model driven developmentkramp.ch/wsn/4-2.bpmn.pdf · (c) 2010 ibm corp. 2 model-driven development...

Model Driven Development

Programming and Debugging Business Processes for WSN

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Model-Driven Development

Model

Generate Code

CompileSimulate &

Debug

Inspect/Modify Generated Code

Instantiate &Deploy

Monitor &Analyze

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Graphical Modeling & Programming Languages

• Open-Industry Standards• Universal Modeling Language (UML) 2.0 • Specification and Description Language (SDL)

• Proprietary Standards• LEGO MINDSTORMS• NI LabVIEW• MathWorks Simulink (MATLAB extension)• Scratch

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Modeling for Wireless Sensor Networks

• Custom graphical notation• Viptos

• Flow

• Srijan

• Based on• UML 2.0 Activity Charts

• Simulink, Embedded Coder

• LabVIEW

• Generate C code from models

• Problems• Languages address technical audience

• Often lack of debugging facilities at the same level of abstraction

• Often simulate abstract model rather than actual application

• May require larger hardware platforms (e.g. 32-bit ARM)

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Business Processes

• Capture the interactions between• Humans• IT systems• Environment

• Capture business requirements

• Enable today's enterprises' to• manufacture products• deliver services

• Means of communication and discussion

• Serve as basis for business re-engineering

• Example: car rental

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Business Process Modeling Notation (BPMN)

• Widely used in the business community

• Intuitive notation, addresses a business audience

• Open-Standard Graphical Notation• Different Perspectives

• Hierarchical encapsulation

• Models− Control Flow− Data Flow− Communication Flow

• Graphical Symbols• Tasks & Events

• Messages & Flows

• Pools

• Annotations

• etc.

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Modeling for Business Processes

• Industry solutions• IBM WebSphere Business Modeler• SAP NetWeaver BPM Process Composer• BizAgi Modeler • Signavio

• Usually generate Business Process Execution Language (BPEL )• to be executed by an engine

• BPMN vs BPEL• BPEL is an XML notation without a standard graphical notation

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BPMN Perspectives

• Conversation• High-level interactions among participants

− Architecture

• Choreography• Message exchanges between participants

− Order of interactions

• Collaboration• Inner working of participants

− What and how

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BPMN Conversation

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BPMN Choreography

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BPMN Collaboration

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BPMN Pools & Swimlanes

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BPMN Activities

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BPMN Gateways

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BPMN Events

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BPMN Data

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Modeling Split Phase Operations

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Mapping WSN to BPMN

• BPMN • Parallelism, thread-based

• WSN• Single process, Event-based, queue

• Simplified mapping• Sensor node (entity) = Pool

• Callbacks = Event Task

• Variables = Data Objects/Messages

• Persistent data = Data Stores

• Data consistency, race conditions• Only allow one event task to be active at a given time

• Explicitly model using an event-based gateway

• Addressing• Implicit through message flow, explicit through message properties

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BPMNHeadquarters Example

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BPMNParcel Example

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BPMNmonitor Example

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ExampleGenerated Source Code (C#)

namespace Parcel { ... static class Monitor { static byte[] messageToTruck; static Timer timer; static uint threshold; .... static void onAlarm(byte param, long time) { timer.setAlarm(onAlarm, time + 2000000); uint value = SampleTemperature.start();

if (value > threshold){ Damaged(value);

return; }

HeartBeat.start(); } ....

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Compiler

Model

BPMNGraphical Editor

Compiler

WSNRun-time Platform

ModelGraph

ModelGraph

ModelGraph

ModelObject

ModelObject

ModelObject

Source Code

SymbolTable

Executable

.bxo

.json

.java

.bxd

.sba

.cs

1. Consistency checks

2. Translation

3. Generation

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Compiler: Consistency Checks

• Each throw event must be matched by a catch event

• Split-phase (asynchronous) tasks should not be blocking

• All data objects required by a task are present and have the right type• Infer data types of objects (if not present)

• Very task signatures (input/output data) against the API for target platform

• Communicate errors to IDE

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Compiler: Translation

• Previous stage ensures we operate on a consistent model• Further “compilation” errors are due to bugs in the tools

• Pattern-based compiler

• Transform to intermediate language (C#)

• Keep map to unique ID of graphical element

• Recursively map• Each process to a class with a given entry point• All event tasks in process to functions• All data objects are mapped to instance variables

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Compiler: Generation

• Link all intermediate representations into an application• Ensure all required intermediate representations are available

• Generate C# and Java code according to the API of the target platform • Construct the debug map

• Run platform compiler

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Simulation & Debugging

• Validate that the process behaves as intended and according to the requirements

• Simulate the execution of a business process

• Debug business process at the same level of abstraction• Break-points at the level of graphical symbols• Map from generated source code back to graphical elements and

vice-versa

• From the model infer the network topology and the cardinality of the sensor types

• Inspect values of data and messages

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WSN Platform Requirements

• Target platform API requirements• Events - queue

• Timers

• Communication

• Simulation environment with a debugging interface

• Reduced hardware resources→ small size factor & low cost

• e.g., 8-bit MCU− Larger platforms inherently consume more energy and are more expensive

• Dynamic management• Re-deploy a business process to adapt to changing business requirements

• Energy management• Efficient management of energy resource to ensure long-lifetime requirements

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Prototype Evaluation

Application Total Energy Max Stack Max Heap Executable Size Lines of CodeName Type (bytes) (bytes) (bytes) (C#)Blink generated 415 20 236 230 44

hand-coded 408 22 236 197 34overhead 1.70% 0.00% 0.00% 16.75% 29.00%

Parcel generated 2682 24 480 573 142hand-coded 2669 20 452 422 100

overhead 0.49% 20.00% 6.19% 35.00% 42.00%Truck generated 403917 14 440 478 120

hand-coded 403917 14 420 369 87overhead 0.00% 0.00% 4.76% 29.50% 37.90%

Average overhead 0.73% 5.16% 27.08% 36.30%Resource Battery RAM Flash ---

(uAs)

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Integrated Modeling & Development

DEMO

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Questions?