SOAP Introduction Tutorial

Transcription

1 SOAP Introduction Tutorial Herry Hamidjaja 1

2 Agenda Introduction What is SOAP? Why SOAP? SOAP Protocol Anatomy of SOAP Protocol SOAP description in term of Postal Service Helloworld Example 2

3 Introduction What is SOAP? Simple Object Access Protocol A communication protocol For communication between applications A format for sending messages Platform independent Language independent XML based Simple, modular and extensible Allows to get around firewalls W3C standard 3

4 Introduction (Continued) What SOAP is NOT Not a component model So it will not replce objects and components, i.e. EJB, JavaBeans, CORBA Component, etc Not a programming language So it will not replace C++, Java Not a solution for all So it will not replace other distributed computing technologies such as RMI, CORBA, DCOM, etc 4

5 Introduction (Continued) Why SOAP? Problem with compatibility issues on existing RPC mechanism (i.e. CORBA and DCOM). Security concern over firewall. SOAP provides a way to communicate between applications running on different operating systems, with different technologies and programming languages. 5

6 SOAP is a protocol What does this mean? It is not a distributed object system It is not an RPC system It is not even a web application This implies no: Objects-by-reference (which requires distributed garbage collection) ; Activation (which requires objects-by-reference). 6

7 SOAP consists of four parts The SOAP envelope, that defines the content of the message, includes: what is in a message; who should deal with it, and whether it is optional or mandatory. The SOAP encoding rules Exchange instance of application defined data types The SOAP RPC representation How to make calls and responses. The protocol binding: HTTP, SMTP, etc 7

8 SOAP Building Blocks SOAP Structure: A SOAP envelope: defines the content of the message. A SOAP header (optional): contains header information. A SOAP body: contains call and response information. You can use postal analogy to describe SOAP Messaging System. Put XML document into SOAP envelope; and write the address of recipient (SOAP header), finally put a stamp on it and post it into the Australian Post Postal box. Australian Post act as the underlying transport protocol which deliver the message to the recipient mail box (you can relate the with protocol binding such as HTTP, SMTP). The recipient reply goes through the same process. 8

9 How SOAP works with Postal Analogy? Figure 1. illustrate the SOAP process in term of Conventional Mailing System. You have to assume a SOAP message as an actual letter with recipient address + postage across the front. SOAP Envelope Transmitting XML Document Figure 1. Recipient Encoded 9

10 SOAP Request Example in HTTP POST /soap/servlet/rpcrouter HTTP/1.0 Host: localhost:8889 Content-Type: text/xml; charset=utf-8 Content-Length: 449 SOAPAction: "" SOAP-HTTP Binding HTTP Request SOAP Body SOAP Envelope <?xml version='1.0' encoding='utf-8'?> <SOAP-ENV:Envelope xmlns:soap-env=" xmlns:xsi=" xmlns:xsd=" <SOAP-ENV:Body> <ns1:printhello xmlns:ns1="urn:helloworld" SOAP-ENV:encodingStyle=" <name xsi:type="xsd:string">herry</name> </ns1:printhello> </SOAP-ENV:Body> </SOAP-ENV:Envelope> 10

11 SOAP Response Example in HTTP HTTP/ OK Content-Type: text/xml; charset=utf-8 Content-Length: 508 Date: Wed, 03 Jul :23:50 GMT Server: Apache Tomcat/4.0.3 (HTTP/1.1 Connector) Set-Cookie: JSESSIONID=87DB613CFF9C9FF489F29FC741FEBA68;Path=/soap HTTP Request SOAP Body SOAP Envelope <?xml version='1.0' encoding='utf-8'?> <SOAP-ENV:Envelope xmlns:soap-env=" xmlns:xsi=" xmlns:xsd=" <SOAP-ENV:Body> <ns1:printhelloresponse xmlns:ns1="urn:helloworld" SOAP-ENV:encodingStyle=" <return xsi:type="xsd:string"> Hello Herry, Welcome to the SOAP World!!!! </return> </ns1:printhelloresponse> </SOAP-ENV:Body> </SOAP-ENV:Envelope> 11

12 How SOAP works in reality? SOAP Request Transport Layer Method call Client Listener Service SOAP Response Figure 2. Response Figure 2. illustrate the SOAP request and response for a Service. Client construct an SOAP request and send it through transport layer to listener. The request is received by Listener and forwarded to an appropriate object service. It will activate or instantiate the object, if it is needed. The response is sent back to the Listener then forwarded back to the client. 12

13 Confused? How do the SOAP request and response fit together? How to exploit this mechanism for our application? Let examine some example. 13

14 Hello World Sample Application SOAP Request Transport Layer printhello() Client Listener Helloworld Object SOAP Response Figure 3. Hello Herry, Welcome to the SOAP World!!!! We have a Helloworld Object which has the printhello() method. Client call printhello() by constructing SOAP Request. Client receives SOAP response. 14

15 Helloworld Class Example public class Helloworld { public Helloworld() { } public String printhello(string name) throws IllegalArgumentException { if (name == null) { throw new IllegalArgumentException( "The name argument must not be null ); } } } return "Hello " + name + ", Welcome to the SOAP World!!!!"; 15

16 HelloClient Class Example public class HelloClient { public static void main(string[] args) throws Exception { String url = ; String encodingstyleuri = Constants.NS_URI_SOAP_ENC; Call call = new Call(); call.settargetobjecturi("urn:helloworld"); call.setmethodname("printhello"); call.setencodingstyleuri(encodingstyleuri); Look similar to DII? Vector params = new Vector(); params.addelement(new Parameter("name", String.class, name, null)); call.setparams(params); try { resp = call.invoke(url, ""); }catch (SOAPException e) { System.err.println("Caught SOAPException (" + e.getfaultcode() + "): + e.getmessage()); return; } 16

17 HelloClient Class Example (Continued) // Check the response. if (!resp.generatedfault()){ Parameter ret = resp.getreturnvalue(); Object value = ret.getvalue(); if (value!= null) { if (value instanceof String) { System.out.println(value + "\n"); }else { System.out.println("I don't understand the type"); } }else { System.out.println("It's null"); } }else { Fault fault = resp.getfault(); System.err.println("Generated fault: " + fault); } 17

18 Client Invocation Trace What actually happens when client call new Call()? A SOAP Request is constructed accordingly When client call invoke() method, the SOAP Request message is sent to the Server. In this instance is Helloworld Object (details are omitted to avoid confusion). Server reply with perform the operation printhello() and put the result into SOAP response. Then sent it back to the client. 18

19 SOAP Client Request Example POST /soap/servlet/rpcrouter HTTP/1.0 Host: localhost:8889 Content-Type: text/xml; charset=utf-8 Content-Length: 449 SOAPAction: "" <?xml version='1.0' encoding='utf-8'?> <SOAP-ENV:Envelope xmlns:soap-env=" xmlns:xsi=" xmlns:xsd=" <SOAP-ENV:Body> <ns1:printhello xmlns:ns1="urn:helloworld" SOAP-ENV:encodingStyle=" <name xsi:type="xsd:string">herry</name> </ns1:printhello> </SOAP-ENV:Body> </SOAP-ENV:Envelope> SOAP Request Client Listener Helloworld Object Transport Layer 19

20 SOAP Server Response Example printhello() Client Listener Helloworld Object SOAP Response Transport Layer HTTP/ OK Content-Type: text/xml; charset=utf-8 Content-Length: 508 Date: Wed, 03 Jul :23:50 GMT Server: Apache Tomcat/4.0.3 (HTTP/1.1 Connector) Set-Cookie: JSESSIONID=87DB613CFF9C9FF489F29FC741FEBA68;Path=/soap Hello Herry, Welcome to the SOAP World!!!! <?xml version='1.0' encoding='utf-8'?> <SOAP-ENV:Envelope xmlns:soap-env=" xmlns:xsi=" xmlns:xsd=" <SOAP-ENV:Body> <ns1:printhelloresponse xmlns:ns1="urn:helloworld" SOAP-ENV:encodingStyle=" <return xsi:type="xsd:string"> Hello Herry, Welcome to the SOAP World!!!! </return> </ns1:printhelloresponse> </SOAP-ENV:Body> </SOAP-ENV:Envelope> 20

21 To be continued Details of what actually happens behind these mechanism will be revealed in the next tutorial.. Stay tuned! 21

22 Reference Simple Object Access Protocol (SOAP) 1.1 Specification, 22