Web Services SOAP. Lecture "XML in Communication Systems" Chapter 12

Size: px

Start display at page:

Download "Web Services SOAP. Lecture "XML in Communication Systems" Chapter 12"

Thomasine Thompson
6 years ago
Views:

1 Web Services SOAP Lecture "XML in Cmmunicatin Systems" Chapter 12 Prf. Dr.-Ing. Nrbert Luttenberger Research Grup fr Cmmunicatin Systems Dept. f Cmputer Science Christian-Albrechts-University in Kiel

2 Recmmended Reading Bth, D. et al.: Web Services Architecture Nil Mitra, Yves Lafn (eds.): SOAP Versin 1.2 Part 0: Primer (Secnd Editin) W3C Recmmendatin 27 April Ballinger, K., Ehnebuske, D., Gudgin, M., Nttingham, M., Yendluri, P.: Web Services Interperability Organizatin Basic Prfile Versin Papazglu, M.: Web Services: Principles and Technlgy. Pearsn Educatin Ltd N. Luttenberger 2

3 Overview 1. Intrductin 2. SOAP Prcessing 3. SOAP Transprt Binding 4. SOAP Message Frmat 5. Remte Prcedure Calls N. Luttenberger 3

4 Chapter 12.1 Intrductin

5 Intrductin Frmer name: Simple Object Access Prtcl prtcl fr exchange f structured and typed data between peers in a distributed envirnment features: XML message cding stateless request/respnse cmmunicatin SOAP endpints identified by URL SOAP binding: definitins fr transprt f SOAP messages ver different Internet prtcls N. Luttenberger 5

6 Intrductin Frmer name: Simple Object Access Prtcl (cnt'd.) N explicit prgramming mdel, unlike DCOM and CORBA: n special cmpnents r tls needed t make an implementatin Can be implemented in any language and OS (Java, Perl, C++, VB, Windws, UNIX) SOAP defines tw types f messages: Requests Respnses N. Luttenberger 6

7 Intrductin Frmer name: Simple Object Access Prtcl (cnt'd.) versins: SOAP 1.1 (2000) and SOAP 1.2 (2003) namespaces fr SOAP namespaces fr SOAP N. Luttenberger 7

8 Intrductin elements Envelpe Header Bdy Fault attributes actr (SOAP 1.1) / rle (SOAP 1.2) mustunderstand encdingstyle relay (SOAP 1.2) N. Luttenberger 8

9 Intrductin Sample SOAP message (frm the SOAP 1.2 standard) <?xml versin='1.0'?> <env:envelpe xmlns:env=" <env:header> <m:reservatin xmlns:m=" env:rle=" env:mustunderstand="true"> <m:reference>uuid:093a2da1-q r-ba5d-pqff98fe8j7d</m:reference> <m:dateandtime> t13:20: :00</m:dateandtime> </m:reservatin> <n:passenger xmlns:n=" env:rle=" env:mustunderstand="true"> <n:name>åke Jógvan Øyvind</n:name> </n:passenger> </env:header> N. Luttenberger 9

10 Intrductin Sample SOAP message (frm the SOAP 1.2 standard) <env:bdy> <p:itinerary xmlns:p=" <p:departure> <p:departing>new Yrk</p:departing> <p:arriving>ls Angeles</p:arriving> <p:departuredate> </p:departuredate> <p:departuretime>late afternn</p:departuretime> <p:seatpreference>aisle</p:seatpreference> </p:departure> <p:return> </p:return> </p:itinerary> <q:ldging xmlns:q=" <q:preference>nne</q:preference> </q:ldging> </env:bdy> </env:envelpe> N. Luttenberger 10

11 Chapter 12.2 SOAP Prcessing

12 Henrik Frystyk Nielsen: SOAP Message Path Mdeling. W3C Wrkshp n Web Services, April 2001, San Jse, CA - USA SOAP Prcessing SOAP Ndes are surces and sinks f SOAP (request/respnse) messages, SOAP faults different types f SOAP ndes Initial SOAP sender Ultimate SOAP Receiver SOAP Intermediary N. Luttenberger 12

13 SOAP Prcessing Message path "A SOAP message generated by A can indicate which part f a message is fr B, C and D. Hwever, it cannt indicate that the intermediaries are t be rganized int a message path " "The SOAP targeting mdel is a decentralized message-prcessing cncept rather than a mechanism fr transferring SOAP messages acrss the Web." N. Luttenberger 13

14 SOAP Prcessing SOAP Intermediaries prcessing intermediaries deal with the message using the same rules as any ther SOAP receiver and/r sender prtcl intermediaries dn't take any part in the SOAP message path ther than acting as a relay at the underlying prtcl level. assignment f rles t SOAP ndes N. Luttenberger 14

15 SOAP Prcessing An aside: RFC-2616 (HTTP 1.1, 1999) n ther kinds f intermediaries A prxy is a frwarding agent, receiving requests fr a URI in its abslute frm, rewriting all r part f the message, and frwarding the refrmatted request tward the server identified by the URI. A gateway is a receiving agent, acting as a layer abve sme ther server(s) and, if necessary, translating the requests t the underlying server's prtcl. A tunnel acts as a relay pint between tw cnnectins withut changing the messages; tunnels are used when the cmmunicatin needs t pass thrugh an intermediary (such as a firewall) even when the intermediary cannt understand the cntents f the messages. N. Luttenberger 15

16 SOAP Prcessing Header blck prcessing determined by the "rle" a SOAP nde adpts SOAP Header blcks may carry a related env:actr (SOAP 1.1) resp. env:rle (SOAP 1.2) attribute (ptinal) N. Luttenberger 16

17 SOAP Prcessing Header blck prcessing (cnt'd.) predefined rles (SOAP 1.2): next fr bth all SOAP Intermediaries and the Ultimate SOAP Receiver nne n nde in this message path ultimatereceiver fr the Ultimate SOAP Receiver N. Luttenberger 17

18 SOAP Prcessing Header blck prcessing (cnt'd.) Optinal attribute env:mustunderstand blck must be prcessed! SOAP fault has t be sent, if blck cannt be prcessed. N. Luttenberger 18

19 SOAP Prcessing Bdy blck prcessing Ultimate SOAP Receiver must prcess SOAP Bdy. N. Luttenberger 19

20 Chapter 12.3 SOAP Transprt Binding

21 SOAP Transprt ver HTTP SOAP HTTP Binding SOAP in Request-Respnse mde HTTP Request carries SOAP Request and HTTP Respnse carries SOAP Respnse. HTTP features methd: POST Cntent-Type: text/xml (SOAP 1.1) r applicatin/sap+xml (SOAP 1.2) SOAP 1.1: additinal HTTP header line SOAPActin r SOAP 1.2: actin parameter in the Cntent-Type (RFC-3902) N. Luttenberger 21

22 SOAP Transprt ver HTTP POST /Service/Stckqutes HTTP/1.0 Cntent-Type: text/xml SOAPActin: "urn:getqute" <env:envelpe xmlns:env=" <env:bdy> <ns:getqute xmlns:ns="urn:example-delayed-qutes"> <ns:symbl>nyse:ibm</ns:symbl> </ns:getqute> </env:bdy> </env:envelpe> N. Luttenberger 22

23 SOAP Transprt ver HTTP HTTP/ OK Cntent-Type: text/xml <env:envelpe xmlns:env=" <env:bdy> <ns:getquterespnse xmlns:ns="urn:example-delayed-qutes"> <ns:result>91.35</ns:result> </ns:getquterespnse> </env:bdy> </env:envelpe> N. Luttenberger 23

24 Chapter 12.4 Message Frmats

25 Message Frmats elements Envelpe Header Bdy Fault attributes actr (SOAP 1.1) / rle (SOAP 1.2) mustunderstand encdingstyle relay (SOAP 1.2) N. Luttenberger 25

26 Message Frmats SOAP header is an ptinal cmpnent has infrmatin abut hw the message is t be prcessed can cntain extensins t the message like transactin ids can als cntain security infrmatin SOAP bdy cntains the message referred t as "paylad" can cntain the encdingstyle attribute can als cntain a <Fault> element N. Luttenberger 26

27 SOAP Message Frmat SOAP message A SOAP message is the basic unit f cmmunicatin between peer SOAP ndes. SOAP envelpe The utermst syntactic cnstruct r structure f a SOAP message defined by SOAP within which all ther syntactic elements f the message are enclsed. N. Luttenberger 27

28 SOAP Message Frmat SOAP header A cllectin f zer r mre SOAP blcks which may be targeted at any SOAP receiver within the SOAP message path. SOAP bdy A cllectin f zer r mre SOAP blcks targeted at the ultimate SOAP receiver within the SOAP message path. SOAP fault A special SOAP blck which cntains fault infrmatin generated by a SOAP nde. N. Luttenberger 28

29 SOAP Message Frmat SOAP blck A syntactic cnstruct r structure used t delimit data that lgically cnstitutes a single cmputatinal unit as seen by a SOAP nde. The type f a SOAP blck is identified by the fully qualified name f the uter element fr the blck, which cnsists f the namespace URI and the lcal name. A blck encapsulated within the SOAP header is called a header blck and a blck encapsulated within a SOAP bdy is called a bdy blck. N. Luttenberger 29

30 SOAP Message Frmat Frmal definitins The dcument element infrmatin item has: A lcal name f Envelpe Zer r mre namespace qualified attribute infrmatin items One r tw element infrmatin item children in rder as fllws: An ptinal Header element infrmatin item A mandatry Bdy element infrmatin item. N. Luttenberger 30

31 SOAP Message Frmat Frmal definitins (cnt'd.) The Header element infrmatin item has: A lcal name f Header Zer r mre namespace qualified attribute infrmatin item children Zer r mre namespace qualified element infrmatin item children Each SOAP header blck element infrmatin item MUST be namespace qualified MAY have an encdingstyle attribute infrmatin item MAY have an actr / rle attribute infrmatin item MAY have a mustunderstand attribute infrmatin item N. Luttenberger 31

32 SOAP Message Frmat Frmal definitins (cnt'd.) The Bdy element infrmatin item has: A lcal name f Bdy Zer r mre namespace qualified element infrmatin item children Each SOAP header blck element infrmatin item MUST be namespace qualified; MAY have an encdingstyle attribute infrmatin item The namespaces fr all Envelpe elements are: (SOAP 1.1) (SOAP 1.2) N. Luttenberger 32

33 SOAP Message Frmat Sample SOAP fault (SOAP 1.1) <env:envelpe xmlns:env=" <env:bdy> <env:fault> <faultcde>env:server</faultcde> <faultstring>server Errr</faultstring> <detail>my applicatin didn't wrk</detail> </env:fault> </env:bdy> </env:envelpe> N. Luttenberger 33

34 SOAP Message Frmat Sample SOAP fault (SOAP 1.2) <env:envelpe xmlns:env=" <env:bdy> <env:fault> <env:cde> <env:value>env:sender</env:value> </env:cde> <env:reasn> <env:text>sender Timeut</env:Text> </env:reasn> <env:detail>have waited 5 minutes</env:detail> </env:fault> </env:bdy> </env:envelpe> N. Luttenberger 34

35 SOAP Message Frmat Fault-Cdes VersinMismatch: invalid SOAP Envelpe MustUnderstand: A mustunderstand header blck culd nt be prcessed DataEncdingUnknwn (nur SOAP 1.2): message encding nt supprted Client (SOAP 1.1) / Sender (SOAP 1.2): message invalid Server (SOAP 1.1) / Receiver (SOAP 1.2): server-side errr N. Luttenberger 35

36 SOAP Message Frmat Message Encding given in the encdingstyle attribute (ptinal) Mstly: literal encding XML serializatin recmmended by WS-I N. Luttenberger 36

37 SOAP Message Frmat Anther example <env:envelpe xmlns:env=" <env:header> <n:alertcntrl xmlns:n=" <n:pririty>1</n:pririty> <n:expires> t14:00:00-05:00</n:expires> </n:alertcntrl> </env:header> <env:bdy> <m:alert xmlns:m=" <m:msg>pick up Mary at schl at 2pm</m:msg> </m:alert> </env:bdy> </env:envelpe> N. Luttenberger 37

38 Chapter 12.5 Remte Prcedure Calls

39 Remte Prcedure Calls Messages are nt a "natural" prgramming mdel require that prgrammer wrry abut message frmats must be packed and unpacked have t be decded by client and server ften asynchrnus may require special errr handling functins N. Luttenberger 39

40 Remte Prcedure Calls Prcedure call: a mre "natural" way t cmmunicate every language supprts it semantics are well defined and understd natural fr prgrammers t use Basic idea: Let s just define a server as a mdule. Let the server exprt a set f prcedures that can be called by clients. Clients just d prcedure calls. N. Luttenberger 40

41 Remte Prcedure Calls Issues Hw d we make RPCs invisible t the prgrammer? What are the semantics f parameter passing? Hw is binding dne (lcating the server)? Hw d we supprt hetergeneity (OS, language)? N. Luttenberger 41

42 Remte Prcedure Calls The basic mdel fr Remte Prcedure Call (RPC) described by Birrell and Nelsn frm Xerx PARC in 1984: A. D. Birrell and B. J. Nelsn: Implementing remte prcedure calls. ACM Transactins n Cmputer Systems, 2(1):39 59, February gals: make RPC lk as much like lcal PC as pssible used OS/language supprt N. Luttenberger 42

43 Remte Prcedure Calls Implementatin: 3 cmpnents n each side a user prgram (client r server) a set f stub prcedures client-side stub appears t the client cde as if it were a callable prcedure server-side stub appears t the server cde as a calling client stubs send messages t each ther t make the RPC happen RPC runtime supprt N. Luttenberger 43

44 Remte Prcedure Calls Building a server Server prgram defines the server s interface using an interface definitin language (IDL) IDL specifies the names, parameters, and types fr all client-callable server prcedures A stub cmpiler reads the IDL and prduces tw stub prcedures fr each server prcedure: a client-side stub and a server-side stub The server cde is linked with the server-side stubs; the client cde is linked with the client-side stubs. N. Luttenberger 44

45 Remte Prcedure Calls client prgram call f(x,y) client makes lcal call t stub prc. server is called by its stub prc f(a,b) begin f... end f server prgram call f call f client stub prc f(a,b) stub builds msg packet, inserts params stub unpacks params and makes call call f(x,y) server stub send msg receive msg RPC runtime runtime sends msg t remte nde runtime receives msg and calls stub RPC runtime Call N. Luttenberger 45

46 Remte Prcedure Calls client prgram call f(x,y) client cntinues server prc returns prc f(a,b) begin f... end f server prgram return return client stub prc f(a,b) stub unpacks msg, returns t caller stub builds result msg with utput args call f(x,y) server stub receive msg send msg RPC runtime runtime receives msg runtime sends msg t client RPC runtime return N. Luttenberger 46

47 Remte Prcedure Calls RPC binding prcess f cnnecting the client and server server, when it starts up, exprts its interface, identifying itself t a netwrk name server and telling the lcal runtime its dispatcher address The client, befre issuing any calls, imprts the server, which causes the RPC runtime t lkup the server thrugh the name service and cntact the requested server t setup a cnnectin. The imprt and exprt are explicit calls in the cde. N. Luttenberger 47

48 Remte Prcedure Calls RPC marshalling packing f prcedure parameters int a message packet The RPC stubs call type-specific prcedures t marshall and unmarshall all f the parameters t the call. On the client side, the client stub marshalls the parameters int the call packet; n the server side the server stub unmarshalls the parameters in rder t call the server s prcedure. On the return, the server stub marshalls return parameters int the return packet; the client stub unmarshalls return parameters and returns t the client. N. Luttenberger 48

49 Remte Prcedure Calls SOAP-based RPC parameter passing by value nly binding via UDDI, WSDL data mdel based n XML Schema N. Luttenberger 49

50 Remte Prcedure Calls SOAP-based RPC namespace f the target bject methd name parameters <env:bdy> <m:getlasttradeprice xmlns:m= <tickersymbl>sunw</tickersymbl> </m:getlasttradeprice> </env:bdy> N. Luttenberger 50

51 Feedback fr this Chapter Well understd easy material Mstly understd material is k Hardly understd difficult material N. Luttenberger 51

Simple Object Access Protocol (SOAP)

Simple Object Access Protocol (SOAP) Simple Object Access Prtcl (SOAP) Languages fr web Prf. Eugeni Di Sciasci Master s Degree Curse in Cmputer Engineering - (A.Y. 2016/2017) Web service architecture (1/2) A ppular interpretatin f Web services