NGTP2.0原版完整文件

TheNGTPGroup

2010-10-01

NGTP2.0Compendium

Version1.0

Page

PAGE

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NGTP2.0

Compendium

RevisionHistory

Date

Version

Description

Author

2010-03-01

0.01

Initialversion

NGTPGroup

2010-03-11

0.03

Initialversionrevised

NGTPGroup

2010-03-26

0.06

Reworkarchitecturedescription

NGTPGroup

2010-03-31

0.07

Reworkaccordingtothecommentsfrommr.Ditzell

NGTPGroup

2010-04-01

0.08

Reworkaccordingtothecommentsfrommr.Zoller

NGTPGroup

2010-04-20

0.12

ReworkaccordingtothecommentsfromWCar

NGTPGroup

2010-04-30

0.15

1stdraftversionforinitialreview

NGTPGroup

2010-05-11

0.17

2nddraftforreview

NGTPGroup

2010-05-20

0.18

3rddraftfor(final)review

NGTPGroup

2010-07-29

0.20

Readyforexternalreview

NGTPGroup

2010-10-01

1.0

Reworkaccordingtoexternalreview

NGTPGroup

TheNGTPGroup

2010-10-01

NGTP2.0Compendium

Version1.0

Page3of44

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TableofContents

Introduction 6

MotivationfortheNGTPGroup 6

AboutNGTP2.0 7

Aboutthiscompendium 9

Glossaryandabbreviations 10

Basic-Pattern:Architectureoverview 12

Shortdescription/summary 12

Maindesignconcepts 14

Communicationconcept 16

Triggerconcept 16

Operations 16

Basic-Pattern:NGTPcomponents/buildingblocks 17

TelematicsUnit(TU) 17

Shortdescription/summary 17

Designprinciples 17

Relatedinterfaces 17

Dispatcher(DSPT) 18

Shortdescription/summary 18

Designprinciples 18

Relatedinterfaces 19

Events 19

ServiceHandler(SH) 20

Shortdescription/summary 20

Designprinciples 20

Relatedinterfaces 20

ServiceIntegrator(SI) 20

Shortdescription/summary 20

Designprinciples 21

Relatedinterfaces 21

PublicSafetyAnsweringPoint(PSAP) 21

Shortdescription/summary 21

Designprinciples 22

Relatedinterfaces 22

CallCenter(CC) 22

Shortdescription/summary 22

Designprinciples 22

Relatedinterfaces 23

OtherServices(OS) 23

Shortdescription/summary 23

Designprinciples 23

Relatedinterfaces 23

ProvisioningDataProvider(PDP) 23

Shortdescription/summary 23

Designprinciples 24

Relatedinterfaces 24

CustomerDataProvider(CDP) 24

Shortdescription/summary 24

Designprinciples 24

Relatedinterfaces 25

ContentProvider(CP) 25

Shortdescription/summary 25

Designprinciples 26

Relatedinterfaces 26

Basic-Pattern:NGTPinterfaces 27

Interface1(TUDSPT) 28

Shortdescription/summary 28

Connectedblocks 28

Operations 28

NGTPmessageformat 28

Interface2(DSPTSH) 30

Shortdescription/summary 30

Connectedblocks 30

Operations 30

Interface3(PDPDSPT) 31

Shortdescription/summary 31

Connectedblocks 32

Operations 32

Interface4(CDPSH) 32

Shortdescription/summary 32

Connectedblocks 32

Operations 33

Interface5(SIPSAP) 33

Shortdescription/summary 33

Connectedblocks 33

Operations 34

Interface6(SHSI) 34

Shortdescription/summary 34

Connectedblocks 35

Operations 35

Interface7(CPSI) 36

Shortdescription/summary 36

Connectedblocks 36

Operations 37

Interface8(SICC) 37

Shortdescription/summary 37

Connectedblocks 37

Operations 38

ProprietaryInterface(SIOS) 38

Shortdescription/summary 38

Connectedblocks 38

Operations 38

Generalaspects 39

Security 39

Logging 40

Monitoring 41

Gettingstarted 42

Furtherreferences 44

Introduction

MotivationfortheNGTPGroup

Historically,vehiclemanufacturershaveofferedcustomersproprietaryservicesandhavebeende-pendentonasingleServiceProvider(SP)fordeliveryoftheseservicesinaspecificmarket.Thissup-plychaininflexibilitymadeitdifficultforproviderstogaineconomiesofscaleandadvancetheiroffer-ings.

Amoreopenandstandardizedapproachtodeliveringserviceshasclearbenefitsforthemarketplace,butpreviousstandardizationeffortsfocusedonreplacingexistingprotocols,ratherthanintegratingthem,whichmetbarrierstoadoption.

Withtheproliferationofnewtechnologies(e.g.,UMTS,Wi-Fi,VoIP),itislikelythatfuturein-vehicledeviceswillaccessservicesusingmultiplemethodsandtechnologies.TheNGTPGroupconcludedthatthetelematicsindustrywouldgreatlybenefitfromatechnology-neutralpatterntoexpandtheop-tionsfordeliveringservices.Ifpossible,NGTPrecommendsusingexistingstandardsandtechnologies(seealsotheNGTPmessageformat)whereapplicable,insteadofre-invention.

SoNGTPprovidesthevehiclemanufacturersawiderrangeofserviceofferingsandserviceproviderstocooperatewithandtheserviceprovidershavethepossibilitytore-usetheirsolutions.

TheNGTPSolution–OpenandAdaptableConnectivity

NGTP(NextGenerationTelematicsPattern)isanewapproachfordeliveringover-the-airservicestoin-vehicledevicesandhandsetsalike,withthefocusonopeninterfacesacrosstheentireservicede-liverychain.

NGTP‟sdeveloperssetthefollowingsixobjectives:

Provideatechnology-neutralpatternandconsistentinterfaceandprotocolfortelematicsser-vices;

Reducebarrierstocollaborationandimplementation;

Enableadoptionofnewtechnologiesastheycomeonline;

Supportlegacysystemsforconnectivitythroughouttheservicelifeofavehicle;Gainwideacceptanceandencourageinnovationthroughanopenapproach;

Increasethevaluepropositionforvehiclemanufacturers,serviceproviders,contentproviders,andmotorists.

NGTPwillenablevehiclemanufacturerstousethebestofferingsfromavarietyofpartnerswhilemaintainingaconsistentdriverexperience.Thenewpatternwillalsoallowserviceprovidersandcon-tentproviderstore-usethesamebasicserviceslikesessionmanagementoravoice/datamatchingtomultiplevehiclemanufacturers.Moreover,theNGTParchitectureenablesaneasyintegrationofleg-acysystems,allowingolderandnewervehiclesaliketoaccessnewtelematicsofferings.

NGTPaccommodatestheEU‟spendingeCallinitiative,andthepattern‟sopenarchitecturewillac-commodatefutureindustrytrends.

Inordertofostercollaborationandinnovation,thespecificationsthatconstituteNGTParepublicunderaCreativeCommonslicence.TheNGTPGroupwillworkwiththetelematicscommunitytocommuni-catethespecificationsandsupporttestingandpotentialadoptionofNGTP.

AboutNGTP2.0

NGTPisneitheratraditionalstandardnoraproduct.NGTPaimstoprovideageneralreusablesolu-tiontoacommonlyoccurringproblem.Inthesoftwaredevelopmentcommunitythisiscalledadesignpattern.Thisiswhytheuseof“pattern”insteadof“protocol”intheNGTP2.0abbreviationmorecor-rectlydescribesthevisionbehindNGTP.Designpatternscanspeedupdevelopmentbyprovidingtestedandprovendevelopmentparadigmswhileatthesametimebeingopenandflexibletonewre-quirements.

Astandardisanestablishednorm,aformaldocumentthatestablishesuniformengineering,andtoachievethis,verydetailedspecificationsarerequired.Standardsprovidecompatibilityattheexpenseofflexibility.TheNGTPGroupbelievesthatflexibilityismoreimportantandhaschosenthepatternapproach.

SincepublishingNGTP1.0inJanuary2008,theNGTPGroupestablishedrealworldimplementationsbasedontheNGTPpatternandreceivedalotofinterestfromthetelematicsindustry.Therearetwomainreasonsforpublishingthesuccessorofthe1.0publicationnow:

TheimplementationofNGTPbasedtelematicsservicesandthetelematicstechnologieshavefurtherevolved.TheNGTPGroupwantstosharetheexperiencesandbestpracticestoNGTPandincorporatetheminanewversion2.0.

The1.0documentationdescribesthearchitectureinhorizontal“layers”.AsthestakeholderareimplementingNGTPinaverticalway(bybuildingblocks),theNGTPGroupdecidedtore-structurethedocumentationbyexplainingeachbuildingblockwithitsinterfaces.Thatcomesinlinewithsomechangesinwordingforanoverallmuchmorecomprehensivedocumenta-tion.

Thereforethe2.0releaseisnotakindofnewpatternbutincorporatesanewviewonthepatternandsomeextensions.NGTP1.0isstillavalidpattern.ThatmeansthatallsolutionsbuiltuponNGTP1.0requirenooronlyminimalchangestocomplytheNGTP2.0specification.Thereisnokindofmigra-tionfromrelease1.0to2.0necessary.

ChangesfromNGTP1.0to2.0

Figure1ChangesfromNGTP1.0toNGTP2.0

Architecture

Organisationalbuildingblock„TSP“hasbeenremovedfromarchitectureandreplacedbyin-frastructureblocks„ServiceHandler“and„ServiceIntegrator“,becauseNGTPshouldprovideatask-based(role-based)viewandnotanorganisationalorphysicalviewonthetelematicsarchitecture.

The„ServiceHandler“enrichesthedataforthe„ServiceIntegrator“thatisresponsibleforin-tegratingtheserviceswiththehelpofContentProviders,CallCentresandsoon.

Interface6(a)connectstothe„ServiceIntegrator“now(formerly:directconnectiontoCallCenter).ThisisagainduetothefactthatNGTPdoesnotwanttodefineanarchitecturebasedonorganizationalresponsibilities,butontasks.TheCallCenternodeintheNGTPar-chitectureistobeseenonlyastheCallCenterservice,anyCallCenterapplicationispro-videdbytheserviceintegrator.OfcoursearealCallCentercanobtainbothrolesandprovideitsownapplication.Theinterfacehasbeenrenamedby„6“astherewon„tbeanInterface6banymore(seenextparagraph).

Interface6bhasbeenremovedasthe„ServiceIntegrator“,getsthecontentthroughInterface7

Interface8hasbeenintroducedforconnectingtheCallCenterviathe„ServiceIntegrator“asthedatafortheCallCentermayhavetobeenrichedandintegratedbythe„ServiceIntegra-tor“beforeroutingdirectlytotheCallCenter.

Interface9isreservedforadditionalother(proprietary)servicesorinterfaces.

Protocol

TheASN.1fileshavebeenre-structuredinacommonpart,adispatcherpartandaservicepart(ASN.1filesarenotmandatoryandareonlyonepossibleformatfortheprotocol)

ThecommonpartincludesgeneralandreusablemessagestructuresthatcanbeimportedinotherASN.1files

Thedispatcherfilesprovidemessagestructuresfordispatchingthemessagesbetweentheinterfaces

TheservicepartcontainsallapplicationservicedatathatareprovidedbyanOEM

Wording

TheuseofpatterninsteadofprotocolinNGTPasthetechnicallymorecorrecttermTermoperationsinsteadofmethods,correspondingtothepatternconcept

ServiceProvider(SP)insteadofTelematicsServiceProvider(TSP)toreflectthetask-basedview(incontrasttoanorganisationalview)andthetechnologyneutralconnectivityforser-vices

Furtheroulook

WhiletheNGTP2.0patterndescribedherestillfocusesonvoicebasedservices,differentpatternsforotherkindsofservices,e.g.web-baseddata-onlyservices,arecurrentlybeingdiscussedintheNGTPgroupandwillbeincorporatedinfuturereleasesofNGTP.

Aboutthiscompendium

TheNGTP2.0compendiumisintendedforallinterestedmembersofthetelematicsindustry.Itgivesanoverviewonthearchitecture,thebuildingblocksandtheinterfacesofbasic-patternofNGTP2.0.Inordertoserviceasatechnologyneutralpattern,whichisindependentfromcustomerspecificrequire-ments,thelevelofdetailiskepttothepointwheretheprinciplesofthesolutionsbecomeclearandaflexibleconnectivityofNGTPbasedimplementationsisassured.Hencethisisnotatechnicalspecifi-cationbutratherasemanticdescriptionofNGTP.

Tokeepthecompendiuminthiscompactsize,theexamplesaresummarizedinanadditionaldocu-ment.Theyshowadditionaldetailsofrealworldimplementationsandprovidesomeideasaboutthepossiblesolutionsthatareinherenttothispattern.

Thecompendiumisaccompaniedbythefollowingappendixes:NGTPexamples

NGTPreleaseprocesses

NGTPinanutshell(presentation)

ThecompendiumwasjointlydevelopedbymembersoftheNGTPGroupandispublishedunderacreativecommonslicence.Anyfeedbackandcommentsarehighlywelcomeandcanbeprovidedbyregistereduserson

Glossaryandabbreviations

Term/abbre-viation

Explanation

API

ApplicationProgrammerInterface,aninterfaceimplementedbyasoftwareprogramtoenableitsinteractionwithothersoftware

ASN.1

AbstractSyntaxNotationOneisastandardandflexiblenotationthatdescribesdatastructuresforrepresenting,encoding,transmitting,anddecodingdata

CC

CallCenter

CCA

CalCenterAgent

CDP

CustomerDataProvider

CP

ContentProvider

DSPT

Dispatcher,oneofthemainNGTPcomponents

ECall

Emergencycall

MSD

minimumsetofdata

NGTP

NextGenerationTelematicsPattern

(formally:NextGenerationTelematicsProtocol)

Operation

Interfacemethodsonabusinesslevel

OS

OtherServices,anyotherpossibletelematicsservicesdeliveredviatheSI

PDP

ProvisioningDataProvider

POI

Pointofinterest,aGPSlocatione.g.thecurrentlocationofavehicle.AGPSPOIcontainsatminimumthelatitudeandlongitudeoftherelatedlocation

PSAP

PublicSafetyAnsweringPoint,aCallCenterforansweringemergencycallsforpo-lice,firefightingandambulanceservices

SH

ServiceHandler,oneofthemainNGTPcomponents

SI

ServiceIntegrator,oneofthemainNGTPcomponents

SP

ServiceProvider

TSP

TelematicsServiceProvider

TU

TelematicsUnit,sometimesalsocalledTCU(TelecommunicationControlUnit)e.g.mobilephones,navigationdevices,communicationunitsinvehicles…

UMTS

UniversalMobileTelecommunicationsSystemisoneofthethird-generation(3G)mobiletelecommunicationstechnologies,whichisalsobeingdevelopedintoa4Gtechnology.

VIN

VehicleIdentificationNumber,auniqueserialnumberusedbytheautomotiveindus-trytoidentifyindividualmotorvehicles.Since1981,VINsconsistof17characterswhichdonotincludethelettersI(i),O(o),orQ(q).CouldalsobetheDriveID

Term/abbre-viation

Explanation

VoIP

VoiceoverInternetProtocolisageneraltermforafamilyoftransmissiontechnolo-giesfordeliveryofvoicecommunicationsoverIPnetworkssuchastheInternetorotherpacket-switchednetworks.

Wi-Fi

Wi-FiisatrademarkoftheWi-FiAlliancethatmanufacturersmayusetobrandcerti-fiedproductsthatbelongtoaclassofwirelesslocalareanetwork(WLAN)devicesbasedontheIEEE802.11standards.Becauseofthecloserelationshipwithitsun-derlyingstandard,thetermWi-FiisoftenusedasasynonymforIEEE802.11tech-nology.

WSDL

TheWebServicesDescriptionLanguageisanXML-basedlanguagethatprovidesamodelfordescribingWebservices.Themeaningoftheacronymhaschangedfromversion1.1wheretheDstoodforDefinition.

Table1Termsandabbreviations

Basic-Pattern:Architectureoverview

Shortdescription/summary

Aglobalintegrationoftelematicsandcontentproviderservicesintothetelematicsunit(TU)becomesmoreandmorebusinessrelevant.Thenumberofservicesincreasesrapidly,serviceprovidersarechangingandlegalrequirementshavetobefulfilled.Thisrequiresahighlyflexiblearchitecture.Ontheotherhand,well-definedandstableinterfacesarenecessary,especiallybetweentheTUandtheoff-boardcomponents,butalsobetweentheoff-boardcomponentsthemselves.

Thisleadstoanewtelematicsarchitecture.

Figure2

showsanoverviewofthemainNGTPelements.

Figure2NGTP2.0Architecture

TelematicsUnit(TU)

TheTelematicsUnitistypicallyintegratedinavehiclebutcanalsobepartofapersonalnavigationdevice(PND)oramobilephone.TheTUcommunicatesoverawirelessnetworkwithonededicatedDispatcher.ThisisdoneviaInterface1(TU-DSPT).

Dispatcher(DSPT)

ThestabilityoftheinterfacebetweentheTUandtheback-endisobtainedbyintroducingtheDis-patcher.TheDispatcherprovidesthisstableinterface(TU-DSPT)totheTUanddispatchesthedataandvoicetrafficbetweentheTUandothercomponentsasaserviceswitchboard.TheDispatcherex-changesinformationusingtheNGTPmessageformatandhastoensurebearerindependance.Asanexample,bearerswitcheswithinanactiveusecase(e.g.fromWLANtoGPRS)havetobehandledtransparentlyfortherestoftheNGTPbackend.TheDSPTdeterminestowhichcomponentavehiclemessageisdeliveredorwhichbearerisusedfordeliveringamessagefromthebackendtotheve-hicle.ButtheDispatcherdoesn‟tcareaboutthecontentofthemessage,thisisthetaskoftheServiceHandlerandtheServiceIntegrator.

ServiceHandler(SH)

TheServiceHandlerdecodesthe“NGTPservicedata“(seechapter

5.1.4

)ofavehiclemessageandenrichesthecasedatawithadditionalcustomerandvehicleinformation.Ifnon-standard,proprietaryparametersorvalueencodingsareusedwithintheservicedata,theSHhasthetasktodecodeandconvertthosevaluestoastandard(state-of-the-art)representation.

Forexample,ifsensorinformationfromthevehicleistransmittedasavehicle-specificbitmap,theSHhastoprovideaninterpretedversionofthisinformation(e.g.anXML-structure)tothenextinstance(SI)andviceversaformessagestothevehicle.

ServiceIntegrator(SI)

TheServiceIntegratoristhecomponentthatbringstogetherallpartnersrequiredtodeliveracertainservicetothecustomer:ItcollectstheTU-originated(andmaybeenriched)datafromtheSH,ac-cessesoneorseveralcontentproviders,andprovidesallrelevantinformationtoPSAPsandCallCen-tersincludingmeanstosendbackinformationtothevehicleifneeded.

GeneralAspects

BesidestheNGTPcomponentsandinterfaces,theillustrationoftheNGTParchitectureshowsthreegeneralaspectsthatshouldbeconsidereddesigningatelematicssystembasedonNGTPprinciples.Theseaspectsare:

security,

loggingandauditingand

monitoring.

Basedonexistingindustrystandards,NGTP2.0definesanend-to-endtelematicsarchitecture.TheNGTP2.0architectureoffershighflexibilityandagilitythroughitsservicecomponents.Newservicescanbeeasilyintegratedinthisstandardizedarchitecturereducingthecostsandthetime-to-marketfornewservices.Toprovidesuchaflexiblearchitecture,itisnecessarytohaveclearassignmentswhichfunctionalitymustbelocatedinwhichcomponentorinterface.ThisassignmentisalsoillustratedinFigure3.

Figure3NGTP2.0Communicationprinciples

Onlythecommunicationbetweenthemobiledevice(TU)andthebackend(DSPT)isbi-directional.In-sidethebackend,thecommunicationviaoperations(=methodsonabusinesslevel)isbasicallyuni-directional(fromrighttoleft),onlytriggersareusedfromlefttoright.

Anexceptiontothatruleisinterface8betweentheServiceIntegratorandtheCallCenter,becauseagentassignmentandcallhandlingmightrequirealotofbi-directionalcommunication.Thereasonsandadvantagesofsuchaunidirectionalapproacharedescribedindetailinsection

3.3.

Maindesignconcepts

Events

EventsarethemostimportantobjectswithinNGTP.Aneventisakindofusecaseinstance,whichisidentifiedbyaworldwideuniqueID.Theso-calledEvent-IDisalogicalEvent-IDentifier,createdeitherbytheTUorintheNGTPbackend(dependingontheoriginatoroftheservice).ItisnotequaltoasessionID,becauseaneventcanconsistofseveralsessionswithdifferentsessionIDs.

OneormoremessagesmaybeassignedtothesameEvent-ID,meaningthatallmessagesarere-latedtothesameusecaseinstance(event).TheEvent-IDtiesthemessagestogetherandidentifiestheeventthroughoutitswholelifecycleinsidetheNGTPsystem.Themessagesmayalsousediffer-entsessionsandtransporttechnologies(e.g.,dataandvoicecall).NGTPidentifiesthemessagesandwillassignamessagetoanexistingeventorcreateanewevent.Thus,theEvent-IDisalsothekeytotechnologyindependence(bearerindependence).TheEvent-IDalsoallowstoresumeeventprocessingafteranabort.Itenablesseamlessbearerswitchingwithinausecaseandisthebaseforseveralcrossfunctionssuchasloggingormonitoring.Event-IDsareeithergeneratedbytheTUortheDSPTdependingonwhethertheusecaseisTU-originatedorbackend-originated

Example:ThedriverinthevehiclewantstouseaservicefromtheCallCenter.TheTUcreatesanEvent-ID,establishesanIP-connectionwiththeNGTPbackend,sendsaninitialdatamessageandthenstartsavoicecall.Duringthecall,theCallCenterrequestsanupdateofthevehicleposi-tion,andthisupdaterequestissenttothevehiclebySMSusingthesameEvent-ID.ThevehiclerespondswithanupdatemessageviaSMSusingthesameEvent-ID,andthustheNGTPbackendcanmatchthisupdatetothecorrectevent(evenifdifferenttechnicalbearersandsessionshavebeenusedinthiscase).

Technologyindependence

OneofthemaindesignprinciplesinNGTPisthetechnologyindependenceoftheservicecomponentsandinterfaces.NGTPdoesnotdefinethetechnologyfor

implementingacertaincomponent,usecaseormethod(operation)

adatacommunicationbetweenthevehicleandthebackend

avoicecommunicationbetweenthebackendandthevehicle

Theusedtechnologymaydependondifferentaspectslikecountryorcompanyspecificrestrictionsoralreadyavailableandreusablesolutions.Itshouldalsobepossibletoswitchatechnologyduringarunningevent.Thiscanbeforexampleaswitchoftheusedcommunicationtechniqueincaseofabadorbrokenradioreception.

Thetechnologyindependencealsorequiresthatasecuritymechanismsisnotbasedonpredefinedtechnologiessuchashttps,tokeeptheflexibilityoftheconcept.Forthisreason,thesecuritymechan-ismisalsobasedonthemessageformatandnotonthetechnology.Securityhastobehandledbyeachservicecomponent.

Loosecoupling

LoosecouplingoftheNGTPcomponentsprovidesflexibilityandextensibilitytothearchitecture.Aneworanadditionalcomponent(i.e.contentprovider)maybeaddedeasilytothesystemaslongasitimplementsthesameinterface.

Flexibility&scalability

Duetomarketorlegalrequirements,thetechnologyorbusinessprocessofausecasemayvaryfromcountrytocountry.Inaddition,differentcapabilitiesofthemobiledevicesordifferentcustomergroupsmayrequiredifferentprocessesand/ortechnologies.TheNGTP2.0architecturesupportsdifferenttechnologiesthroughitstechnologyindependence.Theloosecouplingofthecomponentsoffershigh

flexibilityandsupportsthecountryspecificexchangeorenhancementofcertaincomponents(i.e.changethecontentproviderforacertainusecase).Itshouldbepossibletoaddorremoveservices(=components)withoutaredesignorupdateoftheexistingcomponents.ThefollowingillustrationsshowhowNGTPcomponentsandinterfacescanbeincorporated–orexcluded–dependingontheneedsofthemarket.Forinstance:

ExampleoneillustratesasolutioninwhichallvoiceanddataisroutedtoaPSAP.Thesolu-tionusesallNGPTinterfacesandcomponentswiththeexceptionofthecallcenterandinter-face(8).

Inexampletwo,thesolutionincludesacallcenterandaproprietaryinterfaceto“otherservic-es”.

Examplethreeillustratesasolutionwhereinterface1andtheDispatcherareomittedfromthearchitectureandmultipleproprietaryinterfacesareemployed.Thismightbethecaseifsys-temthreeusestheDSPTfromsystem2butusesthecontentandservicesfromother(local)serviceproviders.…

Figure4ExamplesfordistributedNGTPbackendsystems

Itisalsopossibletoattachseveralcomponentsofthesametypetoabackend.Onereasoncouldbetheneedofloadbalancingortosecuretheavailabilityofaserviceifoncomponentisoutoforder.

Figure5ExampleofaNGTPbackendwithseveralcomponentsofonetype

Communicationconcept

ThecommunicationconceptofNGTPconsistsoftwoaspects:Triggersandoperations.Inordertokeepthearchitecturesimpleandtheinterfacesrobustandeasytouse,NGTPmainlyreliesonuni-directional,statelesscommunicationduetothefollowingadvantages:

Easyandrobustimplementation

Therearenostatefultechnicalcommunicationsessionsnecessarybetweenthecomponents.Acomponentthatoffersaninterfacedoesnotneedtoknowabouttheconsumersusingthatinterfacesonolistofclientsandcall-backaddressesmustbemaintained.

HighFlexibility

Newclientscaneasilyusetheinterfaceswithoutanyconfigurationeffortsonthesideofthein-terfaceprovider,componentscaneasilybeexchangedwithoutinvolvingtheproviderofanin-terface.

Highscalability

Additionalinstancesofacomponentcanbeaddedondemand,quicklywithoutconfigurationchangesinothercomponentsandwithoutlimitationsduetosessionreplicationefforts.

Thefollowingsectionsdescribetheconceptsoftriggersandoperationsindetail.

Triggerconcept

AtriggerisusedbytheDispatchertoinformotherNGTPcomponentsthatnewinformationhasbeenreceived.AlsotheTUcanbeoneoftheinformedcomponents.Thistriggerdoesnottransmitthein-formationitself,itonlycontains

therelatedEvent-IDand

theeventtype.

Therecipientofsuchatriggercanthenretrievethatinformationusingtheoperationsoftheinterfaces.Thistriggerconceptprovidesthefollowingadvantages:

Therecipientcandecide,WHENtoretrievetheeventdata(e.g.deferitalittlebitifresourcesarelimitedatthemoment)

Ifseveralmessagesarereceivedimmediatelyoneaftertheother,thetriggerrecipientcan“collect”thosetriggersandretrieveallinformationwithinONEoperationcall

Datatransmissionsarereducedtoaminimum,e.g.ifmultiplerecipientsaretobeinformedaboutanewmessage,butonlyoneoftherecipientsreallyprocessesthateventandretrievesthedata.

TheonlyNGTPcomponentthatinitiatesandsendstriggers