Sistem

1. Sistem terdistribusi 3 InterprocessCommunication

2. Prinsip Berkomunikasi • Source –generatesdata (text/binary)to be transmitted Transmitter • –Convertsdata Transmission –Carriesdata –Ex:TCP/IP Receiver intotransmittablesignals System • • –Convertsreceivedsignal Destination –Takes incomingdata into data •

3. Interprocess Communication Processeswithin a system may be independent or cooperating • • independent cooperating • Processondifferentcomputer? • Reasonsforcooperatingprocesses: • Informationsharing • Computationspeedup Modularity Convenience • • Cooperatingprocessesneedinterprocesscommunication(IPC) TwomodelsofIPC • • Sharedmemor • Sharedmemory • Messagepassing

4. Communications in local

5. Karakteristik IPC A h i ti •SynchronizationdanAsynchronizationof messages. • Messagedestination: onInternet, addressdanlocalport. using • http://192.168.1.2:8081 • Reliabilitydata:validitydanintegrity. • • Orderingdata: urutanpaketyangdikirim Differentdataprocessing: marshalling/unmarshalling

6. Kategori IPC : merupakanfasilitasyangmenyediakan • Pipes: merupakanfasilitasyangmenyediakan sistem atau disebuthalf-duplex, yaitu data mengalir • FIFO: fasilitaskomunikasisecaraFIFO(first infirst out). • MiripdenganPipes • Messagediantrikan • Terjadidilocalcomputer • Shared memory : suatuprosesberbagiruangdalam wilayahmemoryakanmampumenulisdan • Dalamsingleprocessing(localcomputer) komunikasisatu arahantarprosesdalam sebuah hanya terjadisatu arah.(localcomputer) h t jdi t h virtual address,sehinggaprosesmanapun akanberbagi wilayahmemoryakanmampumenulisdan membacanya.

7. Kategori IPC • Mappedmemory : berhubungandengan mapping sebuah file dalam file systemsesuai denganmemoryyangada. Konsepvirtualmemory Localcomputer – – • MessageQueues:mengirim pesansecara asynchronous. – Asynchronousberartiprosespengirimandata berlanjutdisertaisebuaheksekusitanpaharus menunggupenerimamenerimaataumengenal informasitersebut.

8. Kategori IPC t kt d t di h k • Semaphore : struktur data yang di share ke • Socket : sebagaiendpointdari komunikasidua • RPC (RemoteProcedure Call): adalahsebuah berjalan pada satu host dan mengakibatkan beberapaprosesuntuk sinkronisasi Socket proses pada dua buah sistem komputer. protokol yangmemungkinkanprogramkomputer kode dapat dieksekusi padahost yang laintanpa kebutuhan koneksi secara eksplisit.

9. Ordinary Pipes Ordinary Pipes allow communication in • Ordinary Pipes standard parent-child style • Producer (parent) writes to one end (the write- • Consumer (child)reads from the other end (the • Require parent-child relationship between end of the pipe) read-end of the pipe) d fh i communicating processes A parent program opens anonymous pipes, and • creates a new processand communicateusing these pipes, or creates several new processes and arranges them

10. Pipe UsingFIFOas queuescheme l Examplein UNIX ls -l |less

11. Message Passing z Maybeprovidelatency,incompatibilities latencyincompatibilities

12. Message Passing BasicOperations –Send > kirim message • R i –Receive> terimamessage • Variations –Connection-orientedvs Connectionless –Buffered vs Unbuffered C –Reliablevs Unreliable • Data representation & hlli f t –Marshalling& unmarshalling> pemformatanmessage

13. Communication Link Propertiesof communicationlink –Links are established automatically • –A link usually is associated with exactlyone pair of communicatingprocesses –Between each pair there existsexactly one link –The link may be unidirectional, but is usually bi-directional link di i l

14. Direct Communication Processesmustnameeachotherexplicitly: • send(P,message)–sendamessageto processP • i Q i f Q • receive(Q,message)–receiveamessagefromprocessQ • Propertiesof directcommunication • Linksareestablishedautomatically • Alinkisassociatedwithexactlyonepairofcommunicating processes • Betweeneachpairthereexistsexactlyonelink • Thelinkmaybeunidirectional,butisusuallybi-directional Li k

15. Indirect Communication Messagesaredirectedandreceivedfromports • Eachporthasauniqueid • Wellknownports:0-1023 Recommended:> 1024-65535 • • Processescancommunicateonlyif theyshareaport • • shareaport • Propertiesof indirectcommunicationlink • Linkestablishedonlyif processesshareacommonport • Alinkmaybeassociatedwithmanyprocesses • Eachpairofprocessesmayshareseveralcommunicationlinks • Linkmaybeunidirectional orbi-directional Linkestablishedonlyifprocesses acommonport

16. Indirect Communication • Operations createanew/openport send andreceivemessagesthroughport destroya port • • • • Primitivesare definedas: • send(A, message)– senda messageto portA • receive(A,message)– receiveamessagefrom port A

17. Indirect Communication • Port sharing P1,P2, and P3share portA • P P P • P1,sends; P2andP3receive • Who gets themessage? • Solutions • Allowa linkto be associatedwith at most twoprocesses • Allowonlyoneprocess ata time to execute areceive operation • Allowallprocesses receive the message • Allowthesystemtoselectarbitrarily the receiver. • Senderis notifiedwho thereceiver was. S l i l Allow processes receive the message

18. Model comm: Syn & Asyn S h • Synchronouscommunication –Acknowledgemust bereceived –Blockingcommunication –Sender/Recipientmustbothactive –Example:Registrationsystem / Chatting • Asynchronouscommunication –No acknowledgeneeded –Non-blockingcommunication Bl ki i ti / Chatting N k l d dd –Messagemaybe queued –Example: Email/ Instant Messenger

19. Transient & Persistent Comm. • TransientCommunication – Message discardedif failed to delivered immediately –Example: HTTP Request •PersistentCommunication – – Message Example: stored until receiver can accept Email, Messenger it

20. Group Communications z Multicast:sentto specificgroup :sentto specific z Sender tidak tahu identitas penerima dan berapa yang menerima z Broadcast:sentto everyone z Usedfor z Replication of services/data z Service discovery f / z Eventnotification

21. Group Communications

22. Komunikasi Jaringan

23. Remember: OSI

24. OSI Layers (1) Ph i l • Physical –Physicalinterfacebetweendevices • Mechanical • • Electrical Functional •Procedural – Contoh:EthernetCARD • Data Link –Meansof activating, maintaining anddeactivating a li bl lik reliablelink –Error detection –Contoh:PPP,Router Contoh:PPP

25. OSI Layers (2) N t k • Network –Transportofinformation –Contoh:VirtualCircuit&InternetProtocol • Transport –Exchangeof databetweenendsystems –Error free –In sequence/ No sequence –No losses / losses No duplicates/duplicates –No duplicates/duplicates –Quality of service –Contoh: TCP danUDP

26. OSI Layers (3) S i • Session –Controlof dialoguesbetweenapplications –Recovery • Presentation –Data formatsandcoding –Data compression –Encryption –Contoh:SSL Application • M f li i OSI i –Meansfor applicationsto accessOSIenvironment –Contoh:HTTP,FTP,SMTP

27. The Message

28. Konsep Pengiriman Data • • Datadikirimdalambentukpaket Setiap paketmemilikiheaderuntuk keperluanadministrasirouting •Datadisimpandalambodysebuahpaket •Ukuranpaketsangatbervariasi –Ethernet:64 – 1518 byte •BisadikirimkandenganTCP/UDP b d Bi dikii k d

29. TCP dan UDP • • Duaprotokolpadatransport layer Menggunakankonsepport(16bit) untuk membedakanaplikasi –HTTP: 80, HTTPS: 443, FTP: 21, ...... –Port1-1023: well-knownport HTTP 80 HTTPS 443FTP21 –Port1024-49151:registered port –Portlainbisa digunaka secarabebas –Di Linux: /etc/services

30. TCP TransmissionControlProtocol, –Reliableconnection Adanyapengecekanerror • pada transport layer • • Dijagaurutanmessage • Komunikasiduplex– duaarah • Segmentasi- TCP PDU –CalledTCPsegment –Includessourceanddestination • Identifyapplications port • Connectionrefersto pairofports • TCPtrackssegmentsbetweenentitiesoneach connection

31. UDP UserDatagramProtocol Notguaranteeddelivery • • •Nopreservationof sequence • • Noprotectionagainstduplication Minimumoverhead •Addsportaddressingto IP • Contoh:DNS, streaming

32. Request / Reply

33. Review Failure model • Processfailure: crash • Deteksi dgn timeout •Communicationfailure: messagedrop • Karena: transmission error, buffer overflow • Arbitraryfailure: prosesmelewatkanstep yangharusdilakukanataumembawadata ygsalah •Data korup, data double

34. Mekanisme handle failure dapat Timeout, method jika tidak balasan, mengirim • doOperation akan terusrequestmessagesampaitimeout. • Duplicaterequestmessage,server menerimalebihdarisekalirequest • server messagesehinggamemprosesnya berulangkali. solusi : request identifier & filter out duplicate. –

35. Failure Model of IPC Lostreply message, serverdapat menyimpan hasilproses requestmessage,jikaadarequest message yangsama tidak perlu diproses ulang,servermengirimreplymessage berupahasilprosesdarirequest • • tl hdii message yangtelahdisimpan. • History, server menyimpan struktur rekamanreplymessageyangtelah dikirim.

36. Sockets Menyediakanjembatankomunikasiantar proses • K ik i t ii k •Komunikasiantarproses:mengirimkan pesanantarsocketpadasatuproses menujusebuahsocketpadaproseslain • BisamenggunakanTCP/UDP C i i dd i l • Connection orienteddan connectionless •Melakukanbindingkesebuahport oriented bi di tertentu

37. Sockets and ports socket client socket message server anyport agreedport otherports Internetaddress= 138.37.94.248 Internetaddress= 138.37.88.249

38. Operasi Socket • Socketdapat melakukan operasi: – – – – – Di Koneksikemesinremote Mengirimdata Menerimadata Mentutupkoneksi Bind to a port • tiap mesin yang saling berinterkoneksi, harus terpasang socket. • Hard coded

39. Masalah Socket t kt dt •Informasipadaprogram : strukturdata •Informasipadamessage: urutanbyte • Dataharusdikonversi sebelumdan sesudahpengirimanagarbisadiproses duapihak • Masalah: representasipadasistem bisa berbeda-beda –ASCIIvsUnicode

40. Marshalling / Unmarshalling • Marshalling: proseskonversidatamenjadi bentukyangcocok/tepatuntuk transmisi pesanantarhost –Unmarshalling: proseskebalikannya •Pendekatanyangumumdigunakan: Unmarshalling: proses kebalikannya –CORBA dan RMI Marshalling –Java serialization –XML – XML RPC, Web Services