Heterogeneous Modeling and Design - Edward A. Lee (PI) -

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1 Heterogeneous Modeling and Design - Edward A. Lee (PI) - Staff Jennifer Basler Christopher Hylands Mary P. Stewart Postdoctoral Researchers H. John Reekie Students Albert Chen John Davis, II Mudit Goel Bilung Lee Jie Liu Xiaojun Liu Stephen Neuendorffer Neil Smyth Michael C. Williamson William Wu Yuhong Xiong 1 - Ptolemy 5/21/98

2 Agenda 9:00 Introduction and overview of the project 9:30 Hierarchical FSMs as a model of discrete control 9:45 Ptolemy II architectural overview 10:15 break 10:30 process networks for concurrent systems modeling 10:45 continuous-time modeling in Ptolemy II 11:00 Tycho-based user interface toolkit 11:45 Wrapup and future plans 12:00 Adjourn 2 - Ptolemy 5/21/98

3 Heterogeneous, problem-level description Modeling, mapping, synthesis Heterogeneous, implementation-level description 3 - Ptolemy 5/21/98

4 Approach Theory and techniques for mixing diverse models of computation, e.g. mixed signal, hybrid systems, discrete and continuous events. Software architecture for modular, distributed, and heterogeneous design, modeling and visualization tools. Theory and software for domain-specific modeling of composite concurrent systems. Use of programming language concepts (semantics, type theories, and concurrency theories) for modeling and design of composite systems. Emphasis on visual representations. 4 - Ptolemy 5/21/98

5 Schedule Task Name Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Hybrid System Semantics Tagged signal model Discrete-event system semantics Compositional dataflow semantics Generalized type theory Mixed signal semantics Learn Java PtPlot Ptolemy II abstract syntax pkg Ptolemy II parameters package Ptolemy II graph packages Ptolemy II math package Type resolution package CT domain Mixed signal design PN domain CSP domain SDF Domain DE Domain PtFilter Tycho infrastructure Tycho-based BDE Tycho/Tcl/Java Interaction Visualization tools 5 - Ptolemy 5/21/98

6 Staff schedule: Students and Visiting Scholars in the Ptolemy Project ID Task Name Start Date End Date Albert Chen 1/20/98 5/25/98 2 John Davis 8/15/96 8/27/99 3 Ron Galicia 9/15/94 8/27/99 4 Mudit Goel 1/21/97 8/24/01 5 Bilung Lee 8/15/93 5/27/99 6 Jie Liu 4/20/97 8/24/01 7 Xiaojun Liu 5/26/98 5/24/02 8 James Lundblad 1/28/98 1/31/00 9 Lukito Muliadi 5/26/98 8/27/99 10 Steve Neuendorffer 8/26/98 5/24/00 11 John Reekie 8/15/95 11/12/99 12 Neil Smyth 5/25/97 12/31/98 13 Jeff Tsay 8/26/98 5/24/00 14 Nils Wemhöner 8/26/98 8/24/99 15 Mike Williamson 1/1/92 5/25/98 16 William Wu 8/15/97 12/31/98 17 Yuhong Xiong 1/1/97 8/24/01 Having other support summer '98 graduate students undergraduate students visiting scholars possible graduate students fall '98 spring '99 summer '99 Permanent staff: Jennifer Basler Christopher Hylands Edward A. Lee Mary Stewart 6 - Ptolemy 5/21/98

7 Models of Computation Analog computers (differential equations) Discrete time (difference equations) Discrete-event systems Synchronous-reactive systems Sequential processes with rendezvous Process networks Dataflow Finite state machines A C B D 7 - Ptolemy 5/21/98

8 Shared Properties Strengths and weaknesses (no silver bullet) Domain-specific Modular Amenable to visual syntaxes Hierarchical Concurrent (except FSMs) Abstract A B C D 8 - Ptolemy 5/21/98

9 Issues Being Addressed Semantics (what is a behavior) Determinacy (how many behaviors are there) Simulation (finding a behavior) Analysis (finding properties of behaviors) Compositionality (encapsulating subsystems) Synthesis (translation to implementation) Design (choosing implementations) Heterogeneity A B C D 9 - Ptolemy 5/21/98

10 Examples Requiring Heterogeneity MEMS device with a discrete controller (differential equations plus discrete-event models) Modal models, with regimes of operation (differential equations plus finite-state machines) Mixed signal systems (differential equations plus discrete-time and/or discrete-event systems) Hardware/software systems (differential equations, discrete-events, discrete-time, finite-state machines, dataflow, rendezvous, process networks,...) 10 - Ptolemy 5/21/98

11 State Machines & Block Diagrams guard/action invariant/activity A B signal C D actor Concurrent Sequential 11 - Ptolemy 5/21/98

12 Hybrid Systems A discrete program combined with an analog system. A combination of automata and analog computers. Traditional syntax (classic example: leaking gas burner): x& =1 y & = 1 z& = 1 x 1 leaking x = 0 x 30 x = 0 x& =1 y & = 1 z& = 0 not leaking Here, the differential equations hardly look like a concurrency model, but in fact they are Ptolemy 5/21/98

13 Alternative View of Hybrid Systems Analog computers hierarchically combined with automata. Classic example (leaking gas burner): y& 1 y leaking x = 0;& z = 0 not leaking x x 1 x 30 = 0;& z = 1 x z& z x& 1 z& x z& 13 - Ptolemy 5/21/98

14 Generalized Hybrid Systems Choice of domain here determines concurrent semantics A B C x y D z We have formalized the semantics of FSMs combined with discreteevent, dataflow, and synchronous-reactive models. E F H G FSM for control 14 - Ptolemy 5/21/98

15 Ptolemy 0.7 Prototype 15 - Ptolemy 5/21/98

16 Ptolemy II Hybrid Systems CT domain: ODE solver in continuous time. Generalized wormhole mechanism. Emphasis on specification and simulation (not verification). Hierarchical visual specifications. Interactive, animated simulations Ptolemy 5/21/98

17 Continuous-Time Domain in Ptolemy II Will support a variety of numerical methods for solving ODEs Time marching, Waveform relaxation, Frequency domain methods, Monte-Carlo methods Will mix with: Dataflow DE FSM Applications: Mixed signal design MEMS Hybrid systems 17 - Ptolemy 5/21/98

18 Macro Modeling from Coyote We have incorporated a macro-model of a mechanical comb constructed by Coyote using their electrostatic BEM method Ptolemy 5/21/98

19 Package Structure of Ptolemy II kernel clustered graph topologies plot interactive display of data data encapsulation, parsing, types, dependencies actor flow-oriented computation automata hierarchical FSMs math matrix operations, algorithms graph graph algorithms FSM actor libraries domains filter signal processing filter design 19 - Ptolemy 5/21/98

20 Ptolemy II Abstract Syntax Entity/Relation bipartite graphs Ports are named aggregations of links A topology is a linked collection of entities and relations 20 - Ptolemy 5/21/98

21 Flat Abstract Syntax Classes NamedObj -_name : String -_workspace : Workspace +workspace() : Workspace Nameable +description() : String +getcontainer() : Nameable +getfullname() : String +getname() : String +setname(name : String) Interface for objects with names NamedObj: Naming and synchronization services Entity container 0..n Port -_portlist : NamedList +addport(p : Port) +getconnectedports() : Enumeration +getlinkedrelations() : Enumeration +getport(name : String) : Port +getports() : Enumeration +newport(name : String) : Port +removeallports() +removeport(p : Port) 0..1 containee -_container : Entity -_relationslist : CrossRefList +getconnectedports() : Enumeration +getlinkedrelations() : Enumeration +link(r : Relation) +numlinks() : int +setcontainer(e : Entity) +unlink(r : Relation) +unlinkall() Relation -_portlist : CrossRefList +getlinkedports() : Enumeration +getlinkedportsexcept(p : Port) : Enumeration +numlinks() : int +unlink(p : Port) +unlinkall() link 0..n 0..n link Entity: aggregation of Ports Port: aggregation of links to Relations Relation: aggregation of links to Ports 21 - Ptolemy 5/21/98

22 Synchronization Services Nameable NamedObj -_name : String -_workspace : Workspace +workspace() : Workspace +description() : String +getcontainer() : Nameable +getfullname() : String +getname() : String +setname(name : String) Workspace -_contents : NamedList +add(e : Nameable) +elements() : CollectionEnumeration +getversion() : long +incrversion() +remove(e : Nameable) +removeall() Every NamedObj has an immutable association with an instance of Workspace. A monitor on Workspace is used for thread synchronization, and the workspace tracks versions of a topology Ptolemy 5/21/98

23 Transparent ports Transparent entities Managed containers Clustered Graphs Every object has zero or one containers. If zero, then it is known to its workspace 23 - Ptolemy 5/21/98

24 Entity -_portlist : NamedList +addport(p : Port) +getconnectedports() : Enumeration +getlinkedrelations() : Enumeration +getport(name : String) : Port +getports() : Enumeration +newport(name : String) : Port +removeallports() +removeport(p : Port) container 0..n 0..1 containee Port -_container : Entity -_relationslist : CrossRefList +getconnectedports() : Enumeration +getlinkedrelations() : Enumeration +link(r : Relation) +numlinks() : int +setcontainer(e : Entity) +unlink(r : Relation) +unlinkall() Cluster Classes Relation -_portlist : CrossRefList +getlinkedports() : Enumeration +getlinkedportsexcept(p : Port) : Enumeration +numlinks() : int +unlink(p : Port) +unlinkall() link 0..n 0..n link ComponentEntity -_container : CompositeEntity +isatomic() : boolean +setcontainer(c : CompositeEntity) containee 0..n CompositeEntity 0..1 container -_containedentities : NamedList -_containedrelations : NamedList +addentity(e : ComponentEntity) +addrelation(r : componentrelation) +allowlevelcrossingconnect(b : boolean) +connect(p1 : ComponentPort, p2 : ComponentPort) +connect(p1 : ComponentPort, p2 : ComponentPort, name : String) +deepcontains(e : ComponentEntity) : boolean +deepgetentities() : Enumeration +getentity(name : String) : ComponentEntity +getentities() : Enumeration +getrelation(name : String) : ComponentRelation +getrelations() : Enumeration +newrelation(name : String) : ComponentRelation +numentities() : int +numrelations() : int +removeallentities() +removeallrelations() +removeentity(e : ComponentEntity) +removerelation(r : ComponentRelation) ComponentPort -_insidelinks : CrossRefList +deepgetconnectedports() : Enumeration +deepgetinsideports() : Enumeration +getinsideports() : Enumeration +getinsiderelations() : Enumeration +liberallink(r : Relation) +link(r : Relation) +numinsidelinks() : int +unlink(r : Relation) +unlinkall() ComponentRelation -_container : CompositeEntity +deepgetlinkedports() : Enumeration +setcontainer(c : CompositeEntity) Composite: Design pattern 24 - Ptolemy 5/21/98

25 Level-Crossing Links R3 E1 P1 R1 P4 P6 E6 P2 E2 P3 E3 R2 E4 P5 E5 These are supported, but discouraged Ptolemy 5/21/98

26 Transparent Entities E1 P1 R1 P2 R2 P4 R3 P5 E4 E3 P3 E2 E4 Modularity and compositionality require that relations be able to transparently span the hierarchy Ptolemy 5/21/98

27 TclBlend Interface set e0 [java::new pt.kernel.compositeentity E0] set e1 [java::new pt.kernel.componententity E1] set e2 [java::new pt.kernel.componententity E2] set p1 [$e1 newport P1] set p2 [$e1 newport P2] set r1 [$e0 connect $p1 $p2 R1] E1 P1 R1 P2 E2 E0 We have an extensive, automated test suite that uses this Ptolemy 5/21/98

28 Make entities executable Actors «Interface» Executable +fire() +initialize() +postfire() +prefire() : boolean +wrapup() NamedObj Director containee 0..n 0..1 container ComponentEntity CompositeEntity -_schedulevalid : boolean -_subsystem : CompositeActor +complete() : boolean +invalidateschedule() +iterate() +prefire() : boolean +run() +schedulevalid() : boolean +setactors(subsystem : CompositeActor) 0..1 Actor 0..1 CompositeActor getdirector() : Director +restructure() +refinetype(t : Type) : Type 0..n -_director : Director +getdirector() : Director +setdirector(d : Director) 28 - Ptolemy 5/21/98

29 run method Director initialize iterate complete? Yes No Provides a standard template for execution of a model. Most of the work is done in the iterate method. wrapup Invoke wrapup methods of all actors return 29 - Ptolemy 5/21/98

30 iterate method Iterate Method prefire ready? Fire methods may be invoked multiple times in one iteration. Yes No fire postfire Invoke fire methods of actors according to a schedule Invoke postfire methods of actors according to a schedule Prefire and postfire methods are invoked exactly once. return 30 - Ptolemy 5/21/98

31 Prefire Method prefire method Schedule valid? No Supports graph mutation Type resolution Initialize actors Evaluate type refinement functions of all actors until fixed point Invoke initialize methods of all new actors Topology changed? Static Scheduling Yes Restructure topology Invoke restructure methods of all new actors. end Yes No 31 - Ptolemy 5/21/98

32 Message Passing ComponentPort IOPort -_isinput : boolean -_ismultiport : boolean -_isoutput : boolean -_localreceiverstable : Hashtable +broadcast(message : Token) +get(streamindex : int) : Token +getreceivers() : Receiver[][] +getreceivers(relation : IORelation) : Receiver[][] +getremotereceivers() : Receiver[][] +getwidth() : int +isinput() : boolean +ismultiport() : boolean +isoutput() : boolean +makeinput(t : boolean) +makemultiport(t : boolean) +makeoutput(t : boolean) +newreceiver() : Receiver +send(streamindex : int, message : Token) Support for: Inputs and Outputs Broadcast and Multicast Polymorphic in communication protocols 32 - Ptolemy 5/21/98

33 Polymorphic Message Passing IOPort -_isinput : boolean -_ismultiport : boolean -_isoutput : boolean -_localreceiverstable : Hashtable +broadcast(message : Token) +get(streamindex : int) : Token +getreceivers() : Receiver[][] +getreceivers(relation : IORelation) : Receiver[][] +getremotereceivers() : Receiver[][] +getwidth() : int +isinput() : boolean +ismultiport() : boolean +isoutput() : boolean +makeinput(t : boolean) +makemultiport(t : boolean) +makeoutput(t : boolean) +newreceiver() : Receiver +send(streamindex : int, message : Token) FlowPort 0..n 0..n Mailbox -_container : IOPort -_token : Token +isempty() : boolean QueueReceiver 1..1 Receiver +get() : Token +getcontainer() : Nameable +put(t : Token) 0..n FIFOQueue -_container : Nameable -_historycapacity : int -_historylist : LinkedList -_queuecapacity : int -_queuelist : LinkedList +capacity() : int +elements() : CollectionEnumeration +full() : boolean +get(offset : int) : Object +getcontainer() : Nameable +history() : CollectionEnumeration +historycapacity() : int +historysize() : int +previous(offset : int) : Object +put(element : Object) : boolean +setcapacity(maxsize : int) +sethistorycapacity(maxsize : int) +size() : int +take() : Object RendezvousPort EventPort -_queue : EventQueue 0..n 0..n 0..1 RendezvousReceiver 0..1 EventReceiver The type of port used depends on the model of computation 33 - Ptolemy 5/21/98

34 Point-to-Point Transport Simple transport: send(0,t) receiver.put(t) get(0) Actor Actor IOPort IORelation IOPort token t Sender calls send(channel,token) This calls receiver.put(token) for each receiver Receiver calls get(channel) 34 - Ptolemy 5/21/98

35 Multiports Multiple (scalable) distinct channels: send(0,t0) receiver.put(t0) get(0) send(1,t1) token t0 get(0) receiver.put(t1) token t1 Sender calls send(channel,token) This calls receiver.put(token) for each receiver Receiver calls get(channel) 35 - Ptolemy 5/21/98

36 Multicast Transport send(0,t0) receiver.put(t0) receiver.put(t1) 2 get(0), get(1) send(1,t1) token t0, t1 send(0,t) receiver.put(t) get(0) token t receiver.put(t.clone()) get(0) token (clone of t) Multiple desitnations for the same data Tokens are cloned automatically 36 - Ptolemy 5/21/98

37 Transparent Ports 3 3 * 4 Wildcard bus width P5 P8 P1 4 * P2 4 1 P6 * 1 P9 2 P4 0 P3 2 P7 2 Sets of destination receivers are cached at the sender for efficiency Ptolemy 5/21/98

38 The Data Package Tokens encapsulate data for transport Parameters attach names and dependencies to tokens Expressions operate on tokens Type system maximize polymorphism 38 - Ptolemy 5/21/98

39 PtParser Created using JavaCC & JJTree foo.jjt => JJTREE => foo.jj => JAVACC => foo.java Recognizes full range of arithmetic, relational and logical operators overloading in some cases to do the right thing eg 3+4 ==> 7 3+ hello ==> 3 hello 39 - Ptolemy 5/21/98

40 PtParser allows reference to Ptolemy II Params, passed as an argument to the parser eg if clkfreq and duration are Params in the current Entity then delay Param could be given the value duration/clkfreq or (duration*2)/clkfreq etc. using reflection, all the functionality of java.lang.math is available extendable: easy to add new functionality eg tcl( ) to invoke tcl to evaluate a string readfile( foo.bar ) to read the given file as input 40 - Ptolemy 5/21/98

41 Type System Two-levels of types: data type of atomic exchanges signal type governing the exchange protocol Type hierarchy: a lattice Type specification: a monotonic function on this lattice that refines the estimated types. Type resolution: iterate to a fixed point. E F H G 41 - Ptolemy 5/21/98

42 Use of Infrastructure in CT CTDirector uses graph package for topological sort overrides Director methods to implement a 4-th order Runge-Kutta solver. IOPort use the default Mailbox receiver Data use data package for parameters, signals Plot use ptplot for interactive, animated plots 42 - Ptolemy 5/21/98

43 Use of Infrastructure in PN PNDirector Kahn process networks model of computation uses Java threads, one for each actor manages deadlocks PNPort Uses unbounded FIFO queues Blocking reads Bounded memory, when possible Very different from CT, hence stresses the kernel & actors package designs 43 - Ptolemy 5/21/98

44 Applications of PN Concurrent digital control processes with dynamic behavior. Provides a higher-level concurrency model than threads for programming in Java. (Future) With the addition of nondeterminism, model resource management problems. (Future) With the addition of time, model mappings of applications to hardware Ptolemy 5/21/98

45 Synthesis Director manages synthesis process (vs. simulation) Separate interface from implementation. Support migration from simulation to implementation. Note: We have a subcontract from Lockheed-Sanders in the adaptive computing program to develop technology for FPGA synthesis Ptolemy 5/21/98

46 Additional Packages HOF (Higher-order functions) Graph (Leda-style graph algorithms) Math (Matrix operations, solvers, signal processing) Filter (Linear time-invariant systems) Plot (interactive, animated signal display) 46 - Ptolemy 5/21/98

47 The Filter Package Filter design tool. Highly interactive. Based on Ptplot. Model/view architecture. Uses math library. Designed to interface to Ptolemy filters. Web compatible Ptolemy 5/21/98

48 Modular Tools Architecture Use Java and Itcl Split Ptolemy into Java packages Split Tycho into Itcl packages Make everything network aware Use object modeling Use the model-view design pattern Use object-request broker technology Experiment with reflection, remote method invocation, etc Ptolemy 5/21/98

49 First Released Java Module PtPlot is a Java package for interactive, animated signal plotting on the web. We have used it to learn about Java applets as an interchange and modularization format, and will distribute Ptolemy modules similarly Ptolemy 5/21/98

50 Tycho Tycho is suite of Itcl classes for design representation, manipulation, and visualization Ptolemy 5/21/98

51 Model/View Architecture Abstract data types Publish & subscribe 51 - Ptolemy 5/21/98

52 Software Engineering Code rating system: red, yellow, green, blue. Author/reviewer division of responsibilities. Automated test suites (scripted, in Tcl). Code coverage measurements. Integrated documentation. Tycho support. The Ptolemy group has a tradition of emphasizing code and documentation quality Ptolemy 5/21/98

53 Technology Transfer HP Ptolemy (released in March 98): Supports mixed-signal modeling (DSP + RF). BNeD, in cooperation with HP: Design and simulation of optical communication systems based on Ptolemy. Cadence: SDF and DE technology in SPW 3.0 and higher Ptolemy 5/21/98

54 Interoperability CORBA Java Beans and the Tcl Bean An open architecture Small, modular Java packages Well-defined semantics 54 - Ptolemy 5/21/98

55 Major Accomplishments so Far Ptolemy II kernel, actors, data packages, CT, and PN domains. Semantics for hierarchical interaction of finite-state controllers with several models of computation. Formal semantics for DE systems. Demonstration of a client-server, web-based mechanism supporting Ptolemy simulations. Construction of a network-integrated, scripted design management environment (Tycho). Design of an "information model" and an associated "modelview" software architecture (Tycho). Release on the net of our first Java module, a multipurpose signal plotter. Java/Tycho integration. A well-attended Ptolemy miniconference Ptolemy 5/21/98

56 Actual Deliverables Reports monthly reports annual reports Software Tycho 0.2 released (May, 1997) PtPlot 0.1 released (October, 1997) Ptolemy alpha (May, 1998) Ptolemy II Modules (September December 1999) Annual updates of Tycho (est. October, 1998, 1999) Papers Reports, journal, and conference papers Ptolemy 5/21/98

57 Future Work Finish actors, math, graph, data packages Design the wormhole interface Implement FSMs in Ptolemy II Create hybrid systems modeling Create CORBA interface Implement dataflow, DE, CSP domains Support nondeterminism in PN Add time to PN and CSP 57 - Ptolemy 5/21/98

58 More Information Ptolemy 5/21/98

59 Publications E. A. Lee, Modeling Concurrent Real-Time Processes Using Discrete Events, Memorandum UCB/ERL M98/7 March 4th 1998, Electronics Research Laboratory, University of California, Berkeley, CA M. Goodwin, Adaptive Signal Models: Theory, Algorithms, and Audio Applications, Ph.D. thesis, University of California, Berkeley, December Available as UCB/ERL M97/31. P. K. Murthy, and E. A. Lee, ``Two Cycle Related Problems for Regular Dataflow Graphs: Complexity and Heuristics,'' Memorandum UCB/ERL M97/76, Electronics Research Laboratory, University of California, Berkeley, CA 94720, October S. S. Bhattacharyya, P. K. Murthy, and E. A. Lee, ``Synthesis of Embedded Software from Synchronous Dataflow Specifications,'' Invited paper, to appear in J. of VLSI Signal Processing, A. Girault, B. Lee, and E. A. Lee, ``A Preliminary Study of Hierarchical Finite State Machines with Multiple Concurrency Models,'' Memorandum UCB/ERL M97/57, Electronics Research Laboratory, University of California, Berkeley, CA 94720, August Ptolemy 5/21/98

60 Publications (continued) S. Edwards, L. Lavagno, E. A. Lee, and A. Sangiovanni-Vincentelli, ``Design of Embedded Systems: Formal Models, Validation, and Synthesis,'' Proceedings of the IEEE, Vol. 85, No. 3, March S. A. Edwards, ``The Specification and Execution of Heterogeneous Synchronous Reactive Systems,'' Ph.D. thesis, University of California, Berkeley, May Available as UCB/ERL M97/31. C. Hylands, E. A. Lee, and H. J. Reekie, ``The Tycho User Interface System,'' to be presented at the 5th Annual Tcl/Tk Workshop '97, Boston, Massachusetts, July, S. S. Bhattacharyya, P. K. Murthy, and E. A. Lee, ``Software Synthesis for Synchronous Dataflow,'' International Conference on Application Specific Systems, Architectures, and Processors, July, 1997, invited paper. W.-T. Chang, S.-H. Ha, and E. A. Lee, ``Heterogeneous Simulation -- Mixing Discrete-Event Models with Dataflow,'' invited paper, Journal on VLSI Signal Processing, Vol. 13, No. 1, January Ptolemy 5/21/98

61 Publications (continued) E. A. Lee and A. Sangiovanni-Vincentelli, ``A Denotational Framework for Comparing Models of Computation,'' ERL Memorandum UCB/ERL M97/11, University of California, Berkeley, CA 94720, January 30, P. K. Murthy, E. A. Lee, "Some cycle-related problems for regular dataflow graphs: complexity and heuristics," UCB/ERL Tech. Report, UCB/ERL M97/76, July S. Kim and E. A. Lee, ``An Infrastructure for Numeric Precision Control in the Ptolemy Environment'', Proceedings of the 40th Midwest Symposium on Circuits and Systems, August 3-6, Richard S, Stevens (Naval Research Laboratory), Marlene Wan, Peggy Laramie (UCB), Thomas M. Parks (MIT Lincoln Labs), and Edward A. Lee (UCB), "Implementation of Process Networks in Java, UCB/ERL Tech. Report, number pending, November Ptolemy 5/21/98

62 Publications (continued) Under subcontract to UT Austin (Brian Evans): D. Arifler, C. Duong, B. L. Evans, S. K. Marwat, C. M. Moy, and A. Yuan, ``A Configurable, Portable, Extensible Framework for Web-Enabled Interactive Simulation of Software for Embedded Programmable Processors,'' submitted. A. K. Kulkarni, A. Dube, and B. L. Evans, ``Benchmarking Code Generation Methodologies for Programmable Digital Signal Processors,' submitted. B. Lu, B. L. Evans, and D. V. Tosic, ``Simulation and Synthesis of Artificial Neural Networks Using Dataflow Models in Ptolemy,' Invited Paper, Proc. IEEE Conf. on Neural Network Applications in Engineering, Sep. 8-9, Ptolemy 5/21/98