Download - Deepak Mathur

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EMBEDDED SYSTEM :DEEPAK MATHUR

Real-Time Messaging for Embedded Systems and Mobile Devices

Antenna GPS Embedded SMA

sku: GPS-00177

Description: Embedded antenna for small, mobile applications. Basic

unpackaged antenna with LNA. 5inch cable terminated with standard male

SMA connector. Match it with an SMA interface cable to create a trul

small !"S prototpe#

$his unit works %er well out of the bo&, but the full packaged antennas

ha%e better strain relief where the SMA cable meets the antenna housing. 'fou plan on using this antenna in a %ibration intensi%e application, we

recommend ou reinforce the connection with epo& or Shoe !oo.

Features:

!ain ()dB

*S+ -(.

*oltage /./* 012 .5*

3urrent 4(mA

+eight 4g

Mobile and embedded computer-based devices are becoming integralcomponents of business and mission-critical systems. As a result, device-

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based software must increasingly communicate with software running onother devices as well as with backend enterprise applications. Application-to-application messaging is the enabling technologyfor this

communication.RTIs real-time messaging infrastructure was designed fromthe ground up to meet the uni!ue challenges posed by embedded andmobile computing. These include"

#upport for speciali$ed mobile, embedded and real-time operating systems%RT'

&peration in resource-constrained environments - with limited memory,storage, processor and network bandwidth

Real-time performance - with deterministically low latency and high

throughput

(eterogeneous interoperability - across programming languages,

operating systems and processor types

)eployment in dynamic, ad hoc environments - without system

administration or servers

*ommunicating over +A, wireless and satellite networks - which

can be intermittent, low bandwidth, high delay and lossy

Meeting high-assurance re!uirements - including certification to

safety and security standards

ecause traditional enterprise messaging and integration technologies donot satisfy embedded and mobile re!uirements, developers havetraditionally had to create their own custom communications infrastructure.These in-house solutions can be time-consuming and epensive todevelop. They are also etremely costly to maintain as new re!uirementsare introduced, personnel turns over, and systems become larger, morecomple, more stovepipe and thus more brittle.

+ith a commercial alternative, RTI accelerates time-to-deployment whilesignificantly reducing software lifecycle costs.

RTI Attribute Benefits over Custom Middleware

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Commercial ff-T!e-S!elf

"CTS#

Turnkey messaging

infrastructure

Tracks the latest

operating system anddevelopment environmentreleases

/rovides an ecosystem

of integrated technologiesfrom RTI and partners

#aves time and costs

otherwise re!uired for internalmiddleware development, porting,integration, maintenance andsupport

0asily evaluated against

re!uirements1 an in-housesolutions capabilities, performanceand scalability can not be knownuntil it is complete

/rovides time and cost-

certainty1 eliminates risk thatmiddleware development will takelonger than epected

Standards com$liant

2M#, ))# and #34

applications programminginterfaces %A/Is'

RT/# on-the-wire

protocol

5amiliar, well-documented

interfaces and readily availabletraining improve productivity ofapplication developers%middleware users'

/ortability and interoperability

provide vendor independence andease integration of independentlydeveloped components

Robust

*omprehensive feature

set

/erformance and

Meets current and future

re!uirements, eliminating the riskthat time-consuming and costly re-

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scalability headroom

road platform,

programming language andtransport support

engineering will be re!uired later

Eases integration

4oosely-coupledintegration model based onpublish6subscribe

5ull interoperability

across platforms andprogramming languages

Reduces overall systemcompleity and eliminatesinterdependencies betweensubsystems

Individual components can

be added or upgraded withoutimpacting already running software

ew platforms and

programming languages can betransparently introduced

Reliable

&perationally proven in

some of the worlds most

demanding systems

)eveloped and tested in

accordance with RTIsrigorous !uality process

(igh technology readiness

for mission-critical systems

%eatures of RTI&s real-time messaging infrastructure

Available for embedded' mobile and real-time o$erating systems

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In addition to support for enterprise operating systems such as 4inu,+indows and 7ni, RTIs real-time messaging infrastructure is available forall leading embedded, mobile and real-time operating systems %RT'.

These include"

4inu - i89, 9: and /ower/* distributions

;reen (ills #oftware - IT0;RIT+orks

RTI is continually adding support for new platforms, including separationkernels based on the Multiple Independent 4evels of #ecurity %MI4#'architecture.

Eases a$$lication integration

RTI eases integration of embedded and mobile applications with eachother, with enterprise applications, and into a #ervice-&riented Architecture%#&A'.

Applications using RTIs infrastructure are fully interoperable

across programming languages, operating systems and processortypes

Application /rogramming Interfaces %A/Is' are available for *, *?

?, 2ava %2M# and ))#', .0T and Ada

Message contents are automatically transformed so that they areinterpreted correctly by applications written in different programminglanguages and running on processors with different native datarepresentations

RTI keeps in-memory data caches on embedded and mobile

devices synchroni$ed with enterprise databases

RTIs messaging infrastructure is easily integrated with enterprise

middleware including Application #ervers, *omple 0vent/rocessing %*0/' engines, 0nterprise #ervice usses %0#s' and

visuali$ation platforms

Su$$orts resource-constrained systems

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Applications can automatically discover each other" no

configuration of hostnames or network addresses is re!uired

Runs over a wide variety of networ)s

RTI provides etremely fleible transport support for mobile applicationsand systems deployed outside the enterprise"

&ut-of-the bo support for 4A, +A, secure %T4#', satellite and

wireless communication over I/v: and I/v9

Reliable multicast for efficient broad data distribution #hared memory transport for high-performance inter-process

communication between components running on the same node

/luggable interface for integration with other transports, including

backplanes and switched fabrics, even those without I/ support

*ell-suited for mission-critical systems

RTI meets the re!uirements of the most demanding business and mission-critical applications"

5ault tolerant infrastructure with no single point of failure at either

the node or system level

Automatic failover in the event that an application or node fails or bec

inaccessible

Messages can be simultaneously sent over multiple transports and

networks for redundancy and partitioning

#ystem-level introspection for health monitoring and application-

managed high availability

Technology proven over @E years in hundred of the worlds most

demanding and mission-critical applications

/roducts developed in accordance with RTIs rigorous !uality

process, with more source code and development time dedicated to3uality Assurance %3A' than to technology development

Embedded & Mobile Systems operates as a developer o data!ase a"d e#!edded s$ssol%t&o"s t'at retre&ve data ro# dev&(es )e#!edded s$ste#s* !ar (ode s(a""ers* #o!&lse(%rel$ ro%te &"or#at&o" &"to t'e e"terpr&se or #as',%ps* a"al$s&s* das'!oards a"d d

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load&". )ET+ a"d report&"./ T'&s data!ase e#p'as&s &"(l%des (%sto# appl&(at&o"s or


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E(el* a"d M$S %s&". S* BA* a"d Perl la".%a.es (o#!&"ed &t' (o"vers&o"s

or#ats/ Mo!&le dev&(e data!ases* Bar(ode &"p%t* a"d &"spe(t&o" or# !ased data!aseo%r spe(&alt&es/

E#!edded 0 Mo!&le S$ste#s e#!edded s$ste#s develop#e"t e#p'as&7es !r&".,%p a"d start%p o e#!edded s$ste#s : test!e"(' (ode* d&a."ost&(s* !ootloaders* a"d

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The Global Positioning System (GPS) is the only fully functionalGlobal Navigation Satellite System (GNSS). The GPS uses aconstellation of at least 24 (32 by March 2!) Me"ium #arth

$rbit satellites that transmit %recise micro&ave signals' thatenable GPS receivers to "etermine their location' s%ee"'"irection' an" time. GPS &as "evelo%e" by the nite" Statese%artment of efense. *ts official name is N+,ST+-GPS.

+lthough N+,ST+-GPS is not an acronym/01' a fe&bacronyms have been create" for it/21. The GPS satelliteconstellation is manage" by the nite" States +ir orce thS%ace 5ing.

S&lar satell&te "av&.at&o" s$ste#s &"(l%de t'e R%ss&a" ASS )&"(o#plete aso 2FF?+* t'e %p(o#&". E%ropea" al&leo pos&t&o"&". s$ste#* t'e proposed

9MPASS "av&.at&o" s$ste# o 9'&"a* a"d RSS o "d&a/ T'e lo!alPos&t&o"&". S$ste# )PS+ &s t'e o"l$ %ll$ %"(t&o"al lo!al av&.at&o" Satell&te

S$ste# )SS+/ T'e PS %ses a (o"stellat&o" o at least 24 )32 !$ Mar(' 2FF?+

Med&%# Eart' r!&t satell&tes t'at tra"s#&t pre(&se #&(roave s&."als* t'at e"a!le

PS re(e&vers to deter#&"e t'e&r lo(at&o"* speed* d&re(t&o"* a"d te/ PS asdeveloped !$ t'e U"&ted States Depart#e"t o Dee"se/ ts o&(&al "a#e &s

ASTAR,PS/ Alt'o%.' ASTAR,PS &s "ot a" a(ro"$#G1* a e!a(-ro"$#s 'ave !ee" (reated or &tG2/ T'e PS satell&te (o"stellat&o" &s #a"a.ed

!$ t'e U"&ted States A&r =or(e 5Ft' Spa(e 8&"./

Real Time Os

" (o#p%ter s(&e"(e * real-time computing)RT9+* or Irea(t&ve (o#p%t&".I* &s t'e

st%d$ o 'ardare a"d sotare s$ste#s t'at are s%!e(t to a Ireal,te(o"stra&"tIJ&/e/* operat&o"al deadl&"es ro# eve"t to s$ste# respo"se/ B$ (o"trast*

a non-real-time system&s o"e or '&(' t'ere &s "o deadl&"e* eve" & ast respo"se

or '&.' peror#a"(e &s des&red or preerred/ T'e "eeds o real,te sotare areote" addressed &" t'e (o"tet o real te o operat&". s$ste# * a"d s$"('ro"o%s

pro.ra##&". la".%a.e * '&(' prov&de ra#eor-s o" '&(' to !%&ld real,te

appl&(at&o" sotare/

A real te s$ste# #a$ !e o"e 'ere &ts appl&(at&o" (a" !e (o"s&dered )&t'&"

(o"tet+ to !e #&ss&o" (r&t&(al / T'e a"t& lo(- !rea-es o" a (ar are a sple ea#ple

o a real,te (o#p%t&". s$ste# J t'e real,te (o"stra&"t &" t'&s s$ste# &s t'e

s'ort te &" '&(' t'e !ra-es #%st !e released to preve"t t'e 'eel ro# lo(-&"./

Real,te (o#p%tat&o"s (a" !e sa&d to 'avefailed& t'e$ are "ot (o#pleted !eoret'e&r deadl&"e* 'ere t'e&r deadl&"e &s relat&ve to a" eve"t/ A real,te deadl&"e#%st !e #et/

Designing Real-time Software


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Designing Realtime software involves several steps. The basic steps are

listed below:

Software architecture definition

Co design

Defining software subsystems

Feature design

Task design

Soft&are +rchitecture efinition

This is the first stage of Realtime Software design. Here the software team

understands the system that is being designed. The team also reviews at

the proposed hardware architecture and develops a very basic software

architecture. This architecture definition will be further refined in Co-Design.

Use Cases are also used in this stage to analyze the system. Use cases

are used to understand the interactions between the system and its users.

For example, use cases for a telephone exchange would specify the

interactions between the telephone exchange, its subscribers and the

operators which maintain the exchange.

6oesign

Once the software architecture has been defined, the hardware and

software teams should work together to associate software functionality to

hardware modules. The software handling is partitioned between different

processors and other hardware resources with the following keyconsiderations:

The software functionality should be partitioned in such a

fashion that processors and links in the system do not get

overloaded when the system is operating at peak capacity. This

involves simulating the system with the proposed software and

hardware architecture.

The system should be designed for future growth byconsidering a scalable architecture, i.e. system capacity can be

increased by adding new hardware modules. The system will not

scale very well if some hardware or software module becomes a

bottleneck in increasing system capacity.

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Software modules that interact very closely with each

other should be placed on the same processor, this will reduce

delays in the system. Higher system performance can be achieved

by this approach as inter-processor message communication

taxes the CPU as well as link resources.

This stage is sometimes referred to as Co-Design as the hardware and

software teams work together to define the final system architecture. This is

an iterative process. Changes in system architecture might result in

changes in hardware and/or software architecture.

The next step in Realtime system design is the careful analysis of thesystem to define the software modules.

efining Soft&are Subsystems

1. Determine all the features that the system needs to

support.

2. Group the various features based on the type of work

they perform. Identify various sub-systems by assigning one

subsystem for one type of features. Identify the tasks that willimplement the software features. Clearly define the role of each

task in its subsystem.

3. Within each subsystem, classify and group the features

appropriately and associate the various tasks constituting the

subsystem. For example, the Call Handling subsystem in Xenon

would support features like:

o V5.2 Originating to ISUP Outgoing Call

o V5.2 Originating to V5.2 Terminating Call

o Conference Callo Toll free call

eature esign

A typical Realtime system is composed of various task entities distributed

across different processors and all the inter-processor communication takes

place mainly through messages. Feature Design defines the software

features in terms of message interactions between tasks. This involvesdetailed specification of message interfaces. The feature design is generally

carried out in the following steps:

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1. Specify the message interactions between different tasks

in the system

2. Identify the tasks that would be controlling the feature.

The controlling tasks would be keeping track of progress of

feature. Generally this is achieved by running timers.

3. The message interfaces are defined in detail. All the

fields and their possible values are identified.

%eature Design +uidelines

Keep the design simple and provide a clear definition of

the system composition.

Do not involve too many tasks in a feature.

Disintegrate big and complex features into small sub

features.

Draw message sequence charts for a feature carefully.

Classify the legs of a scenario for a feature in such a way that

similar message exchanges are performed by taking the common

leg.

Provide a clear and complete definition of each message

interface. To check possible message loss, design timer based

message exchanges.

Always consider recovery and rollback cases at each

stage of feature design. One way of doing this is to keep a timer

for each feature at the task that controls the mainline activity of the

feature. And then insert the timeout leg in the message sequence

charts of the feature.

To avoid overloading of message links choose design

alternatives that include fewer message exchanges.

Tas esign

Designing a task requires that all the interfaces that the task needs to

support should be very well defined. Make sure all the message parameters

and timer values have been finalized.

Selecting t!e Tas) Ty$e

Once the external interfaces are frozen, select the type of task/tasks that

would be most appropriate to handle the interfaces:

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Single State Machine:The tasks functionality can be

implemented in a single state machine. The v5.2 call task in Xenon

is a good example of a task of this type.

Multiple State Machines:The task manages multiple state

machines. Such tasks would typically include a dispatcher to

distribute the received messages to an appropriate state machine.

Such tasks would create and delete state machine objects as and

when required.

Multiple Tasks:This type of tasks are similar to the multiple

state machine tasks discussed above. The main difference is that

the task now manages multiple tasks. Each of the managed tasks

implements a single state machine. The manager task is alsoresponsible for creating and deleting the single state machine

tasks.

ComplexTask:This type of task would be required in really

complex scenarios. Here the manager task manages other tasks

which might be managing multiple state machines.

Selecting t!e State Mac!ine Design

After choosing the type of task, the designer should consider dividing the

message interface handling into a sequence of state transitions. Two

different type of state machines can be supported:

Flat State Machines:This is the most frequently used type of

state transition. For example, the states of a call would be

"Awaiting Digits", "Awaiting Connect", "Awaiting Release",

"Awaiting On-hook" etc. This type of state division does not scale

very well with increasing complexity. For a complex system thistechnique results in a state explosion, with the task requiring

hundreds of states.

Hierarchical State Machines:Here the states are viewed as a

hierarchy. For example the states covered above would map to

"Originating : Awaiting Digits", "Originating: Awaiting Connect",

"Releasing : Awaiting Release", "Releasing : Awaiting On-hook".

The total number of states is the same here, but the main

difference is that some states inherit from an "Originating" basestate and others inherit from "Releasing" base state. The total

number of message handlers in each state would be reduced

drastically, as all the messages that have common handling in all

the originating states would be just handled in the "Originating"

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base state. In addition to this, the handlers of inheriting states can

further refine the base state handling by taking additional actions.

Tas) Design +uidelines

Do not complicate the design by introducing too many

states. Such designs are very difficult to understand. Follow a

simple rule of thumb, if you are having difficulty choosing the name

of state, you may have identified the wrong state.

Do not complicate the design by having too few states. If

all the states in the system have not been captured in the state

machine design, you will end up with lot of flags and strange

looking variables which will be needed to control the message flowin the jumbo states.

Keep the data-structure definitions simple. See if a

simpler data-structure would do the same job just as well.

Out of memory conditions should be handled. Tasks can

and will run out of memory. So handle the out of memory

conditions gracefully. This can lead to a lot of "if clutter" so

consider exception handling as an option.

All of the legs of the defined scenarios should behandled. This is easier said than done. Many times all the scenario

legs identified in the feature design stage may not cover all the

possible error scenarios for your task.

Make sure that all the allocated resources are de-

allocated at the end. Again it is very easy to miss out on this one.

Many times designers forget to release resources in the error legs.

Consider using a hierarchical state machine to simplify

the state machine design.

Consider using Object Oriented programming languages

like C++. Contrary to popular belief, languages like C++ might turn

out to be more efficient in runtime performance because of better

locality of reference. (Most objects would be referring to data that

is contained in the same object, thus improving the locality of

reference)

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ple#e"tat&o" t'at &s (apa!le o e"or(&". t'e reservat&o"s pl&ed !$ t'ed&ere"t a(t&ve (o"tra(ts/ T'e (o"tra(ts &ll !e &"te.rated &t' a (o#po"e"t,!ased

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E#!edded data!ase

*ombining in-memory database with storage caching of disk database,ITTIA ) #34%TM' enables application development on embeddedsystems. (ybrid database can contain related data that is divided intomemory and disk tables. Memory tables are optimi$ed to minimi$e */7cycles, while disk tables emphasi$e

throughput when data is saved to blockdevices. y using solid relational

model foundation, relationships are navigated with #34 !ueries oraccessed directly with low-level functions.FFFFFFFFFFFFFFFFFFFF

&ctober G, EBBH - ellevue, +A - 0mbedded devices continuously processinformation from a wide variety of sources, such as sensors, user input,network communications. )evelopers recogni$e cases for whichdata mustbe accessed !uickly with predictable speed and cases for which data mustbe saved continuously to flash media or a hard drive. To address this need,ITTIA unveils the revolutionary new ITTIA ) #34TM hybrid memory and

disk database for application development on embedded systems anddevices.

ITTIA ) #34 hybrid combines the fast, predictable performance of an in-memory database with the robust storage caching of a disk database. ITTIA) #34 hybrid delivers capabilities culminated from decades of database

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evolution in a compact, self-managing package for development ofapplications in consumer electronics, medical devices, portable mediaplayers, network appliances, telecommunication systems, and other

embedded systems.

An ITTIA ) #34 hybrid database can contain related data that is dividedinto memory and disk tables. Memory tables are optimi$ed to minimi$e */7cycles, while disk tables emphasi$e throughput when data is saved to blockdevices such as flash media or a hard disk. y usinga solid relational modelfoundation, relationships are easily navigated with #34 !ueries or accesseddirectly with low-level functions.

All tables share the same transactional database kernel, whether they arestored in memory or on disk. )ata is always accessed through common

A/Is and can be shared between threads and processes. Transactionsensure the integrity and consistency of the data, but, because the data ismanaged within a single database, without the compleity of distributedtransactions. Modular devices can etend their functionality dynamically byadding new tables and fields to the database.

)evices and embedded systems that use ITTIA ) #34 benefit fromITTIAs philosophy of fleibility. +hile ITTIA offers several differenteditionsto target the wide variety of re!uirements for database features andfootprint, all ITTIA ) libraries are source, file, and binary-compatible.

Manufacturers can build a complete line of products that are based on asingle code base for data access. (igh-performancecode can use concise,low-level calls to access and modify individual rows directly. The same datacan also be accessed with high-level #34 !ueries, for interoperability andaccelerated prototyping.

The hybrid model used by ITTIA ) #34 is ideal for devices that log eventsoccurring at a very high fre!uency. The event log itself maybe storedtemporarily in memory, and related data such as event types, criticalevents, and thresholds can be stored in disk tables that are automatically

and continuously saved to flash media. The device can monitor and storethe maimum values for each type of event. oth the event log andassociated data can be shared between the logging task, reportingmechanism, user interface, and any other components.

ITTIA ) #34 hybrid offers developers a broad selection of lightweightR)M# embeddable database features to meet their specific applicationre!uirements, said #asan Montaseri, ITTIA /resident. &ur customersalready benefit from ITTIA ) #34s fleibility, performance at lower cost.The introduction of ITTIA ) #34 hybrid completes this value-added

offering. +e continue our focus to deliver the highest !uality products andservices at a lower cost.

A free, B-day evaluation of ITTIA ) #34 is available at the ITTIA )0valuation *enter. The evaluation kit contains a complete embeddeddatabase library, optional server, and #34 tools.

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About ITTIA

ITTIA offers a leading-edge embedded R)M# for platforms where limitedmemory, storage, and processing power make software developmentchallenging. ITTIA develops fast, high-performance relational lightweightdatabase products and tools with the goal of providing ecellentdatamanagement software for embedded systems and devices. ITTIAsproducts are designed to be suitable for application development anddeployment at significantly reduced cost. ITTIAs customers include5reescale #emiconductor, /anasonic, /uget #ound 0nergy, oeing, andothers.

EMBEDDED DATABASE TE9HY

=R SE9URTY SYSTEMS

RA9E EMBEDDEDSe(%r&t$ s$ste#s L 'et'er p%re sotare or a (o#!&"at&o" oSe(%r&t$ s$ste#s "eed data!ase 'ardare a"d sotare L #%st store a"d #a"a.e

(r&t&(alstora.e %st l&-e #a"$ ot'erappl&(at&o"s/ Hoever* t'e

&"or#at&o" rel&a!l$/ Be(a%se t'ese s$ste#s are a (r%(&al part o t'e

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Pervasive Computing is the main characteristic of the emerging fourth era of computer

evolution. The paper discusses features of a new generation of intelligent sensor-based

information appliancesfor distributed heterogeneous real-time applications. Theseappliances

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will be found in the intelligent homes, offices, automobiles and cities of the future. They will also

offer higher mobility and convenience to professionals and open new avenues to many industrial

and health applications.

1. Introduction

Since its emergence, some forty years go, computing industry has passed through a rapidsequence of technological phases: central computing/mainframe (1950s-1980s), personal

computer/PC (1980s-...), computer networks (1990s -...). A fourth era is emerging now, when

computers become pervasive, i.e. a technology more noticeable by its absence than its presence

[1], [6], [11], [14], [17], [22], [25].

The first mass-produced pervasive computing devices are starting to appear. The Clarion

AutoPC [8] provides an efficient, reliable and secure integrated communications, computing,

navigation, car control and entertainment system. The NCR Microwave Oven/Home Banking

Terminal [21] and the Electrolux Internet Connected Screen Fridge [12], allow effortless home

management.

A good example scenario is given in [16]:

"Opening the fridge to take out a soda, you may notice that there is only one left. The smart

fridge recorded that and adds an action item on your shopping list. The next day, as you drive

home from work, the GPS-enabled AutoPC in your car, previously informed by your fridge

that purchases need to be made, signals that you are near a supermarket. As you cruise the

isles of the supermarket, wearing your augmented-reality goggles and your wearable

computer a soda supply triggers an object recognition program and an alarm reminds you to

buy soda. The same could be done by your pocket Personal Digital Assistant (PDA) when

sensing the presence of the soda supply."

Another pervasive computing example is given in [14]:

,age "Your intelligent car develops an engine problem, but instead of flashing you a warning

light it sends a message directly to the manufacturer over a wireless connection to the

network. The manufacturer's systemsdiagnose the problem and transmit a fix back to the

electronics complex in your car. In fact, that corrective fix is transmitted to all modelseverywhere in the world, without ever having to notify the owners. .... Instant

informationon performance is captured and sent immediately into product development

and manufacturing. "

The recently announced Cisco Internet Home, a 170 square-meter living space, has almost

all house appliances(refrigerator, microwave oven, internet-based phone, television,

computer, Web cams, wireless touch-pads, health maintenance devices, ...) connected to

Internet through a Residential Gateway. Cisco SystemsInc. wants to prove that "... the

Internet is the next utility in the home, and, within three to five years, will be as pervasive as

gas, water or electricity."

Electric servoappliancesare a good example of pervasive technology [4], [6]. The average

North American home contains two dozen or more electric motors. A multitude of sensors is

gathering the informationneeded to control them. As all these are buried inside many appliances(vacuum cleaners, microwave ovens, refrigerators, VCRs, etc.) we have difficulty identifying

them and we actually don't care where and how many they are as long as they are doing their job.

In the future, the same will be true with computers, most of which will be hidden in information

appliances[22]. These new appliancesare "smart devices" embeddedwith microprocessors that

allow users to plug into intelligent networks and gain direct, simple, and secure access to both

relevant informationand services. These devices are as simple to use as calculators, telephones

or kitchen toasters. Pervasive Computing envisions the "networkedhome" where domestic

devices can interact seamlessly with each other and with in-home and external networks. Using

the existing home infrastructure based on open industry standards, a person will be able to

integrate the home network with external networks to easily manage home devices, both locally

and remotely.

Recent progress in computer, integrated circuit, and communications technologies allows theuse of complex algorithms from various domains (such as signal and image processing, system

identification, modelling, control, and AI). It becomes also possible to implement user friendly

virtual environments for the development of an ever growing diversity of real-time intelligent

sensing applications ranging from Computer Integrated Manufacturing (CIM) to smart homes

and offices [15], [18], [23].

Early digital and computer-based instrumentation architectures and communications standards

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asHP-IB (IEEE 488) represented embryonic smart sensing solutions supporting the first

generation of computer based industrial applications. Microprocessor controlled sensors and

virtual instrumentation integration environments such asLabView, together with wireless and

Internet communications, allowed to develop a large variety of embeddedindustrial applications.

The advent of pervasive computing marks an urgent need for a new generation of intelligentsensing agents and information appliancesas well as for related resource management

,age .environments to be used in a broader selection of applications involving loosely coupled, event-

driven, heterogeneous information appliances.

The aim of this paper is to discuss development scenarios for intelligent sensor environments

and pervasive computer architectures able to support a new generation of information appliances

for distributed heterogeneous real-time applications.

2. Sensor-based information appliances

While the smart networkedhome is a very good first example, the development of intelligent

sensing agents and sensor-based information applianceswill spread the pervasive technology

ideas to a multitude of human activities such as mining and manufacturing, security industry,transportation, training and health etc. It is not exaggerate to claim that this technology, when

integrated with the emerging global informationinfrastructure, will have a profound impact on

our personal and professional activities, and will open business opportunities, of a similar or

even higher scale than what we are experiencing presently with the Internet.

As their perception, intelligence and networking abilities grow, the electricappliancesare

evolving into information appliances representing the next, information-intensive, evolutionary

stage for the pervasive computing paradigm. Donald Norman makes a compelling argument in

[22] for the informationappliance paradigm that he sees as being "the natural successor to

today's [computer] complexity ... through the user-centered, human-centered, humane technology

of applianceswhere the technology of the computer disappears behind the scenes into task-

specific devices that maintain all the power without the difficulties." The business model for this

disruptive technology shifts from the technology-driven computer industry to the consumer-driven model of the consumer appliance industry. Lower profit margins are to be expected from

high volumes of consumable devices, services and content.

The nature of pervasive information appliancesrequires that the developed architectures

should distributed rather than centralized. These applianceswill provide a seamless intelligent

connection of the perception to action, [7]. These new developments point to a new type of

intelligent control based on a multisensory perception of the state of the controlled process and

its environment [7], [10]. The use of multiple sensors is beneficial in improving the accuracy, the

cost and robustness of the perception process. World models, built and maintained from

informationgathered by a multitude of sensors, provide a common abstract representation of the

state of the environment. At the perception level, the world model is analyzed to infer

relationships between different objects.

Sensor architectures integrating bothproprioceptors (sensors monitoring the internal state of

information appliances) and exteroceptors (sensors monitoring the state of the environment

outside the informationappliance) using sensor-models and world-models will provide superior

modularity, interchangeability ("plug and play") and transparence. All these will eventually

allow for easier sensor fusion and knowledge extraction.

,age /Intelligent task-directed informationgathering features will allow for a more elastic and

efficient use of the inherently limited sensing and processing capabilities of each sensor. Each

task a sensor has to carry out determines the nature and the level of the informationthat is

actually needed. Sensors should be able of selective environment perception that focuses on

parameters important for the specific task at hand and avoid wasting effort to process irrelevant

data. A task-specific decision making process will guide the incremental refinement of the

environment model.

Informationappliance should be able to learn and adapt their behavior to changes in their

working environment including other appliancesas well as human users. Such adaptability is

already provided by the smart habitat controls of some cars which offer an automatic adjustment

of the seat, mirrors, and drive wheel's column tilt to accommodate every driver's preference.

These appliancesshould also be able to deal with multiple redundant communication carriers

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(Intranet, Internet, power lines, wireless, infrared, etc.).

Some of the specific objectives for the development of these sensor based information

appliancesare:

(i) design of hybrid deliberative/reactive architectures integrating deliberative reasoning and

behavior-based control functions [5];(ii) design of model-based multi-sensor fusion systemsable to integrate a variety of sensors

that cover all four phases in the environment perception process: far away, near to, touching, and

manipulation;

(iii) study of new task-directed sensor fusion and learning methods for an active perception,

which will allow the informationappliance to gather informationby interaction with the

environment;

(iv) design of redundant multi-carrier communication systems.

3. "Symbiont" intelligent appliances

Human-computer interaction (HCI) is a well-established field of computer science and

engineering [1]-[3], [24]. The advent of the embeddedcomputing systemsled to a system

integration approach to HCI design which is quite well summarized by the following quote from

[2]:"Instead of workstations, computers may be in the form of embeddedcomputational

machines, such as parts of spacecraft cockpits or microwave ovens. Because the techniques

for designing these interfaces bear so much relationship to the techniques for designing

workstations interfaces, they can be profitably treated together."

As the era of pervasive computing commences, portable wireless PDAs or wearable

computers will be widely used [4], [19], [20] and [25].

There are applications such as remote sensing, environment monitoring, and telerobotics for

hazardous operating environments requiring very complex monitoring and control processes.

Many of these applications cannot be fully automated. Human operator expertise is still

needed to carry out tasks requiring a higher level of intelligence. In such cases, human operators

,age 0and intelligent sensing systemsare called to work together assymbionts, each contributing the

best of their specific abilities, as illustrated in Figure 1. A proper control of these operations

cannot be accomplished without some telepresence capability allowing the human operator to

experience the feeling that he/she is virtually immersed in the working environment.

Figure 1: Human operators and sensor-based applianceswork together as symbionts, each

contributing the best of their specific abilities. HCI (Human Computer Interaction)

interfaces provide a telepresence capability allowing the human operator to

experience the feeling that he/she is virtually immersed in the working environment.

Appropriate geometric-, force-, and touch-domain human-feedback devices will have to be

developed in addition to the currently available visual and sound HCI devices.

,age 1In order to find efficient solutions to the complex perception tasks, thesesymbiont intelligent

appliances will have to combine their intrinsic reactive-behavior with higher-order world model

representations of the immersive virtual reality systems.

4. Management of heterogeneous functions for a large diversity of information appliances

Pervasive computing environments involve both human-machine and machine-machine

interaction and cooperation paradigms. The discussion will concentrate on machine-machine

aspects.

We are all familiar with human-to-human communication and cooperation, which require a

common language and an underlying system of shared knowledge and common values. In order

to achieve a similar degree of machine-machine interaction and cooperation, a framework should

be developed to allow for the management of heterogeneous functions and knowledge for a large

diversity of pervasive computing devices.

Such a framework should address the communication needs of pervasive devices at a higherlevel than the classical communication network protocols and even distributed computing

frameworks such as CORBA (Common Object Request Broker Architecture) which provide

mainly distribution transparency. Heterogeneous pervasive computing devices cannot

realistically be expected to talk exactly the same language. However, these devices will share

domain-specific knowledge, which may be expressed by each of them in different format/dialect.

Accordingly, the proposed management framework should define a domain specific semantic for

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common knowledge and functions. This framework is expected to act as a universal translator

between different dialects.

In order to provide a flexible extensible open framework allowing for the information

appliancesinteroperability, methods should be developed to allow different devices to exchange

the grammars describing their own dialects and to learn to understand each other. This way, thedevices will be able to advertise their own functions, search and discover providers of required

services, and express their needs in a collaborative environment.

Going beyond its original scope to interchange structured documents conveniently over the

Internet, XML (Extensible Markup Language), [13] and [26], could provide high level protocols

for exchanging informationbetween different information appliances. XML provides a syntax

for building a formal model known as a DTD (Document Type Definition), which describes

relationships between entities, elements and attributes of each class of documents related to a

certain application domain. Since a DTD gives a standard format for informationrelated to a

specific domain, it can be used to simplify the exchange of informationbetween different

sources which refer to the same domain regardless of the internal format used by each source.

Many kinds of domains have standard DTDs, as for example chip manufacturers, chemical

applications, etc. XML could also be developed to facilitate the interoperability of informationappliances.

Figure 2 illustrates the main communication processes an informationappliance is supposed

to manage.

,age 2Figure 2: Information appliancesshould interact in an unobtrusive way with humans, other

appliancesand the rest of the world while carrying on their specific task in their

physical environment. World models, built and maintained from informationgathered

by a multitude of sensors, provide a common abstract representation of the state of

the environment. A hybrid deliberative/reactive architecture integrates the

deliberative reasoning and behavior-based control functions. A distributed computing

frameworks together with high level informationexchange mechanisms provide aflexible extensible open framework allowing for the information appliances

interoperability. Special communication mechanisms will allow the information

appliance to handle a variety of redundant and complementary informationchannels.

5. Networking technologies for pervasive information appliances.

As a very large number of devices will be connected through infrared and radio wireless and

wire-line global networks infrastructure, existing technologies will be rendered inefficient; new

solutions have to be invented.

Bandwidth and resource limitations of the wireless medium require that informationcontent is

compressed as much as possible, in order to consume the least amount of resource possible.

,age 3However, such low redundancy makes the informationvulnerable, especially in an error-proneenvironment such as wireless channels and networks.

Personal Area Network (IEEE 802.15) and existingLocal and Wide Area Network (e.g. IEEE

802.11),Internet Protocols (Mobile IP, IPv6, RTP/RTCP, RSVP, XTP etc.), Wireless

Application Protocol (WAP) are already available. However, it is expected that the size and

complexity of the problem would require the development of new technologies and standards

when developing a new Distributed Networks Architectures (DNA) suitable for the support of

pervasive computing at a large scale.

The development should address wired and wireless networking issues looking for the

development of cost-effective solutions for environments where deployment of advanced

networking infrastructure could be unjustifiably costly. The following appear to be of an

immediate interest:

Service admission control and connection establishment policies, as well as resource

allocation and resource adaptation algorithms for the support of pervasive devices.

Quality of Service capable, error-resilient and resource allocation-efficient multiple-access

protocols for the efficient transportation of sensor traffic.

Intelligent networking infrastructure and definition of suitable architectures of distributed

nature.

Cost -effective network solutions for environments where there is no advanced networking

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infrastructure deployment.

Acknowledgment

This work was funded in part by Communications and InformationTechnology Ontario

(CITO) and the Natural Sciences and Engineering Research Council (NSERC) of Canada.

References1. *** "A Brief History of Wearable Computing,"

http://wearables.www.media.mit.edu/projects/wearables/timeline.html

2. ***, "Human-Computer Interaction Bibliography," http://www.hcibib.org/

3. ***, "Human-Computer Interaction Resources,"

http://dir.yahoo.com/Science/Computer_Science/Human_Computer_Interaction__HCI_/

4. ***, "Special Issue on Information Appliances,"IEEE Computer Graphics and Applications

Magazine, May/June 2000.

5. R.C. Arkin,Behavior-Based Robotics, The MIT Press, 1998

6. J. Birnbaum, "Pervasive Information Systems", Communications of the ACM, Vol. 40, No.2,

pp. 40-41, Feb. 1997

7. A. Brooks, L.A. Stein, "Building Brains for Bodies", Autonomous Robots, Vol. 1, No.1, pp.

7-25, 19948. Clarion Corp., "Auto PC ," http://www.autopc.com/walkthrough/communication/, 1999

9. P. Dabke, "Enterprise Integration via CORBA-Based InformationAgents", IEEE Internet

Computing, vol. 3, no. 5, pp. 49-57, Sept-Oct. 1999

,age 410. B.V. Dasarathy, "Sensor Fusion Potential Exploitation Innovative Architectures and

Illustrative Applications," Proc. IEEE, Vol. 85, No. 1, pp. 24-38, Jan. 1997

11. M.L.Dertouzos, "The Future of Computing", Scientific American, 52, pp.52-55, Aug. 1999

12. Electrolux Inc., "Electrolux screen Fridge",

http://www.wired.com/news/news/email/explode-infobeat/technology/story/%17894.html ,

1999

13. L.M. Garshol, "Introduction to XML,"

http://www.stud.ifi.uio.no/lmariusg/download/xml/xml_eng.html

14. L. Gerstner, "Pervasive Computing" , Keynote -CeBIT 98,

http://195.27.241.3/news/news1/ns-3975.html

15. M. Hardwick, D.L. Spooner, T. Rando, K.C. Morris, "Data Protocols for the Industrial

Virtual Enterprise,"IEEE Internet Computing, vol. 1, no. 1, pp. 20-29, Jan-Feb. 1997

16. A.C. Huang, B. Ling, S. Ponnekanti, and A. Fox. "Pervasive Computing: What Is It Good

For?" Workshop on Mobile Data Management (MobiDE) in conjunction with ACM

MobiCom 99

17. IBM, "What is Pervasive Computing", http://www-3.ibm.com/pvc/pervasive.html

18. R. Itschner, C. Pommerell, M. Rutishausser, "Glass: Remote Monitoring of Embedded

Systemsin Power Engineering,"IEEE Internet Computing, vol. 2, no. 3, pp. 46-52, May-

June. 1998

19. S. Mann, "Wearable Computing: A First Step Toward Personal Imaging", IEEE Computer,30 (2), Feb. 1997

20. S. Mann, "Humanistic Computing: WearComp as a New Framework and Application for

Intelligent Signal Processing," Proc. IEEE, Vol. 86, No. 11, pp. 2123-2151, Nov. 1998

21. NCR Corp., "NCR Microwave Oven / Home Banking,"

http://www.wired.com/news/news/technology/story/14949.html

22. D.A. Norman, The Invisible Computer: Why Good Products Can Fail, the Personal

Computer Is so Complex, andInformation AppliancesAre the Solution, The MIT Press,

1999.

23. C.M. Pancerella, N.M. Berry, "Adding Intelligent Agents to Existing EI Frameworks," IEEE

Internet Computing, vol. 3, no. 5,pp. 60-61, Sept-Oct. 1999

24. R.W. Picard, "Human-Computer Coupling," Proc. IEEE, Vol. 86, No. 8, pp. 1803-1807,

Aug. 1998

25. B. Rhodes, "Context-Aware Computing (or, why context needs wearables and wearables

need context)," http://wearables.www.media.mit.edu/projects/wearables/context.html

26. World Wide Web Consortium (W3C), "Extensible Markup Language (XML) 1.0,"

http://www.w3.org/TR/REC-xml

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T%tor&al: Des&."&". real,te a"d saet$,(r&t&(al e#!edded

Nava appl&(at&o"s , Part 2Sot Real,Te Nava Develop#e"t %&del&"es

B$ Kelv&" &lse"* Ao"&

E#!edded/(o#

)F6


26/37


Rule () *se the +a'a Standard Edition platform

T'e !e"e&ts t'at Nava !r&".s to sot real,te #&ss&o",(r&t&(al

s$ste#s are #ost releva"t to lar.e* (o#ple* d$"a#&(appl&(at&o"s/ S&"(e t'e N2ME plator# represe"ts a"

&"(o#pat&!le s%!set o %ll NSE* &t does "ot prov&de a((ess to

NSE,sta"dard 9TS l&!rar$ (o#po"e"ts/ appl&(at&o"s

reC%&re e"terpr&se ed&t&o" (apa!&l&t&es* o!ta&" t'e spe(&&(

e"terpr&se ed&t&o" l&!rar&es t'at are reC%&red a"d r%" t'e# o" a

sot real,te NSE plator#/ Alter"at&vel$* r%" t'e reC%&red

e"terpr&se ed&t&o" %"(t&o"al&t$ o" trad&t&o"al )"o" real,te+NM plator#s '&(' (o##%"&(ate &t' t'e sot real,te

NM #a('&"es %s&". RM or ot'er "etor-&". proto(ols/

Rule ,) $aseline a particular 'ersion of the +SE libraries

=or a"$ .&ve" develop#e"t proe(t* &t &s porta"t to

sta"dard&7e o" a part&(%lar vers&o" o t'e NSE l&!rar&es/ As

Sta"dard Ed&t&o" Nava 'as evolved* ea(' "e release adds "e(apa!&l&t&es a"d epa"ds #e#or$ ootpr&"t reC%&re#e"ts/

Ea(' "e release also depre(ates )or re#oves+ (erta&"

(apa!&l&t&es '&(' are repla(ed &t' "eer sol%t&o"s/ $o%

are or-&". o" a lar.e proe(t or '&(' sotare #a&"te"a"(e

#%st spa" #a"$ $ears* $o% pro!a!l$ a"t to sele(t a (erta&"

Sta"dard Ed&t&o" plator# a"d ree7e t'at ('o&(e/ t'er&se*

$o% &ll e"d %p #a-&". #a"$ %""e(essar$ ('a".es to $o%r

(ode !ase %st to #a&"ta&" (o#pat&!&l&t$ &t' t'e ever

('a".&". de&"&t&o" o t'e Nava plator#/ Do(%#e"t t'&s

de(&s&o" to all developers a"d #a"a.ers/

Rule ) .ollow /best practices/ recommendations for +a'a

de'elopment

T'e sotare C%al&t$ #eas%res are ver$ s&lar or sot real,

te Nava a"d trad&t&o"al Nava/ U"less spe(&&ed to t'e

(o"trar$* ollo t'e a((epted .%&del&"es or r&t&". porta!le

a"d #a&"ta&"a!le NSE (ode/

26


27/37


Rule 0) *se +.ace and S1" for graphical user interfaces

Most #&ss&o",(r&t&(al sotare does "ot reC%&re .rap'&(al %ser

&"tera(es/ sot real,te s$ste#s do reC%&re .rap'&(al %ser&"tera(es* %se t'e ope",so%r(e S8T a"d N=a(e l&!rar&es

&"stead o t'e propr&etar$ A8T a"d S&". (o#po"e"ts/ S8T

a"d N=a(e r%" &" less #e#or$ a"d r%" aster t'a" S8T a"d

S&"./

Rule 2) *se cooperating hard real-time components to

interface with nati'e codeT'e N proto(ol &"trod%(es s&."&&(a"t data #ars'all&".

over'ead 'e" o!e(ts are s'ared !etee" t'e Nava a"d "at&ve

e"v&ro"#e"t/ =%rt'er#ore* t'e s'ar&". proto(ols #a$ epose

Nava o!e(ts a"d Ipr&vateI v&rt%al #a('&"e data str%(t%res to

%"d&s(&pl&"ed 9 (o#po"e"ts* &"trod%(&". t'e r&s- t'at

#&s!e'av&". 9 (ode &ll (o#pro#&se t'e &"te.r&t$ o t'e

v&rt%al #a('&"e e"v&ro"#e"t/

Eper&e"(e o e&st&". (%sto#ers &" several real proe(ts

&"volv&". '%"dreds o #a" $ears o develop#e"t do(%#e"t

t'at t'ese r&s-s are real* 'av&". (ost develop#e"t tea#s

s&."&&(a"t eort a"d (ale"dar te to (orre(t errors

&"trod%(ed &"to t'e Nava e"v&ro"#e"t !$ 9 developers r&t&".

N (o#po"e"ts/ Better peror#a"(e a"d stro".er separat&o"

o (o"(er"s &s real&7ed !$ ple#e"t&". all &"tera(es to "at&ve

(ode as (ooperat&". 'ard real,te (o#po"e"ts as de&"ed !$

t'e 'ard real,te RTSN pro&le/

Rule 3) *se cooperating hard real-time components with

performance-critical code

t'e t'ro%.'p%t o (erta&" sot real,te (o#po"e"ts &s "ot

s%&(&e"t to #eet peror#a"(e reC%&re#e"ts* ple#e"t t'e

reC%&red %"(t&o"al&t$ as (ooperat&". 'ard real,te

(o#po"e"ts as de&"ed !$ t'e 'ard real,te RTSN pro&le/

Be(a%se t'e (ode .e"erat&o" #odel or 'ard real,te

2


28/37


29/37


java.io libraries:So#e e#!edded tar.ets 'ave "o "ot&o" o

std&"* stdo%t* or stderr/ So#e e#!edded tar.ets 'ave "o "ot&o"

o "o",volat&le &le stora.e/

java.net libraries:So#e e#!edded tar.ets 'ave "o "etor-

(o""e(t&v&t$/

Re(o."&7e t'at t'e %se o t'ese l&!rar&es #a$ l&t t'e

porta!&l&t$ o (ode a"d #a$ (o"tr&!%te to t'e %t%re

#a&"te"a"(e !%rde"/

Rule 6) #solate +7M dependencies

E&st&". sot real,te v&rt%al #a('&"es d&er &" 'o t'e$

s%pport (erta&" porta"t #&ss&o",(r&t&(al (apa!&l&t&es/ 8rap

all NM depe"de"(&es &" spe(&al (lasses t'at (a" !e .&ve"

etra atte"t&o" & t'e (ode #%st !e ported to a d&ere"t NM/

Spe(&&( serv&(es t'at reC%&re t'&s 'a"dl&". &"(l%de:

A8H&.',pre(&s&o" t&". serv&(es: o!ta&"&". real,te &t'

.reater pre(&s&o" t'a" 1 #s dr&t,ree sleep)+* a&t)+* a"d

o&")+ serv&(es/

$89PU,te a((o%"t&".: Ho #%(' 9PU te (o"s%#ed !$

ea(' t'readQ Ho #%(' 9PU te &s (o"s%#ed at ea('pr&or&t$ levelQ

8ar!a.e (olle(t&o" pa(&".: Ho to #o"&tor t'e #e#or$

allo(at&o" !e'av&or o t'e appl&(at&o" sotare a"d t'e

ee(t&ve"ess o 9Q Ho to s('ed%le 9 to #a&"ta&" pa(e

&t' allo(at&o" ratesQ

D8S('ed%l&".: a v&rt%al #a('&"e oers '&.',level

s('ed%l&". s%pport* s%(' as earl&est,deadl&"e &rst or #a%#

2


30/37


a((r%ed %t&l&t$ s('ed%l&".* t'e s('ed%l&". a"d s$"('ro"&7at&o"

serv&(es s'o%ld !e &solated &t'&" a (e"tral&7ed AP/

Rule (9) arefully select an appropriate soft real-time

'irtual machine

"e o t'e #ost porta"t de(&s&o"s &" deter#&"&". t'e

s%((ess o a sot real,te Nava develop#e"t eort &s sele(t&o"

o a s%&ta!le NM/ Ea(' develop#e"t proe(t 'as %"&C%e

reC%&re#e"ts a"d (o"stra&"ts* so &t #a$ !e "e(essar$ to

&"depe"de"tl$ eval%ate t'e releva"(e o var&o%s ava&la!lev&rt%al #a('&"e prod%(ts or ea(' develop#e"t eort/ "

sele(t&". a v&rt%al #a('&"e* (o"s&der at #&"%# ea(' o t'e

ollo&". &ss%es:

A8Real,Te .ar!a.e (olle(t&o" s'o%ld 'ave a #a%#

pree#pt&o" late"($ a"d s'o%ld !e &"(re#e"tal so t'at 'e"

t'e .ar!a.e (olle(tor &s pree#pted !$ '&.'er pr&or&t$appl&(at&o" t'reads* &t (a" res%#e &t' t'e "et &"(re#e"t o

or- 'e" t'e appl&(at&o" t'read rel&"C%&s'es t'e 9PU/

$8T'e .ar!a.e (olle(tor s'o%ld dera.#e"t t'e 'eap &" order

to ass%re rel&a!le lo".,r%""&". operat&o" or s'o%ld prov&de

so#e alter"at&ve #e('a"&s# to avo&d rel&a!&l&t$ pro!le#s

res%lt&". ro# ra.#e"tat&o" o t'e 'eap/ A"d &t #%st

a((%ratel$ re(la all dead #e#or$ rat'er t'a" re(la&".

o"l$ a (o"servat&ve approat&o" o t'e dead #e#or$/

=&"all$* &t #%st !e pa(ed to ass%re t'at #e#or$ &s re(laed at

rates (o"s&ste"t &t' t'e appl&(at&o"@s stead$,state de#a"d or

"e #e#or$ allo(at&o"/

8All s$"('ro"&7at&o" lo(-s #%st ple#e"t pr&or&t$

&"'er&ta"(e/ All a&t C%e%es #%st !e ordered a((ord&". to

t'read pr&or&t&es/

3F


31/37


D8T'e v&rt%al #a('&"e "eeds to prov&de #o"&tor&". a(&l&t&es

to allo s%perv&sor$ t'reads to o!serve a"d #eas%re t'e real,

te reso%r(e reC%&re#e"ts o &"d&v&d%al (o#po"e"ts/ A#o".reC%&red (apa!&l&t&es are t'e a!&l&t$ to deter#&"e 'o #%('

9PU te &s (o"s%#ed !$ part&(%lar t'reads* 'o #%(' 9PU

te &s (o"s%#ed !$ t'e .ar!a.e (olle(t&o" t'read)s+* t'e rates

at '&(' part&(%lar t'reads are allo(at&". #e#or$* a"d t'e

total a#o%"t o #e#or$ !e&". reta&"ed as l&ve/

E8Deter#&"e t'e release level o t'e N2SE l&!rar&es reC%&redor a part&(%lar proe(t a"d ass%re t'at t'e ve"dor &s a!le to

s%pport t'e des&red l&!rar$ vers&o" t'ro%.'o%t t'e d%rat&o" o

$o%r develop#e"t proe(t/

.8Ass%re t'at t'e v&rt%al #a('&"e prov&des l&!rar&es or '&.',

pre(&s&o" te #eas%re#e"ts* a"d or dr&t,ree a&t)+* o&")+*

a"d sleep)+ serv&(es/

G8Ass%re t'at t'e v&rt%al #a('&"e &s s%pported !$ appropr&ate

A'ead,o,Te (o#p&lat&o" a"d l&"-&". tools & t'e s$ste# &s

stat&(all$ (o#p&led a"d loaded/

:8 t'e s$ste# #%st d$"a#&(all$ load (o#po"e"ts* ass%re

t'at t'e d$"a#&( (lass loader (a" !e (o"&.%red to r%" at loerpr&or&t$ t'a" t'e o".o&". real,te appl&(at&o" or-load/

#8 t'e d$"a#&( (lass loader #%st peror# NT (o#p&lat&o"*

ass%re t'at t'e NT (o#p&ler (a" !e (o"&.%red to s%pport

ea.er l&"-&". a"d tra"slat&o"* #ea"&". t'at all (o#po"e"ts are

%ll$ resolved a"d tra"slated 'e" t'e &rst o t'e

&"terdepe"de"t #od%les &s loaded* rat'er t'a" deerr&". NT

tra"slat&o" %"t&l t'e #o#e"t ea(' (ode #od%le &s &rst

ee(%ted/ So#e s$ste#s "eed to d$"a#&(all$ load (o#po"e"ts

'&(' ere t'e#selves a'ead,o,te (o#p&led/ er&$ t'&s

31


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(apa!&l&t$ &s s%pported & releva"t to $o%r proe(t

reC%&re#e"ts/

+8Ass%re t'at t'e v&rt%al #a('&"e &"(l%des "e(essar$

develop#e"t tools* &"(l%d&". s$#!ol&( de!%..&". o !ot'

&"terpreted a"d (o#p&led (ode a"d r%",te peror#a"(e a"d

#e#or$ %sa.e pro&l&"./

;8Ass%re t'at t'e v&rt%al #a('&"e &"(l%des s%pport or

(ooperat&". 'ard real,te Nava (o#po"e"ts & t'e pla""eddevelop#e"t proe(t #a$ reC%&re &"te.rat&o" &t' (ooperat&".

'ard real,te (o#po"e"ts/

Embedded JavabyVincent Perrier

08/15/2001

Java's strong appeal for embedded applications is sometimes offset by concerns about its speed and its memoryrequirements !o"ever# t$ere are tec$niques t$at you can use to boost Java performance and reduce memory needs#and of course t$e Java virtual mac$ine you c$oose affects Java performance# too %ou can ma&e betterinformed

decisions about using Java by understanding t$e factors t$at affect its performance and selecting meaningfulbenc$mar&s for embedded applications

(ec$niques for improving application e)ecution and c$oosing t$e rig$t Java virtual mac$ine *JV+, address only a fe"aspects of system arc$itecture t$at affect overall Java performance -$en selecting an embedded Java platform# you

must ta&e into account a $ost of ot$er factors# beyond t$e scope of t$is article# t$at $ave an impact on performance.mong t$em are $ard"are processor selection# Java compatibility and supported .Ps# application reliability and

scalability# t$e c$oice of a realtime operating system *(, "it$ associated native libraries and drivers# t$eavailability of Java development tool &its and middle"are# grap$ics support# and t$e ability to put t$e application code

into +

nce you've selected a $ard"are and soft"are development platform# t$ere are a variety of factors to consider t$at "ill$elp you c$oose t$e bestperforming Java virtual mac$ine *JV+, for your application

Java Is Big and Slow: Myth or Reality?.lt$oug$ t$e average Java bytecode application e)ecutes about ten times more slo"ly t$an t$e same program "rittenin 3 or 344# $o" "ell an application is "ritten in Java can $ave a tremendous impact on performance# as a study byut6 Prec$elt# 73omparing Java vs 3/344 fficiency 9ifferences to nterpersonal 9ifferences7 *3ommunications of t$e

.3+# ctober 1:::,# $as s$o"n n t$e study# ;8 programmers "ere as&ed to "rite t$e same application program ineit$er 3/344 or Java .pplying statistical analysis to t$e performance data for t$e programs revealed t$at actual

performance differences depended more on t$e "ay t$e programs "ere "ritten t$an on t$e language used ndeed#

32
http://onjava.com/pub/au/232http://onjava.com/pub/au/232http://adserver.adtechus.com/adlink/3.0/5159/425855/0/170/ADTECH;loc=300;key=key1+key2+key3+key4;grp=%5Bgroup%5Dhttp://onjava.com/pub/au/232


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t$e study s$o"ed t$at a "ell"ritten Java program could equal or e)ceed t$e efficiency of an averagequality 3/344

program

Various approac$es are available for boosting bytecode e)ecution speed ($ey include using a to ;2

+? of .+ in addition to t$e application's requirements ($e large memory requirement places J( compilers out ofreac$ for many categories of embedded applications

.$eadoftime compilers rival J( compilers in increasing Java e)ecution speed @nli&e J( compilers# t$ey're usedbefore t$e application is loaded onto t$e target device# as t$eir name indicates ($at eliminates t$e need for e)tra.+# but it creates t$e need for more + or flas$ memory *t$at is# storage static memory,# because compiled

mac$ine code requires four to five times t$e memory of Java bytecode 3ompiling a$ead of time tends to undermineone of t$e great benefits of t$e Java platform because a measure of dynamic e)tensibility can be lost# since it may not

be possible to do"nload ne" versions of compiled classes .dditionally# any dynamically loaded code# li&e an applet#"on't benefit from a$eadoftime compilation and "ill e)ecute more slo"ly t$an resident compiled code

Profiling Java code# alt$oug$ some"$at comple)# can $elp minimi6e code e)pansion "$en you're using an a$eadoftime compiler . good goal is to compile only t$at 20 percent of t$e Java classes in "$ic$ t$e application spends 80

percent or more of its time

9ynamic adaptive compilers offer a good compromise bet"een J( and a$eadoftime compilers *see (able 1, ($ey'resimilar to J( compilers in t$at t$ey translate bytecode into mac$ine code on t$e fly 9ynamic adaptive compilers#

$o"ever# perform statistical analysis on t$e application code to determine "$ere t$e code merits compiling and "$ereit's better to let t$e JV+ interpret t$e bytecode ($e memory used by t$is type of compiler is userconfigurable# so you

can evaluate t$e tradeoff bet"een memory and speed and decide $o" muc$ memory to allocate to t$e compiler

33


34/37


35/37


%ou can trim J2+ by eliminating classes and code components t$at aren't needed for your application ($e JV+#

native libraries# core classes# and application bytecode go into + JV+s for embedded applications generally rununder 500 &?# "$ereas class libraries for J2+ typically don't e)ceed 15 +? Java components t$at affect .+

requirements include t$e JV+ *for bytecode e)ecution,# t$e potential dynamic compiler# t$e Java $eap# and t$e numberof t$reads *t$e latter t"o obviously depend on t$e application, )ecuting as muc$ of t$e application as possible using

an interpreter "$ile maintaining acceptable e)ecution performance $elps contain t$e memory footprint

electing a $ig$ly scalable operating system and 3runtime pac&age allo"s you to tune t$ese soft"are

components for optimal memory efficiency calingt$e Java environment can be comple)# $o"ever

@sually# a t"ostage process is involved Cirst# youcan use t$e command line verbose option#


36/37


Measuring !ppliation Performane

-$en considering a benc$mar& to determine t$e overall performance of a Java application# bear in mind t$at bytecodee)ecution# native code e)ecution# and grap$ics eac$ play a role ($eir impact varies depending on t$e nature of t$e

specific applicationE "$at t$e application does# $o" muc$ of it is bytecode versus native code# and $o" muc$ use itma&es of grap$ics !o" "ell a JV+ "ill perform for a given application depends on $o" t$e unique mi) of t$ese t$ree

functional areas maps onto its capabilities Fiven t$ese variables# t$e best "ay to benc$mar& a JV+ is against youro"n application ince t$at's not possible before t$e application $as been "ritten# you must find t$ose benc$mar&s

t$at are most relevant to t$e application you intend to "rite

orting t$roug$ Java benc$mar&s to find t$e ones t$at are relevant for embedded applications can be confusingpecJV+:8# for e)ample# provides a relatively complete set of benc$mar&s t$at test diverse aspects of t$e JV+ounds good but pecJV+:8 runs in a client/server environment and requires a minimum of B8 +? of .+ on t$e

client side for t$e JV+ ($at e)cludes it from any relevance to most embedded applications n addition# it can't beused "it$ precompiled classes

t$er benc$mar&s $ave different pitfalls Volano+ar for e)ample# is a c$at server implementation and is t$ereforerelevant only for benc$mar&ing applications "it$ t$e same set of requirements as c$at servers ($e J+ar& benc$mar&assumes t$at t$e application includes t$e applet vie"er and a full implementation of Java's .bstract -indo"ing (ool&it

*.-(, ($is benc$mar& can be irrelevant for t$e many embedded applications t$at $ave no grap$ics or $ave limitedgrap$ics t$at don't require full .-( support# suc$ as devices running a PersonalJava minimal.-( implementation

mbedded 3affeine+ar& *3+,# t$e embedded version of t$e 3affeine+ar& benc$mar& from Pendragon oft"are *it

$as no grap$ics tests,# is easy to run on any embedded JV+# since it requires support for basic Java core classes only#and it doesn't require a large amount of memory +ore importantly# t$ere's a $ig$ correlation bet"een good scores on

t$is benc$mar& and improved bytecode performance in embedded applications

(o get t$e most meaningful results from 3+# you must use e)actly t$e same $ard"are "$en testing different JV+s

%ou must also pay attention to implementation differences among t$e JV+s you're testing f# for e)ample# you'recomparing a JV+ "it$ a J( compiler against a JV+ "it$out one# it's important to run t$e JV+ t$at $as t$e J( "it$ t$e


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-ind iver's Personal J-or&s includes a good benc$mar& for evaluating grap$ics performance in embedded systems

($e benc$mar& targets t$e PersonalJava .-( "it$ a set of ;: tests of images# buttons# scrolling# te)t# and basic 29grap$ics

Real#$orld Performane

Cinally# you need to consider t$e performance of your [email protected] (o $elp you identify [email protected] performance# you s$ouldsupplement simple benc$mar&s by running real"orld applications t$at e)ercise large amounts of different# comple)

Java code uc$ test code must meet a number of requirementsE t s$ould contain a large number of classes t$atreflect an estimate of t$e real application *20plus is a good ballpar&, t must also be large *t$ousands of lines# at

least, and $ave no file system access and no grap$ics ome e)isting programs meet all t$ose criteria ($e [email protected] e)pression pac&age# rege)p# for e)ample# comprises about ;#000 lines of code and more t$an 21 classes#providing a large number of e)pressions to parse and matc$ .not$er program# t$e ?ean $ell interpreter# is a simple

prime number sieve t$at $as G0 classes and several t$ousand lines of code Java3ode3ompact# un's PersonalJava+i6ing tool# also "ould ma&e a good test program

($e result of running t$ese programs as test cases illustrates t$e "ide variance in t$e meaning of benc$mar& scoresCor e)ample# a JV+ using a J( compiler may run mbedded 3affeine+ar& up to ;0 times faster t$an "$en t$e no

Download - Deepak Mathur

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