Distributed Control Lab - A component-based application. Overview Architecture Experiments

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1 Distributed Control Lab - A component-based application Overview Architecture Experiments

2 Outline Motivation The Distributed Control Lab (DCL) Architecture Foucault's Pendulum Details Hardware / Software Architecture Control Algorithms Hau den Lukas Hardware Architecture Control Software Additional Experiments Malicious Code Problem / Solutions

3 Motivation Online access to physical experiments over the Web Test-bed for interconnected middlewarecomponents and embedded systems Reach a predictable system behaviour in unstable environments Study techniques to prevent malicious code damaging physical equipment Foucault's Pendulum demonstrates usage of dynamic reconfiguration for online replacement of user control

4 Distributed Control Lab 2001 project start at Hasso-Plattner-Institute Practice of writing control algorithms for real-time control problems study of system predictability, availability and security in context of middleware-based dynamic control systems Extensible architecture for hosting physical control experiments Investigation of algorithms for user code observation and replacement of control components Experiment : physical installation and specific control software

5 The Distributed Control Lab

6 Distributed Control Lab (V2) Architecture DISCOURSE Users R SOAP Ticket Service R Tickets Users Admin Experiment Service Job Queue R DCL Frontend R Experiment Manager R Experiment Controller User R SOAP SOAP Frontend R Result Manager R Experiment Controller Job Results

7 DCL Messaging Protocols http/html ASP.NET Page SOAP DCL- Web Service Client Web-Browser IIS ASP.NET Web/Application Server IIS ASP.NET Web/Application Server Embedded Control Device RT-Linux PC Brick OS... TCP/IP IrDA DCL Experiment- Controller.NET Remoting Service.NET Remoting.NET Remoting DCL Experiment-/ Resultmanager.NET Remoting Service ODBC DBMS

9 Problem : Malicous Code Investigation of Solution for malicious code detection Source code analysis Experiment-specific languages / Language limitations.net code access security Simulation before execution on physical experiment Analytic Redundancy Online observation of user programs Replacement of user programs before reach of uncontrollable state Dynamic reconfiguration of component-based control application Monitoring of environmental settings and component states

10 Foucault s Pendulum First installation 1848 by Leon Foucault in the Pantheon in Paris Demonstrates earth rotation Today many installation including one in UN-building in New York Problem : Pendulum must be kept swinging Solution : electro magnet under an iron ball Experiment: Find best control algorithm to keep the pendulum swinging Using minimum energy Reaching the highest amplitude

14 Safety- Controller Event Duplication Event Creation Binary Reader / Filter, Smooth ReadFile() User- Controller Binary Stream Generation Binary Writer WriteFile() Configuration Manager Operating System I/O User Mode Kernel Mode Pendulum Control detailed Laser light barriers sampled into 4KByte FIFO-memorys with 23,4 khz USB-Controller checks half-full-flag 64 Byte blocks of data transferred via USB 1.1 Real-Time OS-Threads process incoming signals / produce out-going bit stream I/O request packet Check HalfFull Flag Light Sensor USB Host- Controller 64 Byte Cypress EZ-USB Read Write FIFO-Memory 4 KBytes Electro Magnet

15 Pendulum-API : Control Event public class ControlEvent { public int nr; public int state; // sensor or actuator identifier // actuator 1 ON - 0 OFF // light barrier // 1 light -> dark // 0 dark -> light } public long timestamp; // global time stamp

16 Pendulum-API : Interface public interface Pendulum { // Dequeue next event // Blocks if no event present until next event occurs public ControlEvent GetNext(); // Queue next event to put energy on / off public bool SendEvent(ControlEvent input); } // Get global time stamp 1 micro seconds logical resolution public long GetTime();

17 Pendulum: Example Control Code while(true) { // get next event ControlEvent ev = pendel.getnext(); if(ev.state == 1) // pendulum enters light barrier { // switch magnet on pendel.sendevent(new ControlEvent(ev.timestamp+1000,0,1)); // switch it off after 5 ms pendel.sendevent(new ControlEvent(ev.timestamp+6000,0,0)); } }

Pendulum Control Process Generation Configuration Code Control Code user control code while(true) { // get next event ControlEvent ev = pendel.getnext(); if(ev.

18 Pendulum Control Process Generation Configuration Code Control Code user control code while(true) { // get next event ControlEvent ev = pendel.getnext(); if(ev.state == 1) // pendulum enters light barrier { // switch magnet on pendel.sendevent(new ControlEvent(ev.timestamp+1000,0,1)); // switch it off after 5/23 seconds pendel.sendevent(new ControlEvent(ev.timestamp+6000,0,0)); } } send to DCL Public Class UserControl { Public Static void Main(String[] args) { } } while(true) { // get next event ControlEvent ev = pendel.getnext(); if(ev.state == 1) // pendulum enters light barrier { // switch magnet on pendel.sendevent(new ControlEvent(ev.timestamp+1000,0,1)); // switch it off after 5/23 seconds pendel.sendevent(new ControlEvent(ev.timestamp+6000,0,0)); } } generate user control class compile control

19 Pendulum : Increase of amplitude 1. Get current oscillation time Toz ( time for a full oscillation ) 2. Get current time the ball is covers the light barrier Ts ( indicates speed ) 3. If ball enters light barrier : 1. Queue Enable Magnet Event at Tcurrent+Toz/4 2. Queue Disable Mag. Event at : Tcurrent + Toz/2 + Ts/2 Tmf 1. Tmf duration of magnetic field shut down 4. Repeat steps 1-4

20 Code Access Security-CAS in.net Supplements operating system security mechanisms Trust to assemblies vary depending of origin and publisher Based on evidences of assemblies Application directory Strong name URL Signature Permissions restrict access to system resources DCL: Configuration of usable class library classes

21 Code Access Permissions Represent access to a protected resource or the ability to perform a protected operation Environment Variables File Dialog File I/O Isolated Storage File Reflection Registry Security User Interface DNS Printing Event Log Socket Access Web Access Performance Counter Directory Services Message Queue Service Controller SQL Client

22 Evidence Based Security Assembly evidence is matched against code groups to gain permission Code group consist of Membership condition Set of code access permissions Security policies contain code groups that map assemblies to permissions Policies in.net : Enterprise, Machine, User, Application Domain Policy Evaluation: top-down

23 .NET Security in the Pendulum Experiment Code group in machine policy applies only to usercode.exe assembly Custom Permission Set assign to the code group No permissions, except: Execution permission Access to driver component via.net Remoting Localhost, one specified socket, one URI File I/O in the local directory Security exception if any restriction is violated Check required permissions before code execution.net Attributes

24 Pendulum Experiment Dynamic Properties Code Access Security provides safe environment for execution of foreign code There are still dynamic properties at the experiment that can not be handled by CAS Expiration of available execution time (fairness) Expiration of available energy Overheating of the coil the pendulum falls below a critical amplitude (energy) - so it could not be kept swinging Unexpected termination of user programs Exaggerated use of memory

25 Our Approach : Dynamic Reconfiguration as safe-guard mechanism Mapping of profiles to application configurations based on environmental conditions and component states Selection of application configuration according to conditions provides best service for a given situation Definition of observer : monitoring of environmental settings and component states profiles : mapping of environmental conditions to application configurations configurations of component-based applications Online monitoring of environment and components Change of application configuration using dynamic reconfiguration if required (changed conditions)

26 Configuration Creator Tool

27 Pendulum Experiment Control Configurations Configuration 1 : safety controller Safety Controller Configuration 2 : user program (cold standby) Safety Controller User Program USB-Driver Event Queuing USB Configuration 3 : user program (warm standby) Safety Controller User Program Event Duplicator

28 Measurements: Abnormal Termination of User Program

Frequency Short control delay COTS x86 PC Intel Celeron 633 MHz, 128 MB RAM (max 64 MB

29 Higher Striker Hau den Lukas Similar hardware to pendulum experiment Parallel I/O / 38 khz sample rate / 256 Byte buffer Use of Real Time OS Smaller Buffers, Higher Sampling Frequency Short control delay COTS x86 PC Intel Celeron 633 MHz, 128 MB RAM (max 64 MB usable) 10 Mbit/s LAN (NE 2000 PCI) Combination of non-rt.net and RT application CE-PC Windows Ce.Net 4.2

31 Higher Striker - Architecture DCL User Code.Net DCL Controller PC Power Plattform Builder/ Debug Host OS Image Debugging Download COMPILED User Control Algorithms CE-PC Switch Parallel Port I/O light barriers A/D Transformation FIFO-Memory Optical Signal Gen.

32 Higher Striker Minimal Program INITIALIZE; do { READ(); WRITE(buffer); GETSTATUS() if(empty_flag_ls) Sleep(1); } while(!eof(buffer))

33 Controlling the Experiment Abstract from Direct Hardware Programming Provide Higher Level API to the experiment 2 possible control scenarios : Calculation before runtime, analysis of result after experiment execution for next run Calculation of control signals during runtime hard deadlines Investigation of various operating systems.net Compact Framework and real time

34 Higher Striker - Event List - API 0;1; 10;0; 20;2; 25;0; 50;4; 80;0; Definition before runtime Transformation into byte stream before runtime Simple checks possible (temperature of magnet) Generation of event list after runtime for analysis for next experiment runs Not flexible but simple to implement

35 Higher Striker Control API int HDLInitialize ( ); int HDLInitialize ( unsigned char Writeahead, unsigned char Initial[]); int HDLStartClock( ); int HDLStopClock( ); int HDLPerform( unsigned char * Write, unsigned char * Read ); int HDLGetStatus(); int HDLGetError( int * LSError, int * MSError );

36 Higher Striker Watch Dog not signaled for 5 reboots power on 70 sec signal Init Active Stop power off if not signaled for 5 sec reboot Hardware Watchdog connected / signaled via serial communication interface of control PC In case of system hang-up control PC will be rebooted Atmel AVR 8-Bit Tiny 12 microcontroller

37 Higher Striker Simulation Used Buffer (0-255 Byte) Cylinder Speed Height Video Animation

38 DCL - Grid Integration Heterogeneous X86,Itanium, PowerPC Windows 2000/XP, Linux, Mac OS X DRMAA Job Submission and Control for Clusters and Grids GLOBUS IDLE-Time Condor Sun Grid Engine, Condor Grid - Increased Throughput Povray Simulation Grid - Increased Response Time

39 Fischertechnik Production Line Control via Fischertechnik Intelligent Interface Serial communication interface, 9600 Bits/sec 4+4 Digital Outputs, 8+8 Digital Inputs, 2 Analog Inputs Installation: 4 Intelligent Interfaces Pneumatic Actuators 1 robot arm ( 2 free degrees )

40 Controlling Fischertechnik using Beckhoff Industrial-PCs and the DCL IIF.NET Controller ADS.NET D C L Visual Studio Plug-In TwinCat PLC-Control

41 Märklin Railway Märklin Digital Model Railway Control via serial interface 9600 Bit/sec S-88 Bus and controller Configurable train speed Feedback via rail sensors About 20 switches Controlled by x86 PC Currently running W2K

43 Running.NET on devices Why? Rapid software development for embedded devices Object-oriented programming model, type safety Many available tools, know-how, many experts Code access security for remote lab experiments How? Possibilities: PC-based execution Communication to device for I/O Native execution of translated IL-Code Interpretation of stripped IL-Code on the device Running.NET on more powerful embedded devices to control small embedded devices

44 CLI2RCX-.NET runtime for Lego Mindstorm C++.Net C#.Net Assembly ildasm mnemonic CIL Assembly GCC CIL Front End RTL Hitachi H8300 Hitachi Backend H8-300 Back End RCX binary (srec - format) Backends VB.Net target binaries Our gcc (Gnu Compiler Collection) frontend supports the full ECMA-335 standard and can parse any conformant.net assembly. Port for Renesas/Hitachi H8-300 microcontroller underway Extremely small footprint (32 KB memory) Variable and method definitions, method calls, integer ops up and running

45 Mirco.NET -.NET Interpreter for Lego Mindstorm Embeddded Device Host Micro IL Assembly download Micro IL Assembly strip merge Application Assembly Dependencies Dependencies Dependency Interpreter Base Class Library Runtime Operating System Hardware Application assemblies merged and striped (meta data, portable executable header, references) Application merged to one micro assembly and transferred to device embedded device Interpreter reads micro executions according instructions using a separate runtime

46 CLI2RCX-.NET Current State Version 1.0 release implements the following features of the.net platform: primitive datatypes: bool, byte, short, int classes, including instance attributes and properties. static and instance methods, including parameters, local variables, and constructors. arithmethic operations control flow operations: conditional and unconditional branch instructions.

47 CLI2RCX-.NET Current State The following features are not yet supported (as are most features not mentioned in either list): most value types (enums, structs, delegates, floats, doubles) strings single-dimensional zero-based arrays (partially complete) multi-dimensional or non-zero-based arrays Inheritance, polymorphism, and late binding interfaces exceptions static class attributes, class constructors, events boxing and unboxing arithmetic instructions that detect overflows any predefined class except for System.Object

48 Related Work Verbund Virtuelles Labor project at University Reutlingen / Germany ilab project (WebLab) at MIT Virtual Lab at University of Hagen /Germany Tele-Laboratory at University of Pisa Tele-Lab / Simplex architecture Ein ferngesteuertes Labor im Internet

Foucault s Pendulum in the Distributed Control Lab

Foucault s Pendulum in the Distributed Control Lab Andreas Rasche, Peter Tröger, Michael Dirska and Andreas Polze University of Potsdam 14482 Potsdam, Germany {andreas.rasche peter.troeger michael.dirska