SEMI E37-0298 HIGH-SPEED SECS MESSAGE SERVICES (HSMS) GENERIC协议原版文件

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SEMIE37-0298©SEMI1995,1998

SEMIE37-0298©SEMI1995,1998

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SEMIE37-0298

HIGH-SPEEDSECSMESSAGESERVICES(HSMS)GENERICSERVICES

Purpose

HSMSprovidesameansforindependentmanufactur-erstoproduceimplementationswhichcanbecon-nectedandinteroperatewithoutrequiringspecificknowledgeofoneanother.

HSMSisintendedasanalternativetoSEMIE4(SECS-I)forapplicationswherehigherspeedcommu-nicationisneededorwhenasimplepoint-to-pointtopologyisinsufficient.SEMIE4(SECS-I)canstillbeusedinapplicationswheretheseandotherattributesofHSMSarenotrequired.

HSMSisalsointendedasanalternativetoSEMIE13(SECSMessageServices)forapplicationswhereTCP/IPispreferredoverOSI.

ItisintendedthatHSMSbesupplementedbysubsid-iarystandardswhichfurtherspecifydetailsofitsuseorimposerestrictionsonitsuseinparticularapplica-tiondomains.

Scope

High-SpeedSECSMessageServices(HSMS)definesacommunicationinterfacesuitablefortheexchangeofmessagesbetweencomputersinasemiconductorfac-tory.

ReferencedDocuments

SEMIStandards

SEMIE4—SEMIEquipmentCommunicationStan-dard1—MessageTransport(SECS-I)

SEMIE5—SEMIEquipmentCommunicationStan-dard2—MessageContent(SECS-II)

IETFDocuments1

IETFRFC791—InternetProtocol

IETFRFC792—InternetControlMessageProtocol

IETFRFC793—TransmissionControlProtocol

IETFRFC1120—RequirementsforInternetHosts-CommunicationLayers

IETFRFC1340—AssignedNumbers.Note:ThisRFCsupersedesRFC820.

POSIXDocument2

IEEEPOSIXP1003.12—ProtocolIndependentInter-faces(PII)

Terminology

API—ApplicationProgramInterface.InthecaseofTCP/IP,asetofprogrammingconventionsusedbyanapplicationprogramtopreparefororinvokeTCP/IPcapabilities.

communicationfailure—Afailureinthecommunica-tionlinkresultingfromatransitiontotheNOTCON-NECTEDstatefromtheSELECTEDstate.(SeeSection9.)

confirmedservice(HSMS)—AnHSMSservicerequestedbysendingamessagefromtheinitiatortotherespondingentitywhichrequiresthatcompletionoftheservicebeindicatedbyaresponsemessagefromtherespondingentitytotheinitiator.

connection—AlogicallinkageestablishedonaTCP/IPLANbetweentwoentitiesforthepurposesofexchangingmessages.

controlmessage—AnHSMSmessageusedforthemanagementofHSMSsessionsbetweentwoentities.

datamessage—AnHSMSmessageusedforcommu-nicationofapplication-specificdatawithinanHSMSsession.ADataMessagecanbeaPrimaryMessageoraReplyMessage.

entity—AnapplicationprogramassociatedwithanendpointofaTCP/IPconnection.

header—A10-bytedataelementprecedingeveryHSMSmessage.

TheIETFdocumentscanbeobtainedfromTheNetworkInformationCenter,NetworkSolutions,14700ParkMeadowDrive,Suite200,Chantilly,VA22021USA

POSIXdocumentscanbeobtainedfromInstituteofElectricalandElectronicEngineers(IEEE),345East47thStreet,NewYork,NY10017USA

initiator(HSMS)—TheentityrequestinganHSMSservice.TheinitiatorrequeststheservicebysendinganappropriateHSMSmessage.

IPAddress—InternetProtocolAddress.Alogicaladdresswhichuniquelyidentifiesaparticularattach-menttoaTCP/IPnetwork.

localentity—Relativetoaparticularendpointofaconnection,thelocalentityisthatentityassociatedwiththatendpoint.

localentity-specific—Generalqualifiertoanyproce-dure,option,issue,orotherimplementationmatterwhichisnotasubjectofthisstandardandlefttothediscretionoftheindividualsupplier.

message—Acompleteunitofcommunicationinonedirection.AnHSMSMessageconsistsoftheMessageLength,MessageHeader,andtheMessageText.AnHSMSMessagecanbeaDataMessageoraControlMessage.

messagelength—A4-byteunsignedintegerfieldspecifyingthelengthofamessageinbytes.

opentransaction—Atransactioninprogress.

port—AnendpointofaTCP/IPconnectionwhosecompletenetworkaddressisspecifiedbyanIPAddressandTCP/IPPortnumber.

portnumber—(orTCPportnumber).TheaddressofaportwithinanattachmenttoaTCP/IPnetworkwhichcanserveasanendpointofaTCP/IPconnection.

primarymessage—AnHSMSDataMessagewithanoddnumberedFunction.Also,thefirstmessageofadatatransaction.

publishedport—ATCP/IPIPAddressandPortnum-berassociatedwithaparticularentity(server)whichthatentityintendstouseforreceivingTCP/IPconnec-tionrequests.Anentity'spublishedportmustbeknownbyremoteentitiesintendingtoinitiateconnec-tions.

receiver—TheHSMSEntityreceivingamessage.

remoteentity—Relativetoaparticularendpointofaconnection,theremoteentityistheentityassociatedwiththeoppositeendpointoftheconnection.

reply—AnHSMSDataMessagewithaneven-num-beredfunction.Also,theappropriateresponsetoaPri-maryHSMSDataMessage.

respondingentity(HSMS)—TheproviderofanHSMSservice.Therespondingentityreceivesames-sagefromaninitiatorrequestingtheservice.Intheeventofaconfirmedservice,therespondingentityindicatescompletionoftherequestedservicebysend-inganappropriateHSMSresponsemessagetotheini-tiatoroftherequest.Inanunconfirmedservice,therespondingentitydoesnotsendaresponsemessage.

session—Arelationshipestablishedbetweentwoenti-tiesforthepurposeofexchangingHSMSmessages.

sessionentity—AnentityparticipatinginanHSMSsession.

sessionID—A16-bitunsignedintegerwhichidenti-fiesaparticularsessionbetweenparticularsessionentities.

stream(TCP/IP)—AsequenceofbytespresentedatoneendofaTCP/IPconnectionfordeliverytotheotherend.TCP/IPguaranteesthatthedeliveredsequenceofbytesmatchesthepresentedstream.HSMSsubdividesastreamintoblocksofcontiguousbytes-messages.

T3—ReplytimeoutintheHSMSprotocol.

T5—ConnectSeparationTimeoutintheHSMSproto-colusedtopreventexcessiveTCP/IPconnectactivitybyprovidingaminimumtimebetweenthebreaking,byanentity,ofaTCP/IPconnectionorafailedattempttoestablishone,andtheattempt,bythatsameentity,toinitiateanewTCP/IPconnection.

T6—ControlTimeoutintheHSMSprotocolwhichdefinesthemaximumtimeanHSMScontroltransac-tioncanremainopenbeforeacommunicationsfailureisconsideredtohaveoccurred.Atransactionisconsid-eredopenfromthetimetheinitiatorsendstherequiredrequestmessageuntiltheresponsemessageisreceived.

T7—ConnectionIdleTimeoutintheHSMSprotocolwhichdefinesthemaximumamountoftimewhichmaytranspirebetweentheformationofaTCP/IPcon-nectionandtheuseofthatconnectionforHSMScom-municationsbeforeacommunicationsfailureisconsideredtohaveoccurred.

T8—NetworkIntercharacterTimeoutintheHSMSprotocolwhichdefinesthemaximumamountoftimewhichmaytranspirebetweenthereceiptofanytwosuccessivebytesofacompleteHSMSmessagebefore

acommunicationsfailureisconsideredtohaveoccurred.

TCP/IP—TransmissionControlProtocol/InternetProtocol.Amethodofcommunicationswhichprovidesreliable,connection-orientedmessageexchangebetweencomputerswithinanetwork.

TLI—TransportLevelInterface.OneparticularAPIprovidedbycertainimplementationsofTCP/IPwhichprovidesatransportprotocolandoperatingsystemindependentdefinitionoftheuseofanyTransportLevelprotocol.

transaction—APrimaryMessageanditsassociatedReplymessage,ifrequired.Also,anHSMSControlMessageoftherequest(.req)type,anditsresponseControlMessage(.rsp),ifrequired.

unconfirmedservice(HSMS)—AnHSMSservicerequestedbysendingamessagefromtheinitiatortotherespondingentitywhichrequiresnoindicationofcompletionfromtherespondingentity.

HSMSOverviewandStateDiagram

High-SpeedSECSMessageServices(HSMS)definesacommunicationinterfacesuitablefortheexchangeofmessagesbetweencomputersinasemiconductorfac-toryusingaTCP/IPenvironment.HSMSusesTCP/IPstreamsupport,whichprovidesreliabletwowaysimultaneoustransmissionofstreamsofcontiguousbytes.ItcanbeusedasareplacementforSECS-Icom-municationaswellasothermoreadvancedcommuni-cationsenvironments.

TheprocedureforHSMScommunicationsparallelsthemorefamiliarSECS-Icommunicationsitreplaces.Thefollowingstepsarefollowedforanycommunica-tions(HSMSorotherwise):

Obtainacommunicationslinkbetweentwoenti-ties.InSECS-I,thisistheRS232wirephysicallyconnectinghostandequipment.InHSMS,thelinkisaTCP/IPconnectionobtainedbythestandardTCP/IPconnectprocedure.Notethattheabstractterm"entity"isusedinsteadof"host"or"equip-ment."Thisisbecause,whileHSMSisusedforSECS-Ireplacement,ithasmoregeneralapplica-tionsaswell.InaSECS-Ireplacementapplication,the"host"isan"entity"andthe"equipment"isan"entity."

Establishtheapplicationprotocolconventionstobeusedforexchangingdatamessagesbetweentwo

entities.ForSECS-I,thisstepisimplicitinthefactthatsemiconductorequipmentisphysicallycon-nectedonthetwoendsofthewire:theprotocolisSECS-II.

InthecaseofHSMS,thecommunicationslinkisadynamicallyestablishedTCP/IPconnectiononaphysicallinkwhichmaybesharedwithmanyotherTCP/IPconnectionsusingprotocolsotherthanHSMSorconnectionsusingnonTCP/IPprotocols.HSMSaddsamessageexchange(calledtheSelectprocedure)whichisusedtoconfirmtobothentitiesthattheparticularTCP/IPconnectionistobeusedexlusivelyforHSMScommunications.

ExchangeData.Thisisthenormalintendedpur-poseofthecommunicationslink.InbothSECS-IandHSMS,theprocedureistoexchangeSECS-IIencodedmessagesforthecontrolofsemiconductorequipmentand/orprocesses.Dataexchangenor-mallycontinuesuntiloneorbothoftheentitiesaretakenoff-lineforequipment-specificpurposes,suchasmaintenance.

Formallyendcommunications.InSECS-I,thereisnoformalrequirementhere;theequipmenttobetakenoff-linestopscommunicating.

InHSMS,amessageexchange(eitherthe“bilat-eral”Deselectprocedureorthe“unilateral”sepa-rateprocedure)isusedforbothpartiestoconfirmthattheTCP/IPconnectionisnolongerneededforHSMScommunications.

Breakthecommunicationslink.InSECS-I,thisisdonebyphysicallyunpluggingthehostorequip-mentfromthecommunicationscable,whichonlyoccursduringrepairorphysicalreconfigurationofthefactorynetworkenvironment.

InHSMS,sinceitusesthedynamicconnectionenvironmentofTCP/IP,theTCP/IPconnectionislogicallybrokenviaareleaseoradisconnectpro-cedurewithoutanyphysicaldisconnectfromthenetworkmedium.

Twoadditionalprocedures,ofadiagnosticnature,aresupportedinHSMS,whicharegenerallynotrequiredbyasimpleSECS-IlinkoraSECS-Idirectreplace-ment.Thesefollow:

Linktest.Thisprocedureprovidesasimpleconfir-mationofconnectionintegrity.

Reject.BecauseHSMSisintendedtobeextendedtoprotocolsotherthanjustSECS-II(bymeansofsubsidiarystandards),itispossiblethattwoentitiescanbeconnected(duetoaconfigurationerror)whichuseincompati-blesubsidiarystandards.Also,duringinitialimplementation,incorrectmessagetypesmaybesent,ortheymaybesentoutoforderduetosoftwarebugs.Therejectprocedureisusedtoindicatesuchanoccurrence.

HSMSConnectionStateDiagram—TheHSMSstatemachineisillustratedinthediagrambelow.Thebehav-iordescribedinthisdiagramdefinesthebasicrequirementsofHSMS:subsidiarystandardsmayfurtherextendtheseorotherstates.

StateDescriptions

NOTCONNECTED—TheentityisreadytolistenfororinitiateTCP/IPconnectionsbuteitherhasnotyetestablishedanyconnectionsorallpreviouslyestablishedTCP/IPconnectionshavebeenterminated.

CONNECTED—ATCP/IPconnectionhasbeenestablished.Thisstatehastwosubstates,NOTSELECTEDandSELECTED.

NOTSELECTED—AsubstateofCONNECTEDinwhichnoHSMSsessionhasbeenestablishedoranypreviouslyestablishedHSMSsessionhasended.

SELECTED—AsubstateofCONNECTEDinwhichatleastoneHSMSsessionhasbeenestablished.Thisisthenormal"operating"stateofHSMS:datamessagesmaybeexchangedinthisstate.Itishighlightedbyaheavyoutlineinthestatediagram.

StateTransitionTable

#

CurrentState

Trigger

NewState

Actions

Comment

1

...

Localentity-specificpreparationforTCP/IPcommunication.

NOTCONNECTED

Localentity-specific

Actiondependsonconnectionproceduretobeused:activeorpassive.

2

NOTCONNECTED

ATCP/IPconnectionisestablishedforHSMScommunication.

CONNECTED-NOTSELECTED

Localentity-specific

none

3

CONNECTED

BreakingofTCPconnection.

NOTCONNECTED

Localentity-specific

SeeSection6.4.

4

NOTSELECTED

SuccessfulcompletionofHSMSSelectProcedure.

SELECTED

Localentity-specific

HSMScommunicationisnowfullyestablished:datamessageexchangeispermitted.

5

SELECTED

SuccessfulcompletionofHSMSDeselectorSeparate.

NOTSELECTED

Localentity-specific

ThistransitionnormallyindicatestheendofHSMScommunicationandsoanentitywouldimmediatelyproceedtobreaktheTCP/IPconnection(transition3above).

6

NOTSELECTED

T7ConnectionTimeout.

NOTCORRECTED

Localentity-specific

perSection9.2.2

UseofTCP/IP

TCP/IPAPI—ThespecificationofarequiredTCPApplicationProgramInterface(API)foruseinimple-mentationsisoutsidethescopeofHSMS.AgivenHSMSimplementationmayuseanyTCP/IPAPI—sockets,TLI(TransportLayerInterface),etc.—appropriatetotheintendedhardwareandsoftwareplatform,aslongasitprovidesinteroperableTCP/IPstreamsprotocolonthenetwork.

TheappendixcontainsexamplesoftheTCP/IPproceduresreferencedinthisstandardandsamplescenariosusingboththeTLI(POSIXstandard1003.12)andthepopularBSDsocketmodelforTCP/IPcommunication.

TCP/IPNetworkAddressingConventions

IPAddresses—EachphysicalTCP/IPconnectiontoagivenLocalAreaNetwork(LAN)musthaveauniqueIPAddress.IPAddressesmustbeassignableatinstallationtime,andanHSMSimplementationcannotselectafixedIPAddress.AtypicalIPAddressis.

IPimposesrestrictionsonthesenumberswhichareoutsidethescopeoftheHSMSprotocol.ConsultSection2.3ofRFC791,InternetProtocol(IP)inSection3.

TCPPortNumbers—ATCPPortNumbercanbeconsideredasanextensionoftheIPAddress.

HSMSimplementationsshouldallowconfiguringTCPPorttothefullrangeoftheTCP/IPimplementationused.AtypicalTCPPortNumberis5000.

ConventionshavebeenestablishedforselectingTCPPortNumberswhichareoutsidethescopeoftheHSMSpro-tocol.ConsultRFC793,TransmissionControlProtocol(TCP)inSection3.

EstablishingaTCP/IPConnection

ConnectModes—TheproceduresforestablishingaTCP/IPconnectionaredefinedinRFC793.However,notalltheproceduresdefinedbyRFC793aresupportedbycommonlyavailableAPIs.Inparticular,whileRFC793permitsbothentitiestoinitiatetheconnectionsimultaneously,thisfeatureisrarelysupportedinavailable

APIs.Therefore,HSMSrestrictsanentitytooneofthefollowingmodes:

PassiveMode.ThePassivemodeisusedwhenthelocalentitylistensforandacceptsaconnectproce-dureinitiatedbytheRemoteEntity.

ActiveMode.TheActivemodeisusedwhentheconnectprocedureisinitiatedbytheLocalEntity.

Theappendixprovidesanexampleofhowanentitymayoperatealternatelyintheactiveandpassivemodestoachievegreaterflexibilityinestablishingcommunications.

PassiveModeConnectProcedure—Thepro-cedurefollowedbythePassiveLocalEntityisdefinedinRFC793.Itissummarizedasfollows:

Obtainaconnectionendpointandbindittoapub-lishedport.

Listenforanincomingconnectrequesttothepub-lishedportfromaremoteentity.

Uponreceiptofaconnectrequest,acknowledgeitandindicateacceptanceoftheconnection.Atthispoint,theconnectprocedurehascompletedsuc-cessfully,andtheCONNECTEDstateisentered(Section5).

TheseproceduresarecarriedoutthroughtheAPIofthelocalentity'simplementationofTCP/IP.TheappendicesprovidetheAPI-specificproceduresfortheabovestepsusingbothTLIandBSD.

Note:Afailuremayoccurduringtheabovesteps.Thereasonforfailuremaybelocalentity-specificormaybeduetoalackofanyconnectrequestafteralocalentity-specifictimeout.Theactiontobetaken(forexample:returntostep1toretry)isalocalentity-spe-cificissue.

Note:SeeSection9,SpecialConsiderations,forissuesrelatingtomultipleconnectionrequeststothesamepassivemodeentity.

ActiveModeConnectProcedure—Theproce-durefollowedbytheActiveLocalEntityisdefinedinRFC793.Itissummarizedasfollows:

Obtainaconnectionendpoint.

Initiateaconnectiontothepublishedportofapas-sivemoderemoteentity.

Waitforthereceiptoftheacknowledgeandtheacceptanceoftheconnectrequestfromtheremoteentity.Receiptoftheacceptancefromtheremoteentityindicatessuccessfulcompletionofthecon-nectprocedure,andtheCONNECTEDstateisentered(Section5).

TheseproceduresarecarriedoutthroughtheAPIofthelocalentity'simplementationofTCP/IP.TheappendixprovidestheAPI-specificproceduresfortheabovestepsusingbothTLIandBSD.

Note:Afailuremayoccurduringtheabovesteps.Thereasonforfailuremaybelocalentity-specificormaybeduetoalackofanyacceptmessageafteralocalentity-specifictimeout.Theactiontobetakenisalocalentity-specificissue.If,however,thelocalentityintendstoretrytheconnection,itshoulddososubjecttotheT5connectseparationtimeout(see"SpecialConsiderations").

TerminatingaTCP/IPConnection—ConnectionterminationisthelogicalinverseofConnectionestab-lishment.FromtheLocalEntity'sperspective,aTCP/IPconnectionmaybebrokenatanytime.However,HSMSonlypermitsterminationoftheconnectionwhentheconnectionisintheNOTSELECTEDsub-stateoftheCONNECTEDstate.

TheproceduresforterminationofaconnectionaredefinedinRFC793.Eitherentitymayinitiatetermina-tionoftheconnection.TheNOTCONNECTEDstateisentered,indicatingtheendofHSMScommunica-tions.TheappendixillustratestheproceduresforbothreleaseanddisconnectusingtheTLIandBSDAPIs.

HSMSMessageExchangeProcedures

HSMSdefinestheproceduresforallmessageexchangebetweenentitiesacrosstheTCP/IPconnec-tionestablishedaccordingtotheproceduresinthepre-vioussection.Asexplainedintheoverview,oncethe

connectionisestablished,thetwoentitiesestablishHSMScommunicationswiththeSelectprocedure.Thendatamessagesmaybeexchangedineitherdirec-tionatanytime.WhentheentitieswishtoendHSMScommunications,theDeselectorSeparateprocedureisusedtoendHSMScommunications.

SendingandReceivingHSMSMessages—AllHSMSproceduresinvolvetheexchangeofHSMSmessages.ThesemessagesaresentandreceivedasTCP/IPstreamsusingthepreviouslyestablishedTCP/IPconnectionatstandardpriority.Inparticular,theuseof"Urgent"dataisnotsupportedunderHSMS(seeRFC793formoreinformationonsendandreceiveprocedures).

TheappendixgivesexamplesofsendingandreceivingHSMSmessagesusingbothTLIandBSDsocketAPIs.

SelectProcedure—TheSelectprocedureisusedtoestablishHSMScommunicationsonaTCP/IPcon-nectionusingtheSelect.reqandSelect.rspmessagesinacontroltransaction.

AlthoughHSMSpermitsSelectatanytimeintheCONNECTEDstate,subsidiarystandardsmayfurtherrequiretheconnectiontobeintheNOTSELECTEDsubstate(see"SpecialConsiderations").

InitiatorProcedure—Theprocedurefollowedbytheinitiatorisasfollows.

TheinitiatoroftheselectproceduresendstheSelect.reqmessagetotherespondingentity.

IftheinitiatorreceivesaSelect.rspwithaSelectStatusof0,TheHSMSSelectprocedurecompletessuccessfullyandtheSELECTEDstateisentered(seeSection5).

IftheinitiatorreceivesaSelect.rspwithanon-zeroSelectStatus,theSelectcompletesunsuccessfully(nostatetransitions).

IftheT6timeoutexpiresintheinitiatorbeforereceiptofaSelect.rsp,itisconsideredacommuni-cationsfailure(see"SpecialConsiderations").

RespondingEntityProcedure—Theprocedurefollowedbytherespondingentityisasfollows.

TherespondingentityreceivestheSelect.req.

Iftherespondingentityisabletoaccepttheselect,ittransmitstheSelect.rspwithaSelectStatusof0.TheHSMSSelectProcedurefortherespondingentityissuccessfullycompleted,andtheSELECTEDstateisentered(seeSection5).

Iftherespondingentityisunabletopermittheselect,ittransmitstheSelect.rspwithanon-zeroSelectStatus.TheHSMSSelectProcedurefortherespondingentitycompletesunsuccessfully(nostatetransitions).

SimultaneousSelectProcedures—Ifthesub-sidiarystandardsdonotrestricttheuseoftheSelect,itispossiblethatbothentitiessimultaneouslyinitiateSelectProcedureswithidenticalSessionID’s.Insuchacase,eachentitywillaccepttheotherentity'sselectrequestbyrespondingwithaSelect.rsp.

DataProcedure—HSMSdatamessagesmaybeinitiatedbyeitherentityaslongastheconnectionisintheSELECTEDstate.ReceiptofadatamessagewhennotintheSELECTEDstatewillresultinarejectpro-cedure(seeSection7.7).

Datamessagesmaybefurtherdefinedaspartofadatatransactionaseithera"Primary"or"Reply"datames-sage.Inadatatransaction,theinitiatorofthetransac-tionsendsaprimarymessagetotherespondingentity.IfthePrimarymessageindicatesthatareplyisexpected,aReplymessageissentbytherespondingentityinresponsetothePrimary.

ThefollowingtypesofDataTransactionsaresup-ported:

PrimaryMessagewithreplyexpectedandtheasso-ciatedReplyMessage.

PrimaryMessagewithnoreplyexpected.

Thespecificproceduresforthesetransactionsaredeterminedbytheapplicationlayerandaresubjecttootherstandards(forexample,E5andE30forGEMequipmentusingSECS-IIencodedmessages).

Theapplicableupperlayerstandardisidentifiedbythemessagetype.ThetypeisdeterminedfromthespecificformatdefinedinSection8.ThenormaltypeforHSMSmessagesisSECS-IItext.Alsoreferto"SpecialConsiderations"concerningtheT3ReplyTimeout.

DeselectProcedure—TheDeselectprocedureisusedtoprovideagracefulendtoHSMScommunica-tionforanentitypriortobreakingtheTCP/IPconnec-tion.HSMSrequiresthattheconnectionbeintheSELECTEDstate.Theprocedureisasfollows.

InitiatorProcedure

TheinitiatoroftheDeselectproceduresendstheDeselect.reqmessagetotherespondingentity.

IftheinitiatorreceivesaDeselect.rspwithaDese-lectStatusof0,itsDeselectprocedureterminatessuccessfully.TheNOTSELECTEDstateisentered(seeSection5).

IftheinitiatorreceivesaDeselect.rspwithanon-zeroDeselectStatus,itsDeselectproceduretermi-natesunsuccessfully.Nostatechangeoccurs.

IftheT6timeoutexpiresintheinitiatorbeforereceiptofaDeselect.rsp,itisconsideredacommu-nicationsfailure(see"SpecialConsiderations").

RespondingEntityProcedure

TherespondingentityreceivestheDeselect.reqmessage.

IftherespondingentityisintheSELECTEDstate,andifitisabletopermittheDeselect,itrespondsusingtheDeselect.rspwithazeroresponsecode.Therespondingentity'sDeselectprocedurecom-pletessuccessfully.TheNOTSELECTEDstateisentered(seeSection5).

IftherespondingentityisunabletopermittheDeselect,eitherbecauseitisnotintheSELECTEDstateorbecauselocalconditionsdonotpermittheDeselect,itrespondsusingtheDeselect.rspwithanon-zeroresponsecode.Therespondingentity'sDeselectprocedureterminatesunsuccessfully.Nostatechangeoccurs.

SimultaneousDeselectProcedures—Ifthesub-sidiarystandardsdonotrestricttheuseoftheDeselect,itispossiblethatbothentitiessimultaneouslyinitiateDeselectProcedureswithidenticalSessionID’s.Insuchacase,eachentitywillaccepttheotherentity'sDeselectrequestbyrespondingwiththedeselect.rsp.

LinktestProcedure—TheLinktestisusedtodeterminetheoperationalintegrityofTCP/IPand

HSMScommunications.ItsuseisvalidanytimeintheCONNECTEDstate.

InitiatorProcedure

TheinitiatoroftheLinktestproceduresendstheLinktest.reqmessagetotherespondingentity.

IftheinitiatorreceivesaLinktest.rspwithintheT6timeout,theLinktestissuccessfullycompleted.

IftheT6timeoutexpiresintheinitiatorbeforereceiptofaLinktest.rsp,itisconsideredacommu-nicationsfailure(see"SpecialConsiderations").

RespondingEntityProcedure

TherespondingentityreceivestheLinktest.reqfromtheinitiator.

TherespondingentitysendsaLinktest.rsp.

SeparateProcedure—TheSeparateprocedureisusedtoabruptlyterminateHSMScommunicationforanentitypriortobreakingtheTCP/IPConnection.HSMSrequiresthattheconnectionbeintheSELECTEDstatewhenusingSeparate.Therespond-ingentitydoesnotsendaresponseandisrequiredtoterminatecommunicationsregardlessofitslocalstate.Theprocedureisasfollows.

InitiatorProcedure

1.TheinitiatoroftheselectproceduresendstheSepa-rate.reqmessagetotherespondingentity.Theiniti-ator'sSeparateprocedurecompletessuccessfully.

TheNOTSELECTEDstateisentered(seeSection5).

RespondingEntityProcedure

TherespondingentityreceivestheSeparate.reqfromtheinitiator.

IftherespondingentityisintheSELECTEDstate,itsSeparateprocedurecompletessuccessfully.

IftherespondingentityisnotintheSELECTEDstate,theSeparate.reqisignored.

RejectProcedure—TheRejectprocedureisusedinresponsetoanotherwisevalidHSMSmessagereceivedinaninappropriatecontext.Supportingtherejectprocedurecanprovideusefuldiagnosticinfor-mationduringthedevelopmentofadistributedappli-cationusingHSMS.Theprocedureisasfollows:

Initiator(SenderofInappropriateMessage)Procedure

1.Theinitiatoroftheinappropriatemessage,uponreceivingtheReject.req,takesappropriateaction(localentity-specific).

RespondingEntityProcedure

1.TheentityreceivingtheinappropriatemessagerespondswithaReject.reqmessage.

HSMSrequirestherejectprocedureforthereceiptof