Embedded software may end up like this as it scales up.

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1 Ptolemy II - Heterogeneous Modeling and Design in Java The Ptolemy project studies modeling, simulation, and design of concurrent, real-time, embedded systems. The focus is on assembly of concurrent components. The key underlying principle in the project is the use of welldefined models of computation that govern the interaction between components. Principal Investigator Edward A. Lee Technical Staff Christopher Hylands Mary P. Stewart Postdocs and Researchers Jorn Janneck Sonia Sachs Grad Students Elaine Cheong Brian Vogel Chamberlain Fong Paul Whitaker Jie Liu Yuhong Xiong Xiaojun Liu Steve Neuendorffer Embedded Systems Telephones Pagers Cars Audio equipment Aircraft Trains Appliances Toys Security systems Games PDAs Medical diagnostics Weapons Pacemakers Television Network switches... The fate of computers lacking interaction with physical processes. only 2% of computers today are first and foremost computers What we are trying to avoid: Embedded software may end up like this as it scales up. Poor common infrastructure. Weak specialization. Poor resource management and sharing. Poor planning. Elegant Federation Elegant federation of heterogeneous models. Two Rodeo Drive, Kaplan, McLaughlin, Diaz Source: Kaplan McLaughlin Diaz, R. Rappaport, Rockport,

2 Example: An Engine Control System Component-Based Design engine Finite E State H Machine C I fuel air Discrete Event embedded controller power train Continuous Time sensors Location transparency Hierarchy Modularity Reusability Scalability Component & Composition controller car model One Class of Semantic Models: Producer / Consumer H I E engine C power train process { write(); channel port port receiver process { read(); Are s active? passive? reactive? Are communications timed? synchronized? buffered? 2

3 Domains Provide semantic models for component interactions What is a domain? CSP concurrent threads with rendezvous CT continuous-time modeling DE discrete-event systems DT discrete time (cycle driven) PN process networks SDF synchronous dataflow SR synchronous/reactive Globally Asynchronous communication in Polis Each of these defines a component ontology and an interaction semantics between components. There are many more possibilities! Ontology: What is a component? States? Processes? Threads? Differential equations? Constraints? Objects (data + methods)? Epistemology: What knowledge do components have? Time? Name spaces? Signals? State? Protocols: How do components communicate? Rendezvous? Message passing? Continuous-time signals? Streams? Method calls? Lexicon: What do components communicate? Objects? Transfer of control? Data structures? ASCII text? Ptolemy II Our Software Laboratory Ptolemy II Provides Ptolemy II Java based, network integrated Many domains implemented Multi-domain modeling XML syntax for persistent data Block-diagram GUI Extensible type system Code generator on the way Component Architecture Execution Interface Infrastructure Support Expression language Type system Math package Graph package Plot package GUI package library 3

4 Example: Pendulum Ptolemy II Infrastructure CT DDE DE CSP FSM SDF Giotto RTP moml data lang Kernel math gui graph plot PN GR Author: Chamberlain Fong kernel Component Component kernel.util ComponentRelation Attribute Composite CrossRefList IllegalActionException InternalErrorException Relation InvalidStateException KernelException NameDuplicationException Nameable NamedList NamedObj NoSuchItemException PtolemyThread Workspace kernel.event TopologyChangeFailedException TopologyChangeRequest TopologyEvent TopologyListener TopologyMulticaster Listener.util Atomic Composite CQComparator DefaultExecutionListener CalendarQueue Director DoubleCQComparator Executable FIFOQueue ExecutionEvent ExecutionListener IO IORelation Mailbox Manager NoRoomException NoTokenException QueueReceiver Receiver TypeConflictException TypeTerm.lib Typed Add TypedAtomic Const TypedComposite Demux TypedIO Expression TypedIORelation FunctionGenerator.process Gain Multiply NotifyThread Mux ProcessDirector Plot ProcessReceiver Print ProcessThread Repeat TerminateProcessException Select Switch.sched XYPlot NotSchedulableException Scheduler StaticSchedulingDirector graph CPO math DirectedAcyclicGraph ArrayMath DirectedGraph Complex Graph ExtendedMath Inequality Fraction InequalitySolver SignalProcessing InequalityTerm data BooleanMatrixToken BooleanToken data.expr ComplexMatrixToken ASCII_CharStream ComplexToken ASTPtBitwiseNode DoubleMatrixToken ASTPtFunctionNode DoubleToken ASTPtFunctionalIfNode IntMatrixToken ASTPtLeafNode IntToken ASTPtLogicalNode LongMatrixToken ASTPtMethodCallNode LongToken ASTPtProductNode MatrixToken ASTPtRelationalNode Numerical ASTPtRootNode ObjectToken ASTPtSumNode ScalarToken ASTPtUnaryNode StringToken JJTPtParserState Token Node TypeLattice Parameter ParameterEvent ParameterListener ParseException PtParser PtParserConstants PtParserTokenManager PtParserTreeConstants SimpleNode Token TokenMgrError UtilityFunctions plot schematic LogicAnalyzer Domain LogicAnalyzerFrame Type Message Icon Plot IconLibrary PlotApplet PTMLParser PlotApplication PTMLPrinter PlotBox PtolemySystem PlotDataException Schematic PlotFrame SchematicElement PlotLive Schematic PlotLiveApplet SchematicParameter PlotPoint Schematic Pxgraph SchematicRelation XMLElement media Audio AudioViewer Ptolemy II Packages kernel (clusterd graphs) (executable models) data (tokens, expressions) moml (persistent model ) graph (graph algorithms) math (math algorithms) plot (plotting utilities) kernel Component Component ComponentRelation Composite Relation Basic Kernel Classes Attribute NamedObj _container : -_relationslist : CrossRefList +() container +(w : Workspace) n +(container :, name : String) link -_portlist : NamedList +connecteds() : Enumeration +() containee +islinked(r : Relation) : boolean 0..n +isopaque() : boolean +(name : String) +(w : Workspace, name : String) +linkedrelations() : Enumeration +connecteds() : Enumeration +link(r : Relation) +connectionschanged(p : ) +numlinks() : int +setcontainer(c : ) +get(name : String) : +unlink(r : Relation) +gets() : Enumeration +unlinkall() +linkedrelations() : Enumeration +new(name : String) : #_link(r : Relation) +removealls() #_add(p : ) #_remove(p : ) CrossRefList Relation -_portlist : CrossRefList +Relation() 0..n +Relation(name : String) +Relation(w : Workspace, name : String) link +linkeds() : Enumeration +linkeds(except : ) : Enumeration +numlinks() : int +unlinkall() #_check(p : ) #_getlist() : CrossRefList 4

5 Kernel Package Clustering connection Relation Link Link connection Link connection The Ptolemy II kernel provides an abstract syntax - clustered graphs - that is well suited to a wide variety of domains, ranging from state machines to process networks. Here is a simple graph with three interrelated entities. Relation Atomic opaque dangling transparent transparent transparent Composite toplevel Composite The ports deeply connected to the red port are the blue ones. Composite entities and ports in Ptolemy II provide a simple and powerful, domainindependent abstraction mechanism Mutations The kernel.event package provides support for Queuing requests for topology changes Processing requests for topology changes Registering listeners Notifying listeners of changes Thus, models with dynamically changing topologies are cleanly supported, and the in each domain can control when mutations are implemented. Package Basic Transport: send(0,t) receiver.put(t) get(0) E1 P1 R1 IO P2 IORelation token t E2 Receiver (inside port) Services Message passing Executable interface Topology caching Clustering Parameterization Typing Polymorphism 5

6 Executable Interface Manager and Directors execution preinitialize() initialize() iteration () () fire() () Hierarchical Heterogeneity: E0 E1 M: Manager D1: local P1 E2 P2 Opaque Composite D2: local E4 P5 P6 P3 Transparent Composite E3 P4 Directors are domain-specific. A composite with a becomes opaque. The Manager is domainindependent. E5 P7 Hierarchical Heterogeneity vs. Amorphous Heterogeneity Execution Sequencing Execution Sequence: Manager.run() initialization no no execution Amorphous Hierarchical Manager initialize process mutations check types ready? yes fire done? yes Composite initialize fire not ready no Director initialize s select an fire... done? transfer outputs s no more s opaque Composite initialize request transfer inputs fire request transfer outputs Color is a communication protocol only, which interacts in unpredictable ways with the flow of control. Color is a domain, which defines both the flow of control and interaction protocols. Director initialize s transfer inputs fire no... done? s 6

7 Creating a Model Vergil An Extensible Visual Editor Choose applet or application Choose Vergil, MoML, or Java code Pick one or more domains Drag and drop s and make connections Design control interface Soon: Choose distribution architecture Ptolemy II uses features in JDK 1.3, and hence requires use of the Java plug-in with current released browsers. Live editor with XML persistent file format. XML Model Specification (MoML) HTML Internet explorer and Netscape have different plug-in architectures :-( <?xml version="1.0" standalone="no"?> <!DOCTYPE model SYSTEM "DTD location"> <model class="classname"> <entity name="a" class="classname"></entity> <entity name="b" class="classname"></entity> <entity name="c" class="classname"></entity> <relation name="r1"></relation> <OBJECT classid="clsid:8ad9c e-11d1-b3e f499d93" width="700" height="300" codebase=" <PARAM NAME="code" VALUE="doc.tutorial.TutorialApplet.class"> <PARAM NAME="codebase" VALUE="../.."> <PARAM NAME="type" VALUE="application/x-java-applet;version=1.2"> <COMMENT> <EMBED type="application/x-java-applet;version=1.3" width="700" height="300" code="doc/tutorial/tutorialapplet.class" <relation name="r2"></relation> <link port="a.out" relation="r1"/> <link port="b.in" relation="r1"/> <link port="c.out" relation="r2"/> <link port="b.in" relation="r2"/> </model> A B out out r1 r2 in C codebase="../.." pluginspage=" </COMMENT> <NOEMBED> No JDK 1.3 support for applet! </NOEMBED> </EMBED> </OBJECT> 7

8 Simple Applet Directly in Java Compiling and Running package doc.tutorial; import ptolemy.domains.de.gui.deapplet; import ptolemy..lib.clock; import ptolemy..gui.timedplotter; public class TutorialApplet extends DEApplet { public void init() { super.init(); try { Clock clock = new Clock(_toplevel,"clock"); TimedPlotter plotter = new TimedPlotter(_toplevel,"plotter"); _toplevel.connect(clock.output, plotter.input); catch (Exception ex) { cd $PTII/doc/tutorial cp TutorialApplet1.java TutorialApplet.java javac -classpath../.. TutorialApplet.java appletviewer tutorial.htm Example: Sticky Masses Sticky Masses: Block Diagram out = k 1 *(y 1 - in)/m 1 C P:=P1 V:=(V 1 *m 1 +V 2 *m 2 )/(m 1 +m 2 ) s:=5 out = (k 1 *y 1 + k 2 *y 2 - in)/(m 1 +m 2 ) P 1 P 1 V 1 P 2 P 1 =? C V 2 out = k 1 *(y 1 -in) - k 2 *(y 2 - in) F s V P 2 Plot P 2 -s S t The stickiness is exponentially decaying with respect to time. out = k 2 *(y 2 - in)/m 2 F s >S t P 1 :=P P 2 :=P V 1 :=V V 2 :=V 8

9 Sticky Masses: Simulation Nascent Generator Infrastructure Domain semantics defines communication, flow of control Ptolemy II model All s will be given in Java, then translated to embedded Java, C, VHDL, etc. First version created by Jeff Tsay. if block parser method call method call block abstract syntax tree scheduler code generator Schedule: - fire Gaussian0 -fire Ramp1 -fire Sine2 -fire AddSubtract5 - fire SequenceScope10 for (int i = 0; i < plus.getwidth(); i++) { if (plus.hastoken(i)) { if (sum == null) { sum = plus.get(i); else { sum = sum.add(plus.get(i)); target code Generator Approach Experimental Result: Orthogonalcom system libraries are built and maintained in Java more maintainable, easier to write polymorphic libraries are rich and small Java + Domain translates to target language concurrent and imperative semantics Efficiency gotten through code transformations specialization of polymorphic types code substitution using domain semantics removal of excess exception handling Interpreted performance increase between 2.5x and 10x, depending on JIT Statically compiled version has additional 2x performance gain with GCJ Code size reduction around 10x 9

10 e-ptolemy: A Distributed Embedded Software Framework Location Transparent Components Location Transparent Components Publish and Subscribe Message Passing Federation of Networked Embedded Systems UAV s Landing Deck network wireless network Ground Robots Base-Station Publish and Subscribe Design in an Abstract Universe controller fault detection UI Commu nication controller fault detection subscribe UI Commu nication When choosing syntax and semantics, we can invent the laws of physics that govern the interaction of components. sensors Event channel publish sensors As with any such laws, their utility depends on our ability to understand models governed by the laws. Magritte, Gelconde 10