Component Descriptor (CCD), Deployment plan (CDP) Generate container, bootloader (glue) via MicroCCM (joint implementation from Thales and CEA-List, hopefully released soon as OpenSource) Laboratoire d' Intégration des Systèmes et des Technologies

16 Laboratoire d' Intégration des Systèmes et des Technologies

17 Refinement steps Model Level Redundance parameters 1. Style 2. Number of replicas 3. Allocation contraints Calc (cosine) Calc Calc 2 2 FIFO Display Display Display FT parameter domaine 1. FaultDetector- DeployPolicy (Infrastructure) «syscomponent» FaultDetector Node A Calc 2 FD-A Node B Calc 1 FD-B Allocation (automatic) Node C Display FD-C 17

18 Deployment of a component (replica) on multiple nodes Model Level Node A Calc 2 FD-A Node B Calc 1 FD-B Node C Display FD-C Packaging Tool XML D&C <!-- Instance of Calc --> <instance id="instance1"> <name>calc_inst</name> <node>nodea, nodeb</node> <implementation ref="implcalc"/> <configproperty> </instance> <connection id="connexion3"> <name>calc_display</name> <implementation ref="implft-fifo"/> 18

19 Fragment code (example) void FTFIFO_IDisplay_f_conn::display (CORBA::Float value) { if (m_voter!= NULL) { // calculate hash of request (used to simplify comparisons). } Hash hash; hash.add (m_voter->getrequestnr ()); hash.add (value); m_voter->acknowledgerequest (hash.get ()); } for (int i = 0; i<max_nr_of_nodes; i++) { if (m_set.isonnode (i)) m_set.getobj (i)->display (value); } Multiplier: Communication with other instance (maybe replicated) Communication between replicas 19

20 Conclusions Specific support for embedded requirements through Container services Connectors (configurable) Towards adaptive executions & communication platforms (heterogeneity at several levels) Declarative specification of non-funtional properties Complete MDD tool chain Model, Analysis (not shown Thesis H. Espinoza), deployment, execution & operation Future work Convergence of component models based on standards Overcome two worlds separation: integrate formal approaches Laboratoire d' Intégration des Systèmes et des Technologies

21 Questions?