Simple Object Access Protocol

Transcription

1 Simple Object Access Protocol

2 Why Simple Object Access Protocol Light weight replacement for complicated distributed object technology Originally for BizTalk (Microsoft/UserLand/Developmentor) Now a W3C standard Based on XML and HTTP Web Services: SOAP 2

3 Port vs Web Server External Application Internal Service External Application Internal Service TCP External Application Internal Service Web Services: SOAP 3

4 Port vs Web Server External Application External Application External Application Web Server Internal Service Internal Service XML payload TCP Internal Service XML-RPC Port 80? SOAP is not restricted to port 80 Web Services: SOAP 4

5 SOAP over HTTP Request example POST /Temperature HTTP/1.1 Host: Content-Type: text/xml Content-Length: <whatever> SOAPAction: urn:stockquote#getquote <s:envelope xmlns:s= <s:body> </s:body> </s:envelope> HTTP Header Soap Extensions XML Payload (SOAP request) Web Services: SOAP 5

6 SOAP over HTTP Response example HTTP/ OK Content-Type: text/xml Content-Length: <whatever> HTTP Header <s:envelope xmlns:s= <s:body> </s:body> </s:envelope> XML Payload (SOAP response) Web Services: SOAP 6

7 SOAP Example: Request <soap:envelope> <soap:body> <xmlns:m= " /> <m:getbookprice> <m:bookname>fast Food Nation</m:BookName> </m:getbookprice> </soap:body> </soap:envelope> Web Services: SOAP 7

8 SOAP Example: Response <soap:envelope> <soap:body> <xmlns:m=" /> <m:getbookpriceresponse> <m:price>34.5</m:price> </m:getbookpriceresponse> </soap:body> </soap:envelope> Web Services: SOAP 8

9 SOAP Example: Error <soap:fault> <faultcode>0x800700e</faultcode> <faulstring>unknown book</faultstring> </soap:fault> Web Services: SOAP 9

10 SOAP Message A SOAP message is contained within an XML envelope, complete with a Header and Body SOAP Envelope SOAP Header (optional) SOAP Body payload Web Services: SOAP 10

11 SOAP Message with Binary Attachments A SOAP message can also contain binary attachments using MIME encoding MIME Header MIME Boundary Root Body Part SOAP Envelope SOAP Header (optional) SOAP Body payload MIME Boundary Body Part Attachment Web Services: SOAP 11

12 SOAP Structure SOAP Envelope SOAP Header Header Block... Header Block SOAP Body Body Block... Body Block Envelope contains Header Body Header is optional Out-of-band information such as Authentication information Message routes Logging Transaction flow Body contains XML body of RPC call Web Services: SOAP 12

13 SOAP Example <?xml version="1.0" encoding="utf- 8"?> <env:envelope xmlns:env=" envelope"> <env:header> <n:alertcontrol xmlns:n=" <n:priority>1</n:priority> <n:expires> T14:00:00-05:00</n:expires> </n:alertcontrol> </env:header> <env:body> <m:alert xmlns:m=" <m:msg>pick up Mary at school at 2pm</m:msg> </m:alert> </env:body> </env:envelope> Web Services: SOAP 13

14 XML Messaging in SOAP EDI: Electronic Document Interchange SOAP with EDI: XML documents Document style SOAP RPC: distributed computing, web services RPC-style SOAP: parameters and return values Web Services: SOAP 14

15 Purchase Order in Document-Style SOAP <s:envelope xmlns:s= envelope > <s:header> <m:transaction xmlns:m= soap- transaction s:mustunderstand= true > <transactionid>1234</transactionid> </transaction> </s:header> <s:body> <n:purchaseorder xmlns:n= urn:orderservice > <from><person>christopher Robin</person> <dept>accounting</dept> </from> <to><person>pooh Bear</person> <dept>honey></dept> </to> <order><quantity>1</quantity> <item>pooh Stick</item> </order> </n:purchaseorder> </s:body> </s:envelope> Web Services: SOAP 15

16 RPC Messages Typically two messages Request Message SOAP Client SOAP Server Response Message Web Services: SOAP 16

17 An RPC-style SOAP Message public Float getquote (String symbol); <s:envelope xmlns:s= envelope > <s:header> <m:transaction xmlns:m= soap- transaction s:mustunderstand= true > <transactionid>1234</transactionid> </m:transaction> </s:header> <s:body> <n:getquote xmlns:n= urn:quoteservice > <symbol xsi:type= xsd:string > IBM </symbol> </n:getquote> </s:body> </s:envelope> Web Services: SOAP 17

18 SOAP Response <s:envelope xmlns:s= envelope> <s:body> <n:getquoteresponse xmnls:n= urn:quoteservice > <value xsi:type= xsd:float > </value> </n:getquoteresponse> </s:body> </s:envelope> Web Services: SOAP 18

19 SOAP Faults <s:envelope xmlns:s= envelope > <s:body> <s:fault> <faultcode>client.authentication</faultcode> <faultstring>invalid credentials</faultstring> <faultactor> <details> <!-- application specific details></details> </s:fault> </s:body> </s:envelope> Web Services: SOAP 19

20 Standard SOAP Fault Codes Version Mismatch MustUnderstand: specify which header blocks were not understood Server: error can t be directly linked to the processing of the message Client: there is a problem in the message (e.g. invalid authentication credentials) Web Services: SOAP 20

21 SOAP Data Encoding One possible method of serializing data and encode them into XML Section 5 of the SOAP standard General rules Web Services: SOAP 21

22 Compound Values A compound value represents a combination of two or more accessors grouped as children of a single accessor <name> <firstname>joe</firstname> <lastname>smith</lastname> </name> Each accessor has a different name (structs) Web Services: SOAP 22

23 Arrays An array is a compound value in which the accessors have the same name <people> <person name= joe smith /> <person name= john doe /> </people> Web Services: SOAP 23

24 Multi-Referenced Accessor <people> <person name= joe smith > <address href= #address-1 > </person> <person name= john doe > <address href= #address-1 > </person> </people> <address id= address-1 > <street>111 First Street</street> <city>new York</city> <state>new York</state> </address> Web Services: SOAP 24

25 Express the Data Type of an Accessor Use the xsi:type attribute on each accessor, explicitly referencing the data type according to the XML Schema specification: <person><name xsi:type= xsd:string >John Doe</name> Reference an XML Schema document that defines the exact data type of a particular element within its definition: <person xmlns= personschema.xsd > <name>john Doe</name></person> Reference some other type of schema document that defines the data type of a particular element within its definition: <person xmlns= urn:some_namespace > <name>john Doe</name> Web Services: SOAP 25

26 SOAP Data Types Two alternate syntaxes for expressing instances of data types Anonymous accessor: <SOAP-ENC:int>36</SOAP-ENC:int> Anonymous because its name is its type rather than a meaningful id for the value Named accessor: <value xsi:type= xsd:int >36</value> Web Services: SOAP 26

27 Arrays Arrays int a[3] = {1, 2, 3}; b = Add([in]a); <m:add xmlns:m= xmlns:soap-enc= " > <a SOAP-ENC:arrayType= xsd:int[3] > <SOAP-ENC:int>1</SOAP-ENC:int> <SOAP-ENC:int>2</SOAP-ENC:int> <SOAP-ENC:int>3</SOAP-ENC:int> </a> </m:add> Web Services: SOAP 27

28 Values and References By value : Add([in] int a, [in] int b); <m:add xmlns:m= > <a xsi:type= integer >3</a> <b xsi:type= integer >4</b> </m:add> By reference : Square([in, out] int &a); <m:add xmlns:m= > <a href= #arg /> </m:add> <a id= arg xsi:type= integer >8</a> Web Services: SOAP 28

29 Summary SOAP protocol: an XML encoding scheme to exchange information between web processes: Document style: XML documents RPC style: packing parameters in XML format Typically SOAP/HTTP, others are possible Low level in terms of process/service modeling Web Services: SOAP 29