ASN.1 -- Communication between Heterogeneous …

1 ByPhilippe , (AbstractSyntaxNotationOne)is aninternationalstandardwhich a referencebook,didacticaswellaspreciseand OlivierDubuisson oftheseconstructionsis it is used,bothfromtheapplicationviewpointandf romthatofotherspecificationstandardswhic h writtenby ,ofitssyntaxandsemantics,andclearlyconst itutesa intendedforthosemerelyinterestedinfindin ga completeandreliabledescriptionof thelanguageandforprogrammersorexpertswho may want usefultoboththeproficient , theFrench NationalInstituteforResearch inComputerScienceandControlOlivierDubuis sonisa researchengineeratFrance T el ecomR&D, theResearch&Developmentcentre ofFrance T el ecom(formerlyknownasCnet),where T el Fouquartgraduated fromAstonUniversity,UKwithanMScinCompute rScience andApplied :1994grammarandlaterjoinedFrance T el ecomR&Din1999where heused :0-12-6333361-0c OSSN okalva, 2000 Allrights be reproducedortransmittedinany formorby any means,electronicormechanical,includingph otocopy, recording,orany informationstorageandretrievalsystem, CommunicationbetweenHeterogeneousSystems Allright, butdoyouthink,notwithstand-ingsomajoranu nknownfactor,thatyoucanunlock whatsignalit holdsforus?

2 [..] Actually, I wouldcount ona trioofdis-tinctstrataofclassifications. First,youandI lookatit casuallyandthinkofit asjustconfusingpoppycock,fool-ishmumbo jumbo - noticing,though,that,asa signal,it sobviouslynotrandomorchaotic,thatit sanaffirmationofsorts,a productofa codifyingauthority, submittingtoa publicthat sa socialtool as-suringcommunication,promulgatingit with-outany violation,accordingit itscanon,itslaw,itsrights. Whoknowswhatitis?Abylaw?AKoran?Acourtsum mons?Abailiff slogbook?A contractforpurchasingland?Aninvitationto a birthday party?Apolltaxform?Aworkoffiction?Acruci alfactisthat,my workadvancing,whatI llfindrisinginpriority isn titsinitialpoint ofapplicationbutitsongoingarticulationfo r,if youthinkofit, Communication (Imight almostsay communion )is ubiquitous,a signalcoursingfromthisindividualtothat,f romso-and-sotosuch-and-such,atwowaytraff icinanidiomoftransitivityornarrativity, fictionorimagination,affabulationorappro bation,sagaorsong.

3 GeorgesPerec,TheVoid(translatedbyGilbert Adair). diversity ofmachinearchitectures.. diversity ofprogramminglanguages.. :concretesyntax,abstractsyntax,transfers yn-tax.. shouldwe tackletheproblem?.. :fromgeneraltoparticular.. client-serverprotocol.. (ISO).. (ITU).. betweenthe1990and1994 versions.. :1997.. :1990.. layersoftheOSImodel.. (EDI)..91 IIUser .. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. compatibility.. sGuide.. sGuide.. sGuide.. 20212 Constructedtypes,tagging,extensibility .. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. extensibility.. sGuide.. 25313 Subtype .. sGuide.. sGuide.. inclusionconstraint.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. onSEQUENCEOForSETOF elements.. sGuide.. ,SETorCHOICE components.. sGuide.. ofanoctetstring.. sGuide.. combinations.

4 SGuide.. extensibility.. sGuide.. sGuide.. sGuide.. sGuide.. sGuide.. 30715 Informationobjectclasses, .. sGuide.. sGuide.. :theclassesATTRIBUTEandMATCHING-RULEof .. sGuide.. sGuide.. simplecasestudyofhow toextractinformationmod-eledby a class.. sGuide.. sGuide.. sGuide.. macros?.. macro.. :complexnumbers.. :themacroOPERATIONofROSE.. (andmajor!)disadvantagesofmacros.. sGuide.. 389xCONTENTSIIIE ncodingRulesandTransferSyntaxes39118 BasicEncodingRules(BER) .. constraints.. ,encodingof avalueofanopentype.. completeexample.. 41519 CanonicalandDistinguishedEncodingRules(C ERandDER) needformorerestrictive rules.. (CER).. (DER).. 422 CONTENTSxi20 PackedEncodingRules(PER) .. constraints.. wholenumber.. value.. value.. completeexample.. Weight EncodingRules(LWER).. (OER).. (SER).. (XER).. :a troublesomeproblem.. ,TTCN, .. XDRnotation.. sNIDL notation.. 822notationfortheInternet.. 49225 Epilogue495 VAppendices497.

5 VisibleSpeech .. !.. computinglanguages.. typesofcommunications.. systems.. structure.. systemswhosespecificationversionsarediff erent.. ofcheck boxes.. Videotexterminal:theFrench .. betweendifferent extensionsofthesamespecification.. (continued).. associatedwiththeEXTERNAL type.. associatedwiththeEMBEDDEDPDV type.. remoteapplication.. component relationconstraints.. (TLVformat).. formatsofthetagoctets(T).. (L).. s-complement forintegers.. ofa messageanditsdigitalsignature.. formatsofthePERtransfersyntax.. constrainedwholenumber.. compilationprocess.. (toC) compiler.. TTCN table.. cof-feemachine.. diagramofEDIFACT message.. choiceofNULL types.. 6-bitstring( 111111 B).. (continued).. categoriesofparametersandgovernors.. (continued).. 444 ForewordAbstractSyntaxNotationOne( )is a notationthatis usedinde-scribingmessagestobe emailmessageswithintheOpenSystemsInterco nnectionprotocols, a widerangeofotherapplications,such asinnetworkmanage-ment, secureemail,cellulartelephony, airtrafficcontrol, standardizedencodingrulesthatdescribe thebitsandbyteslayoutof particularcomputerarchitecture,operat-in gsystem,languageorapplicationprogramstru cture,andareusedina rangeofprogramminglanguages,includingJav a,C++, theInternationalTelecommunicationsUnion- Telecommuni-cationsSector(ITU-T),by theInternationalOrganizationforStan-dard ization(ISO)andby theInternationalElectrotechnicalCommissi on(IEC).

6 Thoughthestandardsareverythoroughandprec iseintheirdef-initions, suitableforbeginners,andata moredetailedlevel thatis meant forthosewhoseeka solidunderstandingof ,andcomputerprogrammerswhodesirea clearandfullunderstandingof thestandardizedencodingrulesof , CommunicationbetweenHeterogeneousSystems OlivierDubuissonhasdonea verygood jobof , ,andfinishingwithhisdescriptionof waysin which today usedin industry, heprovidesclearexamplestohelpthereaderbe ttergraspwhatis presentedina formthatwillprove enlighteningfortechnicalmanagerswhoseeka , ontheencodingrules,aswellasthoseimplemen terswhomayneedtoknow a memberof ofprovidinga , delightedathavingtheirdesirefora fullerunderstandingof ,OSSN okalvaEditor,ITU-T|ISO/IECJ oint ,NewJersey, , (AbstractSyntaxNotationOne)is a formalno-tationthatallowsspecificationso finformationhandledby highleveltelecomprotocolswithnolossofgen erality, , OpenSystemInterconnection(OSI)andbenefit edfromnumerousimprovements,particularlyi nits1994releaseinwhich substantialfunc-tionalitiesrelatedtotele communicationtechnologicalchanges(highra tedatatransfer,multimediaenvironment, alphabetsofdevelopingcoun-tries,servicep rotocolfrequent updating,etc) , , severalstandardizedsetsofencodingrulesca nbe usedfordescribinghowthesepotentiallycomp lexdatashouldbe transmittedasbitorbytestreamswhilekeepin gtheway theyaretransparent ,whethersimpleorverycom-plex, a pre-eminent , whole.

7 Fromitssemanticstoitsencapsu-lationinoth erlanguages(SDL,TTCNorGDMO) el ecomR&D(theresearch & development centreof FranceT el ecom,which wasnamed Cnet atthattime)anddonemy besttoanswernumerousquestionsfrommy insatiablecolleaguesonthesubjectforsomey ears,convincedmethattherewasindeedmateri alfora have triedtoconsiderseverallevelsforreading,f romtheneophyte1withoutany , butthereadershouldnotfeelrestrictedinany 1 Theneophytecandiscardthenumerousfootnote sof thisbookin CommunicationbetweenHeterogeneousSystems way by them,andnodoubtthespecifierwhois specificnotionwillgodirectlytothecorresp ondingsection:thisbookincludesnumerouscr ossreferencesinordertoguidereadersmorequ icklytorelatednotionsandtohelpthembuildu ptheirownway ,I endeav-oureda fewdigressionsthat,hopefully, a rigorousreaderwillnotholdagainstme!Conte ntsThisbookis called IntroductionandHistoryoftheNotation .Itstartswitha metaphoreaboutthe amaz-ingstoryoftelecommunications ,andmorespecificallyhowit relatestothelayers6 and7 (PresentationandAp-plication).

8 Bymeansofa tutorial,Chapter4presents a real-worlddatatransferspecificationofa mailordercompany. (types,abstractval-ues,modules,informati onobjectclassesandinformationobjects)tol eadmoresmoothlytoChapter6, which , , inthefirstplaceatleast,focusonthisfirstp art,which is independent ,titled User sGuideandReferenceManual ,makesupthecoreof thebook,sinceit , increasingdifficulty pedagogicalviewpoint, it is User sGuide areaimedatthebeginnerswhomay leave the ReferenceManual tosubsequent , EncodingRulesAndTransferSyntaxes ,includesthreechaptersthatdescribe IntroductionandHistoryoftheNotation User sGuideandReferenceManual 8 IntroductiontotheReferenceManual9 Modulesandassignments10 Basictypes11 Characterstringtypes12 Constructedtypes,tagging,extensibility rules13 Subtype constraints14 Presentationcontextswitchingtypes15 Informationobjectclasses,objectsandobjec tsets16 Enoughtoreadmacros17 ParameterizationPartIII EncodingRulesandTransferSyntaxes 18 Basicencodingrules(BER)19 Canonicalanddistinguishedencodingrules(C ERandDER)

9 20 Packedencodingrules(PER)21 OtherencodingrulesPartIV ,TTCN,GDMO24 Otherabstractsyntaxnotations25 EpilogueDiscoveryitinerary(themainprinci ples)Beginningspecifier sitineraryAdvanced itinerary(additionssince 1994)Figure1 CommunicationbetweenHeterogeneousSystems encodingrulesthatmay be setasideby specifiers,whoneednot,in general,be concernedwiththeway meant by ,such asSDLforformalizingtelecommunicationprot ocols, , ,keywordsandnamesofthegrammarelementsis of chaptersandthepotentialvariety of read-ers,we thislistis veryreactive andofa hightechnicallevel; subscribe, subscribeasn1your-name veryunlikelytobe (pleasenotethesection,pageandlinenumberi nfault);theywillbe collectedona specialwebpage3onoursiteandI shallmaintaina mailinglist4ofthereaderswhowanttobe , forthecarefulreaderswhowouldwishfurtherd etail, happentobe dreadfully2 ,thesewillbe reading!AcknowledgementsI amverymuch indebtedtoBancroftScott,ISOandITU-Tedito rof ,forthetechnicalquality askhim(notethetense)almostdaily.

10 Hestronglysupportedtheproject,andI somehow oneofthetwo , ,is itssecondmemory,somethingeverybodyshould be convincedofwhenreadinghisbook[Lar99]. Hishistoricalviewpointsonaspectstoo oldforme(nooffensemeant!)have first-ratecontributoronthestandardandI hope ourreaderswillfindcomplementarity inourrespective ,whenhewasstilla student andabouttomovetoEnglandforhisstudies,Phi lippe hasbeena pleasant surprisetoseehimback,now asa colleagueatFranceT el mcontent toseehow precisely, butalsohoweasily, hemanagedtoputacrosstheveryideaswhich I meant totheoriginaltext(which,hopefully, theFrench-speakingreaderswillbenefitfrom inan-otheredition).I mustpay tributetohimfortheremarkablequality of hasalsoseentocompilingtheoriginalLATEX sourcefilesintoa PDFthatcouldclaimthename,fixingupfonts,c ross-referencesandindexbugs:thanksforcut tingtheGordianknot!MichelMauny is a friendI have beenabletocount onsincemy ,histhoughtfuladvice,hisopen-mindnessand hissereneattitudehave hasbeenmy mproudofsupervisingRodolphe CommunicationbetweenHeterogeneousSystems Thewebsite6associatedwiththisbookisdedic atedtoPhilippeFouquart,Fr ed ericDuwez,GuillaumeLatu,Pierre-MarieH etault,YoannRegardin,St ephaneLevantandGuillaumeMoraine,whothrou ghouttheirplacementsatFranceT el ecomR&D,alwaysworkedenthusiastically, withenergyandproficiencyonthedevelopment of orig-inaltools,someofwhich withoutChristianRinderknecht have alwaysap-preciatedhisCartesianapproach of beenwrittenwithoutthesupportof RolandGrozandPierre-No elFavennecwhoencouragedmeingivingconcret eexpressiontomy amgratefultoAnne-MarieBustos scontribution,withwhomI hadthepleasuretogive el ecomR& firststeps inChapter4areverymuch inspiredby amparticularlygratefultoa numberof peopleforcarefullyreview-ingdraftmateria lofthisbook.