Using Web Service Gateways and Code Generation for Sustainable IoT System Development

KIT – University of the State of Baden-Wuerttemberg and

National Research Center of the Helmholtz Association www.kit.edu

Technology for

Pervasive Computing

Using Web Service Gateways and Code Generation

for Sustainable IoT System Development

T. Riedel, N.L. Fantana*, A. Genaid, D. Yordanov, H. Schmidtke, M. Beigl,

KIT Pervasive Computing Systems Group, * ABB Corporate Research

Technology for Pervasive Computing

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Overview

Motivation

Use Case Driven Analysis

Implementation

Results

Outlook

IoT 2010, IoT Gateways, Till Riedel


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Motivation

How to apply IoT in industrial environments

RFID, most often in logistics, first steps/islands

in industrial environment

WSN, most often in special applications

No real internet

Can IoT technolgies bring benefit in

industrial ad-hoc service case?

How can we be future proof and adaptive to

new developments? IoT 2010, IoT Gateways, Till Riedel


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Internet of Things

Federating data from objects, machines, devices

Closing the reality gap business value

Technology available and installed: RFID, WSN, automation systems, external data

internet of Things

==

Network of

Networks of

Things



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Why proprietary nodes and protocols?

Heterogeneous IoT Nodes

Market quickly evolving

application specific node development

Topologies and Infrastructure: RFID vs. WSN

Sensing the reality everywhere size/energy

Resource optimized IoT protocols

Enable the effective use of WSN/RFID

Lot of research in MAC-Layers, routing etc.

Low overhead by using implicit information



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32 bit ARM7 256K RAM/2M Flash/80 MHz, 802.15.4, Java

8bit PIC18F6720 MCU 4KB RAM /128KB Flash,5MIPS, Awarecon, C/Java

8bit rfPIC 64 Byte RAM/1.4 KB Flash 1MIPS, C/Config only

Organic Label, PolyIC

SPOTS, Sun

IoT Platforms: Networked Sensing+ID

No MCU, 1bit-4kbyte EEPROM



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Why Web Services?

Document oriented Web Service

Loose coupling

Message oriented communication

State less

Not (only) RPC! (see Saif, Greaves: Communication Primitives for Ubiquitous Systems or RPC Considered Harmful)

Typing

Integration into many programming languages

Well-defined Interfaces

Long term documentation (one the ideas behind SGML)



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Device Profile for Web Services

Features:

• Profile of Basic Web Service

functionality

• Infrastructureless setup

• Support for “resource constraint “

device

Socrades Project

http://socrades.eu

Web services in automation and

sensing, realtime

WS4D

http://ws4d.org

DPWS implementations for gsoap

(C,C++), AXIS (Java)

WS

Discovery

WS

Eventing

WS

MEX

WS-Addressing, WS-Security

UDP HTTP

TCP

IP

Service


http://socrades.eu/

http://ws4d.org/


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Are Web Services really the tool for IoT?

Cannot answer this generally!

Other approaches: see other talks in this

session!!!

Use case/requirement driven analysis:

1) Identification

2) Placement

3) Configuration

4) Measurement

5) Storage IoT 2010, IoT Gateways, Till Riedel


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Identification and placement unambiguous association of data to data sources (measurement units or RFID name

plates)

scan the landscape for existing IoT

WS-Discovery

works infrastructure-less and ad-hoc

custom search criteria (type of node, location, measurement grouping)

RFID batch readings EPC over the air protocol

protocols in wireless sensor networks.

URI

Device Profile Metadata

Simple abstraction on Hosting and Hosted Service

Device and Functionality

But also group of devices, networlk and gateway services

Adds services to “things”

WS-MetadataExchange

Extend using context information location information

Identification is not only a machine to machine problem!!



14 05.12.2010 IoT 2010, IoT Gateways, Till Riedel


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Configuration & Storage


Need to archive configuration and data formats with the

document: See e.g. IEEE COMTRADE Format (3 text files)

Not only understand live data

Find out what the capabilities/interfaces are of a sensor WSDL is very expressive

Can easily extended semantically: We started using e.g. UnitsML

Easy to put in text documentation

Configure dynamic capabilities via document oriented

interfaces Clearly communicate and document the state!

Serialize data as XML along with static and dynamic

configuration and context information


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17 05.12.2010 IoT 2010, IoT Gateways, Till Riedel


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Measurement

Again: do not use RPCs

Publish/Subscribe patterns are much more natural to the domain

WS-Eventing provides simple/extensible semantics

Industrial application need to support high data rates:

E.g. 2kHz continues sensor signal

250kHz transient

Do you want to use XML for this: yes

Can we use XML over a IoT network: no



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Mapping Web Services to IoT

Client C Service Proxy S' WebService


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GW

GW

GW

GW




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GW

GW

GW

GW



The question will not be how to

write a single gateway but

how to write all the gateways

needed in the future…


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Mapping IoT Nodes to Web Services

We will need

gateways? But how

many?

Can we afford map

every service by

hand?

Is there a way to do

it once and for all?



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Gateway WS/WSN

Syntactic Transformation

Platform X

WS Comm.

Transformation

Transport

How to write transformations

• Manual Proxies

• Declarative Mapping (uMiddle,

• CoBIS)

• Implicit Mapping!

TransportA

Transformation

Transformation

Platform Y

Transport

Transport

<sample> ….</sample>

111|101001011|1011



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Communication via

Common Models

Generated

Middleware

Efficient Generated

Code

Available as

eclipse plug-in

Ecore Meta Model

Akzeptor

Transformation DSL

SensorNode Gateway

WSDL/XSL,

ASN.1, IDL

Model driven development process

Client



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The nice things about talking XML

bisimulate

Representation R

Encoding E

Representation R’

bisimulate

Encoding E’

WS-Client IoT node Gateway IoT 2010, IoT Gateways, Till Riedel

Lots of tools available!

But also theory available!

Hedge Grammars, nested word languages

Structure best available compromise between expressiveness and complexity?

Can be accepted via automata!


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Domain specific


Formal

Executable


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Aspect oriented Code Generation

Automata generator

templates

C-Code

Eclipse Modeling Framework

Xpand based model to text

DOM struct Writer

Bin Reader

Java-Code

DOM struct Writer

SAX Reader

software product line implementation

(Voelter, et.al)



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Human resources

C# Mobile WCF Client

pPart Sensornode C-Code (DOM based)


Easy new platform adaption:

• Particle (binary encoding, AwareCon MAC, DOM-based code, existing pPart node)

• 6LoWPAN (binary encoding, 6lowpan/802.15.4 MAC,event-based code, Contiki Node)

• “Dummynode” (various encodings, IPv4, dom-based, PC basedtest environment)

Prototypes we are currently working on:

• RFID • Microstrain • Java Nodes

Difference between a Java SAX based implementation and a C proto-thread implementation:

approx. 150 lines of code for all possible service/gateway combinations


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Network resources

using different encoding

allows high data rates/less

energy consumption

Event multiplexing offloads

load from sensor network

WS-Eventing requires

scalable client IoT 2010, IoT Gateways, Till Riedel


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General Issues of Web Services

Web-Service client implementations are often not scalable

Other event delivery modes relax this situation: WS-Management

Discovery is not scalable for the real IoT

Custom scoping is important.

Moving away from the standards again:

Difficult to adapt clients!

You have to make it work once at least

Support for IoT Web Sevice standards is weak and often

incomplete and complicated



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Reason for using Web Services

But:

Interaction patterns from web service community apply

to IoT!

Flexibility needed for IoT deployment

Interacting with things and not aggregating their data

Proprietary, incomplete, non-standardized solution will

give quicker success, but can they really be

sustainable?

Complexity is not an argument just an excuse!

Performance is not an argument either!

A common language for the IoT is needed:

Use (Web) Services for devices !!



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Conclusion

We have show how Web Services can provide a

clean semantic abstraction to an IoT use case.

We can functionally fully capture an industrial service

IoT application with heterogeneous devices using

Web Services

We developed a way to develop a product line of

gateways for Web Services

We functionally enabled a number of IoT platforms

to be used in our application. IoT 2010, IoT Gateways, Till Riedel


36 05.12.2010

Outlook

We only told you half of the story

The Internet of Things not only about

homogeneity but is also about the differences

of real things (and thus technologies)

How can we translate non-functional behavior to a

technology agnostic client application and eventually

user?

time synchronization for high speed sampling, calibration

temporary failure, service availability (especially RFID)

robustness, acceptance by user!



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Questions?

[email protected]

nicolaie.fantana

@de.abb.com

mailto:[email protected]

